Research Publications (Applied Sciences)
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Item Crystallography, molecular modeling, and COX-2 inhibition studies on indolizine derivatives(MDPI AG, 2021-06) Venugopala, Katharigatta N.; Chandrashekharappa, Sandeep; Tratrat, Christophe; Deb, Pran Kishore; Nagdeve, Rahul D.; Nayak, Susanta K.; Morsy, Mohamed A.; Borah, Pobitra; Mahomoodally, Fawzi M.; Mailavaram, Raghu Prasad; Attimarad, Mahesh; Aldhubiab, Bandar E.; Sreeharsha, Nagaraja; Nair, Anroop B.; Alwassil, Osama I.; Haroun, Michelyne; Mohanlall, Viresh; Shinu, Pottathil; Venugopala, Rashmi; Kandeel, Mahmoud; Nandeshwarappa, Belakatte P.; Ibrahim, Yasmine F.The cyclooxygenase-2 (COX-2) enzyme is an important target for drug discovery and development of novel anti-inflammatory agents. Selective COX-2 inhibitors have the advantage of reduced side-effects, which result from COX-1 inhibition that is usually observed with nonselective COX inhibitors. In this study, the design and synthesis of a new series of 7-methoxy indolizines as bioisostere indomethacin analogues (5a–e) were carried out and evaluated for COX-2 enzyme inhibition. All the compounds showed activity in micromolar ranges, and the compound diethyl 3-(4-cyanobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5a) emerged as a promising COX-2 inhibitor with an IC50 of 5.84 µM, as compared to indomethacin (IC50 = 6.84 µM). The molecular modeling study of indolizines indicated that hydrophobic interactions were the major contribution to COX-2 inhibition. The title compound diethyl 3-(4-bromobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5c) was subjected for single-crystal X-ray studies, Hirshfeld surface analysis, and energy framework calculations. The X-ray diffraction analysis showed that the molecule (5c) crystallizes in the monoclinic crystal system with space group P 21/n with a = 12.0497(6)Å, b = 17.8324(10)Å, c = 19.6052(11)Å, α = 90.000°, β = 100.372(1)°, γ = 90.000°, and V = 4143.8(4)Å3. In addition, with the help of Crystal Explorer software program using the B3LYP/6-31G(d, p) basis set, the theoretical calculation of the interaction and graphical representation of energy value was measured in the form of the energy framework in terms of coulombic, dispersion, and total energy.Item International Union of Crystallography(Crystal structure of methyl 4-(4-hydroxyphenyl)-6- methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5- carboxylate monohydrate, 2016-08-19) Bairagi, Keshab M.; Venugopala, Katharigatta Narayanaswamy; Mondal, Pradip Kumar; Odhav, Bharti; Nayak, Susanta K.The title hydrate, C13H14N2O4H2O, crystallizes with two formula units in the asymmetric unit (Z0 = 2). The dihedral angles between the planes of the tetrahydropyrimidine ring and the 4-hydroxyphenyl ring and ester group are 86.78 (4) and 6.81 (6), respectively, for one molecule and 89.35 (4) and 3.02 (4) for the other. In the crystal, the organic molecules form a dimer, linked by a pair of N—HO hydrogen bonds. The hydroxy groups of the organic molecules donate O—HO hydrogen bonds to water molecules. Further, the hydroxy group accepts N—HO hydrogen bonds from amides whereas the water molecules donate O—HO hydrogen bonds to the both the amide and ester carbonyl groups. Other weak interactions, including C—HO, C—H and –, further consolidate the packing, generating a three-dimensional network.Item Synthesis, polymorphism, and insecticidal activity of Methyl 4-(4-chlorophenyl)-8-iodo-2-methyl-6-oxo-1,6-dihydro-4H-pyrimido[2,1-b]quinazoline-3-Carboxylate against Anopheles arabiensis mosquito.(Wiley Online Library, 2016-07) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Gleiser, Raquel M.; Sanchez-Borzone, M. E.; Garcia, D. A.; Odhav, BhartiMosquitoes are the major vectors of pathogens and parasites including those causing malaria, the most deadly vector-borne disease. The negative environmental effects of most synthetic compounds combined with widespread development of insecticide resistance encourage an interest in finding and developing alternative products against mosquitoes. In this study, pyrimido[2,1-b]quinazoline derivative DHPM3 has been synthesized by three-step chemical reaction and screened for larvicide, adulticide, and repellent properties against Anopheles arabiensis, one of the dominant vectors of malaria in Africa. The title compound emerged as potential larvicide agent for further research and development, because it exerted 100% mortality, while adulticide activity was considered moderate.Item {2-[(1,3-Benzothiazol-2-yl)methoxy]-5-bromophenyl}(phenyl)methanone(International Union of Crystallography, 2014-05-21) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Odhav, BhartiIn the title compound, C21H14BrNO2S, the dihedral angle between the planes of the benzothiazole and phenylmethanone groups is 63.4 (2)°. In the crystal, pairs of C-H...N hydrogen bonds link the molecules to form inversion dimers, which are further linked by C-H...O interactions into chains along the c axis. C-H...