Faculty Publications
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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 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 Novel chromeno [2,3-b]-pyrimidine derivatives as potential anti-microbial agents(2010) Sankappa Rai, U.; Isloor, A.M.; Shetty, P.; Vijesh, A.M.; Prabhu, N.; Isloor, S.; Thiageeswaran, M.; Fun, H.-K.An efficient, microwave irradiated synthesis of novel chromeno[2,3-b]-pyrimidine derivatives was carried out. 2-Amino-3,4-dihydro-2H-chromene-3-carbonitrile was converted into imine using N,N-Dimethylacetaldehyde dimethylacetal to give the core intermediate, which was used for the preparation of chromenopyrimidine library, using acetic acid and different amine in microwave irradiation for 5 min. Structures of newly synthesized compounds were confirmed by spectral studies. Compound 6g was characterized by single crystal X-ray analysis. All the compounds were also screened for their anti-microbial activity. Few of the compounds are found to be potential antimicrobials. © 2010 Elsevier Masson SAS. All rights reserved.Item Synthesis, characterization and antimicrobial studies of some new pyrazole incorporated imidazole derivatives(2011) Vijesh, A.M.; Isloor, A.M.; Telkar, S.; Peethambar, S.K.; Rai, S.; Isloor, N.In the present study two series of novel imidazole derivatives containing substituted pyrazole moiety (3a-d and 5a-j) were synthesized. The first series were synthesized by the reaction of 3-aryl-1H-pyrazole-4-carbaldehyde thiosemicarbazones (2a-d) with DMAD and the second series by the reaction of 3-aryl-1H-pyrazole-4-carbaldehydes (1a-e) with 1,2-diketones (4a,b) in the presence of ammonium acetate. Structures of newly synthesized compounds were characterized by spectral studies. New compounds were screened for antifungal and antibacterial activities. Among the synthesized compounds, compound 3c was found to be potent antimicrobial agent. The acute oral toxicity study for the compound 3c was carried out and the experimental studies revealed that compound 3c is safe up to 3000 mg/kg and no death of animals were recorded. © 2011 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 Click chemistry approach: Regioselective one-pot synthesis of some new 8-trifluoromethylquinoline based 1,2,3-triazoles as potent antimicrobial agents(2014) Garudachari, B.; Isloor, A.M.; Satyanarayana, M.N.; Fun, H.-K.; Hegde, G.Three series of 8-trifluoromethylquinoline based 1,2,3-triazoles derivatives (5a-c, 6a-d and 7a-c) were synthesized by multi-step reactions by click chemistry approach. Synthesized compounds were characterized by spectral studies and X-ray analysis. The final compounds were screened for their in-vitro antimicrobial activity by well plate method (zone of inhibition). Compounds 5c, 6b, 8b, 11 and 12 were found to be active against tested microbial strains. The results are summarized in Tables 5 and 6. © 2014 Elsevier Ltd. All rights reserved.Item Optimised microwave-assisted biosynthesis of silver nanoparticles from Nothapodytes foetida leaf extracts and its anti-microbial activities(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2016) Roopesh, R.; Geedhika, G.; D'Souza, J.; Anandhan, S.; Bhat, K.U.; Jaya M, J.; Fathima B, S.; Mohan Balakrishnan, R.M.The present investigation reports the biogenesis of silver nanoparticles (Ag NPs) using extracts of a medicinal plant Nothapodytes foetida. Total phenolic content (TPC) and ferric reducing antioxidant power (FRAP) assay were carried out for the microwave-assisted extract (MAE) of N. foetida using methanol as solvent and the conditions for extraction were optimised by response surface methodology (RSM). The effects of operating variables such as extraction time, temperature and ratio of sample to solvent were studied using central composite design (CCD). A mathematical model with a high determination coefficient (R2) for TPC (0.991) and FRAP (0.995) was obtained. The optimal conditions of extraction for TPC were 48.6 ºC, 23.15 min and 2.04:30 (g/mL) and for FRAP 52.31ºC, 12.32 min and 1.67: 30 (g/mL). Under these conditions, the experimental yields of TPC and FRAP were 2.426 mg gallic acid equivalents (GAE)/g dry powder and 14.985mg of FeSO4·7H2O/g of dry powder, respectively. Ag NPs were characterised using UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The synthesised Ag NPs have also shown potent activity against the human pathogenic Staphylococcus aureus. © 2016 Informa UK Limited, trading as Taylor & Francis Group.Item Polyoxovanadate inhibition of: Escherichia coli growth shows a reverse correlation with Ca2+-ATPase inhibition(Royal Society of Chemistry, 