Faculty Publications

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    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.
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    Synthesis of some new 4-styryltetrazolo[1,5-a]quinoxaline and 1-substituted-4-styryl[1,2,4]triazolo[4,3-a]quinoxaline derivatives as potent anticonvulsants
    (2009) Wagle, S.; Vasudeva Adhikari, A.V.; Suchetha Kumari, N.S.
    4-Methyltetrazolo[1,5-a]quinoxaline (3) was prepared by the azide cyclocondensation of 2-chloro-3-methylquinoxaline (2). The reaction of 3 with aromatic aldehydes furnished 4-styryltetrazolo[1,5-a]quinoxalines (4a-f). Compound 2, on treatment with hydrazine hydrate gave 2-hydrazino-3-methylquinoxaline (5). The ring closure of 5 was achieved by the reaction of orthoesters and trifluoroacetic acid to yield 4-methyl-1-(substituted)[1,2,4]triazolo[4,3-a]quinoxalines (7a-c). Further, reaction of 7a-c with different aromatic aldehydes furnished the title compounds, 4-styryl-1-(substituted)[1,2,4]triazolo[4,3-a]quinoxalines (8a-i) in good yield. In another scheme, the hydrazino compound 5 was treated with different aromatic aldehydes to yield corresponding N-arylidenehydrazino quinoxalines (6a-d). Further, the oxidative cyclization of hydrazones by nitrobenzene yielded 1-aryl-4-methyl[1,2,4]triazolo[4,3-a]quinoxalines (7d-g), which on condensation with aromatic aldehydes gave the title compounds, 1-aryl-4-styryl[1,2,4]triazolo[4,3-a]quinoxalines (8j-u). The newly synthesized compounds have been characterized by FTIR, 1H NMR, 13C NMR and mass spectral data, followed by elemental analysis. Some of the compounds were screened for in vivo anticonvulsant activity. Few of them exhibited promising results. © 2008 Elsevier Masson SAS. All rights reserved.
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    Regioselective reaction: Synthesis, characterization and pharmacological studies of some new Mannich bases derived from 1,2,4-triazoles
    (2009) Isloor, A.M.; Kalluraya, B.; Shetty, P.
    In the present investigation, a series of new 4[(3-substituted-1H-pyrazol-4-yl)methyleneamino]-5-substituted-2-[(4-methylpiperzine-1-yl)methyl]-2H-1,2,4-triazole-3(4H)-thiones (4) were synthesized by the aminomethylation of 4-(3-substituted-1H-pyrazol-3-yl)methyleneamino-5-substituted-4H-1,2,4-triazole-3-thiols (3) with formaldehyde and N-methylpiperzine. These newly synthesized Schiff and Mannich bases were characterized by IR, 1H NMR, mass spectral data and elemental analyses. These compounds were screened for their antibacterial and antifungal activity. Some of the compounds were found to exhibit significant antimicrobial activity. © 2009 Elsevier Masson SAS. All rights reserved.
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    Synthesis and anticonvulsant activity of some new bishydrazones derived from 3,4-dipropyloxythiophene
    (2009) Kulandasamy, R.; Vasudeva Adhikari, A.V.; Stables, J.P.
    A series of new 3,4-dipropyloxy-N2,N5-bis(substituted)thiophene-2,5-dicarbohydrazides (4-30) were synthesized from ethyl thiodiglycolate and diethyloxalate through multistep reactions. Following Dieckmann-Komppa reaction, the required precursor 3,4-dihydroxythiophene-2,5-diester (1) was prepared. This was derivatized with propyl bromide and further converted to corresponding hydrazide (3), which was finally transformed to targeted hydrazones (4-30) by conventional methods. The newly synthesized compounds were characterized using FT-IR, 1H and 13C NMR, EI-MS and elemental analyses. The anticonvulsant activity of all the title compounds was investigated against maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scMET) models and their neurotoxicity was also evaluated. Some of the selected compounds were subjected to 6 Hz test in order to evaluate their uncover activities. Compound 3,4-dipropyloxy-N2,N5-bis[1-(2-thienyl)ethylidene]thiophene-2,5-dicarbohydrazide (15) has emerged as a lead in this series with less neurotoxicity. © 2009 Elsevier Masson SAS. All rights reserved.
