Research on the Influences of Five Food-Borne Polyphenols on In Vitro Slow Starch Digestion and the Mechanism of Action

摘要

Inhibiting starch digestion can effectively control postprandial blood sugar level. In this study, the in vitro digestion differences among the mixtures of five polyphenols (i.e., procyanidins [PAs], catechin [CA], tannic acid [TA], rutin [RU], and quercetin [QU]) and starch were analyzed through an in vitro simulation test of starch digestion. The interaction characteristics of these five polyphenols with alpha-amylase and alpha-glucosidase were investigated in terms of the inhibition effect, dynamics, fluorescence quenching, and circular dichroism (CD). The results revealed that the rapidly digestible starch (RDS) contents decreased, while the resistant starch (RS) contents increased. All five polyphenols inhibited the alpha-amylase activity through the noncompetitive approach but inhibited the alpha-glucosidase activity through the competitive approach. Five polyphenols combined with alpha-amylase spontaneously by using the hydrophobic effect. The interaction of PAs and QU with alpha-glucosidase were recognized as van der Waals forces and H bonding, whereas CA and TA interacted with alpha-glucosidase through the hydrophobic effect. All five polyphenols can cause conformational changes in enzymes.