- Imaging and therapeutic applications of Zn(ii)-cryptolepine-curcumin molecular probes in cell apoptosis detection and photodynamic therapy
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Novel red Zn(ii) complex-based fluorescent probes featuring cryptolepine-curcumin derivatives, namely, [Zn(BQ)Cl2] (BQ-Zn) and [Zn(BQ)(Cur)]Cl (BQCur-Zn), were developed for the simple and fluorescent label-free detection of apoptosis, an important biological process. The probes could synergistically promote mitochondrion-mediated apoptosis and enhance tumor therapeutic effects in vitro and vivo.
- Huang, Xiao-Ling,Liang, Hong,Qin, Qi-Pin,Tan, Ming-Xiong,Wang, Zhen-Feng,Wei, Zu-Zhuang,Zou, Hua-Hong
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- Kinetics of proton transfer between ortho substituted benzoic acids and the carbinol base of crystal violet in toluene. Ortho effect on the reactivity of benzoic acids in apolar aprotic solvents
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Apolar aprotic solvents are particularly advantageous for investigating the intrinsic ortho effect free from complications of specific solvent effects. A kinetic study for toluene-phase proton transfers between ortho F, Cl, Br, I, OMe, OEt, OPh, OAc, Me, NO2, COMe, COPh, OH, NH2, and H benzoic acids and crystal violet carbinol base has shown the forward rate constant (log k+1) is the most appropriate reactivity parameter in toluene. log k+1 (toluene) as compared to other reported reactivity parameters in benzene, toluene, or chlorobenzene has been found more sensitive to the ortho substituent effect. The regression results of the correlation of log k+1 (toluene) of the acids (except OH and NH2 substituted ones) according to seven ortho effect models are all very significant, and the best result is given by Fujita-Nishiokas model. The overall analysis reveals that a substituents ortho effect pattern is a 58:24:18 ratio of its ordinary electrical, proximity electrical, and steric effects and that the proximity electrical effect is the major component to account for the peculiarity of the substituents ortho effect. The results further favor the transmission of this effect mainly through the molecular cavity. The effect may, however, be outweighed by the steric component for bulky enough substituents, e.g., Me. The enhanced strength exhibited by salicylic acid in toluene has been quantitatively described using Pytela-Lisas δHB i parameter. The abnormally high log k+1 observed for anthranilic acid in toluene has been ascribed to a very extensive homoconjugation in its acid-acid anion complex induced by the acids three hydrogen bond donors.
- Sen Gupta, Susanta K.,Mishra, Sangeeta
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- Immobilization of Au nanoparticles on poly(glycidyl methacrylate)-functionalized magnetic nanoparticles for enhanced catalytic application in the reduction of nitroarenes and Suzuki reaction
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We report a novel strategy for the synthesis of magnetic nanocomposite for highly efficient catalysis. Poly(glycidyl methacrylate) (PGMA) chains were grafted to the surface of magnetic nanoparticles (MNPs) through surface-initiated reversible addition-fragmentation chain transfer polymerization. Then, the oxirane rings in the PGMA chains were opened with 2,6-diamino pyridine (DAP) molecules as ligands to prepare the solid support. Finally, this magnetic nanocomposite was used for the immobilization of gold nanoparticles. Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, gel permeation chromatography, vibrating sample magnetometry, and atomic absorption spectroscopy were used for characterization of the catalyst. The loading of gold nanoparticles on the solid support was 0.52 mmol/g. The catalytic activity of the prepared catalyst (MNP@PGMA@DAP@Au) was evaluated for the reduction of nitro compounds and C–C coupling reaction in water. The catalyst can be easily recovered and reused seven times without significant loss of catalytic activity.
- Pourjavadi, Ali,Kohestanian, Mohammad,Keshavarzi, Nahid
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- The flavoenzyme azobenzene reductase AzoR from Escherichia coli binds roseoflavin mononucleotide (RoFMN) with high affinity and is less active in its RoFMN form
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The Gram-positive bacterium Streptomyces davawensis is the only organism known to produce the antibiotic roseoflavin. Roseoflavin is a structural riboflavin analogue and is converted to the flavin mononucleotide (FMN) analogue roseoflavin mononucleotide (RoFMN) by flavokinase. FMN-dependent homodimeric azobenzene reductase (AzoR) (EC 1.7.1.6) from Escherichia coli was analyzed as a model enzyme. In vivo and in vitro experiments revealed that RoFMN binds to the AzoR apoenzyme with an even higher affinity compared to that of the "natural" cofactor FMN. Structural analysis (at a resolution of 1.07 A) revealed that RoFMN binding did not affect the overall topology of the enzyme and also did not interfere with dimerization of AzoR. The AzoR-RoFMN holoenzyme complex was found to be less active (30% of AzoR-FMN activity) in a standard assay. We provide evidence that the different physicochemical properties of RoFMN are responsible for its reduced cofactor activity.
- Langer, Simone,Nakanishi, Shinobu,Mathes, Tilo,Knaus, Tanja,Binter, Alexandra,Macheroux, Peter,Mase, Tomoko,Miyakawa, Takuya,Tanokura, Masaru,Mack, Matthias
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- Design, synthesis and biological evaluation of tacrine-1,2,3-triazole derivatives as potent cholinesterase inhibitors
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We report herein the design and synthesis of a series of 11 novel tacrine-1,2,3-triazole derivatives via a Cu(i)-catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) reaction. The newly synthesized compounds were evaluated for their inhibition activity against Electrophorus electricus acetylcholinesterase (AChE) and horse serum butyrylcholinesterase (BChE) as potential drug targets for Alzheimer's disease (AD). Among the designed compounds, compound 8a2 exhibited potent inhibition against AChE and BChE with IC50 values of 4.89 μM and 3.61 μM, respectively. Further structure-activity relationship (SAR) and molecular modeling studies may provide valuable insights into the design of better tacrine-triazole analogues with potential therapeutic applications for AD.
- Wu, Gaochan,Gao, Yun,Kang, Dongwei,Huang, Boshi,Huo, Zhipeng,Liu, Huiqing,Poongavanam, Vasanthanathan,Zhan, Peng,Liu, Xinyong
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- Indicator Dyes and Catalytic Nanoparticles for Irreversible Visual Hydrogen Sensing
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Using ultraviolet-visible (UV-vis) absorption spectroscopy, we have tested the reactivity of various indicator molecules combined with catalytic bimetallic gold-palladium nanoparticles (Au-Pd NPs) in solution for an irreversible and visual response to H2. Our aim was to identify the most suitable indicator/Au-Pd NP system for the future development of a thin, wearable, and visual H2 sensor for noninvasive monitoring of in vivo Mg-implant biodegradation in research and clinical settings with fast response time. The indicators studied were bromothymol blue, methyl red, and resazurin, and the reactions of each system with H2 in the presence of Au-Pd NPs caused visual and irreversible color changes that were concluded to proceed via redox processes. The resazurin/Au-Pd NP system was deemed best-suited for our research objectives because (1) this system had the fastest color change response to H2 at levels relevant to in vivo Mg-implant biodegradation compared to the other indicator/Au-Pd NP systems tested, (2) the observed redox chemistry with H2 followed well-understood reaction pathways reported in the literature, and (3) the redox products were nontoxic and appropriate for medical applications. Studying the effects of the concentrations of H2, Au-Pd NPs, and resazurin on the color change response time within the resazurin/Au-Pd NP system revealed that the H2-sensing elements can be optimized to achieve a faster or slower color change with H2 by varying the relative amounts of resazurin and Au-Pd NPs in solution. The results from this study are significant for future optical H2 sensor design.
- Smith, Michael E.,Stastny, Angela L.,Lynch, John A.,Yu, Zhao,Zhang, Peng,Heineman, William R.
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- Electrochemical carboxylation of 2-iodoaromatic compounds
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The electrochemical reduction of a series of 2-iodoaromatic substituted compounds in acetonitrile under an atmospheric pressure of carbon dioxide leads to ortho-substitued aromatic carboxylic acid. The maximum yield of acid obtained by electrolysis performed in a diaphragm-less cell at low temperature (5°C) with a sacrificial magnesium anode and by the use of a low current density was slightly higher than 70%.
- Korbi, B. Haouas,Adhoum,Boujlel
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- Discovery of Novel Tacrine-Pyrimidone Hybrids as Potent Dual AChE/GSK-3 Inhibitors for the Treatment of Alzheimer's Disease
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Based on a multitarget strategy, a series of novel tacrine-pyrimidone hybrids were identified for the potential treatment of Alzheimer's disease (AD). Biological evaluation results demonstrated that these hybrids exhibited significant inhibitory activities toward acetylcholinesterase (AChE) and glycogen synthase kinase 3 (GSK-3). The optimal compound 27g possessed excellent dual AChE/GSK-3 inhibition both in terms of potency and equilibrium (AChE: IC50 = 51.1 nM; GSK-3β: IC50 = 89.3 nM) and displayed significant amelioration on cognitive deficits in scopolamine-induced amnesia mice and efficient reduction against phosphorylation of tau protein on Ser-199 and Ser-396 sites in glyceraldehyde (GA)-stimulated differentiated SH-SY5Y cells. Furthermore, compound 27g exhibited eligible pharmacokinetic properties, good kinase selectivity, and moderate neuroprotection against GA-induced reduction in cell viability and neurite damage in SH-SY5Y-derived neurons. The multifunctional profiles of compound 27g suggest that it deserves further investigation as a promising lead for the prospective treatment of AD.
- Yao, Hong,Uras, Giuseppe,Zhang, Pengfei,Xu, Shengtao,Yin, Ying,Liu, Jie,Qin, Shuai,Li, Xinuo,Allen, Stephanie,Bai, Renren,Gong, Qi,Zhang, Haiyan,Zhu, Zheying,Xu, Jinyi
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- A highly selective diarylethene fluorescence sensor of aluminum ion and its application
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A novel diarylethene derivative 1O with the unit of N-(2-(hydrazinecarbonyl)phenyl)benzamide was designed and synthesized successfully. The sensor showed excellent photochromism and specific fluorescent detection toward aluminum ion with rarely interfering. The emission intensity could increase nearly by 100 folds with aluminum ion and the color changed from dark to Aqua green. The low limit of detection (LOD) of 1O was determined as 3.26 × 10-8 mol L-1. Additionally, the sensor could be used in logic circuit and aluminum ion detection in untreated water.
- Fan, Congbin,Liu, Gang,Pu, Shouzhi,Wang, Huaxin,Zhao, Heng
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- Photocatalytic degradation of dyes in water: Case study of indigo and of indigo carmine
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The TiO2/UV photocatalytic degradations of indigo and of indigo carmine have been investigated both in aqueous heterogeneous suspensions and in the solid state. In addition to prompt removal of the color, TiO2/UV-based photocatalysis
- Vautier, Manon,Guillard, Chantal,Herrmann, Jean-Marie
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- Pd nanoparticles/graphene quantum dot supported on chitosan as a new catalyst for the reduction of nitroarenes to arylamines
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A new heterogeneous catalyst was obtained by growing graphene quantum dots on chitosan and subsequent immobilization of Pd nanoparticles. The catalyst after characterization was used in the reduction of nitroarenes to the corresponding amines by NaBH4 as a weak reducing agent of nitro compounds. The catalyst exhibited excellent catalytic activity and selectivity under mild reaction conditions in water as a green solvent during 1?h. Additionally, the catalyst can be reused for five consecutive runs without any significant decrease in its activity and selectivity.
