Ghulam Mustafa Peerzada

Nuclear blebbing of biologically active organoselenium compound towards human cervical cancer cell (HeLa): in vitro DNA/HSA binding, cleavage and cell imaging studies.

New pharmacophore organoselenium compound (1) was designed, synthesized and characterized by various spectroscopic methods (IR, ESI-MS, (1)H, (13)C and (77)Se NMR) and further confirmed by X-ray crystallography. Compound 1 consists of two 3,5-bis(trifluoromethyl)phenyl units which are connected to the selenium atom via the organometallic C-Se bond. In vitro DNA binding studies of 1 was investigated by absorption and emission titration methods which revealed that 1 recognizes the minor groove of DNA in accordance with molecular docking studies with the DNA duplex. Gel electrophoretic assay demonstrates the ability of 1 to cleave pBR322 DNA through hydrolytic process which was further validated by T4 religation assay. To understand the drug-protein interaction of which ultimate molecular target was DNA, the affinity of 1 towards HSA was also investigated by the spectroscopic and molecular modeling techniques which showed hydrophobic interaction in the subdomain IIA of HSA. Furthermore, the intracellular localization of 1 was evidenced by cell imaging studies using HeLa cells.

Catalyst, Co-ion and the media effect on the oscillatory behavior of resorcinol in the BZ reaction

The study pertains to the oscillatory behavior of resorcinol as organic substrate in Belousov-Zhabotinsky (BZ) reaction in presence of different metal ions as catalysts in aqueous acid media. It is found that Mn2+ ion as catalyst is most reactive in comparison to ferroin (Fe2+). On varying the aqueous acid media, it is observed that protonated species with respect to organic substrate (resorcinol) is more easily formed in aqueous sulfuric acid, owing to which maximum number of oscillations are observed in this medium. Moreover, the effect of different anions like acetate, carbonate and sulfate associated with the same metal ion (Mn2+) as catalyst on the oscillatory behavior of the reaction system was also studied. Mixed mode oscillations are seen while changing concentration of aqueous sulfuric acid medium.

Kinetic studies on resorcinol-bromate-manganese(II) ion oscillator with and without additives

The present work pertains to the effect of temperature on the oscillatory behavior of bromate driven, Manganese (II) ion catalyzed BZ reaction with aromatic substrate i.e. resorcinol under batch conditions in 1.3 M sulfuric acid as aqueous acid medium. In order to study the effect of methyl ketones as additives (co-substrates), acetone is added to the aforesaid reaction system and the oscillations of the mixed substrate systems were studied at different temperatures. Further the effect of temperature with respect to ternary systems comprising of acetone with other ketones like butanone, pentanone, hexanone and acetyl acetone in 1:1 (v/v) ratio is also studied. It is found that temperature has a marked influence on the reactivity of the reaction systems, with and without methyl ketones and at all concentrations of the additives. Moreover, the rate of enolization of ketones also affects the oscillatory parameters like tin and tp. Although the exact values of enolization constants for the methyl ketones are not known to us, but by studying the oscillatory behavior, a trend can be predicted. Further the formation of end products in the ternary systems is influenced due to hydrophobic interactions of the ketones.

Computational survey of ligand properties on iron(III)–iron(II) redox potential: exploring natural attenuation of nitroaromatic compounds

This study is a computational investigation of the ligand effect on the redox potential of iron redox couple aimed at screening these systems for novel applications. The influence of common and naturally available organic compounds with diverse ligand characteristics (nature of donor site, chelation, pre-organization, degree of back acceptance) on the redox potential of iron(III)–iron(II) redox couple has been theoretically calculated using an appropriate level of density functional theory (DFT). The DFT calculated redox potentials of iron complexes are explored to supplement, corroborate, and predict the experimental behavior of the studied systems towards environmental reduction of nitroaromatic compounds to corresponding anilines. The comparative avidity of iron complexes with cysteine derivatives for the reduction of nitroaromatic compounds has been theoretically explored and based on structure–activity relationship; new iron complexes with a range of reactivity and enhanced ability towards nitroaromatic reduction have been predicted.Graphical abstract

Synergistic effect of perchlorate ions and acetonitrile medium explored for extension in copper redoximetry

The impact of perchlorate ions and acetonitrile medium on copper redox couple was investigated. The acetonitrile solvent and perchlorate ions were found to synergistically increase the redox potential of Cu(II)-Cu(I) couple, thereby increasing its ability to oxidize more systems and expand the copper redoximetric analysis window. The difference in the behavior of thiourea towards copper(II) salts in aqueous and non-aqueous media was also explored. Based on the synergistic effect, an electroanalytical method for composition analysis of copper(I) thiourea complexes was proposed. Kinetic and quantum chemical studies have been used for mechanistic insight into synergistic effect of acetonitrile and perchlorate ions on copper redox couple.

