Soluble polysaccharides reduce binding and inhibitory activity of tea polyphenols against porcine pancreatic α-amylase

The effects of three soluble polysaccharides on the inhibitory activity of tea polyphenols against porcine pancreatic α-amylase (PPA) were studied through PPA inhibition, half inhibition concentration (IC 50 ), inhibition kinetics and fluorescence quenching. The results show that citrus pectin, wheat arabinoxylan and oat β-glucan could each increase the IC 50 values and competitive inhibition constants ( K ic ), and decrease the fluorescence quenching constants ( K FQ ) of tea polyphenols interacting with PPA. The data show a competitive interaction equilibrium among polysaccharides, polyphenols and PPA. For individual polyphenols, there were negative linear correlations between both the values of 1/ K ic and K FQ and that of IC 50 with and without polysaccharides, indicating that the decreased inhibitory activity of polyphenols induced by the polysaccharides was caused by the reduced binding of polyphenols with PPA. Additionally, the slopes of the linear relationship between IC 50 and K ic and that between K FQ and 1/ K ic remained stable with and without polysaccharides, suggesting that these constants may be combined to characterize the effects of soluble polysaccharides on the PPA inhibition by polyphenols.