Showing papers by "Bharathiar University published in 2011"

Effect of N(4)-phenyl substitution in 2-oxo-1,2-dihydroquinoline-3-carbaldehyde semicarbazones on the structure, DNA/protein interaction, and antioxidative and cytotoxic activity of Cu(II) complexes.

Abstract: A new ligand, 2-oxo-1,2-dihydroquinoline-3-carbaldehyde semicarbazone (OQsc-H) (1);, its N(4)-phenyl derivative (OQsc-Ph) (2); and their corresponding copper(II) complexes [CuCl(2)(OQsc-H)]·H(2)O·CH(3)OH (3), [CuCl(2)(OQsc-Ph)(H(2)O)]·CH(3)OH (4), and [CuNO(3)(OQsc-Ph)(H(2)O)]NO(3)·H(2)O·C(2)H(5)OH (5) have been synthesized and characterized by structural, analytical, and spectral methods, in order to investigate the influence of N(4)-phenyl substitution on structure and pharmacological properties. In all of the complexes, the ligands coordinated to the Cu(II) ion in a neutral fashion via ONO donor atoms. The single-crystal X-ray structures of neutral complex (3) and cationic complex (5) exhibit a slightly distorted square-pyramidal structure, while neutral complex (4) revealed an octahedral structure. The interaction of the compounds with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that compounds 1-5 could interact with CT-DNA through intercalation. A gel electrophoresis pictogram demonstrated the ability of the complexes (3-5) to cleave the pBR322 plasmid DNA through a hydrolytic process. The interactions of the compounds with bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence, and synchronous fluorescence spectroscopic methods. The results indicated that all of the compounds could quench the intrinsic fluorescence of BSA in a static quenching process. Investigations of antioxidative properties showed that all of the compounds have strong radical scavenging potencies against hydroxyl radicals, 2,2-diphenyl-1-picrylhydrazyl radicals, nitric oxide, and superoxide anion radicals. Further, the cytotoxic effect of the compounds examined on cancerous cell lines such as human cervical cancer cells (HeLa), human laryngeal epithelial carcinoma cells (HEp-2), human liver carcinoma cells (Hep G2), human skin cancer cells (A431), and noncancerous NIH 3T3 mouse embryonic fibroblasts cell lines showed that all three complexes exhibited substantial cytotoxic activity. Further, all of the pharmacological investigations support the fact that there exists a strong influence of N(4)-phenyl substitution in semicarbazone.

Larvicidal and repellent potential of Moringa oleifera against malarial vector, Anopheles stephensi Liston (Insecta: Diptera: Culicidae)

Abstract: Objective To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera (M. oleifera) plant seeds against malarial vector Anopheles stephensi (A. stephensi) mosquitoes at different concentrations (20, 40, 60, 80 and 100 ppm).

Effect of terminal N-substitution in 2-oxo-1,2-dihydroquinoline-3-carbaldehyde thiosemicarbazones on the mode of coordination, structure, interaction with protein, radical scavenging and cytotoxic activity of copper(II) complexes

Abstract: Four 2-oxo-1,2-dihydroquinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H2-OQtsc-R, where R = H, Me, Et or Ph) and their corresponding new copper(II) complexes [CuCl2(H2-OQtsc-H)]·2H2O (1), [CuCl2(H2-OQtsc-Me)]·2H2O (2), [CuCl2(H2-OQtsc-Et)(CH3OH)]Cl (3) and [CuCl(H-OQtsc-Ph)]·CH3OH (4) have been synthesized in order to correlate the effect of terminal N-substitution on coordination behaviour, structure and biological activity. Single crystal X-ray diffraction studies revealed that the complexes 1, 2 and 3 have square pyramidal geometry around the central metal ion. In the complexes 1 and 2, the copper ion is coordinated by the ligand with ONS donor atoms, one chloride ion in apical position and the other chloride in the basal plane. Complex 3 consists of [CuCl2(H2-OQtsc-Et)(CH3OH)]+ cation and a chloride as counter ion. The copper ion is coordinated by the ligand with ONS donor atoms and by one chloride ion in the basal plane. One methanol molecule is bonded through its neutral oxygen in the apical position. Complex 4 is square planar with the ligand coordinating through uni-negative tridentate ONS− and by one chloride ion in the basal plane. The binding of complexes with lysozyme protein was carried out by fluorescence spectroscopy. Investigations of antioxidation properties showed that all the copper(II) complexes have strong radical scavenging properties. The cytotoxicity of the complexes 3 and 4 against NIH 3T3 and HeLa cell lines showed that synergy between the metal and ligands results in a significant enhancement in the cell death with IC50 of ∼10–40 μM. A size dependence of substitution at terminal N in the thiosemicarbazones on the biological activities of the complexes has been observed.

