Investigation of synergistic effect and mechanism of green tea extract and coffee extract on α‐amylase and α‐glucosidase inhibition

Abstract

SummaryTo address the adverse effects of current hypoglycaemic drugs and the limited effect of individual extracts, this research investigated the inhibitory effect of combined green tea extract (GTE) and coffee (CE) on α‐amylase (α‐AMY) and α‐glucosidase (α‐GLU) and their inhibitory mechanisms. The inhibitory effects of single extracts and the complexes on α‐AMY and α‐GLU activities were compared by the principle of equivalence line. The results showed that the complexes had a good synergistic inhibition effect on both α‐AMY and α‐GLU at GTE: CE = 4:1 (w/w). Fluorescence spectroscopy and circular dichroism spectroscopy indicated that the complexes of GTE: CE = 4:1 (w/w) altered the secondary and tertiary structures of α‐AMY and α‐GLU more than the individual extracts, resulting in a synergistic inhibitory effect. The orthogonal experiments showed that tea polyphenols (TP) and coffee polyphenols (CP) were the main components responsible for the synergistic inhibitory effect of the two extracts.