- Kalanpour, Nastaran,Nejati, Saeid,Keshipour, Sajjad
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- Conjugation of tacrine with genipin derivative not only enhances effects on AChE but also leads to autophagy against Alzheimer's disease
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Seven tacrine/CHR21 conjugates have been designed and synthesized. Compound 8-7 was confirmed as the most active AChE inhibitor with IC50 value of 5.8 ± 1.4 nM, which was 7.72-fold stronger than tacrine. It was also shown as a strong BuChE inhibitor (IC50 value of 3.7 ± 1.3 nM). 8-7 was clearly highlighted not only as an excellent ChEs inhibitor, but also as a good modulator on protein expression of AChE, p53, Bax, Bcl-2, LC3, p62, and ULK, indicating its functions against programmed cell apoptosis and decrease of autophagy. 8-7 significantly reversed the glutamate-induced dysfunctions including excessive calcium influx and release from internal organelles, overproduction of nitric oxide (NO) and Aβ high molecular weight oligomer. This compound can penetrate blood?brain barrier (BBB). The in vivo hepatotoxicity assay indicated that 8-7 was much less toxic than tacrine. Altogether, these data strongly support that 8-7 is a potential multitarget-directed ligand (MTDL) for treating Alzheimer's disease (AD).
- Lin, Rongtian,Rao, Shuwen,Li, Yanbing,Zhang, Lei,Xu, Liyu,He, Yepu,Liu, Zhijun,Chen, Heru
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- An efficient selective reduction of aromatic azides to amines employing BF3·OEt2/NaI: Synthesis of pyrrolobenzodiazepines
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A selective and facile method for the reduction of aromatic azides to amines by employing borontrifluoride diethyl etherate and sodium iodide. This methodology has been applied towards the preparation of biologically important imine-containing pyrrolobenzodiazepines and their dilactams through intramolecular reductive-cyclization process. In this protocol the reagent systems are amenable for the generation of solution-phase combinatorial synthesis. Georg Thieme Verlag Stuttgart.
- Kamal, Ahmed,Shankaraiah,Markandeya,Reddy, Ch. Sanjeeva
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- Synthesis and characterization of schiff base complexes of o-vanillin and anthranilic acid and their biological evaluation
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Complexes of Schiff base derived from o-vanillin (2-hydroxy-3-methoxybenzaldehyde) and anthranilic acid (2-aminobenzoic acid) has been used for complexation with Mn(II), Fe(II) and Co(II). The complexes have been formulated as [ML2X2] where X = pyridine or α-picoline on the basic of their microanalysis. Infrared spectral study has been made to confirm the coordination sites of the Schiff base. The magnetic susceptibility and electronic spectral study leads to tetragonally distorted octahedral symmetry (T4h) of complexes. Their biological evaluation with different strains of bacteria suggest that the complexes are more active than the ligand against both Gram-positive and Gram-negative bacteria.
- Pradhan, Rajeev,Kumar Sinha, Sumit,Verma, Punam,Kumar, Sunny,Sharma, Shivadhar
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- A new class of heterogeneous platinum catalysts for the chemoselective hydrogenation of nitroarenes
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A new series of nanostructured platinum catalysts able to catalyze the selective reduction of nitroarenes has been developed. The materials, made of organosilica physically doped with nanostructured platinum(0), are stable and efficient. Reactions in general proceed with high yield and often go to completion, while the catalysts can be reused in further reaction runs. This establishes a new class of relevant solid catalysts for synthetic organic chemistry named SiliaCat Platinum-Hydrogel.
- Pandarus, Valerica,Ciriminna, Rosaria,Beland, Francois,Pagliaro, Mario
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- Chemoselective reduction of nitrobenzenes to aminobenzenes having reducible groups by a titanium(iv) oxide photocatalyst under gas- and metal-free conditions
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m-Nitrovinylbenzene was chemoselectively reduced to m-aminovinylbenzene in a suspension of a TiO2 photocatalyst in the presence of a hole scavenger at room temperature under atmospheric pressure without the use of a precious metal or reducing gas, and nitrobenzenes having other reducible groups were also chemoselectively reduced to corresponding aminobenzenes. The Royal Society of Chemistry 2012.
- Imamura, Kazuya,Hashimoto, Keiji,Kominami, Hiroshi
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- Effect of Inhibitors on Azo-Reduction of 4'-Dimethylaminoazobenzene-2-carboxylic Acid by Clostridium Diaphorase
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The effect of inhibitors on the azo-reduction of 4'-dimethylaminoazobenzene-2-carboxylic acid (DMABC) by Clostridium diaphorase together with β-nicotinamide adenine dinucleotide, reduced form (NADH) has been investigated.The reduction was inhibited by o-aminobenzoic acid which is a reduction product of DMABC.Lineweaver-Burk plots indicated that 0-aminobenzoic acid was a competitive inhibitor with respect to DMABC (Ki=10.5*10-3 mol dm-3).Various monosubstituted benzoic acid derivatives were also competitive inhibitors, among which 0-hydroxybenzoic acid was most effective.
- Yatome, Chizuko,Fujimi, Kazuhiko,Ogawa, Toshihiko
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- The phosphate of pyridoxal-5′-phosphate is an acid/base catalyst in the mechanism of Pseudomonas fluorescens kynureninase
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Kynureninase (l-kynurenine hydrolase, EC 3.7.1.3) catalyzes the hydrolytic cleavage of l-kynurenine to l-alanine and anthranilic acid. The proposed mechanism of the retro-Claisen reaction requires extensive acid/base catalysis. Previous crystal structures showed that Tyr226 in the Pseudomonas fluorescens enzyme (Tyr275 in the human enzyme) hydrogen bonds to the phosphate of the pyridoxal-5′-phosphate (PLP) cofactor. This Tyr residue is strictly conserved in all sequences of kynureninase. The human enzyme complexed with a competitive inhibitor, 3-hydroxyhippuric acid, showed that the ligand carbonyl O is located 3.7 A from the phenol of Tyr275 (Lima, S., Kumar, S., Gawandi, V., Momany, C. & Phillips, R. S. (2009) J. Med. Chem. 52, 389-396). We prepared a Y226F mutant of P. fluorescens kynureninase to probe the role of this residue in catalysis. The Y226F mutant has approximately 3000-fold lower activity than wild-type, and does not show the pKa values of 6.8 on kcat and 6.5 and 8.8 on kcat/Km seen for the wild-type enzyme (Koushik, S. V., Moore, J. A. III, Sundararaju, B. & Phillips, R. S. (1998) Biochemistry 37, 1376-1382). Wild-type kynureninase shows a resonance at 4.5 ppm in 31P-NMR, which is shifted to 5.0, 3.3 and 2.0 ppm when the potent inhibitor 5-bromodihydrokynurenine is added. However, Y226F kynureninase shows resonances at 3.6 and 2.5 ppm, and no change in the peak position is seen when 5-bromodihydrokynurenine is added. Taken together, these results suggest that Tyr226 mediates proton transfer between the substrate and the phosphate, which accelerates formation of external aldimine and gem-diol intermediates. Thus, the phosphate of PLP acts as an acid/base catalyst in the mechanism of kynureninase.
- Phillips, Robert S.,Scott, Israel,Paulose, Riya,Patel, Akshay,Barron, Taylor Colt
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- Reduction of aryl nitro compounds with aluminium/NH4Cl: Effect of ultrasound on the rate of the reaction
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Aromatic nitro compounds undergo smooth reduction when treated with aluminium and ammonium chloride in refluxing methanol to give anilines in high yield. The reaction rate is greatly enhanced by irradiating at 35 KHz in a sonic bath at 25°C.
- Nagaraja,Pasha
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- Specific influence of salts on the hydrolysis reaction rate of p-nitrophenyl anthranilate in binary acetonitrile-water solvents
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The hydrolysis reaction rates of p-nitrophenyl anthranilate (p-NPA) have been surveyed in aqueous buffer solutions mixed with acetonitrile (MeCN) containing various salts at 50 ± 0.1 °C. Increase in pH of the buffer solution from 8.50 to 10.0 results in an increase of the hydrolysis rate constant [log (k/s- 1)] in all solutions mixed with 0-75% (v/v) MeCN. The log (k/s- 1) values significantly decelerate as MeCN contents increase to about 50% (v/v). With further increment of MeCN contents, however, the reversal increases in log (k/s- 1) are observed. All the added salts significantly influence the hydrolysis rate in solutions containing the borate buffer of pH = 9.18. Alkali metal perchlorates (LiClO4and NaClO4) cause the deceleration with increasing salt concentration. The presence of as low as 0.1 mol dm- 3of NaN3causes a three-fold acceleration, compared to the rate without the salt in no MeCN media. The rate acceleration by NaN3becomes gradually weaker as the MeCN contents increase. Contrastingly, the rate acceleration by Et4NBr is enhanced with increasing MeCN contents. In 50% (v/v) MeCN solution, the acceleration in log (k/s- 1) caused by added salts is in the order of NaN3> (n-Bu)4NBr ~ Et4NBr > Et4NCl. The Arrhenius plots in the 50% (v/v) MeCN media without salts and with 0.20 mol dm- 3of LiClO4, NaN3and Et4NBr salts give the good linearity of high activation energy values in the temperature range of 35 to 60 ± 0.1°C, suggesting that the hydrolysis reactions are just of temperature dependence. The whole results have been discussed in terms of changes in the water structure and/or activities of H2O and OH-in the presence of both the added organic solvent and salts, and also in terms of the nucleophilicity of anions from the added salts in the modified media.
- Bayissa, Leta Danno,Ohmae, Yoshihito,Hojo, Masashi
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- Crystal Structure of Escherichia coli Enterobactin-specific Isochorismate Synthase (EntC) Bound to its Reaction Product Isochorismate: Implications for the Enzyme Mechanism and Differential Activity of Chorismate-utilizing Enzymes
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EntC, one of two isochorismate synthases in Escherichia coli, is specific to the biosynthesis of the siderophore enterobactin. Here, we report the crystal structure of EntC in complex with isochorismate and Mg2+at 2.3 A resolution, the first structure of a chorismate-utilizing enzyme with a non-aromatic reaction product. EntC exhibits a complex α+β fold like the other chorismate-utilizing enzymes, such as salicylate synthase and anthranilate synthase. Comparison of active site structures allowed the identification of several residues, not discussed previously, that might be important for the isochorismate activity of the EntC. Although EntC, MenF and Irp9 all convert chorismate to isochorismate, only Irp9 subsequently exhibits isochorismate pyruvate lyase activity resulting in the formation of salicylate and pyruvate as the reaction products. With a view to understanding the roles of these amino acid residues in the conversion of chorismate to isochorismate and to obtaining clues about the pyruvate lyase activity of Irp9, several mutants of EntC were generated in which the selected residues in EntC were substituted for those of Irp9: these included A303T, L304A, F327Y, I346L and F359Q mutations. Biochemical analysis of these mutants indicated that the side chain of A303 in EntC may be crucial in the orientation of the carbonyl to allow formation of a hydrogen bond with isochorismate. Some mutations, such as L304A and F359Q, give rise to a loss of catalytic activity, whereas others, such as F327Y and I346L, show that subtle changes in the otherwise closely similar active sites influence activity. We did not find a combination of these residues that conferred pyruvate lyase activity.
