- The role of the disulfide bond in amyloid-like fibrillogenesis in a model peptide system
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Three terminally protected short peptides Bis[Boc-D-Leu(1)-Cys(2)-OMe] 1, Bis[Boc-Leu(1)-Cys(2)-OMe] 2 and Bis[Boc-Val(1)-Cys(2)-OMe] 3 exhibit amyloid-like fibrillar morphology. Single crystal X-ray diffraction analysis of peptide 1 clearly demonstrates that it adopts an overall extended backbone molecular conformation that self-assembles to form an intermolecular hydrogen-bonded antiparallel supramolecular β-sheet structure in crystals. Scanning electron microscopic (SEM) images, transmission electron microscopic (TEM) images and Congo red binding studies vividly demonstrate the amyloid-like fibril formation of peptides 1, 2 and 3. However, after reduction of the disulfide bridge of peptides 1, 2 and 3, three newly generated peptides Boc-D-Leu(1)-Cys(2)-OMe 4, Boc-Leu(1)-Cys(2)-OMe 5 and Boc-Val(1)-Cys(2)-OMe 6 are formed and all of them failed to form any kind of fibril under the same conditions, indicating the important role of the disulfide bond in amyloid-like fibrillogenesis in a peptide model system. The Royal Society of Chemistry 2005.
- Das, Apurba Kumar,Drew, Michael G. B.,Haldar, Debasish,Banerjee, Arindam
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- Crystal-to-Crystal Synthesis of Triazole-Linked Pseudo-proteins via Topochemical Azide-Alkyne Cycloaddition Reaction
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Isosteric replacement of amide bond(s) of peptides with surrogate groups is an important strategy for the synthesis of peptidomimetics (pseudo-peptides). Triazole is a well-recognized bio-isostere for peptide bonds, and peptides with one or more triazole units are of great interest for different applications. We have used a catalyst-free and solvent-free method, viz., topochemical azide-alkyne cycloaddition (TAAC) reaction, to synthesize pseudo-proteins with repeating sequences. A designed β-sheet-forming l-Ala-l-Val dipeptide containing azide and alkyne at its termini (N3-Ala-Val-NHCH2C=CH, 1) was synthesized. Single-crystal XRD analysis of the dipeptide 1 showed parallel β-sheet arrangement along the b-direction and head-to-tail arrangement of such β-sheets along the c-direction. This head-to-tail arrangement along the c-direction places the complementary reacting motifs, viz., azide and alkyne, of adjacent molecules in proximity. The crystals of dipeptide 1, upon heating at 85 °C, underwent crystal-to-crystal polymerization, giving 1,4-triazole-linked pseudo-proteins. This TAAC polymerization was investigated by various time-dependent techniques, such as NMR, IR, DSC, and PXRD. The crystal-to-crystal nature of this transformation was revealed from polarizing microscopy and PXRD experiments, and the regiospecificity of triazole formation was evidenced from various NMR techniques. The MALDI-TOF spectrum showed the presence of pseudo-proteins >7 kDa.
- Krishnan, Baiju P.,Rai, Rishika,Asokan, Aromal,Sureshan, Kana M.
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- Anthracene-labeled pyridinium-based symmetrical chiral chemosensor for enantioselective recognition of l-tartrate
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A new anthracene-based chiral chemosensor 1 has been designed and synthesized. l-Valine has been used as the chiral source in the design. The chemosensor 1 has been established as an efficient enantioselective sensor for l-tartrate. While in the presence of l-tartrate the fluorescent sensor 1 in DMSO exhibits considerable increase in emission, the isomeric tartrate brings relatively small change. The enantiomeric fluorescence difference ratio (ef) has been determined to be 29.38.
- Ghosh, Kumaresh,Sarkar, Tanmay
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- An improved large scale synthesis of the Schoellkopf chiral auxiliaries: (2R)-and (2S)-2,5-Dihydro-3,6-dimethoxy-2-isopropylpyrazine
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Syntheses of the Schoellkopf chiral auxiliaries have been carried out on large scale in high overall yields from D- and L-valine. This method avoids the use of highly toxic phosgene or triphosgene, low-temperature reactions, and unstable intermediates.
- Chen, Jianxie,Corbin, Scott P.,Holman, Nicholas J.
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- A short water-soluble self-assembling peptide forms amyloid-like fibrils
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A water-soluble tripeptide Val-Ile-Ala (VIA) 1, bearing sequence identity with the C-terminal portion of the Alzheimer Aβ-peptide (Aβ40-42), self-assembles, in crystalline form, to produce an intermolecularly hydrogen bonded supramolecular β-sheet structure which self-associates to form straight, unbranched nanofibrils exhibiting amyloid-like behavior; in contrast, the synthetic tripeptide Ala-Val-Ile (AVI) 2 self-assembles to produce a β-sheet structure that forms branched nanofibrils which do not show any characteristic features of amyloid-like fibrils. The Royal Society of Chemistry 2006.
- Ray, Sudipta,Das, Apurba K.,Drew, Michael G. B.,Banerjee, Arindam
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- An amyloid-like fibril-forming supramolecular cross-β-structure of a model peptide: A crystallographic insight
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The peptide Boc-Val-Phe-OMe 1 bearing sequence similarity with the central hydrophobic cluster (CHC) of Alzheimer's Aβ18-19 peptide self-assembles to produce amyloid-like straight unbranched fibrils as examined by atomic force microscopy and Congo red assay. Single crystal X-ray diffraction offers the atomic level structure of the supramolecular parallel β-sheet aggregation and antiparallel separation between layers (cross-β-structure).
- Maity, Sibaprasad,Kumar, Pankaj,Haldar, Debasish
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- Enantioselective sensing of lactate by pyridinium-based chiral receptor
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A simple pyridinium-based chiral receptor 1 containing l-valine as the chiral source has been designed and synthesized. The receptor 1 fluorometrically recognizes d-lactate over l-lactate in CH3CN with an enantiomeric fluorescence ratio (ef) of 5.32.