Interaction of some antioxidants with Belousov-Zhabotinsky reaction based on catechol-BrO3−-Mn2+-H2SO4 system

Temporal evolution of a new Mn(II) catalyzed Belousov-Zhabotinsky (BZ) chemical oscillator with catechol (1.2-dihydroxybenzene) as organic substrate is reported within narrow range of concentrations of initial reagents at 30°C. After optimizing the oscillation parameters the system was perturbed with the antioxidants like ascorbic acid and inosine. It is found that ascorbic acid acts as co-substrate within certain concentration limit, whereas inosine acts as a quencher of oscillations. Addition of ascorbic acid to the BZ system decreases induction time thus acting synergistically to help the reaction to enter quickly into the oscillatory regime. A good linear dependence of induction time on the concentration of ascorbic acid (R2 = 0.9948) and inosine (R2 = 0.955) is reported. Inosine has been found to increase the induction time and quench the oscillations. It is mentioned that the magnitude of induction time decreases to a greater extent with ascorbic acid as compared to the magnitude of its increase with the same concentration of inosine. This is pointing to the fact that ascorbic acid is stronger antioxidant than inosine as depicted by their interaction with catechol-based BZ chemical oscillator. Temporal evolution of the BZ reaction with the injection of antioxidants at different stages of reaction is also reported.

Complexation of Oxovanadium(IV) and Dioxouranium(VI) with Synthesized 1,2-(Diimino-4′-antipyrinyl)-1,2-diphenylethane Schiff Base: A Thermodynamic, Kinetic, and Bioactivity Investigation

We report the comparative synthetic methodologies and characterization of a tetradentate Schiff base ligand 1,2-(diimino-4′-antipyrinyl)-1,2-diphenylethane (DE). The target synthesis of oxovanadium(IV) and dioxouranium(VI) complexes (vanadyl and uranyl) with the (DE) ligand was also attempted to envisage the effect of metal ion steric factor on complexation process through solution phase thermodynamic and kinetic studies. The thermodynamic stabilities of synthesized vanadyl and uranyl (DE) complexes are discussed in light of their solution phase thermodynamic stability constants obtained by electroanalytical method. A comparative kinetic profile of vanadyl and uranyl complexation with DE is also reported. The complexation reaction proceeds with an overall 2nd order kinetics with both metal ions. Temperature dependent studies of rate constants present an activation energy barrier of ca. 40.913 and 48.661 KJ mol−1, for vanadyl and uranyl complexation, respectively, highlighting the metal ion steric and ligand preorganization effects. The synthesized Schiff base ligand and its vanadyl and uranyl complexes were screened for biocidal potential as antibacterial, antifungal, and anthelmintic agents with the results compared to corresponding reference drugs.

Dynamical regime of resorcinol based Belousov–Zhabotinsky chemical oscillator in the presence or absence of some hydrophobic antioxidants in aqueous–organic mixed media

This study aims to overcome the difficulty of using hydrophobic moieties like antioxidants, hormones, etc. in oscillatory chemical reactions due to existing solubility problems in aqueous acid media. Several new perturbants viz. hydrophobic antioxidants have been found to affect the oscillatory parameters under batch conditions in the resorcinol based Belousov–Zhabotinsky (BZ) oscillating system performed in aqueous–organic mixed media. The α-tocopherol, 4,4,4-trifluoro-3-methyl-2-butenoic acid, melatonin and β-carotene react with radicals either generated from BZ reagents or from the organic solvents and scavenge them. One to one interactions of these additives with resorcinol, bromate or Mn(II) ions have been investigated using cyclic voltammetry and potentiometry. These interactions may lead to a better understanding of their mechanism corresponding to their role in the BZ chemical oscillators. A comparative trend of these antioxidants was observed. It is noteworthy to mention here that radical based polymerization has been achieved using a specific solvent system containing monomers of that polymer and an interesting behavior oscillatory parameters was observed during polymer synthesis in situ.