- Sridharan, Sudharsan,Howard, Nigel,Kerbarh, Olivier,Blaszczyk, Michal,Abell, Chris,Blundell, Tom L.
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- Chemoselective hydrogenation of functionalized nitroarenes using MOF-derived co-based catalysts
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The synthesis, characterization, and application of nitrogen-doped carbon supported Co catalysts in selective hydrogenation of nitroarenes are described. The cobalt-based catalysts are prepared by simple pyrolysis of ZIF-67, a typical MOF material, under inert atmosphere. Physicochemical properties of the Co/C-N catalysts have been investigated by X-ray diffraction, elemental analysis, atomic absorption spectroscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The Co-based materials were found to be highly efficient in the chemoselective hydrogenation of nitroarenes. A broad range of substituted nitroarenes are converted to the corresponding anilines in excellent yields under industrially viable conditions with other reducing groups remaining intact. In situ ATR-IR and XPS characterizations reveal that the Co-N centers present in the catalyst favor the preferential adsorption of nitro groups, leading to this unique chemoselectivity. The kinetic parameters of 4-nitrostyrene hydrogenation over the Co/C-N catalyst were investigated.
- Wang, Xi,Li, Yingwei
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- Psychrophilins E-H and versicotide C, cyclic peptides from the marine-derived fungus aspergillus versicolor ZLN-60
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Four new cyclic peptides, psychrophilins E-H (1-4), possessing a rare amide linkage between the carboxylic acid in anthranilic acid (ATA) and the nitrogen from an indole moiety, along with a new ATA-containing hexapeptide, versicotide C (5), were obtained from the culture of the marine-derived fungus Aspergillus versicolor ZLN-60. The structures, including absolute configurations, were elucidated by a combination of HRESIMS, NMR, X-ray crystallography, TDDFT ECD calculations, and Marfeys method. Versicotide C (5) is the first natural cyclic hexapeptide containing two anthranilic acids. Compounds 1-5 were not cytotoxic, and compound 3 showed potent lipid-lowering effects.
- Peng, Jixing,Gao, Huquan,Zhang, Xiaomin,Wang, Shuai,Wu, Chongming,Gu, Qianqun,Guo, Peng,Zhu, Tianjiao,Li, Dehai
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- Facile fabrication of γ-Fe2O3-nanoparticle modified N-doped porous carbon materials for the efficient hydrogenation of nitroaromatic compounds
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Novel γ-Fe2O3-nanoparticle (NP) modified N-doped porous carbon materials (γ-Fe2O3/mCN) were prepared by one-pot pyrolysis of a mixture of melamine, polyacrylonitrile, and FeCl3·6H2O at different temperatures. At a pyrolysis temperature of 900 °C, γ-Fe2O3/mCN-900-20 exhibited a high surface area and a N content of 8.47%, caused by the complete pyrolysis of melamine and polyacrylonitrile at 900 °C. The obtained material γ-Fe2O3/mCN-900-20 was used as a cost-effective catalyst for the hydrogenation of nitrobenzene using N2H4·H2O as the reductant under mild reaction conditions. As compared to other catalysts (e.g., noble metal catalysts), γ-Fe2O3/mCN-900-20 exhibited high catalytic performance (TOF of 311.83 h-1, selectivity of 100%). During the catalytic hydrogenation of nitroaromatic compounds with reducible groups, e.g., alcoholic hydroxyl, halogen, and amino groups, an excellent selectivity close to 100% was achieved. Moreover, because the active sites of γ-Fe2O3 has magnetic performance, the catalyst can be easily recovered using a magnet, and reused at least four runs without an obvious activity decrease. Hence, the easily prepared, cost-effective and reusable γ-Fe2O3/mCN catalyst fabricated in this study demonstrates potential for applications in selective reduction of aromatic nitro compounds.
- Cui, Xueliang,Zhang, Qiaolan,Tian, Meng,Dong, Zhengping
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- 4-Hydroxy-2-quinolones. 37. Simple synthesis of 1-R-2-oxo-3,4-dihydroxyquinolines
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3-Amino-1-R-2-oxo-4-hydroxyquinolines easily undergo acid hydrolysis with formation of the corresponding 1-R-2-oxo-3,4-dihydroxyquinolines. 1998 Plenum Publishing Corporation.
- Ukrainets,Taran,Sidorenko,Gorokhova
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- The roles of Ser-36, Asp-132 and Asp-201 in the reaction of Pseudomonas fluorescens Kynureninase
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Kynureninase from Pseudomonas fluorescens (Pfkynase)catalyzes the pyridoxal-5′-phosphate (PLP)dependent hydrolytic cleavage of L-kynurenine to give anthranilate and L-alanine. Asp-132 and Asp-201 are located in the structure near the pyridine NH of the PLP, with Asp-201 forming a hydrogen bond. Mutation of Asp-132 to alanine and glutamate and Asp-201 to glutamate results in reduced catalytic activity with L-kynurenine and β-benzoyl-L-alanine, but not O-benzoyl-L-serine. D132A, D132E D201E and S36A mutant Pfkynases all can form quinonoid and vinylogous amide intermediates with β-benzoyl-L-alanine, similar to wild-type enzyme. D132A, D132E, and D201E Pfkynase react more slowly with β-benzoyl-L-alanine and benzaldehyde to form an aldol product absorbing at 490 nm than wild-type, with D132E reacting the slowest. The 1H NMR spectra of wild-type and D201E Pfkynase are very similar in the low field region from 10 to 18 ppm, but that of D132A Pfkynase is missing a resonance at 13.1 ppm. These results show that these residues modulate the reactivity of the PLP at different stages during the reaction cycle. Ser-36 is located near the expected location of the carbonyl oxygen of the substrate. Mutation of Ser-36 to alanine results in a 230-fold reduction of kcat and 30-fold reduction in kcat/Km with L-kynurenine, but very little effect on the reaction of O-benzoyl-L-serine. Thus, the rate-determining step in the reaction of S36A Pfkynase is the Cβ-Cγ bond cleavage. These results support the hypothesis that Ser-36 together with Tyr-226 is part of an oxyanion hole that polarizes the carbonyl of the substrate in the catalytic mechanism of Pfkynase.
- Phillips, Robert S.,Crocker, Mori,Lin, Richard,Idowu, O. Elijah,McCannon, David K.,Lima, Santiago
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- Fullerene-catalyzed reduction of azo derivatives in water under UV irradiation
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Metal-free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C 60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N=N bond. UV irradiation increases the ability of C60 to interact with electron-donor moieties in azo dyes. Filling a vacancy: Experimental and theoretical methods have been combined to show that C60-catalyzed reductions of azo compounds form aromatic amines under UV irradiation (see scheme). The obtained results show that C60 acts as an electron acceptor to catalyze the reduction of azo compounds, and the role of UV irradiation is to increase the ability of C60 to interact with electron-donor moieties in azo compounds. Copyright
- Guo, Yong,Li, Wengang,Yan, Jingjing,Moosa, Basem,Amad, Ma'An,Werth, Charles J.,Khashab, Niveen M.
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- Strong in vitro and in vivo cytotoxic effects of two platinum(II) complexes with cryptolepine derivatives
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Two mononuclear Pt(II) compounds, [Pt(BQL1)Cl]Cl (BQL1-Pt) and [Pt(BQL2)Cl]Cl (BQL2-Pt), with [5-(benzo[4,5]furo[3,2-b]quinolin-11-yloxy)-pentyl]-bis-pyridin-2-ylmethyl-amine (BQL1) and [9-(benzo[4,5]furo[3,2-b]quinolin-11-yloxy)-nonyl]-bis-pyridin-2-ylmethyl-amine (BQL2), were prepared as new chemotypes for potential antitumor agents. In this study, the effects of cryptolepine derivatives in BQL1-Pt, 2,2′-dipicolylamine Pt(II) complex, and BQL2-Pt on cellular Pt(II) accumulation, cytotoxicity, and in vitro and in vivo antitumor activities against T-24 cancer cells and normal HL-7702 cells were evaluated. BQL1-Pt and BQL2-Pt displayed cytotoxic activities in the micromolar range (1.3 ± 0.1 and 0.2 ± 0.2 μM, respectively) on T-24 cancer cells; however, they did not exhibit any toxicity against HL-7702 cells. They triggered T-24 cell apoptosis through a mitochondrial dysfunction pathway. BQL1-Pt and BQL2-Pt prepared from the neutral BQL1 and BQL2 ligands with cryptolepine derivatives showed better antitumor activities than 2,2′-dipicolylamine. Furthermore, BQL2-Pt effectively inhibited the growth of bladder T-24 tumor in vivo. BQL2-Pt could be a potential therapeutic candidate for cancers. [Figure not available: see fulltext.]
- Qin, Li-Qin,Wei, Zu-Zhuang,Yang, Lin,Qin, Qi-Pin,Zeng, Jia-Jing,Tan, Ming-Xiong,Liang, Hong
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- Cu-catalyzed reduction of azaarenes and nitroaromatics with diboronic acid as reductant
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A ligand-free copper-catalyzed reduction of azaarenes with diboronic acid as reductant in an aprotic solvent under mild conditions has been developed. Most interestingly, the nitroazaarenes could be reduced exclusively to give the corresponding amines without touching the azaarene moieties. Furthermore, the reductive amination of aromatic nitro compounds and aromatic aldehydes has also been realized. A series of hydrogenated azaarenes and secondary amines were obtained with good functional group tolerance.
- Pi, Danwei,Zhou, Haifeng,Zhou, Yanmei,Liu, Qixing,He, Renke,Shen, Guanshuo,Uozumi, Yasuhiro
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- Facile reduction of aromatic nitro/azido functionality on solid support employing Al/NiCl2·6H2O and Al/NH4Cl: Synthesis of pyrrolo[2,1-c][1,4]benzodiazepines
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An efficient and mild method for the reduction of aromatic nitro and azido groups on solid support using Al/NiCl2·6H2O and Al/NH4Cl is described. This solid phase reduction technique has been applied towards the synthesis
- Kamal, Ahmed,Reddy, K. Laxma,Devaiah,Reddy, G. Suresh Kumar
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- Efficient reduction of nitroarenes to the corresponding anilines with sulfur in basic media under solvent-free conditions
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Aromatic nitro compounds can be conveniently reduced to the corresponding primary amines in the presence of S8 under solvent-free conditions in excellent yields. Alumina supported NaOH catalyses this transformation. Chemoselectivity was observed in the reduction of the nitro group in the presence of phenol, carboxylic acid, aldehyde, and benzyl halide groups.