- Ghosh, Kumaresh,Majumdar, Anupam
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- Short-peptide-based hydrogel: A template for the in situ synthesis of fluorescent silver nanoclusters by using sunlight
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N-terminally Fmoc-protected dipeptide, Fmoc-Val-Asp-OH, forms a transparent, stable hydrogel with a minimum gelation concentration of 0.2 % w/v. The gelation property of the hydrogel was investigated by using methods such as transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy. The silver-ion-encapsulating hydrogel can efficiently and spontaneously produce fluorescent silver nanoclusters under sunlight at physiological pH (7.46) by using a green chemistry approach. Interestingly, in the absence of any conventional reducing agent but in the presence of sunlight, silver ions were reduced by the carboxylate group of a gelator peptide that contains an aspartic acid residue. These clusters were investigated by using UV/Vis spectroscopy, photoluminescence spectroscopy, high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) studies. Mass spectrometric analysis shows the presence of a few atoms in nanoclusters containing only Ag2. The reported fluorescent Ag nanoclusters show excellent optical properties, including a very narrow emission profile and large Stokes shift (>100 Nm). The reported fluorescent Ag nanoclusters within hydrogel are very stable even after 6 Months storage in the dark at 4 °C. The as-prepared hydrogel-nanocluster conjugate could have applications in antibacterial preparations, bioimaging and other purposes. Silver nanoparticles: An N-terminally protected dipeptide-based hydrogel has been used to make fluorescent silver nanoclusters in the presence of sunlight at room temperature and at physiological pH by using a green chemistry approach. The fluorescent silver nanoclusters exhibit interesting fluorescence properties with a very narrow emission profile and large Stokes shift that may be useful in future applications. Copyright
- Adhikari, Bimalendu,Banerjee, Arindam
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- Synthesis and biological evaluation of new pleuromutilin derivatives as antibacterial agents
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Several pleuromutilin derivatives possessing thiadiazole moieties were synthesized via acylation reactions under mild conditions. The in vitro antibacterial activities of the derivatives against methicillin-resistant S. aureus, methicillin-resistant S. epidermidis, S. aureus, S. epidermidis, E. coli, and B. cereus were tested by the agar dilution method and Oxford cup assay. All the screened compounds displayed potent activity. Compound 6d was the most active antibacterial agent because of its lowest MIC value and largest inhibition zone. Docking experiments were performed to understand the possible mode of the interactions between the derivatives and 50S ribosomal subunit. Moreover, the absorption, distribution, metabolism, excretion and toxicity properties of the synthesized compounds were analyzed after prediction using the Advanced Chemistry Development/Percepta Platform available online.
- Shang, Ruo-Feng,Wang, Guan-Hua,Xu, Xi-Ming,Liu, Si-Jie,Zhang, Chao,Yi, Yun-Peng,Liang, Jian-Ping,Liu, Yu
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- Synthesis of Majusculamides A and B
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The synthesis of two marine lipodipeptides, majusculamides A and B, is described. The key feature of this synthesis is the stereoselective construction of an α-methyl-β-keto-carboxamide moiety.
- Nakajima, Daisuke,Sueyoshi, Kosuke,Orihara, Kensuke,Teruya, Toshiaki,Yokoshima, Satoshi
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- Heating reactions of N-t-Butyloxycarbonyl-Asparagine and related compounds
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N-t-Butyloxycarbonyl-amino acids (Boc-) are labile on heating to afford free amino acids, but Boc-aspartic acid gives a kind of polypeptide. This chemical feature of Boc-aspartic acid may be caused by dehydration between two carboxyl groups as well as the formation of a free amino group. Boc-Asparagine may have a similar reactivity to Boc-aspartic acid. This research describes polypeptide formation by heating Boc-asparagine and its isomer Boc-aspartic acid amide.
- Munegumi,Akao,Kawatu,Yamada,Harada
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- Construction and activity evaluation of novel benzodioxane derivatives as dual-target antifungal inhibitors
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Ergosterol exert the important function in maintaining the fluidity and osmotic pressure of fungal cells, and its key biosynthesis enzymes (Squalene epoxidase, SE; 14 α-demethylase, CYP51) displayed the obvious synergistic effects. Therefore, we expected to discover the novel antifungal compounds with dual-target (SE/CYP51) inhibitory activity. In the progress, we screened the different kinds of potent fragments based on the dual-target (CYP51, SE) features, and the method of fragment-based drug discovery (FBDD) was used to guide the construction of three different series of benzodioxane compounds. Subsequently, their chemical structures were synthesized and evaluated. These compounds displayed the obvious biological activity against the pathogenic fungal strains. Notably, target compounds 10a-2 and 22a-2 possessed the excellent broad-spectrum anti-fungal activity (MIC50, 0.125–2.0 μg/mL) and the activity against drug-resistant strains (MIC50, 0.5–2.0 μg/mL). Preliminary mechanism studies have confirmed that these compounds effectively inhibited the dual-target (SE/CYP51) activity, they could cause fungal rupture and death by blocking the bio-synthetic pathway of ergosterol. Further experiments discovered that compounds 10a-2 and 22a-2 also maintained a certain of anti-fungal effect in vivo. In summary, this study not only provided the new dual-target drug design strategy and method, but also discover the potential antifungal compounds.
- An, Yunfei,Fan, Haiyan,Han, Jun,Liu, Wenxia,Sun, Bin,Xie, Honglei
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- PRODRUGS OF ABIRATERONE
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The present invention relates to compounds of formula (I), or their isotopic forms, stereoisomers, tautomers, or pharmaceutically acceptable salt(s) thereof as prodrugs of abiraterone. The present invention also describes method of making such compounds, pharmaceutical compositions comprising such compounds and the use of the compounds of formula (I).
