Kirthi S. Byadagi

Multi-spectral characterization & effect of metal ions on the binding of bovine serum albumin upon interaction with a lincosamide antibiotic drug, clindamycin phosphate.

The interaction of clindamycin phosphate (CP) with bovine serum albumin (BSA) is studied by using fluorescence spectra, UV-visible absorption, synchronous fluorescence spectra (SFS), CD, 3D fluorescence spectra and lifetime measurements under simulated physiological conditions. CP effectively quenched intrinsic fluorescence of BSA. The binding constants KA values are 2.540×10(5), 4.960×10(5), 7.207×10(5) L mol(-1), the number of binding sites n and corresponding thermodynamic parameters ΔG(o), ΔH(o) and ΔS(o) between CP and BSA were calculated at different temperatures. The interaction between CP and BSA occurs through dynamic quenching and the effect of CP on the conformation of BSA was also analyzed using SFS. The average binding distance r between the donor (BSA) and acceptor (CP) was determined based on Försters theory. The results of fluorescence spectra, UV-vis absorption spectra and SFS show that the secondary structure of the protein has been changed in the presence of CP.

Kinetics and Mechanism of Cerium(IV) Oxidation of Fosfomycin Disodium Salt: An Antibiotic Drug in Acid Perchlorate Solutions

The kinetics of the oxidation of fosfomycin disodium salt by cerium(IV) in an aqueous perchloric acid medium at constant ionic strength, I = 1.10 mol dm−3, has been investigated spectrophotometrically at 25°C. The reaction is of first order in cerium(IV) concentration, fractional order in both fosfomycin and H+ ion concentrations. The active species of oxidant is found to be Ce(OH)3+. Based on the experimental results a suitable mechanism is proposed. The reaction constants involved in the different steps of the reaction mechanism and the activation parameters with respect to the slow step of the mechanism are determined and discussed.

In vitro studies on the interaction between human serum albumin and fosfomycin disodium salt, an antibiotic drug by multi-spectroscopic and molecular docking methods

The interaction between the human serum albumin (HSA) and drug, fosfomycin disodium salt (FOS) has been studied by different spectroscopic techniques. The experimental results showed a static quenching mechanism in the interaction of FOS with HSA. The number of binding sites, n and observed binding constant Ka were measured by fluorescence quenching method. The thermodynamic parameters ΔG°, ΔH° and ΔS° were calculated according to van’t Hoff equation. The calculated distance r between FOS and the protein is evaluated according to the theory of Förster energy transfer. A change in the secondary structure of the protein was evident from the circular dichroism measurements, synchronous fluorescence and three-dimensional fluorescence spectra.

Kinetics and mechanism of ruthenium(III) catalyzed oxidation of chloromphenicol—An antibiotic drug by diperiodatocuprate(III) in aqueous alkaline medium

The kinetics of ruthenium(III) catalyzed oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.1 mol l−1 was studied spectrophotometrically. The reaction between DPC and CHP in alkaline medium exhibits 1: 2 stoichiometry (CHP: DPC). The main oxidation products were identified by spot test, IR, NMR, and GC-MS spectral studies. The reaction is first order with respect to ruthenium(III) and DPC concentrations. The order with respect to chloramphenicol concentration varies from first order to zero order as the chloramphenicol concentration increases. As the alkali concentration increases the reaction rate increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A mechanism adequately describing the observed regularities is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to limiting step of the mechanism are computed and discussed. Thermodynamic quantities are determined.

Kinetics and Mechanism of Oxidation of Chloramphenicol — an Antibiotic Drug by Diperiodatocuprate(III) in Aqueous Alkaline Medium

Abstract The kinetics of oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm-3 was studied spectrophotometrically. The reaction between DPC and CHP in alkaline medium exhibits 1:2 stoichiometry (CHP: DPC). The main oxidation products were identified by spot test, IR, NMR and GCMS spectral studies. The reaction is of first order in DPC and CHP concentrations. As the alkali concentration increases the rate of reaction increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A suitable mechanism is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed. Thermodynamic quantities are also determined.

Oxidation of a Anticholinergic Drug Atropine Sulfate Monohydrate by Alkaline Copper(III) Periodate Complex: A Kinetic and Mechanistic Study

Abstract The oxidation of a anticholinergic drug, Atropine sulfate monohydrate (ASM) by diperiodatocuprate(III) (DPC) has been investigated spectrophotometrically in aqueous alkaline medium at a constant ionic strength of 0.50 mol dm-3. The reaction between diperiodatocuprate(III) and atropine sulfate exhibits 1:2 stoichiometry (atropine sulfate: diperiodatocuprate(III)). The main oxidation products were identified and confirmed by spectral studies including IR, 1H NMR and GC-MS. A suitable mechanism is proposed. The order with respect to diperiodatocuprate(III) concentration was unity, while the order with respect to atropine sulfate concentration was less than unity over the concentration range studied. The rates increased with an increase in alkali concentration and decreased with an increase in periodate concentration. The activation parameters with respect to slow step of the mechanism were calculated and the thermodynamic quantities we are also determined. Kinetic experiments suggest that [Cu(OH)2(H3IO6)]- is the reactive species of copper(III).

Investigation of binding behaviour of procainamide hydrochloride with human serum albumin using synchronous, 3D fluorescence and circular dichroism

Interaction of procainamide hydrochloride (PAH) with human serum albumin (HSA) is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp–214 was estimated employing the Försters theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain IIA (Sudlows site I). The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra (SFS), 3D fluorescence spectra and circular dichroism (CD) results indicated the conformational changes in the structure of HSA.