Acteoside and Acyl-Migrated Acteoside, Compounds in Chinese Kudingcha Tea, Inhibit α-Amylase In Vitro.

Acteoside, the predominant polyphenol of small-leaved kudingcha, the Chinese tea, has various biological activities. In this study, we examined the acyl migration of acteoside to isoacteoside with high-temperature treatment of acteoside. The inhibitory effects of acyl-migrated acteoside and acteoside on alpha-amylase were investigated, as were their binding interaction with alpha-amylase. The binding of acteoside and isoacteoside to alpha-amylase was investigated by using the fluorescence spectra assay, circular dichroism, and protein-ligand docking studies. Acteoside was more effective than pre-heated acteoside and isoacteoside in inhibiting alpha-amylase activity. Acteoside and isoacteoside binding to alpha-amylase may induce conformational changes to alpha-amylase, and the binding site of acteoside and isoacteoside being near the active site pocket of alpha-amylase may explain the decreased activity of alpha-amylase. The different affinities and binding sites of acteoside and isoacteoside for alpha-amylase resulted in different inhibition rates, which may be due to structural differences between acteoside and isoacteoside.