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(2021/05/29)
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- α-Amino Acids and α,β-Dipeptides Intercalated into Hydrotalcite: Efficient Catalysts in the Asymmetric Michael Addition Reaction of Aldehydes to N-Substituted Maleimides
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In this work, a series of α-amino acids (L-Phe, D-Phe, L-Trp) and several α,β-dipeptides (H2N-L-Val-N-Bn-β-Ala-COOH and H2N-L-Leu-N-Bn-β-Ala-COOH) intercalated into hydrotalcite (Mg/Al, x=0.333) were prepared by high speed ball milling (HSBM) assisted rehydration/reconstruction methods, followed by sonication and mechanical stirring. All organic-inorganic hybrid samples were characterized by powder X-ray diffraction (XRD) and FTIR-ATR spectroscopy. The catalytic activity of the resulting hydrotalcite-supported materials (natural and hybrid) was evaluated in the asymmetric Michael addition reaction of α,α-disubstituted-aldehydes to N-substituted-maleimides. Pristine (HTS), calcined (HTC) and water-reconstructed (HTR-l) hydrotalcite-derived materials exhibited very low catalytic activities, affording racemic mixtures of the anticipated Michael adduct. By contrast, hybrid materials showed better activities, especially HTR-α-amino acid catalysts afforded Michael products in up to 94 % yield and with rather high enantioselectivity (enantiomeric ratio (e.r.) up to 99 : 1) at room temperature under neat reaction conditions. The effect of solvents and Br?nsted basic or acidic additives was evaluated using the best hybrid catalyst, HTR-L-Phe. In addition, recycling and reuse of the catalyst (up to 4 cycles) and large-scale experiments was successfully carried out.
- Landeros, José M.,Cruz-Hernández, Carlos,Juaristi, Eusebio
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supporting information
p. 5117 - 5126
(2021/09/13)
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- Convenient Synthesis of Alternatively Bridged Tryptophan Ketopiperazines and Their Activities against Trypanosomatid Parasites
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There is an urgent need for the development of new treatments against trypanosomatid parasites; the causative agents of some of the most debilitating diseases in the developing world. This work targets an interesting 6-5-6-6 fused carboline scaffold, accessing a range of substituted derivatives through stereospecific intramolecular Pictet–Spengler condensation. Modification of the cyclisation conditions allowed retention of the carbamate protecting group and gave insight into the reaction mechanism. Compounds’ bioactivities were measured against T. brucei, T. cruzi, L. major and HeLa cells. We have identified promising pan-trypanocidal lead compounds based on the core scaffold, and highlight key SAR trends which will be useful for the future development of these compounds as potent trypanocidal agents.
- Cockram, Peter E.,Slawin, Alexandra M. Z.,Smith, Terry K.,Turner, Callum A.
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supporting information
(2022/01/11)
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- Design and preparation of a novel prolinamide-based organocatalyst for the solvent-free asymmetric aldol reaction
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The preparation of four novel organocatalysts as highly diastereo and enantioselective catalysts for the solvent-free asymmetric aldol reaction was described. These organocatalysts were synthesized in eight steps applying simple and commercially available starting materials. The best results were obtained for the proline-derived catalyst, providing access to the desired adducts in up to 95% yield, 1:19 syn/anti and 98% e.e. Moreover, even sterically bulky aldehydes and substituted cyclohexanones were well tolerated. DFT calculations and control experiments indicated that several hydrogen bonding interactions between the aldehyde and the enamine intermediate are responsible for the stereoselective chiral induction process and that the trifluoroacetate counter-anion is crucial for the attainment of higher stereoselectivities.
- Martins, Rafaela de S.,Pereira, Mathias P.,de Castro, Pedro P.,Bombonato, Fernanda I.
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- Cytotoxic activity of synthetic chiral amino acid derivatives
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Cancer is a chronic degenerative disease considered one of the most important causes of death worldwide. In this context, a series of dual-protected amino acid derivatives was synthesized and evaluated as potential novel anticancer agents. The 40 derivatives were prepared in up to three reaction steps. The cytotoxic activities were screened in vitro against a panel of tumor and non-tumor cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among the synthesized derivatives, three of them showed promising activity against cancer cells with half-maximal inhibitory concentration (IC50) ranging between 1.7-6.1 μM. The most promising derivative, bearing both a lipophilic N-alkyl diamine moiety and a protected amino acid scaffold showed a selectivity index of 3.4 towards tumor cells. The N-alkyl diamine moiety seems to play a crucial role in the enhancement of the anticancer activity. On the other hand, the incorporation of an amino acid scaffold resulted in increase in the selectivity towards cancer cell lines.
- de Castro, Pedro P.,Siqueira, Raoni P.,Conforte, Luiza,Franco, Chris H.J.,Bressan, Gustavo C.,Amarante, Giovanni W.
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p. 193 - 200
(2019/12/28)
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- Synthesis, in vitro and in vivo biological evaluation of dihydroartemisinin derivatives with potential anti-Toxoplasma gondii agents
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In this study, four series of dihydroartemisinin derivatives were designed, synthesized, and evaluated for anti-toxoplasma gondii activity, and calculated the selectivity index (SI). It was the higher the SI, the better the effect of this compound against Toxoplasma gondii. Our goal was to filter out compounds that were bigger SI than the lead compound. The compound with the highest SI was selected for the anti-toxoplasmosis test in mice in vivo. Among the synthesized compounds, the (3R,5aS,6R,8aS,9R,12R,12aR)-3,6,9-trimethyl-decahydro-12H-3,12-epoxy[1,2]di-oxepino[4,3 -i]isochromen-10-yl-(te-rt-butoxycarbonyl)-L-alaninate (A2) exhibited the most potent anti-T. gondii activity and low cytotoxicity (SI: 6.44), yielding better results than the lead compound DHA (SI: 1.00) and the clinically used positive-control drug spiramycin (SI: 0.72) in vitro. Furthermore, compound A2 had better growth inhibitory effects on T. gondii in vivo than spiramycin did and significantly reduced the number of tachyzoites in the peritoneal cavity of mice (P 0.01). The evaluation of the data generated in the T. gondii mouse infection model indicates that compound A2 treatment was a good inhibitor of T. gondii in vivo and that it was effective in relieving the liver damage induced by T. gondii. In addition, the results of a docking study revealed that A2 could become a better T. gondii calcium-dependent protein kinase1 (TgCDPK1) inhibitor. For this reason, compound A2 has potential as an anti-parasitic drug. Further studies are required to elucidate the mechanism of the action of compound A2, as well as to develop drug delivery systems for patients.