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    Screening and optimisation of bioconversion parameters for the reduction of 3-[5-[(4-flurophenyl)-1,5, di-oxopentol]-yl] -4-(S) phenyl oxazolidin-2-one
    (2009) Brahmani Priyadarshini, S.R.; Mugeraya, G.; Sandhyavali, M.S.
    The reduction of ketones is one of the most important and practical reaction for producing non racemic alcohols, which are needed to synthesize industrially important chemicals such as pharmaceuticals, agrochemicals and natural products. Biocatalysis has turned out to be a highly competitive technology for asymmetric ketone reduction. In the present work, an attempt was made to identify a potential microorganism for the reduction of 3-[5-[(4-flurophenyl)-1,5, di-oxopentol]-yl] -4-(S) phenyl oxazolidin-2-one. Some of the fungi screened were Saccharomyces cerevisiae, Aspergillus niger(2 strains), Pichia farinosa, Candida vishwanathii, Rhizopus stolonifer and Penicillin species. The experimental results showed that S. cerevisiae, Aspergillus niger and C. viswanathii strains were able to bring about the conversion of selected ketone to alcohol. As Saccharomyces cerevisiae was found to be more effective in bringing about reduction, it was selected for further experiment. In order to improve the yield certain bioconversion parameters like pH of reaction medium, time of incubation, incubation temperature and biomass to substrate ratio were studied. The results showed that the bioreduction of the above mentioned substrate was maximum in pH 7.6 at 30°C when incubated for 48 h. The conversion increased with increase in biomass, however it reached saturation at the ratio of 300:1.
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    A new class of anticonvulsants possessing 6 Hz activity: 3,4-Dialkyloxy thiophene bishydrazones
    (2009) Kulandasamy, R.; Vasudeva Adhikari, A.V.; Stables, J.P.
    Thirty nine new 3,4-di(substituted)oxy-N2,N5-bis(substituted)thiophene-2,5-dicarbohydrazides were synthesized starting from ethyl thiodiglycolate through multi-step reactions. In the synthetic sequence, 3,4-dihydroxythiophene-2,5-diester (1) was obtained by condensing the ethyl thiodiglycolate with diethyl oxalate. It was derivatized using different alkyl halides to give disubstituted thiophene esters (2-5), which were then converted to corresponding hydrazides (6-9) following usual methods. Finally, these hydrazides, on treatment with various substituted carbonyl compounds underwent smooth condensation to yield target hydrazones (10-13). The new compounds were characterized using FT-IR, 1H NMR and 13C NMR, mass spectral and elemental analyses. The anticonvulsant activity of the title compounds was established after intraperitoneal (ip) administration in three seizure models, which include maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and 6 Hz screens and their neurotoxicity was also evaluated. Compound 11f has emerged as an active compound with no neurotoxicity in this series. Also, the structure-activity relationship of the tested compounds was discussed. © 2009 Elsevier Masson SAS. All rights reserved.
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    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.
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    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.
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    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.
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    Synthesis, characterization and biological activities of some new benzo[b]thiophene derivatives
    (2010) Isloor, A.M.; Kalluraya, B.; Pai, K.
    Benzo[b]thiophene molecules are found to be important tools in synthetic medicinal chemistry. They are of current interest due to their wide spectrum of pharmacological properties. In view of the biological activities of benzo[b]thiophene containing molecules, in this present research work, we propose the synthesis of some new benzo[b]thiophene derivatives such as thiadiazoles, oxadiazoles, pyrazolin & diaryl pyrazoles starting from 3-chlorobenzo[b]thiophene-2-carboxyl chloride. These newly synthesized compounds were characterized by elemental analyses, I.R, NMR and Mass spectral studies. Some of the selected compounds were screened for their antibacterial, antifungal and anti-inflammatory studies. Many of the molecules were found to be potent. © 2009 Elsevier Masson SAS. All rights reserved.