Interação da hidroclorotiazida com a albumina em condições fisiológicas normais e hiperglicêmica: estudo baseado em Técnicas Espectrofotométricas e Modelagem Molecular

Abstract

The present work presents the results of a study on the interaction between hydrochlorothiazide and human serum albumin in buffer solution (phosphate buffer pH= 7.4) and solutions containing glucose in normoglycemic (80 mg/dl) and hyperglycemic (320 mg) concentrations, through Ultraviolet-Visible, absorption, steady-state and synchronized fluorescence, and circular dichroism at 37 ºC. A molecular docking study was also performed to verify possible interactions between the drug and Human Serum Albumin in the absence and presence of glucose. Hydrochlorothiazide is a commercial antihypertensive drug widely used in diabetic hypertensive patients. HSA is the main carrier protein used to study biodistribution of drugs. The UV-Vis and spectrofluorimetric results indicated that the association between albumin and hydrochlorothiazide generates a disturbance in the microenvironment around the aromatic amino acid residues. Even spontaneous (ΔG° < 0 in all case), the glucose binding directly affected the binding capacity of HSA for hydrochlorothiazide, with a decrease in the binding constant, Kb, from 2.17 ± 0.02 ×103 M-1 to 0, 02 ± 0.02 × 103 M-1. Circular dichroism analysis confirmed that glucose, at hyperglycemic concentrations, can disrupt protein structure. Overall, the experimental and theoretical results indicated that the increase in glucose level can cause functional disturbance in the ability of albumin to bind hydrochlorothiazide, reinforcing the suggestion of the need for glycemic control to achieve the expected pharmacotherapeutic action and avoid side effects