- Niknam, Khodabakhsh,Kiasat, Ali Reza,Kazemi, Foad,Hossieni, Abolghasem
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- Cis-Dihydroxylation of Tricyclic Arenes and Heteroarenes Catalyzed by Toluene Dioxygenase: A Molecular Docking Study and Experimental Validation
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Molecular docking studies of toluene dioxygenase led to the prediction that angular and lateral cis-dihydroxylation of tricyclic arene and heteroarene substrates could occur. Biotransformations of biphenylene, dibenzofuran, carbazole and dibenzothiophene, using Pseudomonas putida UV4 whole cells, expressing toluene dioxygenase, confirmed that both angular and lateral cis-dihydroxylation had occurred in the predicted regioselective and stereoselective manner. The toluene dioxygenase-catalysed (Pseudomonas putida UV4) biotransformation of dibenzofuran was optimized, to produce 1,2-dihydrodibenzofuran-1,2-diol as the major metabolite in excellent yield. 2-Hydroxydibenzofuran, resulting from dehydration of 1,2-dihydrodibenzofuran-1,2-diol, was also found to undergo cis- dihydroxylation to give a very minor cis-dihydrodiol metabolite. The enantiopurity (>98% ee) and (1R,2S) absolute configuration of the major dibenzofuran cis -dihydrodiol was rigorously established by catalytic hydrogenation and formation of methoxy(trifluoromethyl)phenylacetate derivatives and by X-ray crystallography of an epoxide derivative. Biotransformation of carbazole yielded anthranilic acid as the major metabolite and was consistent with angular cis-dihydroxylation. Synthesis of a cis- diol epoxide derivative showed that the main cis-dihydrodiol metabolite of dibenzofuran has potential in the chemoenzymatic synthesis of natural products. (Figure presented.).
- Boyd, Derek R.,Sharma, Narain D.,Brannigan, Ian N.,McGivern, Christopher J.,Nockemann, Peter,Stevenson, Paul J.,McRoberts, Colin,Hoering, Patrick,Allen, Christopher C. R.
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- Pd(0) supported on N-doped graphene quantum dot modified cellulose as an efficient catalyst for the green reduction of nitroaromatics
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A new efficient catalyst was introduced for the green reduction of nitroaromatics. The catalyst was obtained via modification of cellulose with N-doped graphene quantum dots and Pd nanoparticles. The new cellulose nanocomposite after characterization was applied as the catalyst in the reduction reaction of nitroaromatics using NaBH4 at room temperature. Aromatic amines were obtained as the product of the reduction reaction over 2 h. This reaction has green reaction conditions such as mild reaction conditions, high yield, green solvent and recyclable catalyst. Also, the recovered catalyst is applicable in the reduction reaction 6 times without significant decrease in activity.
- Keshipour, Sajjad,Adak, Kamran
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- A highly selective and sensitive turn-on catalytic chemodosimeter for Cu2+ in aqueous solution
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We report herein the first diaminocyclopent-2-enone-based catalytic chemodosimeter (3) for naked-eye and turn-on fluorescent detections of Cu2+ in pure aqueous solution. Compound 3 easily made available from furan-2-carbaldehyde and 2-aminobenz
- Wang, Qiang-Li,Zhang, Han,Jiang, Yun-Bao
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- Copper mediated C-H amination with oximes: En route to primary anilines
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Here we report an efficient Cu(i)-mediated C-H amination reaction with oximes as amino donors to introduce NH2 groups directly. Various strongly coordinating heterocycles including quinoline, pyrimidine, pyrazine, pyrazole and triazole were tolerated well. The potential utility was further demonstrated in a late-stage modification of telmisartan (an antagonist for the angiotensin II receptor).
- Xu, Lin-Lin,Wang, Xing,Ma, Biao,Yin, Ming-Xing,Lin, Hai-Xia,Dai, Hui-Xiong,Yu, Jin-Quan
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- Graphene oxide/carbon nanotubes-Fe3O4 supported Pd nanoparticles for hydrogenation of nitroarenes and C-H activation
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Fe3O4 magnetic nanocomposites combined with graphene oxide (GO) and carbon nanotubes (CNTs) are synthesized by a hydrothermal method, followed by synthesis of GO/CNT-Fe3O4 supported Pd nanoparticles using a gas-liquid interfacial plasma (GLIP) method with Pd(OAc)2 as a precursor, and the Pd nanoparticles show a uniform particle size distribution. The catalysts exhibit remarkable catalytic activity during the hydrogenation of nitroarenes under H2 atmosphere at 60°C in water using a small amount of catalyst, and the catalyst can be magnetically separated from the reaction mixture. The addition of the Fe3O4 component to the GO/CNTs can be used to effectively prevent aggregation and restacking of GO and the CNTs, and the GO/CNT composite can adjust the hydrophilic-hydrophobic property of the catalysts. Furthermore, the Pd catalyst can be readily recovered and reused several times without a significant decrease in activity. It is worth mentioning that the Pd-3 catalysts show remarkable activity during C-H functionalization.
- Yang, Fan,Feng, Andong,Wang, Chunxia,Dong, Sen,Chi, Cheng,Jia, Xilai,Zhang, Liqiang,Li, Yongfeng
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- Aglycone Ebselen and β- D -Xyloside Primed Glycosaminoglycans Co-contribute to Ebselen β- D -Xyloside-Induced Cytotoxicity
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Most β-d-xylosides with hydrophobic aglycones are nontoxic primers for glycosaminoglycan assembly in animal cells. However, when Ebselen was conjugated to d-xylose, d-glucose, d-galactose, and d-lactose (8A-D), only Ebselen β-d-xyloside (8A) showed significant cytotoxicity in human cancer cells. The following facts indicated that the aglycone Ebselen and β-d-xyloside primed glycosaminoglycans co-contributed to the observed cytotoxicity: 1. Ebselen induced S phase cell cycle arrest, whereas 8A induced G2/M cell cycle arrest; 2. 8A augmented early and late phase cancer cell apoptosis significantly compared to that of Ebselen and 8B-D; 3. Both 8A and phenyl-β-d-xyloside primed glycosaminoglycans with similar disaccharide compositions in CHO-pgsA745 cells; 4. Glycosaminoglycans could be detected inside of cells only when treated with 8A, indicating Ebselen contributed to the unique property of intracellular localization of the primed glycosaminoglycans. Thus, 8A represents a lead compound for the development of novel antitumor strategy by targeting glycosaminoglycans.
- Tang, Yang,Zhang, Siqi,Chang, Yajing,Fan, Dacheng,Agostini, Ariane De,Zhang, Lijuan,Jiang, Tao
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- MOF-derived Ni-based nanocomposites as robust catalysts for chemoselective hydrogenation of functionalized nitro compounds
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Porous graphitic carbon layers encapsulating Ni nanoparticles (Ni@C) were prepared by a facile thermolysis of a Ni-containing metal-organic framework, the structure of which were characterized by power X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) in detail. The resulting Ni@C nanocomposites served as highly efficient and magnetically recyclable catalysts for the hydrogenation of diverse functionalized nitro compounds to the corresponding anilines under relatively milder conditions. The high catalytic performance and the enhanced stability are ascribed to the synergistic effects and electron transfer between the metallic Ni and graphitic carbon as well as the unique encapsulation structure. The achieved success in the MOF-derived Ni@C nanocomposites may pave the way for designing environmentally benign catalytic hydrogenation processes for industrial applications.
- Tang, Bo,Song, Wei-Chao,Yang, En-Cui,Zhao, Xiao-Jun
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- Molecular-docking-guided design and synthesis of new IAA-tacrine hybrids as multifunctional AChE/BChE inhibitors
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A series of new indole-3-acetic acid (IAA)-tacrine hybrids as dual acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) inhibitors were designed and prepared based on the molecular docking mode of AChE with an IAA derivative (1a), a moderate AChE inhibitor identified by screening our compound library for anti-Alzheimer's disease (AD) drug leads. The enzyme assay results revealed that some hybrids, e.g. 5d and 5e, displayed potent dual in vitro inhibitory activities against AChE/BChE with IC50 values in low nanomolar range. Molecular modeling studies in tandem with kinetic analysis suggest that these hybrids target both catalytic active site and peripheral anionic site of cholinesterase (ChE). Molecular dynamic simulations and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) calculations indicate that 5e has more potent binding affinity than hit 1a, which may explain the stronger inhibitory effect of 5e on AChE. Furthermore, their predicted pharmacokinetic properties and in vitro influences on mouse brain neural network electrical activity were discussed. Taken together, compound 5e can be highlighted as a lead compound worthy of further optimization for designing new anti-AD drugs.
- Cheng, Zhi-Qiang,Zhu, Kong-Kai,Zhang, Juan,Song, Jia-Li,Muehlmann, Luis Alexandre,Jiang, Cheng-Shi,Liu, Chang-Liang,Zhang, Hua
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- Gold nanoparticles anchored onto the magnetic poly(ionic-liquid) polymer as robust and recoverable catalyst for reduction of Nitroarenes
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Gold nanoparticles supported on poly ionic-liquid magnetic nanoparticles (MNP@PIL@Au) were synthesized by reduction of HAuCl4 with sodium borohydride. The synthesized catalyst was characterized using by AAS, TEM, FT-IR, EDS, TGA and XRD techniques. The performance of the synthesized catalyst was investigated in the reduction of nitroarenes with NaBH4. The reaction was carried out for various nitroarenes in water and mild conditions with high yields. The catalyst selectivity for the reduction of nitro group in the presences of other functional groups such as halides and alkynes was fairly well. The recycling of the catalyst was done 8 times without any significant loss of its catalytic activity.
- Moghaddam, Firouz Matloubi,Ayati, Seyed Ebrahim,Firouzi, Hamid Reza,Hosseini, Seyed Hassan,Pourjavadi, Ali
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- Cloning and characterization of genes responsible for m-fluoro-D,L-phenylalanine resistance in Brevibacterium lactofermentum.
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Two kinds of 3-deoxy-D-arabino-hepturosonate-7-phosphate (DAHP) synthase genes were cloned from an L-Phe-producing mutant of Brevibacterium lactofermentum, AJ11957, which was resistant to m-fluoro-D,L-phenylalanine (mFP) and p-fluoro-D,L-phenylalanine (pFP) and which had DAHP synthase free from feedback inhibition. Both genes were cloned using a vector plasmid, pAJ1844, and the resulting recombinant plasmids were named pAR1 and pAR2. They had different structures on the restriction maps. Both plasmids, pAR1 and pAR2, conferred mFP and pFP resistance and L-Phe and L-Tyr productivity on a wild-type strain of B. lactofermentum, AJ12036. The degrees of L-Phe-analogue resistance and aromatic amino acid productivity of the pAR1-transformant were larger than those of the pAR2-transformant. The introduction of pAR1 to AJ12036 resulted in the alteration of DAHP synthase activity from a feedback-sensitive mechanism to a feedback-insensitive one accompanied by an elevated level of specific activity. A DAHP synthase deficient mutant of Escherichia coli was complemented by pAR2, but not by pAR1. Characteristics of the two kinds of DAHP synthase genes are discussed.
