- Effects of urea, Na+ and Li+ ions on the kinetics and mechanism of intramolecular general base-catalyzed glycolysm of ionized phenyl salicylate in ethane-1,2-diol-acetonitrile solvents at a constant water concentration
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Pseudo-first-order rate constants (k1) for the reaction of ethane-1,2-diol (DOL) with ionized phenyl salicylate (PS-), obtained in mixed DOL-CH3CN solvent at constant [H2O] and [NaOH], obey the relationship k1 = α[DOL]T/(1 + 2KA[DOL]T), where α is the apparent second-order rate constant, KA is the association constant for the dimerization of DOL and [DOL]T is the total concentration of DOL. The values of KA, in the presence of Na+ ions, decrease with increase in [H2O]. Lithium ions cause almost complete depolymerization of polymeric DOL (i.e. KA ≈ 0) under the experimental conditions imposed. The effect of 0.5 M urea on the structural behavior of the mixed solvent is kinetically insignificant.
- Khan, M. Niyaz
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- Design and synthesis of tricyclic terpenoid derivatives as novel PTP1B inhibitors with improved pharmacological property and in vivo antihyperglycaemic efficacy
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Overexpression of protein tyrosine phosphatase 1B (PTP1B) induces insulin resistance in various basic and clinical research. In our previous work, a synthetic oleanolic acid (OA) derivative C10a with PTP1B inhibitory activity has been reported. However, C10a has some pharmacological defects and cytotoxicity. Herein, a structure-based drug design approach was used based on the structure of C10a to elaborate the smaller tricyclic core. A series of tricyclic derivatives were synthesised and the compounds 15, 28 and 34 exhibited the most PTP1B enzymatic inhibitory potency. In the insulin-resistant human hepatoma HepG2 cells, compound 25 with the moderate PTP1B inhibition and preferable pharmaceutical properties can significantly increase insulin-stimulated glucose uptake and showed the insulin resistance ameliorating effect. Moreover, 25 showed the improved in vivo antihyperglycaemic potential in the nicotinamide–streptozotocin-induced T2D. Our study demonstrated that these tricyclic derivatives with improved molecular architectures and antihyperglycaemic activity could be developed in the treatment of T2D.
- Chen, Feng,Chen, Jiabao,Gao, Cheng,Li, Junyan,Liu, Siyan,Qian, Shan,Wang, Zhouyu,Yang, Lingling,Zhang, Yuanyuan
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p. 152 - 164
(2019/11/25)
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- Methyl salicylate as a selective methylation agent for the esterification of carboxylic acids
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Methyl salicylate is a selective and inexpensive methylating agent for the esterification of carboxylic acids with a wide range of functional group tolerance. The intramolecular hydrogen bonds between the carboxylate and hydroxyl groups in methyl salicylate are essential for the transformation. Allyl, benzyl, methallyl, and propargyl salicylates can also be used as alkylating agents for the preparation of the corresponding alkyl carboxylates.
- Chen, Si,Jia, Lei,Li, Xiaonan,Luo, Meiming
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p. 263 - 268
(2014/03/21)
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- Novel benzo-1,2,3-thiadiazole-7-carboxylate derivatives as plant activators and the development of their agricultural applications
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Plant activators are a novel kind of agrochemicals that could induce resistance in many plants against a broad spectrum of diseases. To date, only few plant activators have been commercialized. In order to develop novel plant activators, a series of benzo-1,2,3-thiadiazole-7-carboxylate derivatives were synthesized, and the structures were characterized by 1H NMR, IR, elemental analyses, and HRMS or MS. Their potential systemic acquired resistance as plant activators was evaluated as well. Most of them showed good activity, especially, fluoro-containing compounds 3d and 3e, which displayed excellent SAR-inducing activity against cucumber Erysiphe cichoracearum and Colletotrichum lagenarium in assay screening. Field test results illustrated that compounds 3d and 3e were more potent than the commercial plant activator, S-methyl benzo[1,2,3]thiadiazole-7-carbothioate (BTH) toward these pathogens. Further, the preparation of compound 3d is more facile than BTH with lower cost, which will be helpful for further applications in agricultural plant protection.