Effect of substitution and planarity of the ligand on DNA/BSA interaction, free radical scavenging and cytotoxicity of diamagnetic Ni(II) complexes: A systematic investigation

Abstract: Four new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl2(PPh3)2] with H2L {L = dianion of the hydrazones derived from the condensation of salicylaldehyde or o-hydroxy acetophenone with p-toluic acid hydrazide (H2L1) (1), (H2L2) (2) and o-hydroxy acetophenone or o-hydroxy naphthaldehyde with benzhydrazide (H2L3) (3) and (H2L4) (4)} and formulated as [Ni(L1)(PPh3)] (5), [Ni(L2)(PPh3)] (6), [Ni(L3)(PPh3)] (7) and [Ni(L4)(PPh3)] (8). Structural characterization of complexes 5–8 were accomplished by using various physico-chemical techniques. In order to study the influence of substitution in the ligand and its planarity on the biological activity of complexes 5–8 containing them, suitable hydrazone ligands 1–4 have been selected in this study. Single crystal diffraction data of complexes 5, 7 and 8 proved the geometry of the complexes to be distorted square planar with a 1 : 1 ratio between the metal ion and the coordinated hydrazones. To provide more insight on the mode of action of complexes 5–8 under biological conditions, additional experiments involving their interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were monitored by UV-visible and fluorescence titrations respectively. Further, the ligands 1–4 and corresponding nickel(II) chelates 5–8 have been tested for their scavenging effect towards OH and O2− radicals. The effect of complexes 5–8 to arrest the growth of HeLa and Hep-2 tumour cell lines has been studied along with the cell viability against the non-cancerous NIH 3T3 cells under in vitro conditions.

Green algae Chlorococcum humicola- a new source of bioactive compounds with antimicrobial activity

Abstract: Objective To analyse the existence of bioactive phytochemicals and their antimicrobial role of green algae Chlorococcum humicola (C. humicola). Methods The various organic solvents such as acetone, benzene, chloroform, diethyl ether, ethyl acetate, ethanol, hexane and methanol were used for the preparation of the algal extracts then subjected to chemical analysis and further used for the screening of antimicrobial assay. The purified carotenoid pigments and chlorophylls were used for the antimicrobial studies against the harmful pathogens Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Klebsiella pneumoniae, Vibreo cholerae, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Aspergillus niger and Aspergillus flavus. Results The chemical analysis showed the existence of bioactive compounds such as carotenoids, alkaloids, favanoids, fattyacids, saponins, aminoacids and carbohydrates. In vitro screening of organic solvent extracts of green algae C. humicola shows activity in inhibiting the growth of virulent strains of bacteria and fungi pathogenic to human. Eight different extracts showed effective inhibitory action against the selected pathogens. Depends upon their existence of the bioactive compounds the different organic algal extracts shows difference in their inhibitory zone against the microbes. Out of all the organic extracts benzene and ethyl acetate extracts showed excellent effect nearly 80% microbial growth inhibition. The separated carotenoid and chlorophyll fractions of C. humicola, also results in the microbial growth inhibition. Conclusions The present study concludes that green algae C. humicola are a rich and varied source of pharmacologically active natural products and nutraceuticals. While nutraceutical and pharmaceutical content in the baseline algae strain is very small, they showed excellent effect against the microbial pathogens.

Energy storage studies of bare and doped vanadium pentoxide, (V1.95M0.05)O5, M = Nb, Ta, for lithium ion batteries

Abstract: The bare V2O5 and doped (V1.95M0.05)O5 (M = Nb, Ta) nano/submicron sized compounds were prepared by the simple polymer precursor method. The compounds were characterized by different physical and electroanalytical techniques. The effects of doping and different synthesis conditions on the energy storage performance of the V2O5 compounds were discussed. All compounds delivered a discharge capacity (at the end of the 2nd cycle) in the range 245 to 261 (±3) mA h g−1, except for the tantalum doped compound (V1.95Ta0.05)O5 which exhibited a discharge capacity of 210 (±3) mA h g−1, cycled in the range 2.0–4.0 V at a current rate of 120 mA g−1. An excellent cycling stability of 96% till twenty cycles was achieved for the compound V2O5 prepared by the polymer precursor method. Electrochemical impedance spectroscopy studies at different voltages during discharge and charge cycles were discussed in detail.

Conductivity and dielectric properties of polyvinyl alcohol–polyvinylpyrrolidone poly blend film using non-aqueous medium

Abstract: Several methods such as copolymerization, plasticization and blending etc., have been used to modulate the conductivity of polymer electrolytes. Polymer blending is one of the most important contemporary ways for the development of new polymeric materials and it is a useful technique for designing materials with a wide variety of properties. Polymer blend electrolyte has been prepared with different concentrations of PVA and PVP by solution casting technique using DMSO as solvent. The prepared films have been investigated by different techniques. The increase in amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. The FTIR analysis reveals that the interchain hydrogen bonding within a PVA–PVP blends. The dielectric permittivity (e*) and modulus (M*) have been calculated from the ac impedance spectroscopy in the frequency range 42 Hz– 1 MHz and the temperature range 308–373 K. The maximum conductivity has been found to be 1.58 × 10 − 6 S cm − 1 at room temperature for 70PVA:30PVP concentration. The conductivity has been increased to 5.49 × 10 − 5 S cm − 1 when the temperature is increased to 373 K. The activation energy of all samples was calculated using the Arrhenius plot and it has been found to be 0.53 eV to 0.78 eV.