- Deng, Hao,Huang, Xing,Jin, Chun-Mei,Jin, Chunmei,Quan, Zhe-Shan
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- Development of Chiral Ureates as Chiral Strong Br?nsted Base Catalysts
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Recently, chiral Br?nsted bases having high basicity have emerged as a powerful tool in developing new catalytic enantioselective reactions. However, such chiral strong Br?nsted base catalysts are still very scarce. Herein, we report the development of a chiral anionic Br?nsted base having a N,N′-dialkyl ureate moiety as a basic site. Its prominent catalytic activity was demonstrated in the enantioselective addition reactions of α-thioacetamides as less acidic pronucleophiles with various electrophiles. Thus, the newly developed chiral catalyst with high accessibility and structural tunability would expand the scope of viable enantioselective transformations under Br?nsted base catalysis.
- Ishikawa, Sho,Kondoh, Azusa,Terada, Masahiro
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supporting information
p. 3724 - 3728
(2020/03/11)
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- A Facile Approach to the Synthesis of Benzothiazoles from N-Protected Amino Acids
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Abstract: –A simple trituration method for the synthesis of 2-substituted benzothiazoles derived from N-protected amino acids and 2-aminothiophenol using molecular iodine as a mild Lewis acid catalyst has been proposed. The reaction occurs in one step for 20–25 min in solve-free conditions and provides the target products in excellent yields.
- Arfan, M.,Fatima, T.,Mannan, A.,Tahira, A.
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p. 292 - 297
(2020/04/21)
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- HMOX1 inducers
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The present invention is related to compounds of structure (I) as heme oxygenase 1 (HMOX 1) inducers. The present invention is also related a method of controlling the activity or the amount, or both the activity and the amount, of heme-oxygenase 1 in a mammalian subject. The definitions of the variables are provided herein.
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Page/Page column 59
(2020/09/18)
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- Synthesis of Phenylcyclopropane-Based Secondary Amine Catalysts and Their Applications in Enamine Catalysis
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A novel chiral motif based on a phenylcyclopropane scaffold has been designed, and a facile synthetic route to the key intermediate for the synthesis of phenylcyclopropane-based chiral secondary amines has been developed. Newly synthesized chiral amines function as effective catalysts for several asymmetric reactions through enamine intermediates.
- Kano, Taichi,Maruoka, Keiji,Takeshima, Aika
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supporting information
(2019/10/08)
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- Highly Diastereoselective Metal-Free Catalytic Synthesis of Drug-Like Spiroimidazolidinone
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A four-step procedure has been developed for the synthesis of (S)-3-isopropyl-1-[(R)-1-phenylethyl)- 1,4-diazaspiro[4.5]decan-2-one with high diastereoselectivity (up to 95% de) from (S)-α-aminoisovaleric acid (L-valine). Quantum chemical computations of the synthesized compound have been performed using Gaussian 09 software package.
- Jassem,Raheemah,Radhi,Alid,Jaber
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p. 1598 - 1603
(2019/12/28)
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- Monoglycosyl-containing heterocyclic compound for inhibiting hepatitis C viruses and preparation method
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The invention discloses a monoglycosyl-containing heterocyclic compound for inhibiting hepatitis C viruses and a preparation method. The monoglycosyl-containing heterocyclic compound has a chemical structure represented by a formula I shown in the description. The monoglycosyl-containing heterocyclic compound disclosed by the invention can be used for effectively inhibiting protease of the hepatitis C viruses and treating infection of the hepatitis C viruses (HCV).
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Paragraph 0124-0127
(2019/03/28)
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- General [4 + 1] Cyclization Approach to Access 2,2-Disubstituted Tetrahydrofurans Enabled by Electrophilic Bifunctional Peroxides
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A general [4 + 1] cyclization reaction of carbonyl nucleophiles with 2-iodomethylallyl peroxides, which function as unique electrophilic oxygen synthons, for the synthesis of a broad range of 2,2-disubstituted tetrahydrofurans is achieved under operationally simple conditions. The unprecedented asymmetric version of such reaction is also realized via chiral auxiliary-assisted cyclization, thus providing a distinct approach to access chiral tetrahydrofurans with high diastereoselectivities. The new method can be applied to the synthesis of core structure of posaconazole drug.
- Gao, Min,Zhao, Yukun,Zhong, Chen,Liu, Shengshu,Liu, Pengkang,Yin, Qi,Hu, Lin
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supporting information
p. 5679 - 5684
(2019/08/01)
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- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
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A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
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supporting information
p. 4781 - 4789
(2019/09/16)
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- Amine compound for inhibiting SSAO/VAP-1 and application thereof in medicines
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The present invention relates to an amine compound for inhibiting SSAO/VAP-1 and application thereof in medicines. In particular, the present invention relates to an amine compound for inhibiting a semicarbazide-sensitive oxidase (SSAO) and/or vascular adhesion protein-1 (VAP-1) inhibitor, or a pharmaceutically acceptable salt thereof, a stereoisomer or an/a E/Z isomer, further relates to a pharmaceutical composition containing the amine compound. The invention further relates to the application of the amine compound and the pharmaceutical composition in manufacture of the medicines for treatment of inflammation, inflammation-related diseases and immune diseases.
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Paragraph 0392; 0393; 0395; 0396
(2018/09/08)
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- Synthesis of Histidine-Containing Oligopeptides via Histidine-Promoted Peptide Ligation
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Histidine-containing peptides are valuable therapeutic agents for a treatment of neurodegenerative diseases. However, the synthesis of histidine-containing peptides is not trivial due to the potential of imidazole sidechain of histidine to act as a nucleophile if unprotected. A peptide ligation method utilizing the imidazole sidechain of histidine has been developed. The key imidazolate intermediate that acts as an internal acyl transfer catalyst during ligation is generated by deprotonation. Transesterification with amino acids or peptides tethered with C-terminal thioester followed by N→N acyl shifts led to the final ligated products. A range of histidine-containing dipeptides could be synthesized in moderate to good yields via this method without protecting the imidazole sidechain. The protocol was further extended to tripeptide synthesis via a long-range N→N acyl transfer, and tetrapeptide synthesis.
- Huang, Kai-Jin,Huang, Yi-Chen,Lin, Yuya A.
