Faculty Publications
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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 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.Item 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.Item 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.Item New dihydropyridine derivatives: Anti-inflammatory, analgesic and docking studies(2013) Ulloora, S.; Kumar, S.; Shabaraya, R.; Vasudeva Adhikari, A.V.The present article describes synthesis of new diethyl 2,6-dimethyl-4-(4- (2-substituted amino-2-oxoethoxy) phenyl)-1,4-dihydropyridine-3,5-dicarboxylates (6a-10b) following multistep synthetic route. Structures of newly synthesized intermediates and title compounds were established by spectral and elemental analyses. The final compounds were screened for their in vivo anti-inflammatory and analgesic activities by carrageenan-induced paw oedema and tail immersion methods, respectively. Moreover, molecular docking studies were carried out for active compounds 6c, 6d, 7d, 8 and 10b to study their mode of action, meanwhile in vivo results indicated that these compounds displayed rapid onset of anti-inflammatory action and exhibited prominent activity when compared with the standard drug. Compounds 6d and 7d carrying amide functionality showed the highest anti-inflammatory as well as analgesic activities. The molecular docking results emphasised the in vivo data and all docked molecules were found to display very low binding constant values in nanomolar scale. © 2012 Springer Science+Business Media, LLC.Item New 6-bromoimidazo[1,2-A]pyridine-2-carbohydrazide derivatives: Synthesis and anticonvulsant studies(Birkhauser Boston, 2014) Ulloora, S.; Shabaraya, R.; Vasudeva Adhikari, A.V.In the present work, we report the facile synthesis and anticonvulsant study of new imidazo[1,2-A]pyridines carrying biologically active hydrazone functionality (3a-3e) and suitably substituted 1,2,4-triazole moieties (4, 5a-5d, 6, and 7a-7d). The newly synthesized intermediates and final compounds were characterized by various spectral techniques such as FTIR, 1H NMR, 13C NMR, and mass spectral and elemental analysis studies. The in vivo anticonvulsant study of the target compounds were carried out following maximal electroshock seizure and subcutaneous pentylene tetrazole methods, while their toxicity study was performed following rotarod method by taking 20, 40, and 100 mg/kg dose levels. Most of the new compounds displayed remarkable anticonvulsant properties at these doses. Particularly, compounds 3b and 4 carrying hydrogen bond donor groups, viz. hydroxyl and amine moieties respectively, exhibited complete protection against seizure and their results are comparable to that of standard drug diazepam. Further, the motor impairment study revealed that all the compounds are nontoxic upto 100 mg/kg. © 2013 Springer Science+Business Media New York.