Research Publications (Applied Sciences)
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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 Silica-sulfuric acid : novel, simple, efficient and reusable catalyst for hydration of nitrile to amide(Asian Publication Corporation, 2016) Chandrashekharappa, Sandeep; Venugopala, Katharigatta Narayanaswamy; Venugopala, Rashmi; Odhav, BhartiSilica-sulfuric acid efficiently catalyzes conversion of aliphatic, substituted aromatic and hetero aromatic nitriles to their corresponding amides in good to excellent yields under reflux condition. Products obtained were purified by column chromatography method and characterized by ¹H NMR, ¹³C NMR and mass spectral analysis.Item Antimycobacterial, docking and molecular dynamic studies of pentacyclic triterpenes from Buddleja saligna leaves(Taylor and Fancis Online, 2017) Singh, Alveera; Venugopala, Katharigatta Narayanaswamy; Khedr, Mohammed A.; Pillay, Mellendran; Nwaeze, Kenneth U.; Coovadia, Yacoob; Shode, Francis; Odhav, BhartiBuddleja saligna (family Buddlejaceae) is a medicinal plant endemic to South Africa. Two isomeric pentacyclic triterpenes, oleanolic acid and ursolic acid, were isolated from the leaves of B. saligna using silica gel column chromatography. Compounds oleanolic acid and ursolic acid were subjected to derivatization with acetic anhydride in the presence of pyridine to obtain oleanolic acid-3-acetate and ursolic acid-3-acetate, respectively. The structures of these compounds were fully characterized by detailed nuclear magnetic resonance (NMR) investigations, which included 1H and 13C NMR. Molecular docking studies predicted the free binding energy of the four triterpenes inside the steroid binding pocket of Mycobacterium tuberculosis fadA5 thiolase compared to a reported inhibitor. Thus, their ability to inhibit the growth of M. tuberculosis was predicted and was confirmed to possess significant antimycobacterial activity when tested against Mycobacterium smegmatis, M. tuberculosis H37Rv (ATCC 25177), clinical isolates of multi-drug-resistant M. tuberculosis (MDR-TB) and extensively drug-resistant M. tuberculosis (XDR-TB) using the Micro Alamar Blue Assay. Ursolic acid was isolated from this plant for the first time.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 The chemical composition of leaf essential oils of Psidium guajava L. (white and pink fruit forms) from South Africa(Taylor and Francis, 2015-02-23) Chalannavar, Raju K.; Venugopala, Katharigatta Narayanaswamy; Baijnath, Himansu; Odhav, BhartiThe leaf oils of Psidium guajava (white fruit) and Psidium guajava (pink fruit) collected in KwaZulu-Natal province of South Africa has been examined by Gas chromatography-Mass spectrometry (GC-MS), and the apparent concentrations were determined by gas chromatography with a flame ionization detector. A total of twenty compounds of 88.9 % from white fruit and forty eight compounds representing 97.5 % from pink fruit of the oils were identified. P. guajava (white fruit) produced oil that was much richer in hydrocarbons (38.8 %), sesquiterpenes hydrocarbons (24.0 %), oxygenated sesquiterpenes (19.1 %) and alcohol (6.8 %). The major constituents of the essential oil were caryophyllene oxide (14.0 %), caryophyllene (13.9 %), 1H-cycloprop[e]azulene (11.6 %), adamantane (9.4 %), 3,7,11-trimethyl-1,6,10-dodecatrien-3-ol (6.8 %), α-cubebene (6.7 %), 1,2,3,4-tetrahydronaphthalene (3.9 %), β-humulene (3.5 %), 1,2,4a,5,6,8a-hexahydronaphthalene (3.2 %) and α-caryophyllene (3.0 %). The leaf oil of P. guajava (pink fruit) contained a mixture of hydrocarbons (30.5 %), sesquiterpene hydrocarbons (25.4 %), alcohol (24.4 %) and oxygenated sesquiterpenes (15.0 %). The major constituents of the essential oil were caryophyllene oxide (13.0 %), tetracyclo[6.3.2.0(2,5).0(1,8)]tridecan-9-ol (12.9 %), caryophyllene (9.5 %), 3,7,11-trimethyl-1,6,10-dodecatrien-3-ol (9.5 %), 1H-cycloprop[e]azulene (8.1 %), Z-3-hexadecen-7-yne (4.6 %) and eudesma-4(14),11-diene (4.1 %). High concentration of caryophyllene oxide and caryophyllene in both the oils suggests its usefulness as natural preservatives in the food industry. The terpenic and ester compounds could contribute to the unique flavor of P. guajava leaves.Item Chemical composition of essential oil from the seed Arils of Strelitzia nicolai Regel & Koern from South Africa(Taylor and Francis, 2015-02-23) Chalannavar, Raju K.; Venugopala, Katharigatta Narayanaswamy; Baijnath, Himansu; Odhav, BhartiThe essential oil components of arils from seeds of Strelitzia nicolai were investigated by GC and GC-MS. The oil yields of dried arils obtained by hydrodistillation were 0.86 %. Twenty-five compounds representing 94.2 % of the S. nicolai aril oil were identified. The main chemical constituents belongs to alcohols (1.24 %), amides (3.14 %), amine (31.75 %), aromatic compounds (4.86 %), esters (0.65 %), ethers (28.18 %), hydrocarbons (5.13 %) and ketones (19.30 %).Item Design, synthesis, and computational studies on dihydropyrimidine scaffolds as potential lipoxygenase inhibitors and cancer chemopreventive agents(Dove Press, 2015-02-15) Venugopala, Katharigatta Narayanaswamy; Govender, Reshme; Khedr, Mohammed A.; Venugopala, Rashmi; Aldhubiab, Bandar E.; Harsha, Sree; Odhav, BhartiDihydropyrimidine scaffold has a wide range of potential pharmacological activi-ties such as antiviral, antitubercular, antimalarial, anti-inflammatory, and anticancer properties. 5-Lipoxygenase enzyme is an enzyme responsible for the metabolism of arachidonic acid to leukotrienes. The elevated levels of this enzyme and its metabolites in cancer cells have a direct relation on the development of cancer when compared to normal cells. The development of novel lipoxygenase inhibitors can have a major role in cancer therapy. A series of substituted 1,4-dihydropyrimidine analogues were synthesized and characterized by 1H-NMR, 13C-NMR, and HRMS. Molecular docking against lipoxygenase enzyme (protein data bank code =3V99) was done using Molecular Operating Environment 2013.08 and Leadit 2.1.2 softwares and showed high affinities. The synthesized compounds were tested for their lipoxygenase inhibitory activity and showed inhibition ranging from 59.37%±0.66% to 81.19%±0.94%. The activity was explained by a molecular docking study. The title compounds were also tested for cyto-toxic activity against two human cancer cell lines Michigan Cancer Foundation-7 and human melanoma cells and a normal peripheral blood mononuclear cell line.Item Functional and physical properties of instant beverage powder made from two different varieties of pearl millet(Science and Education Publishing, 2014) Odhav, Bharti; Obilana, Anthony Olusegun; Jideani, V. A.The objective of this experiment was to assess the effects of malting, extrusion and a combination of both processes on the physical and functional properties of the pearl millet flour (PMF) and pearl millet based instant beverage powder (PMIBP) produced. PMF and PMIBP were prepared by malting, extrusion and a combination of malting and extrusion cooking from two different varieties of pearl millet (Agrigreen (AgG) and Babala (Ba)). Malted pearl millets were produced by germinating at 30°C and 98% RH for 36 h, kilned at 50°C for 48 h then cooled to room temperature, ground and stored in a chiller at 5°C until used. Extrusion was carried out using a co-rotating twin-screw extruder under different parameters to obtain the pearl millet instant beverage powder. The different processes significantly (p ≤ 0.05) affected the colour (L, a & b) of AgG and Ba. Malting and extrusion significantly (p ≤ 0.05) reduced the peak viscosity of the starches from the raw pearl millet of both varieties of pearl millet as measured by rapid visco analyser (RVA). This can be considered as advantageous with respect to producing an instant beverage powder with a high nutrient content.Item Antimosquito properties of 2-substituted phenyl/benzylamino-6-(4-chlorophenyl)-5-methoxycarbonyl-4-methyl-3,6-dihydropyrimidin-1-ium