Naveed Kausar Janjua

Spectrophotometric analysis of flavonoid-DNA binding interactions at physiological conditions.

Mode of interactions of three flavonoids [morin (M), quercetin (Q), and rutin (R)] with chicken blood ds.DNA (ck.DNA) has been investigated spectrophotometrically at different temperatures including body temperature (310 K) and at two physiological pH values, i.e. 7.4 (human blood pH) and 4.7 (stomach pH). The binding constants, K(f), evaluated using Benesi-Hildebrand equation showed that the flavonoids bind effectively through intercalation at both pH values and body temperature. Quercetin, somehow, showed greater binding capabilities with DNA. The free energies of flavonoid-DNA complexes indicated the spontaneity of their binding. The order of binding constants of three flavonoids at both pH values were found to be K(f(Q)) > K(f(R)) > K(f(M)) and at 310 K.

Flavonoid-DNA binding studies and thermodynamic parameters.

Interactional studies of new flavonoid derivatives (Fl) with chicken blood ds.DNA were investigated spectrophotometrically in DMSO-H2O (9:1 v/v) at various temperatures. Spectral parameters suggest considerable binding between the flavonoid derivatives studied and ds.DNA. The binding constant values lie in the enhanced-binding range. Thermodynamic parameters obtained from UV studies also point to strong spontaneous binding of Fl with ds.DNA. Viscometric studies complimented the UV results where a small linear increase in relative viscosity of the DNA solution was observed with added optimal flavonoid concentration. An overall mixed mode of interaction (intercalative plus groove binding) is proposed between DNA and flavonoids. Conclusively, investigated flavonoid derivatives are found to be strong DNA binders and seem to be promising drug candidates like their natural analogues.

Preparation via a solution method of La0.2Sr0.25Ca0.45TiO3 and its characterization for anode supported solid oxide fuel cells

La0.2Sr0.25Ca0.45TiO3 is a carefully selected composition to provide optimal ceramic and electrical characteristics for use as an anode support in solid oxide fuel cells. In this study we focus on the process optimization and characterization of A-site deficient perovskite, La0.2Sr0.25Ca0.45TiO3 (LSCTA-), powders prepared via a solution method to be integrated into the SOFC anode supports. A Pechini method has been applied to successfully produce single phase perovskite at 900 °C. Processing conditions have been modified to yield a powder that displays a similar sintering profile to commercial yttria stabilised zirconia. The conductivity behavior of porous bodies under redox has been investigated showing a 2 stage process in both oxidation and reduction cycling that exhibits strong reversibility. For the reduction process, addition of impregnated ceria reduces the onset delay period and increases the apparent rate constant, k values, by 30–50% for both stages. The addition of ceria had less influence on the oxidation kinetics, although the conductivity values of both oxidised and reduced porous bodies were enhanced.

β-Cyclodextrin assisted solubilization of Cu and Cr complexes of flavonoids in aqueous medium: a DNA-interaction study.

Cu and Cr complexes of three flavonoids (morin, quercetin and 6-hydroxyflavone) were synthesized and included in beta-cyclodextrin (βCD) with the objective of improving their pharmacokinetic profiles. Then binding with ds.DNA was studied to monitor their interactive tendencies at physiological conditions. The binding constants and other thermodynamic data from UV-vis spectroscopy and cyclic voltammetry revealed Cr-flavonoid-βCD to interact with ds.DNA at pH-7.4 through electrostatic mode of binding while Cu-flavonoid-βCD can intercalate into DNA. The strong binding propensity of Cu-flavonoid-βCD with ds.DNA encourages their application as anticancerous agent.

Radical scavenging propensity of Cu(2+), Fe(3+) complexes of flavonoids and in-vivo radical scavenging by Fe(3+)-primuletin.

Cu2+ and Fe3+ complexes of three flavonoids (morin or mo, quercetin or quer and primuletin or prim) were synthesized with the objective of improving antioxidant capacities of flavonoids. The radical scavenging activities of pure flavonoids and their metal complexes were assayed to monitor their tendencies towards sequestering of radicals at physiological conditions. The scavenger potencies of metal-flavonoid complexes were significantly higher than those of the parent flavonoids. Further, influence of the solvent polarity on the radical capturing by flavonoids and their metal complexes was in favor for the polar solvent. Fe3+-prim displayed its radical scavenging ability via up gradation of CAT and SOD activities in in-vivo antioxidant assays.