- Ito,Sato,Matsui,Sano,Nakamori,Tanaka,Enei
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- Synthesis of oxazolidinones from N-aryl-carbamate and epichlorohydrin under mild conditions
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The reaction conditions for an enantiospecific synthesis of various N-aryl-oxazolidinones from N-aryl-carbamates and (R) or (S) epichlorohydrin were optimized. The N-aryl-oxazolidinones were applied to the synthesis of compounds of biological interest such as DuP 721, toloxatone and a linezolid analogue.
- Buscemi, Silvestre,Insuasty, Braulio,Marzullo, Paola,Moreno, Leydi Marcela,Piccionello, Antonio Palumbo
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supporting information
p. 140 - 155
(2022/03/27)
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- Benzoselenazolone compound and application thereof and bactericide
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The invention relates to the field of antifungal drugs, and discloses a benzoselenazolone compound and application thereof and a bactericide, and the benzoselenazolone compound has a structural general formula shown in a formula (I). The benzoselenazolone compound provided by the invention can take candida albicans fructose-1, 6-diphosphate aldolase (Ca-FBA-II) as a target spot to inhibit the activity of the candida albicans fructose 1, 6-diphosphate aldolase (Ca-FBA-II), and has a good resistance effect on drug-resistant bacteria generated by taking cytochrome P450 as an action target.
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Paragraph 0090; 0119; 0120; 0122
(2021/01/24)
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- The Discovery of Novel ACA Derivatives as Specific TRPM2 Inhibitors that Reduce Ischemic Injury Both in Vitro and in Vivo
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The transient receptor potential melastatin 2 (TRPM2) channel is associated with ischemia/reperfusion injury, inflammation, cancer, and neurodegenerative diseases. However, the limit of specific inhibitors impedes the development of TRPM2-targeted therapeutic agents. To discover more potent and selective TRPM2 inhibitors, 59 N-(p-amylcinnamoyl) anthranilic acid (ACA) derivatives were synthesized and evaluated using calcium imaging and electrophysiology approaches. Systematic structure-activity relationship studies resulted in some potent compounds inhibiting the TRPM2 channel with sub-micromolar half-maximal inhibitory concentration values. Among them, the preferred compound A23 exhibited TRPM2 selectivity over TRPM8 and TRPV1 channels as well as phospholipase A2 and showed neuroprotective activity in vitro. Following pharmacokinetic studies, A23 was further evaluated in a transient middle cerebral artery occlusion model in vivo, which significantly reduced cerebral infarction. These data indicate that A23 might serve as a useful tool for TRPM2-related research as well as a lead compound for the development of therapeutic agents for ischemic injury.
- Zhang, Han,Yu, Peilin,Lin, Hongwei,Jin, Zefang,Zhao, Siqi,Zhang, Yi,Xu, Qingxia,Jin, Hongwei,Liu, Zhenming,Yang, Wei,Zhang, Liangren
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p. 3976 - 3996
(2021/05/04)
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- Expedient discovery for novel antifungal leads: 1,3,4-Oxadiazole derivatives bearing a quinazolin-4(3H)-one fragment
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Developing novel fungicide candidates are intensively promoted by the rapid emergences of resistant fungi that outbreak on agricultural production. Aiming to discovery novel antifungal leads, a series of 1,3,4-oxadiazole derivatives bearing a quinazolin-4(3H)-one fragment were constructed for evaluating their inhibition effects against phytopathogenic fungi in vitro and in vivo. Systematically structural optimizations generated the bioactive molecule I32 that was identified as a promising inhibitor against Rhizoctonia solani with the in vivo preventative effect of 58.63% at 200 μg/mL. The observations that were captured by scanning electron microscopy and transmission electron microscopy demonstrated that the bioactive molecule I32 could induce the sprawling growth of hyphae, the local shrinkage and rupture on hyphal surfaces, the extreme swelling of vacuoles, the striking distortions on cell walls, and the reduction of mitochondria numbers. The above results provided an indispensable complement for the discovery of antifungal lead bearing a quinazolin-4(3H)-one and 1,3,4-oxadiazole fragment.
- Chai, Jianqi,Chen, Min,Jin, Fei,Kong, Xiangyi,Wang, Xiaobin,Xue, Wei,Yang, Chunlong
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- Aluminum ion detection fluorescent probe based on bifunctional organic small molecule as matrix and preparation method and application thereof
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The invention discloses an aluminum ion detection fluorescent probe based on a bifunctional organic small molecule as a matrix and a preparation method and application of the fluorescence probe, and the structural formula is shown I. To the invention, 1, 8 - naphthalimide and isoquinoline hydrazide or 2 - benzamide benzoyl hydrazine are used as fluorescent groups, and the prepared Schiff base type probe NIQ or NBP is prepared into a solution Al through condensation reaction. 3 + High sensitivity and high selectivity are exhibited, and at the same time, the structure is stable. The low toxicity and cell infiltration capability is strong, and the trace metal aluminum ions in the living Hela cells are successfully detected. The preparation method of the fluorescent probe is simple, the raw materials are easily available, the obtained product is solid powder, is easy to store, and has a high application development prospect.
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Paragraph 0095-0099
(2021/11/14)
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- 1, 2, 4 - Oxadiazole Nrf2 activator - tacrine split product as well as preparation method and application thereof
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The invention discloses 1,oxadiazole Nrf2 activator - tacrine split products as well as a preparation method and application thereof. The invention relates to an acetylcholinesterase inhibitory activity. Nrf2 Activation activity, selective screening and Morris water maze test was carried out to evaluate the compound of general formula I, II, III for the treatment of's disease (in particular, severe's disease), found to have good in vitro, in vivo activity and extremely high selectivity, and can be used as a precursor substance for further development through selective inhibition of acetylcholinesterase and activation Nrf2.
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Paragraph 0019; 0040; 0045; 0047
(2021/11/06)
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- Hydroxamic acid rearrangement method for O-amino aromatic acid
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The invention relates to the field of organic functional new material chemicals, and discloses a novel process technology for preparation of a hydroxamic acid precursor body weight discharge method of a plurality of o-amino aromatic acids in the first time. These substances are well known dyes and pigment and pharmaceutical pesticide-related fields and have a wide range of critical fine chemicals.
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Paragraph 0018-0026
(2021/09/29)
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- NaI/PPh3-Mediated Photochemical Reduction and Amination of Nitroarenes
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A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 was found to enable highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (Cl, Br, and even I), aldehyde, ketone, carboxyl, and cyano. Moreover, the photoredox catalysis with NaI and stoichiometric PPh3 provides also an alternative entry to Cadogan-type reductive amination when o-nitrobiarenes were used.
- Qu, Zhonghua,Chen, Xing,Zhong, Shuai,Deng, Guo-Jun,Huang, Huawen
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supporting information
p. 5349 - 5353
(2021/07/21)
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- Aluminum Metal-Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis
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The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal-organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon-oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Dwivedi, Ashutosh,Manna, Kuntal
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p. 3943 - 3957
(2021/04/12)
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- Copper nanoparticles (CuNPs) catalyzed chemoselective reduction of nitroarenes in aqueous medium
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Abstract: A procedure for practical synthesis of CuNPs from CuSO4·5H2O is established, under appropriate reaction conditions, using rice (Oryza sativa) as an economic source of reducing as well as a stabilizing agent. Optical and microscopic techniques are employed for the characterization of the synthesized CuNPs and the sizes of the particles were found to be in the range of 8 ± 2 nm. The nanoparticles are used as a catalyst for chemoselective reduction of aromatic nitro compounds to corresponding amines under ambient conditions and water as a reaction medium. Graphic abstract: CuNPs are synthesized using hydrolysed rice and used as catalyst for chemoselective reduction of nitroarenes to their corresponding amines in water. [Figure not available: see fulltext.]
- Chand, Dillip Kumar,Rai, Randhir
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- Chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes using carbon-supported palladium catalytic system in water
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Developing and/or modifying fundamental chemical reactions using chemical industry-favorite heterogeneous recoverable catalytic systems in the water solvent is very important. In this paper, we developed convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of the recoverable heterogeneous carbon-supported palladium (Pd/C) catalytic system in water. The utilize of the simple, effective, and recoverable catalyst and also using of water as an entirely green solvent along with relatively short reaction times and good-to-excellent yields of the desired products are some of the noticeable features of the presented synthetic protocols. Graphic abstract: [Figure not available: see fulltext.].
- Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
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p. 3289 - 3312
(2021/05/11)
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- Synthesis of CoFe2O4@Pd/Activated carbon nanocomposite as a recoverable catalyst for the reduction of nitroarenes in water
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Efficient reduction of nitro compounds into amines is an important industrial transformation. So, it is a great deal to design new catalysts for efficient reduction of the nitro compounds especially in water. In this work, a new magnetic Pd/activated carbon nanocomposite (CoFe2O4@Pd/AC) was synthesized via metal-impregnation-pyrolysis method. The CoFe2O4@Pd/AC was fully characterized by FT-IR, PXRD, FESEM, TEM, VSM, EDX-mapping and BET techniques. The results showed that CoFe2O4@Pd/AC is a highly reactive and easily recoverable magnetic catalyst for the reduction of the nitro compounds by using NaBH4 in water. For instance, aniline was obtained in high yield (99%) after 75 ?min at 25 ?C by using just 6 ?mg of the catalyst. In addition, CoFe2O4@Pd/AC was recovered by a simple magnetic decantation and it exhibits stable activity and remains intact during the catalytic process with no significant loss in activity (8 cycles).
- Hamadi, Hosein,Kazeminezhad, Iraj,Mohammadian, Sara
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- Reduction of dinitrobenzenes by electron-carrying catalysts in the electrosynthesis of diaminobenzenes
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The interaction of isomeric dinitrobenzenes (DNBs) with titanium(III), tin(II), and vanadium(II) chlorides, which are reducing agents used as electron carriers in the electrosynthesis of diaminobenzenes, has been studied. Rate constants of the reduction of isomeric DNBs and nitrophenylhydroxylamines by SnCl2 and TiCl3 in a 2 M water-alcohol solution (10 vol.% C2H5OH) of HCl were measured, and activation energies of the reduction of isomeric DNBs were determined. The rates of interaction of DNBs with the listed mediators increase in the series SnCl2 3 2. It is shown that the electrolysis of DNBs in the presence of an excess of these mediators makes it possible to obtain the corresponding diaminobenzenes with a yield of 60–90%.
- Abakumov, M. V.,Leonova, M. Yu.,Mikhalchenko, L. V.,Novikov, V. T.,Zaplavin, A. P.