[pi] and [pi]-[pi] interactions [centroid-centroid distance = 3.863 (1) Å] further stabilize the molecular assembly.Item {2-[(1,3-Benzothiazol-2-yl)methoxy]-5- bromophenyl}(phenyl)methanone(International Union of Crystallography, 2013) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Odhav, BhartiIn the title compound, C21H14BrNO2S, the dihedral angle between the planes of the benzothiazole and phenylmethanone groups is 63.4 (2)°. In the crystal, pairs of C-H...N hydrogen bonds link the molecules to form inversion dimers, which are further linked by C-H...O interactions into chains along the c axis. C-H...[pi] and [pi]-[pi] interactions [centroid-centroid distance = 3.863 (1) Å] further stabilize the molecular assembly.Item Synthesis and antimosquito properties of 2,6-substituted benzo[ d ] thiazole and 2,4-substituted benzo[ d ]thiazole analogues against Anopheles arabiensis(Elsevier, 2013-07) Venugopala, Katharigatta Narayanaswamy; Krishnappa, Krishnappa; Nayak, Susanta K.; Subrahmanya, Bhat K.; Vaderapura, Jayashankaragowda P.; Chalannavar, Raju K.; Gleiser, Raquel M.; Odhav, BhartiA novel and efficient one pot synthesis was developed for 2,6-substituted-benzo[d]thiazole analogues 4a–k and 2,4-substituted-benzo[d]thiazole analogues 4l–pvia three component condensation reaction of substituted arylaldehyde, 2-amino-6-halo/4-methyl-benzo[d]thiazole and 2-naphthol or 6-hydroxyquinoline in presence of 10% w/v NaCl in water by microwave method. This method enabled for short reaction times, easy work-up and significant high yields. The title compound 4b was used for single crystal X-ray studies in order to understand its conformation and packing features. The title compounds 4a–p were screened for antimosquito properties such as repellency, insecticidal and larvicidal activity against Anopheles arabiensis by mosquito feeding-probing assay, cone bio-assay and standard WHO larvicidal assay, respectively. Among these analogous 4b, 4d and 4p exhibit the highest repellent activity comparable to the positive control DEET, and 4a and 4k knockdown most mosquitoes on repellent assays.Item 2-(4-Bromoanilino)-6-(4-chlorophenyl)-5-methoxycarbonyl-4- methyl-3,6-dihydropyrimidin-1-ium chloride(International Union of Crystallography, 2013-03-09) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Odhav, BhartiIn the title molecular salt, C19H18BrClN3O2+·Cl-, the dihedral angles between the pyrimidine ring and the chlorobenzene and bromobenzene rings are 72.4 (2) and 45.5 (2)°, respectively. The dihedral angle between the chlorobenzene and bromobenzene rings is 27.5 (2)°. The conformation of the molecule is stabilized by an intramolecular C-H...O interaction. In the crystal, the anion and cation are linked by an N-H...Cl hydrogen bond. Pairs of weak C-H...O and C-H...Cl hydrogen bonds form inversion dimers. Further N-H...Cl hydrogen bonds form R21(6) motifs and link the dimers into chains along [101]. Br...Cl short contacts [3.482 (2) Å] interlink the hydrogen-bonded chains along the b-axis direction.Item Methyl 4-(4-chlorophenyl)-8-iodo-2-methyl-6-oxo-1,6-dihydro-4H-pyrimido-[2,1-b]quinazoline-3-carboxylate(International Union of Crystallography, 2012-12-13) Nayak, Susanta K.; Venugopala, Katharigatta Narayanaswamy; Odhav, BhartiItem Methyl (E)-2-[(3-chloro-4-cyanophenyl)imino]-4-(4-chlorophenyl)-6-methyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate(International Union of Crystallography, 2012-10) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Odhav, BhartiIn the title compound, C20H16Cl2N4O2, the dihedral angles between the planes of the chlorophenyl, chlorocyanophenylimine and ester groups and the plane of the six-membered tetrahydropyrimidine ring are 86.9 (2), 72.6 (2) and 7.9 (2)°, respectively. The Cl atom substituent on the cyanophenyl ring is disordered over two rotationally related sites [occupancy factors 0.887 (2):0.113 (2)], while the molecular conformation is stabilized by the presence of an intramolecular aromatic C-H...[pi] interaction. Both N-H groups participate in separate intermolecular hydrogen-bonding associations with centrosymmetric cyclic motifs [graph sets R22(8) and R22(12)], resulting in ribbons parallel to [010]. Further weak C-H...O hydrogen bonds link these ribbons into a two-dimensional molecular assembly.Item Methyl 2,6-diphenyl-1-p-tolyl-4-(p-tolyl- amino)-1,2,5,6-tetrahydropyridine-3- carboxylate(Acta Cryst., 2012) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Odhav, BhartiIn the title compound, C33H32N2O2, the tetrahydropyridine ring adopts a boat conformation with the carbonyl group in an s-cis conformation with respect to the C=C bond of the six-membered tetrahydropyridine ring. The molecular conformation is stabilized by intramolecular N-H...O, C-H...O and C-H...[pi] interactions. Formation of centrosymmetric head-to-head dimers is observed through pairwise intermolecular N-H...O hydrogen bonds. Additional weak C-H...O and C-H...[pi] interactions stabilize the three-dimensional molecular assembly.