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supporting information
p. 400 - 403
(2018/02/21)
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- Antiplasmodial activity of hydroxyethylamine analogs: Synthesis, biological activity and structure activity relationship of plasmepsin inhibitors
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Malaria, particularly in endemic countries remains a threat to the human health and is the leading the cause of mortality in the tropical and sub-tropical areas. Herein, we explored new C2 symmetric hydroxyethylamine analogs as the potential inhibitors of Plasmodium falciparum (P. falciparum; 3D7) in in-vitro cultures. All the listed compounds were also evaluated against crucial drug targets, plasmepsin II (Plm II) and IV (Plm IV), enzymes found in the digestive vacuole of the P. falciparum. Analog 10f showed inhibitory activities against both the enzymes Plm II and Plm IV (Ki, 1.93 ± 0.29 μM for Plm II; Ki, 1.99 ± 0.05 μM for Plm IV). Among all these analogs, compounds 10g selectively inhibited the activity of Plm IV (Ki, 0.84 ± 0.08 μM). In the in vitro screening assay, the growth inhibition of P. falciparum by both the analogs (IC50, 2.27 ± 0.95 μM for 10f; IC50, 3.11 ± 0.65 μM for 10g) displayed marked killing effect. A significant growth inhibition of the P. falciparum was displayed by analog 12c with IC50 value of 1.35 ± 0.85 μM, however, it did not show inhibitory activity against either Plms. The hemolytic assay suggested that the active compounds selectively inhibit the growth of the parasite. Further, potent analogs (10f and 12c) were evaluated for their cytotoxicity towards mammalian HepG2 and vero cells. The selectivity index (SI) values were noticed greater than 10 for both the analogs that suggested their poor toxicity. The present study indicates these analogs as putative lead structures and could serve as crucial for the development of new drug molecules.
- Kumar Singh, Amit,Rajendran, Vinoth,Singh, Snigdha,Kumar, Prashant,Kumar, Yogesh,Singh, Archana,Miller, Whelton,Potemkin, Vladimir,Poonam,Grishina, Maria,Gupta, Nikesh,Kempaiah, Prakasha,Durvasula, Ravi,Singh, Brajendra K.,Dunn, Ben M.,Rathi, Brijesh
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p. 3837 - 3844
(2018/07/13)
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- Dual-protected amino acid derivatives as new antitubercular agents
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Tuberculosis is an infectious disease with high incidence and growing drug-resistant rates. In an attempt to develop new antitubercular agents, 35 compounds were synthesized, most of them bearing a carbamate and enantiopure amino acid moiety. These compounds had their activity evaluated toward a Mycobacterium tuberculosis strain (ATCC 27294) and cytotoxicity against fibroblast MRC-5 cells (ATCC CCL-171). Three of the prepared derivatives presented a good antimicrobial inhibition and two of them a moderate cytotoxicity. The lipophilicity seems to play a vital role in the cell growth activity, with best results for the derivatives with a higher logP.
- de Castro, Pedro P.,Campos, Débora L.,Pavan, Fernando R.,Amarante, Giovanni W.
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p. 1576 - 1580
(2018/06/06)
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- Amino acid conjugated antimicrobial drugs: Synthesis, lipophilicity- activity relationship, antibacterial and urease inhibition activity
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Present work describes the in vitro antibacterial evaluation of some new amino acid conjugated antimicrobial drugs. Structural modification was attempted on the three existing antimicrobial pharmaceuticals namely trimethoprim, metronidazole, isoniazid. Twenty one compounds from seven series of conjugates of these drugs were synthesized by coupling with some selected Boc-protected amino acids. The effect of structural features and lipophilicity on the antibacterial activity was investigated. The synthesized compounds were evaluated against five standard American type culture collection (ATCC) i.e. Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi strains of bacteria. Our results identified a close relationship between the lipophilicity and the activity. Triazine skeleton proved beneficial for the increase in hydrophobicity and potency. Compounds with greater hydrophobicity have shown excellent activities against Gram-negative strains of bacteria than Gram-positive. 4-amino unsubstituted trimethoprim-triazine derivative 7b have shown superior activity with MIC = 3.4 μM (2 μg/mL) for S. aureus and 1.1 μM (0.66 μg/mL) for E. coli. The synthesized compounds were also evaluated for their urease inhibition study. Microbial urease from Bacillus pasteurii was chosen for this study. Triazine derivative 7a showed excellent inhibition with IC50 = 6.23 ± 0.09 μM. Docking studies on the crystal structure of B. pasteurii urease (PDB ID 4UBP) were carried out.
- Ullah, Atta,Iftikhar, Fatima,Arfan, Muhammad,Batool Kazmi, Syeda Tayyaba,Anjum, Muhammad Naveed,Haq, Ihsan-ul,Ayaz, Muhammad,Farooq, Sadia,Rashid, Umer
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p. 140 - 153
(2018/01/10)
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- NOVEL SUBSTITUTED AMIDES OF TRITERPENE DERIVATIVES AS HIV INHIBITORS
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The present invention relates to compounds of novel substituted amides of triteripene derivatives of formula (I); or pharmaceutically acceptable salts, pharmaceutically acceptable solvates, pharmaceutically acceptable hydrates, tautomers, stereoisomers, prodrugs, compositions or combination thereof, wherein R1, R2, R3, R4, R5, R6, R7, R8, X, Y, Z1, Z2, Z3 and formula (II) are as defined herein. The present invention also relates to,, and pharmaceutical compositions comprising compounds of formula (I) useful for the treatment of viral diseases and particularly HIV mediated diseases.
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Page/Page column 22; 23
(2017/02/28)
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- Enantioselective Synthesis of Quaternary Δ4- and Δ5-Dehydroprolines Based on a Two-Step Formal [3+2] Cycloaddition of α-Aryl and α-Alkyl Isocyano(thio)acetates with Vinyl Ketones
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A divergent synthesis of optically active quaternary Δ4- and Δ5-dehydro prolines is developed based on the first catalytic enantioselective conjugate addition of α-substituted isocyano(thio)acetates to vinyl ketones that is general for both α-aryl and α-alkyl isocyano(thio)acetates. The new tetrasubstituted C?N stereocenter is formed without the need of any metal salt due to a bifunctional tertiary amine/squaramide catalyst, featuring a bulky polyaryl sidearm and an unusually short squaramide diamide H???H interatomic distance in the solid state.
