Praveen N. Naik

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.

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.

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

Non-covalent binding analysis of sulfamethoxazole to human serum albumin： Fluorescence spectroscopy, UV-vis, FT-IR, voltammetric and molecular modeling

This study was designed to examine the interaction of sulfamethoxazole (SMZ) with human serum albumin(HSA). Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of human serum albumin by SMZ was static mechanism. The binding constant values for the SMZ–HSA system were obtained to be 22,500 L/mol at 288 K, 15,600 L/mol at 298 K, and 8500 L/mol at 308 K. The distance r between donor and acceptor was evaluated according to the theory of Föster energy transfer. The results of spectroscopic analysis and molecular modeling techniques showed that the conformation of human serum albumin had been changed in the presence of SMZ. The thermodynamic parameters, namely enthalpy change (∆H0) −36.0 kJ/mol, entropy change (∆S0) −41.3 J/mol K and free energy change (∆G0) −23.7 kJ/mol, were calculated by using van׳t Hoff equation. The effect of common ions on the binding of SMZ to HSA was tested.

Quenching of fluorescence by meclizine, a probe study for structural and conformational changes in human serum albumin

The goal of this study was to investigate the interactions between meclizine (MEC) and human serum albumin (HSA) under physiological conditions by different spectroscopies and molecular modeling technique. The drug, MEC quenched the intrinsic fluorescence of HSA and the analysis of the results revealed that static quenching mechanism. The binding of MEC quenches the HSA fluorescence; stoichiometry was 1:1 interaction. Thermodynamic quantities were calculated at different temperatures suggested that hydrophobic and van der Waals interaction with HSA–MEC. The molecular distance, r, between donor and acceptor was estimated according to Forster’s theory of non-radiation energy transfer. CD and FT-IR studies confirm changes of secondary structure of HSA. Molecular docking studies validate MEC molecule interact to HSA in sub domain IIA.

Kinetics and mechanistic studies of oxidation of fluoroquionoline antibacterial agent norfloxacin by diperiodatocuprate(III) in aqueous alkaline medium

Abstract The kinetics of the oxidation of norfloxacin by diperiodatocuprate(III) in aqueous alkaline medium has been studied spectrophotometrically at 300 K and at constant ionic strength of 0.20 mol dm−3. The oxidation products were identified by LC–ESI–MS technique and other spectral studies. The stoichiometry was found to be 1:2 ([NOR]:[DPC]. The active species of DPC is understood to be as monoperiodatocuprate(III). A suitable mechanism was proposed on the basis of experimental results. The reaction constants involved in the different steps of the reaction mechanism were calculated. The activation parameters with respect to the slow step of mechanism were determined and discussed.

Mechanistic Investigation of Oxidation of Diclofenac Sodium by Diperiodatocuprate(III) Complex in Aqueous Alkaline Medium

The kinetics of oxidation of diclofenac sodium (DFS) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.60 mol dm−3 have been studied spectrophotometrically. The reaction showed first-order kinetics in [DPC] and less than unit order with respect to [DFS] and [alkali] and negative fractional order in [periodate]. The reaction between (DFS) and (DPC) in alkaline medium exhibits 1:2 stoichiometry (DFS): (DPC). The ionic strength and dielectric constant did not affect the rate of reaction. The oxidation products were identified by LC-ESI-MS and IR spectral studies. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to the slow step of the mechanism were computed and discussed, and thermodynamic quantities were also determined.

Oxidation of 6-Aminopenicillanic Acid by Diperiodatoargantate(III) in Aqueous Alkaline Medium: A Kinetic and Mechanistic Study

Many pharmaceutical compounds and metabolites are being found in surface and ground waters, indicating their ineffective removal by conventional wastewater treatment technologies. Advanced oxidation processes for the transformation of 6-aminopenicillanic acid in water are alternatives to traditional water treatment. Therefore the kinetics of oxidation of 6-aminopenicillanic acid by diperiodatoargentate(III) in alkaline medium at a constant ionic strength of 0.04 mol dm -3 was studied spectrophotometrically at 25 °C. The oxidation products, 2-formyl-5,5-dimethylthiazolidine-4-carboxylic acid and Ag(I), were identified by LC-ESI-MS and IR spectral studies. Thereaction between 6-aminopenicillanic acid and diperiodatoargentate(III) in alkaline medium exhibits 1:1 stoichiometry. The reaction shows first order with respect to diperiodatoargentate(III) concentration. The order with respect to 6-aminopenicillanic acid and alkali concentrations is less than unity. The rate goes on decreasing with the increase in the concentration of periodate. Monoperiodatoargentate(III) is considered the active species of the diperiodatoargentate(III). A possible mechanism is proposed. The reaction constants involved in the different steps of the mechanisms are determined. The activation parameters with respect to the slow step of the mechanism are calculated and discussed. The thermodynamic quantities are also determined.