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p. 1927 - 1933
(2021/11/05)
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- Mitochondria-localizing curcumin-cryptolepine Zn(II) complexes and their antitumor activity
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Many metal complexes are potent candidates as mitochondrial-targeting agents. In this study, four novel Zn(II) complexes, [Zn(BPQA)Cl2] (Zn1), [Zn(BPQA)(Curc)]Cl (Zn2), [Zn(PQA)Cl2] (Zn3), and [Zn(PQA)(Curc)]Cl (Zn4), containing N,N-bis(pyridin-2-ylmethyl)benzofuro[3,2-b]quinolin-11-amine (BPQA), N-(pyridin-2-ylmethyl)benzofuro[3,2-b]quinolin-11-amine (PQA), and curcumin (H-Curc) were synthesized. An MTT assay showed that Zn1–Zn4 had strong anticancer activities against SK-OV-3/DDP and T-24 tumor cells with IC50 values of 0.03–6.19 μM. Importantly, Zn1 and Zn2 displayed low toxicities against normal HL-7702 cells. Mechanism experiments demonstrated that probe Zn2 showed appreciable fluorescence in the red region of the spectrum, and substantial accumulation of Zn2 occurred in the mitochondria after treatment, indicating increases in Ca2+ and reactive oxygen species levels, loss of the mitochondrial membrane potential, and consequent induction of mitochondrial dysfunction at low concentrations. In addition, the probe Zn2 effectively (50.7%) inhibited the growth of T-24 bladder tumor cells in vivo. The probe Zn2 shows potential for use in cancer therapy while retaining the H-Curc as an imaging probe.
- Qin, Li-Qin,Liang, Chun-Jie,Zhou, Zhen,Qin, Qi-Pin,Wei, Zu-Zhuang,Tan, Ming-Xiong,Liang, Hong
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- Selenium-catalyzed intramolecular atom- And redox-economical transformation ofo-nitrotoluenes into anthranilic acids
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Anthranilic acids (AAs) are significant basic chemicals used in pharmaceuticals, agrochemicals, dyes, fragrances,etc. Superfluous steps are always involved in obtaining AAs. Herein, we demonstrate a straightforward strategy to transform abundanto-nitrotoluenes into biologically and pharmaceutically significant AAs without any extra reductants, oxidants and protecting groups. Various sensitive groups, such as halogens, sulfide, aldehyde, pyridines, quinolines,etc., can be tolerated in this transformation. A hundred-gram-scale operation is realized efficiently with almost quantitative selenium recycling. Further mechanistic studies and DFT calculations disclosed the proposed atom-exchange processes and the key roles of the selenium species.
- Jiang, Xuefeng,Li, Yiming,Lin, Zhenyang,Wang, Yuhong,Yang, Tilong
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supporting information
p. 2986 - 2991
(2021/05/05)
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- Anthranilic acid and derivatives thereof as well as synthesis method and application thereof
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In the reaction solvent, o-methyl (hetero) aryl nitro compound is taken as a reaction raw material and is used for water. The anthranilic acid and its derivatives are synthesized by the action of a catalyst, a base and an additive. The synthetic method has the advantages of cheap and easily available raw materials, simple reaction operation, high yield and excellent functional group tolerance, and provides a simple and efficient method for synthesizing o-aminobenzoic acid which is widely used in the aspects of dyes, medicines, pesticides, spices and the like. The invention further discloses the anthranilic acid and derivatives and application thereof, and has a wide application prospect.
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Paragraph 0041-0043
(2021/09/15)
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- A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
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A simple, efficient and pot-economic approach in a single vessel has been developed for conversion of aromatic and aliphatic carboxamides into primary amines with one fewer carbom atom (Hofmann reaction) in 38–89 % yield by reacting with trichloro- or tribromoisocyanuric acid and sodium hydroxide in aqueous acetonitrile. Under the same reaction conditions, cyclic imides gave amino acids (69–83 %). The role of the trihaloisocyanuric acids is the in situ generation of N-haloamides, key-intermediates for the Hofmann reaction. The scalability of the methodology was demonstrated by a multigram-scale transformation of phthalimide into anthranilic acid in 77 % yield.
- Bastos, Gustavo A.,de Mattos, Marcio C.S.
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- Biotransformations of anthranilic acid and phthalimide to potent antihyperlipidemic alkaloids by the marine-derived fungus Scedosporium apiospermum F41-1
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A new diphenylamine derivative, scediphenylamine A (1), together with six phthalimide derivatives (2–7) and ten other known compounds (8–17) were obtained from the marine-derived fungus Scedosporium apiospermum F41-1 fed with synthetically prepared anthranilic acid and phthalimide. The structure and absolute configuration of the new compound were determined by HRMS, NMR, and X-ray crystallography. Evaluation of their lipid-lowering effect in 3T3-L1 adipocytes showed that scediphenylamine A (1), N-phthaloyl-tryptophan-methyl ester (4), 5-(1,3-dioxoisoindolin-2-yl) pentanamide (5), perlolyrine (10) and flazine (11) significantly reduced triglyceride level in 3T3-L1 cells by inhibiting adipogenic differentiation and synthesis with the EC50 values of 4.39, 2.79, 3.76, 0.09, and 4.52 μM, respectively. Among them, perlolyrine (10) showed the most potent activity, making it a candidate for further development as a potential agent to treat hyperlipidemia.
- Chen, Pei-Nan,Hao, Meng-Jiao,Li, Hou-Jin,Xu, Jun,Mahmud, Taifo,Lan, Wen-Jian
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- Design and synthesis of novel tacrine-dipicolylamine dimers that are multiple-target-directed ligands with potential to treat Alzheimer's disease
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Alzheimer's disease (AD) is a prevalent neurodegenerative disorder that has multiple causes. Therefore, multiple-target-directed ligands (MTDLs), which act on multiple targets, have been developed as a novel strategy for AD therapy. In this study, novel drug candidates were designed and synthesized by the covalent linkings of tacrine, a previously used anti-AD acetylcholinesterase (AChE) inhibitor, and dipicolylamine, an β-amyloid (Aβ) aggregation inhibitor. Most tacrine-dipicolylamine dimers potently inhibited AChE and Aβ1-42 aggregation in vitro, and 13a exhibited nanomolar level inhibition. Molecular docking analysis suggested that 13a could interact with the catalytic active sites and the peripheral anion site of AChE, and bind to Aβ1-42 pentamers. Moreover, 13a effectively attenuated Aβ1-42 oligomers-induced cognitive dysfunction in mice by activating the cAMP-response element binding protein/brain-derived neurotrophic factor signaling pathway, decreasing tau phosphorylation, preventing synaptic toxicity, and inhibiting neuroinflammation. The safety profile of 13a in mice was demonstrated by acute toxicity experiments. All these results suggested that novel tacrine-dipicolylamine dimers, especially 13a, have multi-target neuroprotective and cognitive-enhancing potentials, and therefore might be developed as MTDLs to combat AD.
- Benjamin Naman, C.,Cui, Wei,Dong, Jiahui,He, Shan,Huang, Xinghan,Jin, Haixiao,Lin, Dongdong,Liu, Fufeng,Liu, Hao,Liu, Zhiwen,Mao, Yuechun,Mou, Chenye,Wang, Ning,Wang, Ze,Wei, Jiaxin,Xie, Yanfei,Yang, Mengxiang,Zhang, Bin,Zhang, Panpan,Zhou, Fei,Zou, Jiamei
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supporting information
(2021/10/12)
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- Synthesis and antioxidant evaluation of some heterocyclic candidates from 3-(1,3-diphenyl-1H-pyrazol-4-yl)-2-(4-oxo-4H-benzo[d][1,3]oxazin-2-yl)propenonitrile
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A new series of quinazoline derivatives bearing a 1,3-diphenylpyrazole core was synthesized starting from 3-(1,3-diphenyl-1H-pyrazol-4-yl)-2-(4-oxo-4H-benzo[d][1,3]oxazin-2yl)propenonitrile (4) through reactions with some nitrogen nucleophiles. Hydrazinolysis of 4 furnished the biquinazoline and diheterylazine derivatives depending on the reaction conditions. Noteworthy, the benzimidazole derivatives were obtained via treatment with 2-aminoaniline under different reaction conditions. Inspect of the reactions of 4 with hydrazinecarbothioamide and hydrazinecarbothiohydrazide provided thiosemicarbazide, triazepinoquinazoline, and mercaptotetrazine derivatives. The antioxidant screening disclosed that some of these compounds such as 3, 5, 11, 12, and 13 exhibited significant potency.
- Ramadan, Sayed K.,El-Ziaty, Ahmed K.,El-Helw, Eman A. E.
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supporting information
p. 1272 - 1283
(2021/02/06)
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- Palladium(II)/Lewis Acid-Catalyzed Oxidative Olefination/Annulation of N-Methoxybenzamides: Identifying the Active Intermediates through NMR Characterizations
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Although Pd(II)-catalyzed C-H activation in arenes has been widely successful in organic synthesis with many palladacycle compounds isolated as the intermediates in ligand-directed C-H activation, direct identification of the reaction intermediates such as the π-complex prior to the C-H activation is still not successful because of their instability. In the present study, we introduce a Pd(II)/LA (LA: Lewis acid)-catalyzed oxidative olefination/annulation reaction between N-methoxybenzamides and acrylates with oxygen as the oxidant source, in which two intermediates, including an unsymmetrical η6-complex and a palladacycle species without the proton releasing to the environment, were identified through NMR characterizations. The in situ formation of the heterobimetallic Pd(II)/LA species such as Pd(II)/Sc(III) may have enhanced the electrophilic properties of the Pd2+ cation, thus improving the stability of the π-complex, herein, an unsymmetrical η6-complex, and improving its catalytic efficiency. The observed insensitive electronic effect preferred the concerted metalation-deprotonation (CMD) mechanism for this C-H activation, and the detected palladacycle intermediate without the proton releasing to the environment offered an experimental clue to support the proposed CMD mechanism.
- Xue, Jing-Wen,Zeng, Miao,Jiang, Hongwu,Li, Kaiwen,Chen, Zhuqi,Yin, Guochuan
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p. 8760 - 8772
(2020/08/14)
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- Pyrimidinone compound or pharmaceutically acceptable salt, and preparation method and application thereof
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The invention discloses a pyrimidinone compound with a structure represented by a general formula I or a pharmaceutically acceptable salt, and a preparation method and application thereof. Tacrine fragments and pyrimidinone structures are fused in a molecular skeleton, and the application of the skeleton structure in a multi-target anti-AD strategy is realized for the first time. Pharmacological experiments show that the pyrimidinone compound disclosed by the invention has an obvious inhibition effect on AChE/GSK-3[beta] double targets.
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Paragraph 0110-0111
(2020/07/15)
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- Aldoxime-containing tacrine derivative selective butyrylcholine esterase inhibitors, and preparation method and application thereof
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The invention relates to aldoxime-containing tacrine derivative selective butyrylcholine esterase inhibitors, and a preparation method and application thereof. The compounds have a structure represented by a formula I or a formula II. The invention also relates to a pharmaceutical composition containing the compounds with the structures of the formula I or the formula II. The invention also provides application of the compounds and the composition containing one or more of the compounds in preparation of anti-Alzheimer's disease drugs.