- Odriozola, Amaiur,Oiarbide, Mikel,Palomo, Claudio
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supporting information
p. 12758 - 12762
(2017/09/25)
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- Bioproduction of l-2-Aminobutyric Acid by a Newly-Isolated Strain of Aspergillus tamarii ZJUT ZQ013
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Abstract: l-2-Aminobutyric acid (l-ABA), an unnatural amino acid, is a key intermediate of several important drugs. Although some methods have been developed to prepare pure chiral l-ABA, there are still many drawbacks, including low catalytic efficiency, cumbersome steps and high cost due to the addition of some expensive catalysts or coenzymes. Herein, with chemical and biological approaches together, we discovered a newly isolated Aspergillus tamarii ZJUT ZQ013 strain containing a microbial lipase which could be employed to resolve racemic methyl N-Boc-2-aminobutyrate to produce l-ABA with high enantioselectivity (e.e.s?>?99.9%, E = 257). Moreover, the subsequent gram scale experiment confrimed that A. tamarii ZJUT ZQ013 could be an attractive biocatalyst for the efficient preparation of optically pure acid. Graphical Abstract: [Figure not available: see fulltext.]
- An, Zhengfang,Gu, Xiaoxu,Liu, Yue,Ge, Jingyan,Zhu, Qing
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p. 837 - 844
(2017/03/24)
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- SPIROCYCLIC HAT INHIBITORS AND METHODS FOR THEIR USE
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Compounds having a structure of Formula (IX) or a stereoisomer, tautomer or pharmaceutically acceptable salt thereof, wherein R1, R2a, R2b, R3a, R3b, R4a, R4b, Q1----Q2, R6, R7, A, B, W, x, and y are as defined herein and are provided. Pharmaceutical compositions comprising such compounds and methods for treating various HAT-related conditions or diseases, including cancer, by administration of such compounds are also provided.
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Page/Page column 555
(2016/04/10)
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- Total synthesis of the azolemycins
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The first total syntheses of newly isolated polyazole natural products azolemycins A-D, along with the synthesis of the tetra-oxazole non-natural analogue, are described.
- Anderson, Zoe J.,Fox, David J.
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supporting information
p. 1450 - 1454
(2016/02/03)
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- Design, synthesis, and in vitro antiplasmodial activity of 4-aminoquinolines containing modified amino acid conjugates
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Abstract: A new series of side chain-modified 4-aminoquinolines were synthesized and screened for in vitro antiplasmodial activity against both chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum. Among the series, compounds 30 and 31 showed significant inhibition of parasite growth against K1 strain of P. falciparum with IC50 values 0.28 and 0.31?μM, respectively, whereas compounds 34, 35, and 38 exhibited superior activity against K1 strain with IC50 values 0.18, 0.22, and 0.17?μM, respectively, as compared to 0.255?μM for chloroquine (CQ). All the compounds displayed good resistance factor between 1.54 and >34.48 as against 51.0 for CQ. All these analogues were found to form strong complex with hematin and inhibited the β-hematin formation in vitro, suggesting that this class of compounds act on a heme polymerization target. Overall results suggest that present series of compounds appear to be promising for further lead optimization to obtain compounds active against drug-resistant parasites. Graphical Abstract: [Figure not available: see fulltext.]
- Srinivasarao, Kondaparla,Agarwal, Pooja,Srivastava, Kumkum,Haq,Puri, Sunil K.,Katti
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p. 1148 - 1162
(2016/07/06)
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- Stereoselective synthesis of hantupeptins A, B and C common fragment
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The stereoselective synthesis of the common fragment of Hantupeptine A, B and C is described using N-methylation of aminoacids, HATU mediated coupling reaction and diazotization of L-phenylalanine.
- Srinivas,Sunitha,Rao, C. Govind
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p. 1239 - 1242
(2017/04/28)
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- Chemo- and Diastereoselective N-Heterocyclic Carbene-Catalyzed Cross-Benzoin Reactions Using N-Boc-α-amino Aldehydes
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N-Boc-α-amino aldehydes are shown to be excellent partners in cross-benzoin reactions with aliphatic or heteroaromatic aldehydes. The chemoselectivity of the reaction and the facial selectivity on the amino aldehyde allow cross-benzoin products to be obtained in good yields and good diastereomeric ratios. The developed method is utilized as the key step in a concise total synthesis of d-arabino-phytosphingosine.
- Haghshenas, Pouyan,Gravel, Michel
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supporting information
p. 4518 - 4521
(2016/09/28)
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- Study of the Paternò–Büchi type photolabile protecting group and application to various acids
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An efficient photolabile protecting group, thiochromone S,S-dioxides with the diazomethyl group for phosphate derivatives, amino acids and sulfonic acids was developed. Protection and photodeprotection reactions proceeded smoothly under mild conditions without any catalyst.1H NMR and HPLC spectra studies demonstrated the photolysis properties of the photolabile protecting group and gave an exact quantification of the released substrates. Specially, the photoproduct derived from the thiochromone derivatives following Paternò–Büchi type photo-cycloaddition showed high fluorescence intensity. This fluorescent characteristic demonstrated the photodeprotection progress also can be monitored by fluorescence spectra.
- Zhang, Youlai,Zhang, Huan,Ma, Chi,Li, Junru,Nishiyama, Yasuhiro,Tanimoto, Hiroki,Morimoto, Tsumoru,Kakiuchi, Kiyomi
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supporting information
p. 5179 - 5184
(2016/11/13)
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- Paliperidone amino acid ester and its preparation method
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The invention discloses a preparation method of a paliperidone amino-acid ester compound or medicinal salt thereof used for treating mental disease, wherein the structural formula of the compound is shown as a formula (I) (described in the specification). The compound can be an optical isomer and also can be a racemic mixture. The paliperidone amino-acid ester can be metabolized and converted into paliperidone (II) with pharmacological activity in vivo after being ingested in a human body, the paliperidone (II) is taken as an antagonist for neurotransmission substance to play a pesticide effect, and the paliperidone (II) is used for treating related mental diseases such as schizophrenia.
