- Regioselectivity of Cobalamin-Dependent Methyltransferase Can Be Tuned by Reaction Conditions and Substrate
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Regioselective reactions represent a significant challenge for organic chemistry. Here the regioselective methylation of a single hydroxy group of 4-substituted catechols was investigated employing the cobalamin-dependent methyltransferase from Desulfitobacterium hafniense. Catechols substituted in position four were methylated either in meta- or para-position to the substituent depending whether the substituent was polar or apolar. While the biocatalytic cobalamin dependent methylation was meta-selective with 4-substituted catechols bearing hydrophilic groups, it was para-selective for hydrophobic substituents. Furthermore, the presence of water miscible co-solvents had a clear improving influence, whereby THF turned out to enable the formation of a single regioisomer in selected cases. Finally, it was found that also the pH led to an enhancement of regioselectivity for the cases investigated.
- Pompei, Simona,Grimm, Christopher,Farnberger, Judith E.,Schober, Lukas,Kroutil, Wolfgang
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p. 5977 - 5983
(2020/10/06)
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- Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
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Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
- Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
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p. 4348 - 4358
(2020/09/22)
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- Application of quebrachitol in hydrolysis reaction of copper-catalyzed aryl halide
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The invention belongs to the technical field of drug synthesis, and provides application of quebrachitol in a hydrolysis reaction of a copper-catalyzed aryl halide. According to the hydrolysis reaction, copper serves as a catalyst, quebrachitol serves as a ligand, and the hydrolysis reaction is carried out on the aryl halide. The invention further provides a catalytic system of the hydrolysis reaction of the aryl halide. The reaction system comprises the copper catalyst, the quebrachitol, alkali and water, and the system is environmentally friendly and is suitable for industrial application.
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Paragraph 0072-0074
(2019/07/16)
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- Specific Residues Expand the Substrate Scope and Enhance the Regioselectivity of a Plant O-Methyltransferase
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An isoeugenol 4-O-methyltransferase (IeOMT), isolated from the plant Clarkia breweri, can be engineered to a caffeic acid 3-O-methyltransferase (CaOMT) by replacing three consecutive residues. Here we further investigated functions of these residues by constructing the triple mutant T133M/A134N/T135Q as well as single mutants of each residue. Phenolics with different chain lengths and different functional groups were investigated. The variant T133M improves the enzymatic activities against all tested substrates by providing beneficial interactions to residues which directly interact with the substrate. Mutant A134N significantly enhanced the regioselectivity. It is meta-selective or even specific against most of the tested substrates but para-specific towards 3,4-dihydroxybenzoic acid. The triple mutant T133M/A134N/T135Q benefits from these two mutations, which not only expand the substrate scope but also enhance the regioselectivity of IeOMT. On the basis of our work, regiospecific methylated phenolics can be produced in high purity by different IeOMT variants.
- Tang, Qingyun,Bornscheuer, Uwe T.,Pavlidis, Ioannis V.
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p. 3227 - 3233
(2019/07/04)
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- Synthesis and biological evaluation of novel neoflavonoid derivatives as potential antidiabetic agents
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Various substituted neoflavonoid derivatives were synthesized using sulfated montmorillonite K-10 as a catalyst. This method is environmental friendly, sustainable and economical, convenient in isolation and purification processes, with little byproducts, using earth-abundant catalysts and has relatively high yield. Those neoflavonoid derivatives were screened for antioxidant, a-glucosidase inhibitory, aldose reductase 2 (ALR2) inhibitory and advanced glycation end-product formation inhibitory effects. Most compounds exhibited significant antioxidant and advanced glycation end-product (AGE) formation inhibitory activities. It was interesting to note that out of thirty compounds, 8k and 8l were found to have greater ALR2 inhibitory activity than the standard drug quercetin. The pharmacological studies suggested neoflavonoid with adjacent 7,8-dihydroxy groups were more effective in inhibiting ALR2. Antidiabetic activity studies had shown that compounds 8l and 8m were equipotent to the standard drug glibenclamide in vivo. In summary, the target compound 8l provided a potential drug design concept for the development of therapeutic or prophylactic agents of diabetes and diabetes complications.