Electrochemical study of natural gas fueled electrodes for low temperature solid oxide fuel cell

Fuel cell is undoubtedly widespread energy conversion technology, which can convert fuel (biogas) energy into electricity. Solid oxide fuel cell (SOFC) is one of the best choices among the fuel cell’s family due to high efficiency and fuel flexibility. In this study, zinc-based nanostructured Mn0.20FexZn0.80−xOδ electrode materials were successfully developed by solid state reaction. The proposed materials have been characterized by XRD and SEM. The electrical conductivities have been examined by four-probe DC method in the temperature range of 300–600∘C, the maximum values were recorded and found to be 12.019 and 5.106 S/cm at natural gas and air atmosphere, respectively. The electrochemical performance has been measured employing NK-SDC electrolyte material and their current density versus voltage and current density versus power density (I-V and I-P characteristics) have been drawn. The maximum power density was found to be 170 mW/cm2 using natural gas as a bio-fuel over a temperature of 600∘C.

AuCu@Pt Nanoalloys for Catalytic Application in Reduction of 4-Nitrophenol

To enhance and optimize nanocatalyst ability for nitrophenol (4-NP) reduction reaction we look beyond Au-metal nanoparticles and describe a new class of Au nanoalloys with controlled composition for core of AuCu-metals and Pt-metal shell. The reduction of 4-NP was investigated in aqueous media spectroscopically on 7.8 nm Au nanospheres (AuNSs), 8.3 nm AuCuNSs, and 9.1 nm AuCu@Pt core-shell NSs in diameter. The rate constants of the catalyzed reaction at room temperature, activation energies, and entropies of activation of reactions catalyzed by the AuCu@Pt core-shell NSs are found to have different values to those of the pure metal NSs. The results strongly support the proposal that catalysis by nanoparticles is taking place efficiently on the surface of NSs. These core-shell nanocatalysts exhibited stability throughout the reduction reaction and proved that heterogonous type mechanisms are most likely to be dominant in nanoalloy based catalysis if the surface of the NSs is not defected upon shell incorporation.

Electrochemical studies of the interactional mechanism and scavenging activity of antioxidants towards dinitroaromatics

In the work discussed in this paper, cyclic voltammetric results obtained for the interaction of ascorbic acid, β-carotene, and three structurally related flavonoids (quercetin, rutin, and morin) with the anion radical of 1,3-dinitrobenzene were used to determine their antioxidant activity. The extent of the antioxidant–anion radical interactions was measured as the antioxidant activity coefficient. Higher values of this coefficient obtained for the three flavonoids in DMF are indicative of their greater antioxidant activity than ascorbic acid and β-carotene in this solvent. On the basis of cyclic voltammetric responses, a possible mechanism of the reaction of the reduction product of 1,3-dinitrobenzene with the antioxidants is proposed. Hyperchem PM3 quantum mechanical semi-empirical calculations of charges on reactive sites of the antioxidants and the 1,3-dinitrobenzene anion radical were also carried out; the results obtained supported the proposed mechanism of interaction.Graphical abstract

Study on thermal, spectroscopic and electrochemical behavior of some ferrocene-containing organometallic polyesteramides and their siloxane-based block copolymers

The thermal, spectroscopic and electrochemical behavior of some novel ferrocene-containing polyesteramides and their siloxane-based block copolymers are described in the present study. The thermal properties of the organometallic materials were investigated by thermogravimetric analysis (TGA) and compared with their terephthaloyl- and isophthaloyl-based organic analogues. The energies of activation of pyrolysis for the polymeric materials were calculated using Horowitz and Metzger method. The spectroscopic and electrochemical properties of the organometallic polymeric materials were examined by means of UV-visible (UV) and cyclic voltammetric (CV) studies. The interactions of these materials with ds.DNA (extracted from chicken blood) were also investigated.