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Paragraph 0029; 0030; 0031
(2017/01/12)
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- Enantioselective Synthesis of Dialkylated α-Hydroxy Carboxylic Acids through Asymmetric Phase-Transfer Catalysis
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In the presence of an L-tert-leucine-derived urea-ammonium salt as phase-transfer catalyst, a highly enantioselective alkylation of 5H-oxazol-4-ones with various benzyl bromides and allylic bromides has been developed to furnish catalytic asymmetric synthesis of biologically important dialkylated α-hydroxy carboxylic acids with a broad scope. This is the first example of an L-amino acid-derived urea-ammonium salt being used as a phase-transfer catalyst with excellent catalytic efficiency.
- Duan, Shaobo,Li, Sanliang,Ye, Xinyi,Du, Nuan-Nuan,Tan, Choon-Hong,Jiang, Zhiyong
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supporting information
p. 7770 - 7778
(2015/08/18)
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- Liquid chromatographic resolution of amino acid esters of acyclovir including racemic valacyclovir on crown ether-based chiral stationary phases
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Valacyclovir, a potential prodrug for the treatment of patients with herpes simplex and herpes zoster, and its analogs were resolved on two chiral stationary phases (CSPs) based on (3,3′-diphenyl-1,1′-binaphthyl)-20-crown-6 covalently bonded to silica gel. In order to find out an appropriate mobile phase condition, various mobile phases consisting of various organic modifiers in water containing various acidic modifiers were applied to the resolution of valacyclovir and its analogs. When 30% acetonitrile in water containing any of 0.05 M, 0.10 M, or 0.15 M perchloric acid was used as a mobile phase, valacyclovir and its analogs were resolved quite well on the two CSPs with the separation factors (α) in the range of 2.49~6.35 and resolutions (RS) in the range of 2.95 ~ 12.21. Between the two CSPs, the CSP containing residual silanol protecting n-octyl groups on the silica surface was found to be better than the CSP containing residual silanol groups.
- Ahn, Seong Ae,Hyun, Myung Ho
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p. 268 - 273
(2015/03/18)
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- Antiplasmodial activity of new 4-aminoquinoline derivatives against chloroquine resistant strain
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Emergence and spread of multidrug resistant strains of Plasmodium falciparum has severely limited the antimalarial chemotherapeutic options. In order to overcome the obstacle, a set of new side-chain modified 4-aminoquinolines were synthesized and screened against chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of P. falciparum. The key feature of the designed molecules is the use of methylpiperazine linked α, β3- and γ-amino acids to generate novel side chain modified 4-aminoquinoline analogues. Among the evaluated compounds, 20c and 30 were found more potent than CQ against K1 and displayed a four-fold and a three-fold higher activity respectively, with a good selectivity index (SI = 5846 and 11,350). All synthesized compounds had resistance index between 1.06 and >14.13 as against 47.2 for chloroquine. Biophysical studies suggested that this series of compounds act on heme polymerization target.
- Sinha, Manish,Dola, Vasanth R.,Agarwal, Pooja,Srivastava, Kumkum,Haq, Wahajul,Puri, Sunil K.,Katti, Seturam B.
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p. 3573 - 3586
(2014/07/07)
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- Synthesis and properties of l-valine based chiral long alkyl chain appended 1,2,3-triazolium ionic liquids
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The increasing importance of ionic liquids (ILs) in various strata of chemical sciences is largely due to the fact that modification in the architecture of the cation and/or the anion imparts favorable and specific properties to an IL. Consequently, there is a need to develop new ILs with different functionalities. A series of l-valine based alkyl chain-appended 1,2,3-triazolium ILs (alkyl = hexyl, octyl, dodecyl, cetyl and octadecyl) with iodide and hexafluorophosphate anions, respectively, are synthesized and characterized. These new ILs show optical activity and hence are termed chiral ILs (CILs). All ten CILs are room temperature ILs (RTILs) as their melting points, obtained from differential scanning calorimetry (DSC), are found to be below ambient temperature. Thermogravimetric analysis indicates these CILs to have adequate thermal stability. The longer alkyl chain containing CILs exhibit facile self-aggregation when dissolved in ethanol. There is a hint of pre-micellar aggregation by short alkyl chain possessing CILs along with the long alkyl chain containing ones. These CILs demonstrate weak absorbance and emission of UV-Vis radiation and hence can be considered ideal solvents for photochemical applications. These CILs, consisting of different functionalities, possess interesting properties and have potential to be used in many areas of chemistry. the Partner Organisations 2014.
- Mishra, Roli,Pandey, Shubha,Trivedi, Shruti,Pandey, Siddharth,Pandey, Pramod S.
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p. 33478 - 33488
(2014/08/18)
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- CYANOGUANIDINES AND THEIR USE AS ANTIVIRAL AGENTS
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This disclosure relates to: (a) compounds and salts thereof that, inter alia, inhibit RSV infection and/or replication; (b) intermediates useful for the preparation of such compounds and salts; (c) compositions comprising such compounds and salts; (d) methods for preparing such intermediates, compounds, salts, and compositions; (e) methods of use of such compounds, salts, and compositions; and (f) kits comprising such compounds, salts, and compositions.
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Page/Page column 150
(2014/01/17)
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- General solvent-free highly selective N-tert-butyloxycarbonylation strategy using protic ionic liquid as an efficient catalyst
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A simple, rapid and solvent-free protocol is described for the chemo-selective transformation of amines to tert-butyloxycarbonyl protected derivatives (NHBoc) using Boc2O and imidazolium trifluoroacetate protic ionic liquid (5-20 mol%). Unwanted side products such as isocyanate, urea or N,N-di-Boc were not detected. The scope of the protection strategy was successfully explored for substrate alcohols, phenols and thiol at elevated temperatures. Optically pure amino acids, amino acid esters and amino alcohols were efficiently converted to the corresponding N-Boc protected derivatives in excellent yields without racemization at the chiral center. The distinct advantages of this method are: operational simplicity, cleaner reaction, high selectivity, excellent yield, rapid reaction convergence, easy preparation and recyclability of the catalyst.
