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Item Synthesis and antimicrobial activities of some novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines carrying thioalkyl and sulphonyl phenoxy moieties(2007) Karabasanagouda, T.; Vasudeva Adhikari, A.V.; Shetty, N.S.Thirty one new 6-aryl-3-{(4-substituted phenoxy) methyl}-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles (6a-s) and 6-aryl-3-{(4-substituted phenoxy methyl}-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines (7a-l) have been synthesized from 4-thioalkyl phenols (1a-b) through a multi-step reaction sequence. Compounds 1a-b reacted with ethyl chloroacetate in presence of acetone and potassium carbonate to give ethyl [4-(thioalkyl) phenoxy] acetates (2a-b). Further, 2a was oxidized to [4-(methyl sulphonyl) phenoxy] acetate (2c) using hydrogen peroxide in acetic acid. Reactions of (2a-c) with hydrazine hydrate in alcoholic medium furnished 2-[4-thiosubstituted phenoxy] acetohydrazides (3a-b) and 2-[4-methyl sulphonyl phenoxy] acetohydrazide (3c) which on treatment with carbon disulphide and methanolic potassium hydroxide yielded corresponding potassium dithiocarbazates (4a-c). They were then converted to 4-amino-5-{(4-thioalkyl phenoxy) methyl}-4H-1,2,4-triazole-3-thiols (5a-b) and 4-amino-5-{(4-methyl sulphonyl phenoxy) methyl}-4H-1,2,4-triazole-3-thiol (5c) by refluxing them with aqueous hydrazine hydrate. The title compounds 6a-s were prepared by condensing 5a-c with various aromatic carboxylic acids in presence of phosphorus oxychloride. The intermediates 5a-c, on condensation with various substituted phenacyl bromides afforded a series of title compounds (7a-l). The structures of new compounds 2a-7l were established on the basis of their elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data. All the title compounds were subjected to in vitro antibacterial testing against four pathogenic strains and antifungal screening against three fungi. Preliminary results indicate that some of them exhibited promising activities and they deserve more consideration as potential antimicrobials. © 2006 Elsevier Masson SAS. All rights reserved.Item Synthesis and antimicrobial activities of novel quinoline derivatives carrying 1,2,4-triazole moiety(2009) Eswaran, S.; Vasudeva Adhikari, A.V.; Shetty, N.S.A new class of quinoline derivatives containing 1,2,4-triazole moiety were synthesized from derivatives of 4-hydroxy-8-(trifluoromethyl)quinoline-3-carbohydrazide 4 through multi-step reactions. The compound 4, on treatment with substituted Isothiocyanates yielded quinoline-thiosemicarbazides 5a-c, which were conveniently cyclized to (5-mercapto-4H-triazol-3-yl)-quinolin-4-ols 6a-c in basic medium. These intermediates were then transformed to their respective chloro derivatives 7a-c by treatment with phosphorus oxychloride, which on further reaction with different biologically active rare amines yielded the target compounds 8a-g, 9a-h and 10a-h in good yield. The ultimate step, involving nucleophilic substitution reaction was achieved by microwave-induced technique, which has reduced the reaction time drastically as well as improved the yield when compared to conventional heating. The newly synthesized final compounds were evaluated for their in vitro antibacterial and antifungal activities against four strains each. Preliminary results indicated that most of the compounds demonstrated very good antimicrobial activity, comparable to the first line standard drugs. The most effective compounds have exhibited activity at MIC of 6.25 ?g/mL. © 2009 Elsevier Masson SAS. All rights reserved.Item New quinoline derivatives: Synthesis and investigation of antibacterial and antituberculosis properties(Elsevier Masson SAS, 2010) Eswaran, S.; Vasudeva Adhikari, A.V.; Chowdhury, I.H.; Pal, N.K.; Thomas, K.D.Four new series of quinoline derivatives were synthesized starting from 2-trifluoromethyl aniline through multi-step reactions. In the reaction sequence,substituted aniline was cyclized to 4-hydroxy quinoline 1,which was then transformed to 4-chloro-2,8-bis(trifluoromethyl)quinoline 2. The key scaffold 