On the optical and thermal properties of in situ/ex situ reduced Ag NP’s/PVA composites and its role as a simple SPR-based protein sensor

Abstract: Silver/polyvinyl alcohol (Ag-PVA) nanocomposite films have been prepared via in situ generation of silver nanoparticles (Ag NPs) by the respective metallic salts and dispersion of preformed Ag NPs (ex situ synthesis) inside polyvinyl alcohol (PVA) and its effect of sensing towards a model protein (bovine serum albumin—BSA) was investigated. The influence of Ag NPs, irrespective of their reduction methodology on the optical and the thermal properties of the PVA, had been investigated using UV–Vis spectrophotometer and differential scanning calorimetry. The absorption peak around 400 nm indicates the surface plasmon resonance response of Ag NPs. The interaction of the dispersed and preformed Ag NPs with the PVA chains is confirmed by the corresponding vibrational signatures of the PVA through Fourier transform infrared spectroscopy (FTIR). The changes in the glass transition and melting temperatures (Tg and Tm) of the pure PVA upon the presence of Ag NPs are reported using differential scanning calorimeter (DSC). The sizes of the synthesized Ag NPs are found to be in the range of 200 ± 10 nm for in situ reduction of silver nitrate (AgNO3) and 100 ± 10 nm for the external addition of preformed Ag NPs by sodium borohydride (NaBH4) reduction using scanning electron microscopy (SEM).

Larvicidal efficacy of Jatropha curcas and bacterial insecticide, Bacillus thuringiensis, against lymphatic filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae)

Abstract: The present study explored the effects of Jatropha curcas leaf extract and Bacillus thuringiensis israelensis larvicidal activity against the lymphatic filarial vector, Culex quinquefasciatus. Wights were selected for investigating the larvicidal potential against the first to fourth instar larvae of the laboratory-reared mosquito species, C. quinquefasciatus Say, in which the major lymphatic filariasis was used. The medicinal plants were collected from the area around Bharathiar University, Coimbatore. The dried plant materials were powdered by an electric blender. From the powder, 100 g of the plant materials was extracted with 300 ml of organic solvents of methanol for 8 h, using a Soxhlet apparatus, and filtered. The crude plant extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal effects after 24 h of exposure; however, the highest larval mortality was found in the leaf extract of methanol J. curcas against the first to fourth instar larvae of values LC50 = 1.200%, 1.290%, 1.358%, and 1.448% and LC90 = 2.094%, 2.323%, 2.444%, and 2.544% and B. thuringiensis israelensis against the first to fourth instar larvae of values LC50 = 9.332%, 9.832%, 10.212%, 10.622% and LC90 = 15.225%, 15.508%, 15.887%, and 15.986% larvae of C. quinquefasciatus, respectively. No mortality was observed in the control. These results suggest methanol extracts of J. curcas and B. thuringiensis israelensis have potential to be used as an ideal eco-friendly approach for the control of the major lymphatic filarial vector, C. quinquefasciatus.

Chromatographic finger print analysis of steroids in Aerva lanata L by HPTLC technique

Abstract: Objective To determine the chemical profile and steroids composition of the medicinally important plant Aerva lanata (A. lanata) L.

Synthesis, electrical and dielectric properties of FeVO4 nanoparticles

Abstract: The electrical and dielectric properties of FeVO 4 nanoparticles were studied at different temperatures from ambient to 200 °C. The samples were prepared by simple co-precipitation method using ferric nitrate and ammonium metavanadate as the starting precursors. The powder X-ray diffraction pattern inferred the single phase formation and triclinic structure of FeVO 4 . The morphology of the particles was elucidated from SEM studies. Detailed studies on the electrical and dielectric properties of the compound were carried out by using solid state impedance spectroscopy. A maximum dc conductivity of 4.65×10 −5 S cm −1 was observed at the measuring temperature of 200 °C. The calculated activation energy from dc conductivity was found to be 0.28 eV. It was evident that the electrical transport process in the system was due to the hopping mechanism. The detailed dielectric studies were also carried out.

Characterization of nano-crystalline ZrO2 synthesized via reactive plasma processing

Abstract: Nano-crystalline ZrO 2 powder has been synthesized via reactive plasma processing. The synthesized ZrO 2 powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and FTIR spectroscopy. The synthesized powder consists of a mixture of tetragonal and monoclinic phases of zirconia. Average crystallite size calculated from the XRD pattern shows that particles with crystallite size 20 nm or less than 20 nm are in tetragonal phase, whereas particles greater than 20 nm are in the monoclinic phase. TEM results show that particles have spherical morphology with maximum percentage of particles distributed in a narrow size from about 15 nm to 30 nm.