Probing the mechanism of interaction of metoprolol succinate with human serum albumin by spectroscopic and molecular docking analysis

A simple method for obtaining human albumin and its use for in vitro interaction assays with indole-thiazole and indole-thiazolidinone derivatives

This work aimed to develop a simple and low-cost method to obtain human serum albumin (HSA) and its consequent application for in vitro drug interaction assays. The HSA was purified by classic principles of plasma precipitation and thermocoagulation, using a multiple-stage fractionation. The quality of the final product was assessed by electrophoresis, protein dosage by the Lowry method and the pharmacopeial thermal stability. At the end, an isotonic solution of HSA with a total protein concentration of 2.7 mg·mL^-1 was obtained, which was visualized as a single band corresponding to the molecular weight of 66 kDa. After the thermal stability test, there was no indication of turbidity or color change of the solution. Finally, the HSA was useful for interaction assays with indole-thiazole and indole-thiazolidinone derivatives through UV-vis absorption and fluorescence spectroscopic studies, as well as by docking molecular analysis. Derivatives quenched the intrinsic fluorescence of HSA, disrupted the tryptophan residues microenvironment, and probably bind at Sudlow's site I. Therefore, the simplified methodology developed in this work proved to be effective in obtaining HSA that can be applied to research goals including drug interaction assays.

Study on the stereoselective binding of cytosine nucleoside enantiomers to human serum albumin

Nucleoside drugs are known for their remarkable anticancer and antiviral properties. The development of nucleoside drugs has attracted much attention and generated a great deal of research interest. β-L-cytidine and β-D-cytidine are a pair of cytosine nucleoside enantiomers. In this work, the interactions between cytosine nucleoside enantiomers and human serum albumin were studied by ultraviolet-visible spectra, fluorescence spectrum and circular dichroism spectrum under simulated human physiological environment. The data of fluorescence spectra were corrected for the inner-filter effect to improve accuracy. Stern-Volmer quenching constants and binding constants in addition to thermodynamic parameters have been analyzed, which established that complexes formation have taken place via static quenching mechanism, and that hydrophobic force involved in these interactions. CD spectrum revealed that on addition of cytosine nucleoside enantiomers, the α-helix% of HSA increased slightly. What's more, molecular modeling method indicated that cytosine nucleoside enantiomers prefer binding at the IIIA site of HSA.

Insight into the interaction of benzothiazole tethered triazole analogues with human serum albumin: Spectroscopy and molecular docking approaches

The interaction of four benzothiazole tethered triazole analogues (MS43, MS70, MS71, and MS78) with human serum albumin (HSA) was investigated using various spectroscopic techniques (ultraviolet-visible (UV-vis) light absorption, fluorescence, circular dichroism (CD), molecular docking and density functional theory (DFT) studies). Fluorescence quenching constants (~10¹² ) revealed a static mode of quenching and binding constants (K_b ~10⁴ ) indicating the strong affinity of these analogues for HSA. Further alteration in the secondary structure of HSA in the presence of these analogues was also confirmed by far UV-CD spectroscopy. The intensity loss in CD studied at 222 nm indicated an increase in random coil/β-sheet conformations in the protein. Binding energy values (MS71 (-9.3 kcal mol^-1 ), MS78 (-8.02 kcal mol^-1 ), MS70 (-7.16 kcal mol^-1 ) and MS43 (-6.81 kcal mol^-1 )) obtained from molecular docking revealed binding of these analogues with HSA. Molecular docking and DFT studies validated the experimental results, as these four analogues bind with HSA at site II through hydrogen bonding and hydrophobic interactions.