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Paragraph 0050-0053
(2020/09/08)
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- Palladium nanoparticles embedded in mesoporous carbons as efficient, green and reusable catalysts for mild hydrogenations of nitroarenes
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The reduction of nitroarenes is the most efficient route for the preparation of aromatic primary amines. These reductions are generally performed in the presence of heterogeneous transition metal catalysts, which are rather efficient but long and tedious to prepare. In addition, they contain very expensive metals that are in most cases difficult to reuse. Therefore, the development of efficient, easily accessible and reusable Pd catalysts obtained rapidly from safe and non-toxic starting materials was implemented in this report. Two bottom-up synthesis methods were used, the first consisted in the impregnation of a micro/mesoporous carbon support with a Pd salt solution, followed by thermal reduction (at 300, 450 or 600 °C) while the second involved a direct synthesis based on the co-assembly and pyrolysis (600 °C) of a mixture of a phenolic precursor, glyoxal, a surfactant and a Pd salt. The obtained composites possess Pd nanoparticles (NPs) of tunable sizes (ranging from 1-2 to 7.0 nm) and homogeneously distributed in the carbon framework (pores/walls). It turned out that they were successfully used for mild and environment-friendly hydrogenations of nitroarenes at room temperature under H2(1 atm) in EtOH in the presence of only 5 mequiv. of supported Pd. The determinations of the optimal characteristics of the catalysts constituted a second objective of this study. It was found that the activity of the catalysts was strongly dependent on the Pd NPs sizes,i.e., catalysts bearing small Pd NPs (1.2 nm obtained at 300 °C and 3.4 nm obtained at 450 °C) exhibited an excellent activity, while those containing larger Pd NPs (6.4 nm and 7.0 nm obtained at 600 °C, either by indirect or direct methods) were not active. Moreover, the possibility to reuse the catalysts was shown to be dependent on the surface chemistry of the Pd NPs: the smallest Pd NPs are prone to oxidation by air and their surface was gradually covered by a PdO shell decreasing their activity during reuse. A good compromise between intrinsic catalytic activity (i.e. during first use) and possibility of reuse was found in the catalyst made by impregnation followed by reduction at 450 °C since the hydrogenation could be performed in only 2 h in EtOH or even in water. The catalyst was quantitatively recovered after reaction by filtration, used at least 7 times with no loss of efficiency. Advantageously, almost Pd-free primary aromatic amines were obtained since the Pd leaching was very low (0.1% of the introduced amount). Compared to numerous reports from the literature, the catalysts described here were both easily accessible from eco-friendly precursors and very active for hydrogenations under mild and “green” reaction conditions.
- Becht, Jean-Michel,Enneiymy, Mohamed,Fioux, Philippe,Le Drian, Claude,Matei Ghimbeu, Camelia
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p. 36741 - 36750
(2020/10/19)
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- POLYMERS FOR USE IN ELECTRONIC DEVICES
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Disclosed is a dianhydride having Formula (I). In Formula (I): Q1 is CR4, SiR4, GeR4, PR4, or N; Q2 is CR5, SiR5, GeR5, PR5, or N; R1, R2, and R3 are the same or different at each occurrence and are F, CN, alkyl, fluoroalkyl, unsubstituted or substituted hydrocarbon aryl, unsubstituted or substituted heteroaryl, alkoxy, fluoroalkoxy, unsubstituted or substituted aryloxy, silyl, or siloxy, where adjacent R1 groups can be joined together to form a fused aromatic ring; R4 and R5 are the same or different and are H, F, CN, alkyl, fluoroalkyl, unsubstituted or substituted hydrocarbon aryl, unsubstituted or substituted heteroaryl, alkoxy, fluoroalkoxy, unsubstituted or substituted aryloxy, silyl, or siloxy; a is an integer from 0-4; b and c are the same or different and are an integer from 0-2; and the double dashed lines between two rings indicate that the two rings can be fused at any available position.
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Page/Page column 67; 69
(2020/02/14)
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- Method for reducing aromatic nitro into arylamine
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The invention relates to a method for reducing aromatic nitro to arylamine. The method comprises the following steps: (1) taking an aromatic nitro compound as a raw material, water as a hydrogen source, a palladium compound, cheap and easy to obtain, as a catalyst and tetrahydroxydiboron as an additive to reduce nitro to obtain a product; (2) taking the aromatic nitro compound as the raw material, a copper salt, cheap and easy to obtain, as the catalyst, the tetrahydroxydiboron as the additive to reduce the nitro to obtain a product; and (3) taking the aromatic nitro compound as the raw material, water as the hydrogen source, and the tetrahydroxydiboron as the additive, without needing a metal catalyst, to reduce the nitro to obtain a product. A preparation method for the arylamine, which is provided by the invention, is mild in reaction condition, low in costs, environment-friendly, high in yield, and suitable for industrial production.
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Paragraph 0141-0144; 0237-0240
(2020/07/15)
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- Heterogeneous AgPd Alloy Nanocatalyst for Selective Reduction of Aromatic Nitro Compounds Using Formic Acid as Hydrogen Source
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Abstract: A Heterogeneous catalyst developed for selective reduction of nitroarenes to the analogous anilines using formic acid as hydrogen source. This catalytic procedure offers a simplistic path to prepare aromatic amines in good to excellent yields. Especially, even anilines functionalized with other potentially reducible moieties are obtained with high selectivity. Herein, we report convenient and stable bimetallic AgPd nanocatalyst supported on metal organic framework coated with polyaniline. Hydrogenation of nitroarenes gave analogues anilines with excellent yields at 90?°C in 6?h with no use of additives. Catalyst maintained stable performance in five repeated cycles. Graphic Abstract: [Figure not available: see fulltext.].
- Babel, Vikram,Hiran
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p. 1865 - 1869
(2020/01/28)
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- A cyclometalated Ir(iii)-NHC complex as a recyclable catalyst for acceptorless dehydrogenation of alcohols to carboxylic acids
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In this work, we have synthesized two new [C, C] cyclometalated Ir(iii)-NHC complexes, [IrCp?(C∧C:NHC)Br](1a,b), [Cp? = pentamethylcyclopentadienyl; NHC = (2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazoline-2-ylidene (a); (2-flurobenzyl)-1-(4-formylphenyl)-1H-imidazoline-2-ylidene (b)] via intramolecular C-H bond activation. The molecular structure of complex 1a was determined by X-ray single crystal analysis. The catalytic potentials of the complexes were explored for acceptorless dehydrogenation of alcohols to carboxylic acids with concomitant hydrogen gas evolution. Under similar experimental conditions, complex 1a was found to be slightly more efficient than complex 1b. Using 0.1 mol% of complex 1a, good-to-excellent yields of carboxylic acids/carboxylates have been obtained for a wide range of alcohols, both aliphatic and aromatic, including those involving heterocycles, in a short reaction time with a low loading of catalyst. Remarkably, our method can produce benzoic acid from benzyl alcohol on a gram scale with a catalyst-to-substrate ratio as low as 1?:?5000 and exhibit a TON of 4550. Furthermore, the catalyst could be recycled at least three times without losing its activity. A mechanism has been proposed based on controlled experiments and in situ NMR study.
- Borah, Dhrubajit,Das, Pankaj,Saha, Biswajit,Sarma, Bipul
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p. 16866 - 16876
(2020/12/18)
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- Glucose as an Eco-Friendly Reductant in a One-Pot Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones
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Carbohydrates such as glucose are an abundant renewable resource that can be employed in synthetic processes as a source of carbon and/or hydrogen to yield products of high economical and biological impact. Herein, we report a versatile and environmentally friendly protocol for the one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones, a privileged scaffold in medicinal chemistry, based on the use of glucose as an eco-friendly reductant in alkaline aqueous medium. This method can be viewed as a blueprint for the development of further one-pot sequences involving glucose as a reductant.
- dos Santos, Thiago,Grundke, Caroline,Lucas, Tobias,Gro?mann, Luca,Clososki, Giuliano Cesar,Opatz, Till
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supporting information
p. 6429 - 6432
(2020/09/02)
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- Coordination among Bond Formation/Cleavage in a Bifunctional-Catalyzed Fast Amide Hydrolysis: Evidence for an Optimized Intramolecular N-Protonation Event
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A density functional theory (DFT) computational analysis, using the ωB97X-D functional, of a rapid amide cleavage in 2-carboxyphthalanilic acid (2CPA), where the amide group is flanked by two catalytic carboxyls, reveals key mechanistic information: (a) General base catalysis by a carboxylate coupled to general acid catalysis by a carboxyl is not operative. (b) Nucleophilic attack by a carboxylate on the amide carbonyl coupled to general acid catalysis at the amide oxygen can also be ruled out. (c) A mechanistic pathway that remains viable involves general acid proton delivery to the amide nitrogen by a carboxyl, while the other carboxylate engages in nucleophilic attack upon the amide carbonyl; a substantially unchanged amide carbonyl in the transition state; two concurrent bond-forming events; and a spatiotemporal-base rate acceleration. This mechanism is supported by molecular dynamic simulations which confirm a persistent key intramolecular hydrogen bonding. These theoretical conclusions, although not easily verified by experiment, are consistent with a bell-shaped pH/rate profile but are at odds with hydrolysis mechanisms in the classic literature.
- Affeldt, Ricardo F.,Caramori, Giovanni F.,De Souza, Fábio P. S.,Ferraz, Matheus S.,Menger, Fredric M.,Nome, Faruk,Oliveira, Bruno S.,Scorsin, Leandro,Silveira, Eduardo V.,Souza, Bruno S.
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supporting information
p. 4663 - 4671
(2020/05/01)
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- Multi-target tacrine derivative and preparation method and application thereof
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The invention provides a multi-target tacrine derivative and a preparation method and application thereof. The compound has the structure shown in a formula (I) (please see the specification in the formula (I)), wherein n is a natural number greater than 1; m is 1 or 2; p is 0 or 1; R1 is H or halogen; and Y is selected from the following structures (please see the specification for the structures) or, a pharmaceutically acceptable salt of a compound in a formula (X). According to the compound, activity of histone deacetylase (HDACs), acetylcholinesterase (AChE) or butyryl cholinesterase (BChE) can be effectively inhibited.
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Paragraph 0135-0137
(2019/12/25)
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- Br?nsted Acid-Catalyzed Asymmetric Ring-Closing Alkylation of Inert N-substituted Pyrroles with α, β-Unsaturated Ketones
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A Chiral Br?nsted acid catalyzed asymmetric intramolecular ring-closing alkylation of inert pyrroles with α, β-unsaturated ketones has been developed. This approach gave a wide range of 4-phenyl-4,5-dihydro-6H-benzo[f]pyrrolo[1,2-a]azepin-6-ones in high yields with good enantioselectivities under mild reaction conditions. (Figure presented.).