- Wang, Bing,Li, Na,Liu, Teng,Sun, Jie,Wang, Xiaojing
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p. 34448 - 34460
(2017/07/22)
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- Preparation method of 3,4-dihydro-4-arylcoumarin compounds
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The invention relates to the field of chemical synthesis, and concretely relates to a preparation method of 3,4-dihydro-4-arylcoumarin compounds. The method is characterized in that: substituted benzaldehyde is used as an initial raw material, propane diacid is added, a reaction is carried out with catalysis of piperidine, and substituted phenyl acrylic acid derivatives are obtained; montmorillonite K-10 which is acidified by sulfuric acid is used as a catalyst, a reaction between the substituted phenyl acrylic acid derivatives and phenolic compounds is carried out with heating, and the 3,4-dihydro-4-arylcoumarin compounds are obtained. Compared with the prior art, the preparation method of the 3,4-dihydro-4-arylcoumarin compounds has the advantages of easily available and cheap raw materials, simple operation, recyclable catalyst, environmental protection, simple post-treatment, low production cost, good promotion application, etc.
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Paragraph 0065
(2016/11/14)
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- Preparation method of neoflavonoids
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The invention relates to the field of chemical synthesis, in particular to a preparation method of neoflavonoids. The preparation method is characterized by comprising the following steps of using substituted benzaldehyde as an initial raw material to be reacted with malonic acid to generate a substituted phenylacrylic acid compound; performing an addition reaction, an elimination reaction and the like on the substituted phenylacrylic acid compound, or performing acetylation so as to protect a phenolic hydroxyl group, then performing a bromination reaction and the elimination reaction so as to synthesize the substituted phenylpropiolic acid compound ; and using montmorillonite K-10 after being acidulated by sulfuric acid as a catalyst, enabling the substituted phenylpropiolic acid compound and a phenolic compound to perform a heating reaction so as to generate the neoflavonoids. Compared with the prior art, the preparation method of the neoflavonoids, disclosed by the invention, has the characteristics that raw materials are cheap, and easy to obtain, the operation is simple, the catalyst can be recovered for use, and the method is environmentally-friendly, the post-treatment is simple, and the production cost is low, and the method has a high popularization and application value.
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Paragraph 0094; 0095
(2017/04/26)
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- Monoamine Oxidase Inhibitory Activity of Ferulic Acid Amides: Curcumin-Based Design and Synthesis
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Ferulic acid has structural similarity with curcumin which is being reported for its monoamine oxidase (MAO) inhibitory activity. Based on this similarity, we designed a series of ferulic acid amides 6a-m and tested for their inhibitory activity on human MAO (hMAO) isoforms. All the compounds were found to inhibit the hMAO isoforms either selectively or non-selectively. Nine compounds (6a, 6b, 6g-m) were found to inhibit hMAO-B selectively, whereas the other four (6c-f) were found to be non-selective. There is a gradual shift from hMAO-B selectivity (6a,b) to non-selectivity (6c-f) as there is an increase in chain length at the amino terminus. In case of compounds having an aromatic nucleus at the amino terminus, increasing the carbon number between N and the aromatic ring increases the potency as well as selectivity toward hMAO-B. Compounds 6f, 6j, and 6k were subjected to membrane permeability and metabolic stability studies by in vitro assay methods. They were found to have a better pharmacokinetic profile than curcumin, ferulic acid, and selegiline. In order to understand the structural features responsible for the potency and selectivity of 6k, we carried out a molecular docking simulation study.