- Du, Qingshan,Zhu, Weiping,Zhao, Zhenjiang,Qian, Xuhong,Xu, Yufang
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scheme or table
p. 346 - 353
(2012/04/10)
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- Synthesis and biological evaluation of some new 2-oxazoline and salicylic acid derivatives
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Starting from methyl salicylate and 2-amino-2-(hydroxymethyl)propane-1,3- diol 1a, or 2-amino- 2-methylpropane-1-ol 1b, the 2-oxazoline derivatives 2a, 2b or 3, as well as mono- 4a and 4b and bis- 5a and 5b derivatives of salicylic acid were synthesized. Reactions were performed by microwave irradiation in the presence of tetrabutylammonium bromide or metallic sodium as catalyst, as well as by conventional heating. Microwave-induced reaction of some diols, diamines and amino alcohols with methyl salicylate gave mono- and/or bis- derivatives of salicylic acid 4c, 5c, 5d, 6c, 8c, 7a, 7b, 8a and 8b. The mono- and bis-salicyloyl derivatives 4c, 5c and 5d were transformed to the corresponding phenyl-azo derivatives 9, 10c and 10d. The structure of compound 3 was proved by the X-ray analysis and the R-configuration on its stereocenter was confirmed. The antioxidant and cytotoxic activities of the synthesized derivatives were evaluated in a series of in vitro tests. Compounds 5d, 8b and 8c exhibited very strong activity against hydroxyl radical. Six 4c, 5d, 8a-c, 10c of 16 tested compounds inhibited growth of MDA-MB-231 cells at a nanomolar concentration. Compounds 8c and 10c showed high cytotoxicity against MCF7 cells, whereas compounds 4c, 5d, 8a-c and 10d showed high activity against K562 cells. ARKAT-USA, Inc.
- Djurendic, Evgenija,Vujaskovic, Sanja Dojcinovic,Sakac, Marija,Ajdukovic, Jovana,Gakovic, Andrea,Kojic, Vesna,Bogdanovic, Gordana,Klisuric, Olivera,Gasi, Katarina Penov
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experimental part
(2011/05/11)
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- Novel, unnatural benzo-1,2,3-thiadiazole-7-carboxylate elicitors of taxoid biosynthesis
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In order to establish the chemical biological technology for production of valuable secondary metabolites, a novel family of unnatural elicitors derived from the plant activator benzo-1,2,3-thiadiazole-7-carboxylic acid were designed and synthesized. New synthetic elicitors that showed powerful eliciting activities upon taxoid biosynthesis by Taxus chinensis suspension cells were obtained. For example, benzo-1,2,3-thiadiazole-7-carboxylic acid 2-(2-hydroxybenzoxyl)ethyl ester was more effective and resulted in nearly 40% increase in taxuyunnanine C content and production in comparison with methyl jasmonate, which was previously reported as the most powerful chemical elicitor for taxoid biosynthesis. The novel class of elicitors was found to induce plant defense responses, including promotion of H2O2 levels originating from oxidative burst and activation of phenylalanine ammonia lyase. Interestingly the plant defense responses induced corresponded well to the superior stimulating activity in T. chinensis cell cultures. The work indicates that the newly synthesized benzothiadiazoles can act as a new family of elicitors for taxoid biosynthesis in plant cells.
- Xu, Yufang,Zhao, Zhengjiang,Qian, Xuhong,Qian, Zhigang,Tian, Wenhong,Zhong, Jianjiang
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p. 8793 - 8798
(2007/10/03)
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- Highly selective methodology for the direct conversion of aromatic aldehydes to glycol monoesters
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Al2O3/MeSO3H (AMA) was found to be an extremely efficient reagent for the conversion of aromatic aldehydes and diols to glycol monoesters. The remarkable selectivity achieved with this reagent is an attractive feature of t
- Sharghi, Hashem,Sarvari, Mona Hosseini
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p. 4096 - 4099
(2007/10/03)
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- Competitive degradation and detoxification of carbamate insecticides by membrane anodic fenton treatment
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The competitive degradation of six carbamate insecticides by membrane anodic Fenton treatment (AFT), a new Fenton treatment technology, was carried out in this study. The carbamates studied were dioxacarb, carbaryl, fenobucarb, promecarb, bendiocarb, and carbofuran. The results indicate that AFT can effectively degrade these insecticides in both single component and multicomponent systems. The carbamates compete for hydroxyl radicals, and their kinetics obey the previously developed AFT kinetic model quite well. Hydroxyl radical reaction rate constants were obtained, and they decrease in the following order: dioxacarb ≈ carbaryl > fenobucarb > promecarb > bendiocarb > carbofuran. The AFT is shown to have higher treatment efficiency at higher temperature. Degradation products of the carbamates were determined by gas chromatography/mass spectrometry, and it appears that degradation can be initiated by hydroxyl radical attack at different sites in the molecule, depending on the individual structure of the compound. Substituted phenols are the commonly seen degradation products. The AFT treatment can efficiently remove the chemical oxygen demand of the carbamate mixture, significantly increasing the biodegradability. Earthworm studies show that the AFT is also an effective detoxification process.
- Wang, Qiquan,Lemley, Ann T.
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p. 5382 - 5390
(2007/10/03)
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