- Wei, Zhao,Zhang, Jinlong,Yang, Huameng,Jiang, Gaoxi
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supporting information
p. 3694 - 3697
(2019/07/12)
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- 2-carboxyl piperazine linked tacrine-8-amino(hydroxyl) quinoline derivative as well as preparation and application
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The invention relates to the technical field of chemical synthesis, and specifically relates to a 2-carboxyl piperazine linked tacrine-8-amino(hydroxyl) quinoline derivative as well as preparation andapplication. The 2-carboxyl piperazine linked tacrine-8-amino(hydroxyl) quinoline derivative is a chemical compound shown in a formula I (the formula I is shown in the description) or a pharmaceutically acceptable salt thereof, and a solvent chemical compound, an enantiomer, a diastereoisomer, a tautomer or a mixture in any proportion of the chemical compound shown in the formula I or the pharmaceutically acceptable salt thereof, and includes a racemic mixture. Confirmed by a pharmacological test, the kind of chemical compound has an inhibiting effect on the activity of acetylcholinesterase(AChE) and butyrylcholinesterase(BuChE), and belongs to a cholinesterase inhibitor; the chemical compound also has an inhibiting effect on self-aggregation of beta-amyloid protein, and has delayed action on hydrolysis of acetylcholine and self-aggregation of the beta-amyloid protein, thereby improving the effect of the acetylcholine on a synapse, and finally realizing the purpose of effectively treating alzheimer's disease (AD).
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Paragraph 0046; 0129-0132
(2019/08/06)
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- Green reusable Pd nanoparticles embedded in phytochemical resins for mild hydrogenations of nitroarenes
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A green chemical preparation of Pd nanoparticles (NPs) embedded in phytochemical resins using a plant extract from Pulicaria odora L. and PdCl2 under ambiant conditions is reported. Two batches of Pd NPs have been prepared: they present homogeneous sizes of respectively 2.2 nm and 3.2 nm depending on the preparation conditions. The Pd NPs were characterized by different techniques (TEM, HRTEM, XRD, XPS and BET) and have been successfully used for the reduction of nitroarenes in EtOH under H2 at atmospheric pressure at rt in the presence of only 5 mequiv. of Pd. Finally the Pd NPs embedded in resin particles were easily recovered by filtration and used at least seven times without significant loss in efficiency. The residual amount of palladium found in the reaction product is very low (0.6% of the initial amount). Therefore both preparation of the Pd NPs and their use for hydrogenations of nitroarenes are environmentally benign.
- Enneiymy, Mohamed,Le Drian, Claude,Becht, Jean-Michel
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supporting information
p. 17383 - 17389
(2019/11/20)
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- Hydrogenation of nitroarenes to anilines in a flow reactor using polystyrene supported rhodium in a catalyst-cartridge (Cart-Rh@PS)
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The present methodology described the chemo-selective hydrogenation of various nitroarenes in a flow reactor under polystyrene supported rhodium in a catalyst-cartridge (Cart-Rh@PS) as a heterogeneous nano-catalyst. The polystyrene supported Rh (Rh@PS) nanoparticles (NPs) were prepared by following our earlier reported protocol and packed inside the catalyst-cartridge (Cat-Cart) to obtain Cart-Rh@PS, which is compatible with ThalesNano's H-Cube Pro flow system. The advantages of the prepacked catalyst Cart-Rh@PS are as follows: no need for catalyst activation up to 12 runs, negligible metal leaching detected by ICP-AES analysis and significantly less back pressure generated under the flow conditions. The same catalyst, Cart-Rh@PS, was also effective up to a 1 gram scale for the reduction of nitroarenes and reusable for successive runs. The hydrogenation in the flow reactor is a greener approach for the reduction of nitroarenes to their corresponding anilines in high yields.
- Sharma, Saurabh,Yamini,Das, Pralay
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supporting information
p. 1764 - 1769
(2019/01/28)
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- Green and convenient protocols for the efficient reduction of nitriles and nitro compounds to corresponding amines with NaBH4 in water catalyzed by magnetically retrievable CuFe2O4 nanoparticles
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Abstract: In this study, firstly, CuFe2O4 nanoparticles were prepared by a simple operation. The structure of the mentioned nanoparticles was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma-optical emission spectrometry, vibrating sample magnetometer and also Brunauer–Emmett–Teller and Barrett–Joyner–Halenda analyses. The prepared magnetically copper ferrite nanocomposite was successfully applied as a simple, cost-effective, practicable, and recoverable catalyst on the green, highly efficient, fast, base-free, and ligand-free reduction of nitriles and also on the affordable and eco-friendly reduction of nitro compounds with the broad substrate scope to the corresponding amines with NaBH4 in water at reflux in high to excellent yields. Graphical abstract: [Figure not available: see fulltext.].
- Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
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- Design, synthesis, and evaluation of isoflavone analogs as multifunctional agents for the treatment of Alzheimer's disease
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A series of novel isoflavone analogs were designed, synthesized, and evaluated as multitarget-directed ligands for the treatment of Alzheimer's disease. In vitro evaluations revealed that some ligands had multifunctional profiles, including potent blockage of histamine 3 receptor (H3R), excellent inhibition of acetylcholinesterase (AChE), neuroprotective effects and anti-neuroinflammatory properties. Among these derivatives, compound 9b exhibited the highest ability to block H3R (IC50 = 0.27 μM) and good inhibitory activity against AChE (IC50 = 0.08 μM). Additionally, compound 9b showed obvious neuroprotective effect on SH-SY5Y by preventing copper-induced neuronal damage and potent anti-neuroinflammatory activity by inhibiting the production of inflammatory factors on BV-2 cells. A molecular modeling study revealed that 9b acts as a mixed-type inhibitor that interacts simultaneously with H3R and AChE. Moreover, in vivo data revealed that compound 9b did not cause acute toxicity in mice at doses up to 1000 mg/kg, and had desirable pharmacokinetic properties, as well as a good blood-brain barrier (BBB) permeability (log BB = 1.24 ± 0.07). Further studies demonstrated that chronic oral treatment with 9b significantly improved cognitive dysfunction in scopolamine-induced AD mice in the step-down passive avoidance test. Taken together, the present study showed that compound 9b is a promising multifunctional drug candidate for the treatment of Alzheimer's disease.
- Wang, Dongmei,Hu, Min,Li, Xinpeng,Zhang, Dan,Chen, Chengjuan,Fu, Junmin,Shao, Shuai,Shi, Gaona,Zhou, Yu,Wu, Song,Zhang, Tiantai
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p. 207 - 220
(2019/02/28)
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- Tacrine-Hydrogen Sulfide Donor Hybrid Ameliorates Cognitive Impairment in the Aluminum Chloride Mouse Model of Alzheimer's Disease
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Alzheimer's disease (AD) is a neurodegenerative disorder, characterized by progressive loss of memory and cognitive function, and is associated with the deficiency of synaptic acetylcholine, as well as chronic neuroinflmmation. Tacrine, a potent acetylcholinesterase (AChE) inhibitor, was previously a prescribed clinical therapeutic agent for AD, but it was recently withdrawn because it caused widespread hepatotoxicity. Hydrogen sulfide (H2S) has neuroprotective, hepatoprotective, and anti-inflammatory effects. In this study, we synthesized a new compound, a tacrine-H2S donor hybrid (THS) by introducing H2S-releasing moieties (ACS81) to tacrine. Subsequently, pharmacological and biological evaluations of THS were conducted in the aluminum trichloride (AlCl3)-induced AD mice model. We found that THS (15 mmol/kg) improved cognitive and locomotor activity in AD mice in the step-through test and open field test, respectively. THS showed strong AChE inhibitory activity in the serum and hippocampus of AD mice and induced increased hippocampal H2S levels. Furthermore, THS reduced mRNA expression of the proinflammatory cytokines, TNF-α, IL-6, and IL-1β and increased synapse-associated proteins (synaptophysin and postsynaptic density protein 95) in the hippocampus of AD mice. Importantly, THS, unlike tacrine, did not increase liver transaminases (alanine transaminase and aspartate transaminase) or proinflammatory cytokines, indicating THS is much safer than tacrine. Therefore, the multifunctional effects of this new hybrid compound of tacrine and H2S indicate it is a promising compound for further research into the treatment of AD.
- Cheng, Xiao-Jing,Gu, Jing-Xue,Pang, Yi-Peng,Liu, Jiao,Xu, Ting,Li, Xin-Rui,Hua, Yu-Zhou,Newell, Kelly A.,Huang, Xu-Feng,Yu, Yinghua,Liu, Yi
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p. 3500 - 3509
(2019/07/04)
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- Synergistic Effects of ppm Levels of Palladium on Natural Clinochlore for Reduction of Nitroarenes
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Augmenting the modified naturally occurring clay clinochlore with ppm amounts of palladium leads to a new and very effective reagent for the reduction of numerous aromatic nitro species. When palladium nanoparticles are supported on pyridyltriazole-modified clinochlore, iron within clinochlore acts synergistically with palladium to catalyze the reduction of a wide variety of nitroarenes at room temperature in aqueous media. Based on E-factor calculations, the catalyst system is found to be in line with green chemistry standards and can be recycled up to five times.
- Gholinejad, Mohammad,Oftadeh, Erfan,Shojafar, Mohammad,Sansano, José M.,Lipshutz, Bruce H.
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p. 4240 - 4248
(2019/09/06)
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- Molecular Hybridization-Inspired Optimization of Diarylbenzopyrimidines as HIV-1 Nonnucleoside Reverse Transcriptase Inhibitors with Improved Activity against K103N and E138K Mutants and Pharmacokinetic Profiles
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Molecular hybridization is a powerful strategy in drug discovery. A series of novel diarylbenzopyrimidine (DABP) analogues were developed by the hybridization of FDA-approved drugs etravirine (ETR) and efavirenz (EFV) as potential HIV-1 nonnucleoside reverse transcriptase inhibitors (NNRTIs). Substituent modifications resulted in the identification of new DABPs with the combination of the strengths of the two drugs, especially compound 12d, which showed promising activity toward the EFV-resistant K103N mutant. 12d also had a favorable pharmacokinetic (PK) profile with liver microsome clearances of 14.4 μL/min/mg (human) and 33.2 μL/min/mg (rat) and an oral bioavailability of 15.5% in rat. However, its activity against the E138K mutant was still unsatisfactory; E138K is the most prevalent NNRTI resistance-associated mutant in ETR treatment. Further optimizations resulted in a highly potent compound (12z) with no substituents on the phenyl ring and a 2-methyl-6-nitro substitution pattern on the 4-cyanovinyl-2,6-disubstitued phenyl motif. The antiviral activity of this compound was much higher than those of ETR and EFV against the WT, E138K, and K103N variants (EC50 = 3.4, 4.3, and 3.6 nM, respectively), and the cytotoxicity was decreased while the selectivity index (SI) was increased. In particular, this compound exhibited acceptable intrinsic liver microsome stability (human, 34.5 μL/min/mg; rat, 33.2 μL/min/mg) and maintained the good PK profile of its parent compound EFV and showed an oral bioavailability of 16.5% in rat. Molecular docking and structure-activity relationship (SAR) analysis provided further insights into the binding of the DABPs with HIV-1 reverse transcriptase and provided a deeper understanding of the key structural features responsible for their interactions.
- Han, Sheng,Sang, Yali,Wu, Yan,Tao, Yuan,Pannecouque, Christophe,De Clercq, Erik,Zhuang, Chunlin,Chen, Fen-Er
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