- Badavath, Vishnu N.,Baysal, Ipek,Uar, Gülberk,Mondal, Susanta K.,Sinha, Barij N.,Jayaprakash, Venkatesan
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- Design, Synthesis and Pharmacological Evaluation of Novel Piperlongumine derivatives as Potential Antiplatelet Aggregation Candidate
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A series of novel piperlongumine derivatives (4a-i, 6a-i) were designed and synthesized. The inhibitory activities of platelet aggregation induced by ADP and AA in vitro have been evaluated by bron turbidimetry and liver microsomal incubated assay. The assay results show that compounds 4e and 6e exhibited remarkable potency to that of the positive control piplartine and aspirin.
- Wang, Yujun,Wang, Jie,Li, Jiaming,Zhang, Yanchun,Huang, Weijun,Zuo, Jian,Liu, Huicai,Xie, Di,Zhu, Panhu
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p. 833 - 840
(2016/05/19)
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- Alkaloids and phenolic glycosides from Clematis mandshurica and their inhibitory effects against NO production in LPS-induced RAW 246.7 macrophages
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Two new alkaloids (1 and 2), one new phenolic glycoside (3), and five known structures (4–8) were isolated from the roots and rhizomes of Clematis mandshurica. Their structures were elucidated on the basis of spectroscopic evidence and hydrolysis products
- Fu, Qiang,Chen, Jiang,Yuan, Hai-Mei,Ma, Yu,Yu, Tian,Zou, Liang
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p. 238 - 241
(2016/08/15)
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- Recyclable Hypervalent-Iodine-Mediated Dehydrogenative α,β′-Bifunctionalization of β-Keto Esters under Metal-Free Conditions
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We have developed a method for recyclable hypervalent-iodine-mediated direct dehydrogenative α,β′- bifunctionalization of β-ketoesters and β-diketones under metal-free conditions, which affords a straightforward way to synthesize benzo-fused 2,3-dihydrofurans. This efficient, mild method, which has a wide substrate scope and good functional-group tolerance, was used for the multistep synthesis of the protected aglycone of a naturally occurring phenolic glycoside. A mechanism involving Michael addition to an enone intermediate and subsequent oxidative cyclization is proposed.
- Duan, Ya-Nan,Cui, Li-Qian,Zuo, Lin-Hong,Zhang, Chi
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supporting information
p. 13052 - 13057
(2015/09/07)
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- 1,5-DI-O-Isoferuloylquinic acid and other phenolic compounds from pollen of calendula officinalis
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A new phenylpropanoid that was identified as 1,5-di-O-isoferuloylquinic acid (1) and 17 known compounds including 1,5-di-O-feruloylquinic acid (2), which was obtained for the first time from a plant and was synthesized previously, were isolated from pollen of Calendula officinalis. Compounds 1 and 2 were the dominant phenolic compounds from pollen of C. officinalis. It was found that 1 possessed pronounced inhibitory activity against tyrosinase (IC50 11.26μg/mL).
- Olennikov,Kashchenko
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p. 589 - 593
(2015/02/02)
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- Synthesis, cytotoxicity and molecular modelling studies of new phenylcinnamide derivatives as potent inhibitors of cholinesterases
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The present study reports the synthesis of cinnamide derivatives and their biological activity as inhibitors of both cholinesterases and anticancer agents. Controlled inhibition of brain acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) may slow neurodegeneration in Alzheimer's diseases (AD). The anticholinesterase activity of phenylcinnamide derivatives was determined against Electric Eel acetylcholinesterase (EeAChE) and horse serum butyrylcholinesterase (hBChE) and some of the compounds appeared as moderately potent inhibitors of EeAChE and hBChE. The compound 3-(2-(Benzyloxy)phenyl)-N- (3,4,5-trimethoxyphenyl)acrylamide (3i) showed maximum activity against EeAChE with an IC50 0.29 ± 0.21 μM whereas 3-(2-chloro-6- nitrophenyl)-N-(3,4,5-trimethoxyphenyl)acrylamide (3k) was proved to be the most potent inhibitor of hBChE having IC50 1.18 ± 1.31 μM. To better understand the enzyme-inhibitor interaction of the most active compounds toward cholinesterases, molecular modelling studies were carried out on high-resolution crystallographic structures. The anticancer effects of synthesized compounds were also evaluated against cancer cell line (lung carcinoma). The compounds may be useful leads for the design of a new class of anticancer drugs for the treatment of cancer and cholinesterase inhibitors for Alzheimer's disease (AD).