- Majumdar, Swapan,De, Jhinuk,Chakraborty, Ankita,Maiti, Dilip K.
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p. 24544 - 24550
(2014/07/07)
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- Synthesis and antibacterial activity of amino acid and dipeptide prodrugs of IMB-070593, a fluoroquinolone candidate
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A series of amino acid and dipeptide prodrugs of IMB-070593, a fluoroquinolone candidate discovered in our lab, were synthesized and evaluated for their water solubility and then antibacterial activity. Our results reveal that four amino acid prodrugs 4a,b,e,f and two dipeptide prodrugs 4k,l have much greater solubility (>85 mg/mL) than IMB-070593 mesylate (22.5 mg/mL). Compounds 4a and 4k show good in vivo efficacy against MSSA 12-1 (p.o./i.v., 5.32-7.68 mg/kg) and S. pneumoniae12-10 (p.o., 18.39-23.13 mg/kg) which is 1.19-1.50 fold more active than the parent drug.
- Zhang, Tingting,Wu, Jinwei,Chen, Shihong,Liu, Kaixiang,Lin, Yabin,Guo, Huiyuan,Liu, Mingliang
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p. 6822 - 6837
(2014/06/10)
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- Easy access to evans' oxazolidinones. Stereoselective synthesis and antibacterial activity of a new 2-oxazolidinone derivative
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An interesting new approach was developed for the synthesis of Evans' chiral auxiliaries with excellent yields. In turn, another new stereoselective and efficient strategy has also allowed for the preparation of a 2-oxazolidinone derivative in 34% overall yield from the Morita-Baylis-Hillman adduct. The antibacterial activity of this oxazolidinone was tested against Staphylococcus aureus strains isolated from animals with mastitis infections.
- Diaz, Gaspar,De Freitas, Michelle A.A.,Ricci-Silva, Maria E.,Diaz, Marisa A.N.
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p. 7429 - 7439
(2014/07/08)
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- Α-BORYL ISOCYANIDES, BOROPEPTIDES AND BORON HETEROCYCLES
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This application pertains to α-boryl isocyanates, wherein the boronate moiety is in the form of an N-methyliminodiacetic acid (MIDA) boronate of the Formula (2) and the utility of said compounds in the synthesis of the borylamide motif (Β-C-Namide) in the scaffold of biologically-active boropeptides, such as bortezomib, in the enablement of heterocycle synthesis, and in multi-component reactions (MCRs), such as the Ugi and Passerini processes.
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Page/Page column 23
(2014/10/18)
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- Thioacetic acid/NaSH-mediated synthesis of N -protected amino thioacids and their utility in peptide synthesis
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Thioacids are recently gaining momentum due to their versatile reactivity. The reactivity of thioacids has been widely explored in the selective amide/peptide bond formation. Thioacids are generally synthesized from the reaction between activated carboxylic acids such as acid chlorides, active esters, etc., and Na2S, H2S, or NaSH. We sought to investigate whether the versatile reactivity of the thioacids can be tuned for the conversion of carboxylic acids into corresponding thioacids in the presence of NaSH. Herein, we report that thioacetic acid- and NaSH-mediated synthesis of N-protected amino thioacids from the corresponding N-protected amino acids, oxidative dimerization of thioacids, crystal conformations of thioacid oxidative dimers, and the utility of thioacids and oxidative dimers in peptide synthesis. Our results suggest that peptides can be synthesized without using standard coupling agents.
- Mali, Sachitanand M.,Gopi, Hosahudya N.
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supporting information
p. 2377 - 2383
(2014/04/17)
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- NUCLEAR TRANSPORT MODULATORS AND USES THEREOF
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The present invention relates to compounds of formula I: and pharmaceutically acceptable salts thereof, pharmaceutical compositions comprising the compounds of formula I, and methods of using said compounds, salts and compositions in the treatment of various disorders associated with CRM1 activity.
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Paragraph 00276
(2013/12/03)
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- Design, synthesis and biological evaluation of novel L-isoserine tripeptide derivatives as aminopeptidase N inhibitors
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Aminopeptidase N (APN/CD13) is one of the essential proteins for tumour invasion, angiogenesis and metastasis as it is over-expressed on the surface of different tumour cells. Based on our previous work that L-isoserine dipeptide derivatives were potent APN inhibitors, we designed and synthesized L-isoserine tripeptide derivatives as APN inhibitors. Among these compounds, one compound 16l (IC50=2.51±0.2 M) showed similar inhibitory effect compared with control compound Bestatin (IC50=6.25±0.4 M) and it could be used as novel lead compound for the APN inhibitors development as anticancer agents in the future.
- Pan, Huili,Yang, Kanghui,Zhang, Jian,Xu, Yingying,Jiang, Yuqi,Yuan, Yumei,Zhang, Xiaopan,Xu, Wenfang
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p. 717 - 726
(2013/07/26)
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- α-boryl isocyanides enable facile preparation of bioactive boropeptides
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Entry to bioactive boropeptides: MIDA-containing α-boryl isocyanides are isolable molecules which allow one-step access to boroalkyl-functionalized heterocycles as well as biologically active boropeptides through a multicomponent approach. Among these derivatives are 6-boromorpholinones, novel borocycles with nanomolar IC50 values for 20S proteasome inhibition. MIDA=N-methyliminodiacetyl. Copyright
- Zajdlik, Adam,Wang, Zezhou,Hickey, Jennifer L.,Aman, Ahmed,Schimmer, Aaron D.,Yudin, Andrei K.
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supporting information
p. 8411 - 8415
(2013/09/02)
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- PYRAZOLOPYRIMIDONE AND PYRAZOLOPYRIDONE INHIBITORS OF TANKYRASE
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There are provided compounds of the formula (I) or a pharmaceutically acceptable salt thereof, wherein Q, R1 and R2 are as defined herein. The compounds of formula I are useful in the treatment of cancer.
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Page/Page column 124
(2014/01/08)
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