4-hydrazinyl-2,8-bis(trifluoromethyl)quinoline 3,obtained from the compound 2,was successfully converted to target quinoline derivatives,viz. hydrazones 4aet,ureas 5aee,thioureas 6aec and pyrazoles 7aed,in good yields. The newly synthesized title compounds were evaluated for their in vitro antibacterial activity against Escherichia coli,Staphylococcus aureus,Pseudomonas aeruginosa and Klebsiella pneumoniae (recultured) and antituberculosis activity against Mycobacterium tuberculosis H37Rv and MDR-TB. Preliminary results indicated that most of the hydrazone derivatives demonstrated very good antibacterial and antituberculosis activities while other derivatives showed moderate activity. © 2010 Elsevier Masson SAS. All rights reserved.Item Design and synthesis of some new quinoline-3-carbohydrazone derivatives as potential antimycobacterial agents(Elsevier Ltd, 2010) Eswaran, S.; Vasudeva Adhikari, A.V.; Pal, N.K.; Chowdhury, I.H.A series of 26 new quinoline derivatives carrying active pharmacophores has been synthesized and evaluated for their in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv (MTB), Mycobacterium smegmatis (MC2), and Mycobacterium fortuitum following the broth micro dilution assay method. Compounds 13e, 13i, 13k, 14a, 14c, 14i, and 14k exhibited significant minimum inhibition concentrations, when compared with first line drugs isoniazid (INH) and rifampicin (RIF) and could be ideally suited for further modifications to obtain more efficacious compounds in the fight against multi-drug resistant tuberculosis. © 2009 Elsevier Ltd. All rights reserved.Item New 1,3-oxazolo[4,5-c]quinoline derivatives: Synthesis and evaluation of antibacterial and antituberculosis properties(2010) Eswaran, S.; Vasudeva Adhikari, A.V.; Ajay Kumar, R.A new class of fused oxazoloquinoline derivatives was synthesized starting from 2-bromo-1-phenylethanones 1a-b through multi-step reactions. The newly synthesized compounds were evaluated for their in vitro antibacterial against Escherichia coli (ATTC-25922), Staphylococcus aureus (ATTC-25923), Pseudomonas aeruginosa (ATCC-27853) and Klebsiella pneumoniae (recultured) and antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294). Preliminary results indicated that most of the compounds demonstrated very good antibacterial and antituberculosis activities which are comparable with the first line drugs. Compounds 6a, 6c, 6g, 6j, 6k and 6n emerged as the lead antitubercular agents with MIC, 1 ?g/mL and 99% bacterial inhibition while eight compounds, viz., 5a, 15k, 6a, 6c, 6g, 6j, 6k and 6n were found to be more potent than INH (MIC: 1.5 ?g/mL) with MIC 1 ?g/mL. © 2009 Elsevier Masson SAS. All rights reserved.Item New quinolin-4-yl-1,2,3-triazoles carrying amides, sulphonamides and amidopiperazines as potential antitubercular agents(2011) Thomas, K.D.; Vasudeva Adhikari, A.V.; Chowdhury, I.H.; Sumesh, E.; Pal, N.K.Three new series of quinoline-4-yl-1,2,3-triazoles carrying amides, sulphonamides and amidopiperazines were synthesized through multi-step reactions. The required intermediate, [1-(6-methoxy-2-methylquinolin-4-yl)-1H-1, 2,3-triazol-4-yl]methanol (2) was prepared by treating 4-azido-6-methoxy-2- methylquinoline (1) with propargyl alcohol. Three different series of compounds were synthesized from this intermediate. All the newly synthesized compounds were characterized by spectral and elemental analyses. The structure of 2 was confirmed by X-ray crystallographic study. Further, the title compounds were evaluated for their in vitro anti-bacterial activity against five different bacterial strains and antimycobacterial activity against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis (ATCC 19420) and Mycobacterium fortuitum (ATCC 19542). Title compounds, 6a, 6d, 6i, 6j, 7e, 10a and 10i were found to be active against Mycobacterium tuberculosis H37Rv strain and could be lead molecules of interest. © 2011 Elsevier Masson SAS.Item Design, synthesis and docking studies of quinoline-oxazolidinone hybrid molecules and their antitubercular properties(2011) Thomas, K.D.; Vasudeva Adhikari, A.V.; Chowdhury, I.H.; Sandeep, T.; Mahmood, R.; Bhattacharya, B.; Sumesh, E.New