2019) Marques-Da-Silva, D.; Fraqueza, G.; Lagoa, R.; Anandan Vannathan, A.A.; Mal, S.S.; Aureliano, M.Recently, a global analysis of the structure-activity-relationship of a series of polyoxometalates (POMs) revealed that the most active POMs were ascribed to be polyoxovanadates (POVs), especially decavanadate (V10), which was very active against certain bacteria (Bijelic et al., Chem. Commun., 2018). The present study explores this observation and compares the effects of three POVs namely MnV11, MnV13 and V10 against Escherichia coli growth. It was observed that MnV11 presents the lowest growth inhibition (GI50) value for Escherichia coli followed by the MnV13 compound, being about 2 times lower than that of V10; respectively, the values obtained were 0.21, 0.27 and 0.58 mM. All three compounds were more effective than vanadate alone (GI50 = 1.1 mM) and also than decaniobate, Nb10 (GI50 > 10 mM), an isostructural POM of V10. However, the POVs exhibiting the highest antibacterial activity (MnV11) were shown to have the lowest Ca2+-ATPase inhibitor capacity (IC50 = 58 ?M) whereas decavanadate, which was also very active against this membranar ATPase (IC50 = 15 ?M), was less active against bacterial growth, suggesting that POV inhibition of ion pumps might not be associated with the inhibition of Escherichia coli growth. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Structural modification of zolpidem led to potent antimicrobial activity in imidazo[1,2-: A] pyridine/pyrimidine-1,2,3-triazoles(Royal Society of Chemistry, 2019) Reddyrajula, R.; Udayakumar, U.Ambien (zolpidem), an imidazo[1,2-a]pyridine derivative, is a commercial drug to treat insomnia which also possesses antitubercular activity against Mycobacterium tuberculosis H37Rv. In this paper, we describe the synthesis of three diverse lead series of imidazo[1,2-a]pyridine/pyrimidine-1,2,3-triazoles (IPTs) which are designed by specific structural modifications of zolpidem. Most of the IPTs exhibited remarkable in vitro antitubercular activity with an MIC of 1.56 ?g mL-1, which is two-fold higher than the MIC of zolpidem. Further, the synthesized IPTs displayed moderate inhibitory activity against several bacterial and fungal strains as well, and also showed an acceptable safety profile as verified through in vitro cytotoxicity assessment against Vero cells. In addition, the potent IPTs exhibited promising binding interactions within the active site of the InhA enzyme. An interesting correlation between the in vitro inhibitory activity and the binding mode was observed: most of the potent molecules (MIC = 1.56 ?g mL-1) interact through a H-bond with the Tyr 158 residue of the target enzyme. These efforts toward the structural modification of zolpidem could be helpful for further optimization of the IPT core to develop new anti-TB drugs. This journal is © 2019 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Molecular hybridization approach for phenothiazine incorporated 1,2,3-triazole hybrids as promising antimicrobial agents: Design, synthesis, molecular docking and in silico ADME studies(Elsevier Masson SAS 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2019) Reddyrajula, R.; Udayakumar, U.; Madan Kumar, S.The objective of the current study is to synthesize a library consisting of four sets of phenothiazine incorporated 1,2,3-triazole compounds using molecular hybridization approach. In total, 36 new hybrid molecules were synthesized and screened for in vitro growth inhibition activity against Mycobacterium tuberculosis H37Rv strain (ATCC-27294). Among the tested compounds, nineteen compounds exhibited significant activity with MIC value 1.6 ?g/mL, which is twofold higher than the MIC value of standard first-line TB drug Pyrazinamide. In addition, all these compounds are proved to be non-toxic (with selective index > 40) against VERO cell lines. However, these compounds did not inhibit significantly the growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa strains: the activity profile is similar to that observed for standard anti-TB drugs (isoniazid and pyrazinamide), indicating the specificity of these compounds towards the Mycobacterium tuberculosis strain. Also, we report the molecular docking studies against two target enzymes (Inh A and CYP121) to further validate the antitubercular potency of these molecules. Furthermore, prediction of in silico-ADME and pharmacokinetic parameters indicated that these compounds have good oral bioavailability. The results suggest that these phenothiazine incorporated 1,2,3-triazole compounds are a promising class of molecular entities for the development of new antitubercular leads. © 2019 Elsevier Masson SAS