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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    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 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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    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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    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.
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    Synthesis, characterization and biological activity of some new 1,3,4-oxadiazole bearing 2-flouro-4-methoxy phenyl moiety
    (2010) Chandrakantha, B.; Shetty, P.; Nambiyar, V.; Isloor, N.; Isloor, A.M.
    In the present study a series of new 1,3,4-oxadiazole derivatives containing 2-fluoro-4-methoxy moiety were synthesized. These newly synthesized compounds were characterized by NMR, mass spectral, IR spectral study and also by C, H, N analyses. All the newly synthesized compounds were screened for their antibacterial and antifungal studies. Antimicrobial studies revealed that compounds 4a and 4b showed significant antibacterial activity against Escherichia coli and Pseudomonas aeruginosa Compound 4i showed significant antifungal activity against C. albicans. © 2009 Elsevier Masson SAS. All rights reserved.
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    Synthesis, characterization and anti-microbial studies of some novel 2,4-disubstituted thiazoles
    (2010) Vijesh, A.M.; Isloor, A.M.; Prabhu, V.; Ahmad, S.; Malladi, S.
    In the present study a series of novel 2,4-disubstituted thiazole derivatives containing substituted pyrazole moiety was synthesized by the reaction of 3-Aryl-1H-pyrazole-4-carbaldehyde thiosemicarbazone with 6-Bromo/H-3-(bromoacetyl)-2H-chromen-2-one/phenacyl chloride. Structures of newly synthesized compounds were characterized by spectral studies. New compounds were screened for their antibacterial studies against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The results revealed that compounds 7c, 8e, and 8f having 2,5-dichlorothiophene substituent and 8c, 8d having 2,4-dichlorophenyl substituent showed significant antibacterial activity against all tested microorganisms. © 2010 Elsevier Masson SAS. All rights reserved.
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    Synthesis and biological evaluation of aminoketones
    (2010) Sankappa Rai, U.; Isloor, A.M.; Shetty, P.; Isloor, N.; Malladi, S.; Fun, H.-K.
    A three-component Mannich reaction of different ketones with aromatic aldehydes and different amines in microwave irradiation under solvent free condition afforded corresponding ?-amino carbonyl compounds in excellent yields. This method proved as a novel and improved modification of the reported three-component Mannich reaction in terms of milder reaction conditions, reaction times, clean reaction profiles, very small quantity of catalyst and simple workup procedure. Newly synthesized ?-aminoketones were characterized by spectral studies. Structure of compound 4a was also confirmed by single-crystal X-ray analysis. All the compounds were screened for their antimicrobial activity by MIC method. Few of the molecules were found to be biologically potent. © 2010 Elsevier Masson SAS. All rights reserved.
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    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.
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    New pyrazole derivatives containing 1,2,4-triazoles and benzoxazoles as potent antimicrobial and analgesic agents
    (2013) Vijesh, A.M.; Isloor, A.M.; Shetty, P.; Sundershan, S.; Fun, H.-K.
    Azole class of compounds are well known for their excellent therapeutic properties. Present paper describes about the synthesis of three series of new 1,2,4-triazole and benzoxazole derivatives containing substituted pyrazole moiety (11a-d, 12a-d and 13a-d). The newly synthesized compounds were characterized by spectral studies and also by C, H, N analyses. All the synthesized compounds were screened for their analgesic activity by the tail flick method. The antimicrobial activity of the new derivatives was also performed by Minimum Inhibitory Concentration (MIC) by the serial dilution method. The results revealed that the compound 11c having 2,5-dichlorothiophene substituent on pyrazole moiety and a triazole ring showed significant analgesic and antimicrobial activity. © 2012 Elsevier Masson SAS. All rights reserved.