Shivamurti A. Chimatadar

Study on the interaction between antibacterial drug and bovine serum albumin: A spectroscopic approach

The binding of sulfamethoxazole (SMZ) to bovine serum albumin (BSA) was investigated by spectroscopic methods viz., fluorescence, FT-IR and UV-vis absorption techniques. The binding parameters have been evaluated by fluorescence quenching method. The thermodynamic parameters, Delta H degrees, DeltaS degrees and Delta G degrees were observed to be -58.0 kJ mol(-1), -111 J K(-1)mol(-1) and -24 kJ mol(-1), respectively. These indicated that the hydrogen bonding and weak van der Waals forces played a major role in the interaction. Based on the Forsters theory of non-radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (SMZ) was evaluated and found to be 4.12 nm. Spectral results showed the binding of SMZ to BSA induced conformational changes in BSA. The effect of common ions and some of the polymers used in drug delivery for control release was also tested on the binding of SMZ to BSA. The effect of common ions revealed that there is adverse effect on the binding of SMZ to BSA.

Multi-spectroscopic investigation of the binding interaction of fosfomycin with bovine serum albumin☆

The interaction between fosfomycin (FOS) and bovine serum albumin (BSA) has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters ΔG0, ΔH0 and ΔS0 were calculated at different temperatures according to the van’t Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlow’s site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA) and acceptor (FOS) molecules was obtained according to the Förster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS), circular dichroism (CD) and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies.

Kinetics and mechanism of palladium(II) catalyzed chromium(VI) oxidation of mercury(I) in aqueous sulphuric acid

The CrVI oxidation of HgI in an aqueous acid medium occurs to a modest extent only in presence of PdII and in H2SO4 above ca. 0.20 mol dm−3. The reaction is first order in [CrVI] in the presence of PdII catalyst. The order in [HgI] is less than unity, whereas that in [PdII] is unity. Increase in [H2SO4] accelerates the reaction rate. The added products, CrIII and HgII, do not significantly effect the reaction rate. A mechanism involving HCrO4− and PdCl+ as the reactive species of oxidant and catalyst respectively, is proposed. The reaction constants involved in the mechanism have been evaluated.

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.

Study of fluorescence interaction and conformational changes of bovine serum albumin with histamine H1-receptor–drug epinastine hydrochloride by spectroscopic and time-resolved fluorescence methods

The fluorescence, ultraviolet (UV) absorption, time resolved techniques, circular dichroism (CD), and infrared spectral methods were explored as tools to investigate the interaction between histamine H1 drug, epinastine hydrochloride (EPN), and bovine serum albumin (BSA) under simulated physiological conditions. The experimental results showed that the quenching of the BSA by EPN was static quenching mechanism and also confirmed by lifetime measurements. The value of n close to unity indicated that one molecule of EPN was bound to protein molecule. The binding constants (K) at three different temperatures were calculated (7.1 × 104, 5.5 × 104, and 3.9 × 104M−1). Based on the thermodynamic parameters (ΔH0, ΔG0, and ΔS0), the nature of binding forces operating between drug and protein was proposed. The site of binding of EPN in the protein was proposed to be Sudlows site I based on displacement experiments using site markers viz, warfarin, ibuprofen, and digitoxin. Based on the Försters theory of non‐radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (EPN) was evaluated and found to be 4.48 nm. The UV–visible, synchronous fluorescence, CD, and three‐dimensional fluorescence spectral results revealed the changes in secondary structure of the protein upon its interaction with EPN.

A kinetic and mechanistic study of thallium(I) oxidation by quinolinium dichromate (QDC), a new oxidant

Quinolinium dichromate (QDC) oxidation of TlI in aqueous AcOH containing large concentrations of HCl is considerably accelerated both by H+ and Cl− ions as well as by increasing the AcOH concentration in the medium; oxidation is made possible by altering the redox potentials. The reaction is first order in oxidant and in reductant but apparently less than unit order in [Cl−] and nearly second order in [H+]. The active species of QDC and TlI are ClCrO3− and TlCl2− respectively. A possible mechanism is proposed and verified, and the reaction constants involved have been evaluated.

Evaluation of the binding interaction between bovine serum albumin and dimethyl fumarate, an anti-inflammatory drug by multispectroscopic methods.

The information of the quenching reaction of bovine serum albumin with dimethyl fumarate is obtained by multi-spectroscopic methods. The number of binding sites, n and binding constants, KA were determined at different temperatures. The effect of increasing temperature on Stern-Volmer quenching constants (KD) indicates that a dynamic quenching mechanism is involved in the interaction. The analysis of thermodynamic quantities namely, ∆H° and ∆S° suggested hydrophobic forces playing a major role in the interaction between dimethyl fumarate and bovine serum albumin. The binding site of dimethyl fumarate on bovine serum albumin was determined by displacement studies, using the site probes viz., warfarin, ibuprofen and digitoxin. The determination of magnitude of the distance of approach for molecular interactions between dimethyl fumarate and bovine serum albumin is calculated according to the theory of Förster energy transfer. The CD, 3D fluorescence spectra, synchronous fluorescence measurements and FT-IR spectral results were indicative of the change in secondary structure of the protein. The influence of some of the metal ions on the binding interaction was also studied.

Pharmacokinetic study on the mechanism of interaction of sulfacetamide sodium with bovine serum albumin: a spectroscopic method

The binding of sulfacetamide sodium (SAS) to bovine serum albumin (BSA) was investigated by spectroscopic methods, namely fluorescence, FT‐IR and UV‐vis absorption spectral studies. The binding parameters were evaluated by a fluorescence quenching method. The thermodynamic parameters, ΔH0, ΔS0and ΔG0 were observed to be −49.03 k J mol−1, −99.9 J K−1 mol−1 and −18.96 k J mol−1, respectively. These indicated that the hydrogen bonding and weak van der Waals forces played major roles in the interaction. Based on Försters theory of non‐radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (SAS) was evaluated and found to be 3.72 nm. The spectral results showed that binding of SAS to BSA induced conformational changes in BSA. The effect of common ions and some of the polymers used in drug delivery for controlled release were also tested on the binding of SAS to BSA. Copyright

Osmium(VIII) mediated oxidation of mercury(I) by cerium(IV) in aqueous sulphuric acid – a kinetic and mechanistic study

The oxidation of HgI by CeIV has been studied in aqueous H2SO4. A minute amount (10−6 mol dm−3) of OsVIII is sufficient to catalyse the reaction. The active catalyst, substrate and oxidant species are H2OsO5, [Hg2(SO4)HSO4]− and H3Ce(SO4)−4, respectively. Possible mechanisms are proposed and the reaction constants involved have been determined.

Interaction between carisoprodol and bovine serum albumin and effect of β-cyclodextrin on binding: insights from molecular docking and spectroscopic techniques

Biomolecular interactions of carisoprodol (CAP) with bovine serum albumin (BSA) have been studied by fluorescence and UV-visible spectroscopy and confirmed by multispectroscopic methods including molecular docking studies. The intrinsic intensity of BSA was quenched by a dynamic quenching mechanism. The binding constant and number of binding sites were calculated according to the Stern–Volmer equation. The effect of β-cyclodextrin on the binding has been studied. Thermodynamic parameters were calculated which reveal the involvement of hydrophobic interactions in the binding. Based on Forsters theory of non-radiation energy transfer, the average binding distance (r) between BSA and CAP was evaluated. Spectral results showed that the binding of CAP to BSA induced conformational changes in BSA. A molecular docking study confirmed the drug binding sites and interaction of CAP with amino acid residues.