series of quinoline-oxazolidinone hybrid molecules were synthesized based on the preliminary docking studies. All the newly synthesized compounds were characterized by spectral analyses. The newly synthesized compounds were screened for their antimycobacterial properties based on the promising preliminary antibacterial screening results. Amongst tested compounds, compounds 8a, 8j and 13a were active at 0.65 ?g/mL against Mycobacterium tuberculosis H 37Rv strain. The mode of action of these active compounds was carried out by docking of receptor enoyl-ACP reductase with newly synthesized candidate ligands 8a, 8j and 13a. These compounds exhibited well established bonds with one or more amino acids in the receptor active pocket. From the docking studies, compound 8j was considered to be the best inhibitor. © 2011 Elsevier Masson SAS. All rights reserved.Item Extraction, characterization and biological studies of phytochemicals from Mammea suriga(Xi'an Jiaotong University, 2015) Poojary, M.M.; Vishnumurthy, K.A.; Vasudeva Adhikari, A.V.Abstract The present work involves extraction of phytochemicals from the root bark of a well-known Indian traditional medicinal plant, viz. Mammea suriga, with various solvents and evaluation of their in vitro antimicrobial and antioxidant activities using standard methods. The phytochemical analysis indicates the presence of some interesting secondary metabolites like flavonoids, cardiac glycosides, alkaloids, saponins and tannins in the extracts. Also, the solvent extracts displayed promising antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Cryptococcus neoformans with inhibition zone in a range of 20-33 mm. Further, results of their antioxidant screening revealed that aqueous extract (with IC50 values of 111.51±1.03 and 31.05±0.92 ?g/mL in total reducing power assay and DPHH radical scavenging assay, respectively) and ethanolic extract (with IC50 values of 128.00±1.01 and 33.25±0.89 ?g/mL in total reducing power assay and DPHH radical scavenging assay, respectively) were better antioxidants than standard ascorbic acid. Interestingly, FT-IR analysis of each extract established the presence of various biologically active functional groups in it. © 2015 Xi'an Jiaotong University.Item Green Synthesis of Silver and Gold Nanoparticles Using Root Bark Extract of Mammea suriga: Characterization, Process Optimization, and Their Antibacterial Activity(Springer New York LLC barbara.b.bertram@gsk.com, 2016) Poojary, M.M.; Passamonti, P.; Vasudeva Adhikari, A.V.The present study reports the green synthesis of silver and gold nanoparticles (NPs) from their respective precursors AgNO3 and HAuCl4, using root bark extract of Mammea suriga. Further, it describes the influence of various reaction parameters, such as pH, temperature, precursor concentration, and volume of the extract, on the morphology and size of the newly synthesized NPs. The biosynthesized NPs were characterized using UV–Vis spectroscopy, SEM, EDX, XRD, and FTIR. The formation of Ag and Au NPs was confirmed by their UV–Vis spectra. Ag NPs were efficiently synthesized at pH 10, with precursor concentration of 1 mM of AgNO3 and a reaction temperature of 80 °C, while Au NPs were successfully obtained at pH 8, with precursor concentration of either 1 or 3 mM HAuCl4, and the reaction was maintained at room temperature. The SEM study revealed that the particle size decreases with an increase in the extract volume used in the reaction. The XRD analysis confirmed the formation of metallic Ag and Au NPs having an average size of 50 and 22 nm, respectively. Further, the FTIR spectral data established the role of various functional groups of biomolecules involved in bioreduction as well as capping of NPs. The in vitro antibacterial screening results indicated that the NPs are potential antibacterial agents. Conclusively, the overall study showed that the root bark extract of M. suriga is an excellent eco-friendly and non-toxic source for the synthesis of biologically active Ag and Au NPs at optimal conditions. © 2016, Springer Science+Business Media New York.