chlorides against anopheles arabiensis(Bentham Science Publishers, 2014) Gleiser, Raquel M.; Chalannavar, Raju K.; Odhav, Bharti; Odhav, Bharti; Venugopala, Katharigatta NarayanaswamyEight novel dihydropyrimidine analogs named DHPM1-DHPM8 was synthesized in their hydrochloride salt form using one pot synthesis between methyl 2-chloro-4-(4-chlorophenyl)-6-methyl-1,4-dihydropyrimidine-5-carboxylate and substituted arylamines in isopropanol. The antimosquito effect of the test compounds were assessed against the adult mosquito Anopheles arabiensis. For adulticidal properties the test compounds were sprayed onto ceramic tiles and screened using the cone bio-assay method. The larvicidal activity was tested by monitoring larval mortality daily and up to 3 days of exposure. Repellency properties were tested in a feeding-probe assay using unfed female Anopheles arabien-sis. Compounds DHPM1, DHPM4, DHPM5 and DHPM6 exerted larval mortality equivalent to temephos (trade name Abate, a commercial larvicidal compound). Compounds DHPM1 to DHPM5 repelled or knocked down 92 to 98% of mosquitoes exposed to rodent skin treated with the compounds. None of the compounds showed any significant activity against the adult mosquito Anopheles arabiensis.Item Quantitative analysis of intermolecular interactions in 7-hydroxy-4-methyl-2H-chromen-2-one and Its hydrate(The National Academy of Sciences, 2014-03-09) Venugopala, Katharigatta Narayanaswamy; Panini, Piyush; Odhav, Bharti; Chopra, DeepakThe determination of the crystal and molecular structure of organic compounds has contributed immensely towards the area of crystal engineering. This contributes towards the understanding of the molecular geometry and the different intermolecular interactions which control crystal packing. An approach which quantifies the energetics associated with the formation of different “molecular pairs” is of importance to recognize the hierarchy of intermolecular interactions present in the crystal. We intend to explore different computational tools which contribute towards the field of crystal engineering. In this regard, the crystal structure of 7-hydroxy-4-methyl-2H-chromen-2-one and its hydrate were re-determined and their crystal packing were analyzed in terms of the interaction energy of different intermolecular interactions, calculated by PIXEL method, contributing towards the stabilization of the crystal packing. The system is so chosen such that it allows the analysis of weak interactions like C–H···O, C–H···π, π···π, lp···π etc. in the presence of strong O–H···O hydrogen bonds and also allows for a systematic exploration of the effect of solvent (water in the present case) on the crystal packing. The calculation of the lattice energy reveals that the anhydrous form is 7 kcal/mol more stable than the corresponding hydrate. The major stabilization towards the crystal packing were observed to come from strong O–H···O=C hydrogen bonds (9 kcal/mol) in case of the anhydrous form while in case of its hydrate, water acts as both an acceptor and a donor of the hydrogen bonds, the interaction energy ranging from 5 to 9 kcal/mol. The weak C–H···O hydrogen bond were found to be the second highest contributor (I.E = 3.5–5.5 kcal/mol) towards the stabilization of the packing in both the crystal structures. The main differences in the crystal packing were observed in the presence of weaker interactions in their crystal packing. The weak C–H···π, O(lp)···C=O interactions were observed in the crystal packing of the anhydrous form while the π···π, O(lp)···π interactions stabilize the crystal packing in case of its hydrate. This phenomenon were further well supported by the analysis of the Hirshfeld surfaces mapped with different properties, 2D-fingerprint plots, electrostatic potential mapped on the Hirshfeld surface and electron density isosurface (calculated by ab initio calculation at DFT-D3/B97-D) at both solid state and optimized geometry.
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