Inhibitory mechanism of sinensetin on α-glucosidase and non-enzymatic glycation: Insights from spectroscopy and molecular docking analyses

Inhibition of alpha-glucosidase and non-enzymatic glycation is regarded as an effective method to prevent and treat type 2 diabetes and its complications. In this study, the inhibition of sinensetin on alpha-glucosidase and nonenzymatic glycation was studied with multi-spectroscopic techniques and molecular docking analysis. The results of fluorescence spectroscopy analysis indicated that sinensetin quenched the endogenous fluorescence of alpha-glucosidase in static manner. The binding of sinensetin with alpha-glucosidase was a spontaneous process primarily driven by hydrophobic interaction. At 298 K, the binding constant was (5.70 +/- 0.12) x 10(4) L.mol(-1) and the binding site number was 1. The conformation of alpha-glucosidase was altered by sinensetin, which was revealed by circular dichroism (CD), FTIR spectra, synchronous fluorescence and three-dimensional (3D) fluorescence spectroscopy methods. Molecular docking analysis demonstrated that sinensetin interacted with the amino acid residues of alpha-glucosidase, which might prevent the entrance of substrate, leading to the decrease of catalytic efficiency of alpha-glucosidase. Furthermore, glycation assays showed that sinensetin stabilized the structure of bovine serum albumins (BSA), interacted with BSA, strongly inhibited the formation of dityrosine, N'-formylkynurenine and advanced glycation end products (AGEs). This study provided useful information concerning sinensetin preventing and treating type 2 diabetes and its related complications. (C) 2020 Elsevier B.V. All rights reserved.