- Synthesis, characterization, antibacterial and antioxidant potency of nsubstituted- 2-sulfanylidene-1,3-thiazolidin-4-one derivatives and QSAR study
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Background: Rhodanine is known for its potential and important role in the medicinal chemistry since its derivatives exhibit a wide range of pharmacological activities such as antibacterial, antifungal, antidiabetic, antitubercular, anti-HIV, antiparasitic, antioxidant, anticancer, antiproliferative and anthelmintic agents. Objectives: Since N-substituted rhodanine synthons are rarely commercially available, it is desirable to develop a straightforward synthetic approach for the synthesis of these key building blocks. The objective was to synthesize a series of rhodanine derivatives and to investigate their antimicrobial and antioxidant activity. Also, in order to obtain an insight into their structure-activity relationship, QSAR studies on the antioxidant activity were performed. Methods: 1H and 13C FTNMR spectra were recorded on Bruker Avance 600 MHz NMR Spectrometer, mass analysis was carried out on ESI+ mode by LC-MS/MS API 2000. 2,2-Diphenyl-1- picrylhydrazyl radical scavenging activity (% DPPH) was determined in dimethylsulfoxide (DMSO) as a solvent. The antibacterial activity was assessed against Bacillus subtilis, Staphylococcus aureus (Gram positive) and Escherichia coli, Pseudomonas aeruginosa (Gram negative) bacteria in terms of the minimum inhibitory concentrations (MICs) by a modified broth microdilution method. Results: A series of N-substituted-2-sulfanylidene-1,3-thiazolidin-4-ones were synthesized and characterized by 1H NMR, 13C NMR, FTIR, GC MS, LCMS/MS and C,H,N,S elemental analysis. Most of the synthesized compounds showed moderate to excellent antibacterial activity (MIC values from 125 μg/ml to 15.62 μg/mL) and DPPH scavenging activity (from 3.60% to 94.40%). Compound 2-thioxo-3- (4-(trifluoromethyl)-phenyl)thiazolidin-4-one showed the most potent activity against Escherichia coli (3.125 μg/mL), equivalent to antibiotic Amikacin sulphate and against Staphylococcus aureus (0.097 μg/ml), 100 times superior then antibiotic Amikacin sulphate. It has also shown a potent antioxidant activity (95% DPPH scavenging). Two best QSAR models, obtained by GETAWAY descriptor R7p+, Balabans molecular connectivity topological index and Narumi harmonic topological index (HNar), suggest that the enhanced antioxidant activity is related to the presence of pairs of atoms higher polarizability at the topological distance 7, substituted benzene ring and longer saturated aliphatic chain in N-substituents. Conclusion: A series of novel N-substituted-2-thioxothiazolidin-4-one derivatives were designed, synthesized, characterized and evaluated for their antibacterial and antioxidant activity in vitro. Majority of the compounds showed excellent antibacterial activity compared to ampicillin and few of them have an excellent activity as compared to Chloramphenicol standard antibacterial drug. The QSAR study has clarified the importance of presenting a pairs of atoms higher polarizability, such as Cl and S at the specific distance, as well as the substituted benzene ring and a long saturated aliphatic chain in N-substituents for the enhanced antioxidant activity of 2-sulfanylidene-1,3- thiazolidin-4-one derivatives.
- Brahmbhatt, Harshad,Molnar, Maja,Pavi?, Valentina,Rastija, Vesna
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p. 840 - 849
(2020/01/25)
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- Synthesis and antimicrobial activity of some new 1,2,4-trizoles
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A series of 1,2,4-triazole derivatives were synthesized using appropriate synthetic route and structures were confirmed by IR,1H NMR and elemental analysis. All the synthesized compounds (6a-6h and 7a-7h) were evaluated for antimicrobial activity by determining their minimum inhibitory concentrations (MICs) against a panel of Gram-positive, Gram-negative bacteria and fungi. Most of the compounds showed significant antimicrobial activity against Gram-positive bacteria viz. S. aureus, B. subtilis, Gram-negative bacteria viz. E. coli, P. aerugenosa and fungi viz. C. albicans, A. niger. Some of the compounds showed better antibacterial activities against Gram-positive bacteria compared to Gram-negative bacteria. Compounds 7g, 6g, 6a exhibited good MICs against Gram-positive bacteria and 7f showed better MICs against Gram-negative bacteria compared to reference norfloxacin. Compounds 7f and 7d exhibited MICs which is equipotent to the reference drug ketoconazole.
- Jain, Rakesh Kumar,Mishra, Vikash Kumar,Kashaw, Varsha
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p. 1317 - 1322
(2017/05/02)
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- Synthesis and biological activities of novel artemisinin derivatives as cysteine protease falcipain-2 inhibitors
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A series of novel artemisinin derivatives were synthesized from artemisinin and different anilines. All compounds were obtained as β-isomers. The target compounds were evaluated for inhibition activity against Plasmodium falciparum falcipain-2 in vitro, and most of them exhibited potent inhibition in the low micromolar range and proved to be new types of falcipain-2 inhibitors.
- Liu, Yang,Lu, Wei-Qiang,Cui, Kun-Qiang,Luo, Wei,Wang, Jian,Guo, Chun
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p. 1525 - 1531
(2013/03/14)
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- Mechanisms of acid decomposition of dithiocarbamates. 3. Aryldithiocarbamates and the torsional effect
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The acid decomposition of some p-substituted aryldithiocarbamates (arylDTCs) was observed in 20% aqueous ethanol at 25°C, μ = 1.0 (KCl, for pH > 0). The pH-rate profiles showed a dumbell shape with a plateau where the observed first-order rate constant kobs was equal to ko, the rate constant of the decomposition of the dithiocarbamic acid species. The acid dissociation constants of the dithiocarbamic acids (pKa) and their conjugate acids (pK+) were calculated from the pH-rate profiles. Comparatively, ko was more than 104-fold faster than alkyldithiocarbamates (alkDTCs) with similar pKN (the acid dissociation constant of the parent amine). It was observed that the values of pKa and pK+ were 5 and 8 units of pK, respectively, higher than the expected values from the pKN of alkylDTCs. The higher values were attributed to the inhibition of the delocalization of the nitrogen electron pair into the benzene ring because of the strong electron withdrawal effect of the thiocarbonyl group. Comparison of the activation parameters showed that the rate acceleration was due to a decrease in the enthalpy of activation. Proton inventory indicated the existence of a multiproton transition state, and it was consistent with an S to N proton transfer through a water molecule. There are two hydrogens contributing to a secondary SIE, and there are also two protons that are being transferred at the transition state to form a zwitterion followed by fast C-N bond cleavage. The mechanism could also be a concerted asynchronic process where the N-protonation is more advanced than the C-N bond breakdown. The kinetic barrier is similar to the torsional barrier of thioamides, suggesting that the driving force to reach the transition state is the needed torsion of the C-N bond that inhibits the resonance with the thiocarbonyl group and the aromatic moiety, increasing the basicity of the nitrogen and making the proton transfer thermodynamically favorable.
- Humeres, Eduardo,Debacher, Nito A.,Franco, Jose Dimas,Lee, Byung Sun,Martendal, Adriano
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p. 3662 - 3667
(2007/10/03)
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