- Saeed, Aamer,Mahesar, Parvez Ali,Zaib, Sumera,Khan, Muhammad Siraj,Matin, Abdul,Shahid, Mohammad,Iqbal, Jamshed
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- Three new triterpene saponins from Clematis chinensis
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Three new triterpene saponins, clematochinenosides H-J (1-3), were isolated from the roots and rhizomes of Clematis chinensis. Their structures were elucidated on the basis of spectroscopic means including 1D and 2D NMR experiments and hydrolysis products
- Fu, Qiang,Zan, Ke,Zhao, Ming-Bo,Zhou, Si-Xiang,Shi, She-Po,Jiang, Yong,Tu, Peng-Fei
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p. 610 - 618
(2013/07/26)
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- Synthesis of some phenylpropanoid glycosides (PPGs) and their acetylcholinesterase/xanthine oxidase inhibitory activities
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In this research, three categories of phenylpropanoid glycosides (PPGs) were designed and synthesized with PPGs isolated from Rhodiola rosea L. as lead compounds. Their inhibitory abilities toward acetylcholinesterase (AChE) and xanthine oxidase (XOD) were also tested. Some of the synthetic PPGs exhibited excellent enzyme inhibitory abilities.
- Li, Xiao-Dong,Kang, Shuai-Tao,Li, Guo-Yu,Li, Xian,Wang, Jin-Hui
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experimental part
p. 3580 - 3596
(2011/07/07)
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- Triterpene saponins from clematis chinensis and their potential anti-inflammatory activity
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Seven new triterpene saponins, clematochinenosides A-G (1-7), together with 17 known saponins (8-24), were isolated from the roots and rhizomes of Clematis chinensis. Their structures were elucidated on the basis of spectroscopic evidence and hydrolysis products. Compounds 1, 3-7, and 20-24 showed inhibitory activities against COX-1 and COX-2 enzymes.
- Fu, Qiang,Zan, Ke,Zhao, Mingbo,Zhou, Sixiang,Shi, Shepo,Jiang, Yong,Tu, Pengfei
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experimental part
p. 1234 - 1239
(2010/11/04)
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- Aphyllin, the first isoferulic acid glycoside and other phenolics from Tamarix aphylla flowers
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The first glycosylated isoferulic acid, isoferulic acid 3-O-β-glucopyranoside, together with the new phenolics, tamarixetin 3,3′-di-sodium sulphate and dehydrodigallic acid dimetyl ester have been characterized from a flower extract of Tamarix aphylla. Th
- Nawwar, Mahmoud A. M.,Hussein,Ayoub,Hofmann,Linscheid,Harms,Wende,Lindequist
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body text
p. 342 - 347
(2010/07/10)
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- A Formal Total Synthesis of the ACE Inhibitor K-13. An Application of Arene-Ruthenium Chemistry to Complex Chemical Synthesis
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Stoichiometric ruthenium activation of 4-chlorophenylalanine derivatives toward nucleophilic substitution, using phenoxide nucleophiles that are derived from protected dipeptides, allowed the formation of isodityrosine derivatives that are synthetic precursors to the ACE inhibitor K-13.An evaluation of carboxyl blocking groups revealed that a 2-bromoethyl ester is the most useful in terms of its compatibility with ruthenium complexation and subsequent nucleophile addition but that its removal is problematic.Conversion to iodoethyl ester using Finkelstein reaction conditions, in the presence of the peptide and amino acid functionality, provided a solution to this problem, since the iodoethyl group was easily removed on treatment with samarium diiodide.
- Pearson, Anthony J.,Lee, Kieseung
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p. 2304 - 2313
(2007/10/02)
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