Effects of tea polyphenols and different teas on pancreatic α-amylase activity in vitro

- TP had mild inhibitory effect against α-amylase at high concentrations.
- Enzyme activity was different when TP was pre-incubated with α-amylase or starch respectively.
- Green tea, black tea and oolong tea all improved α-amylase activity.
- Drinking tea could help starch digestion.

The effects of tea polyphenols (TP) and different types of teas (green, black and oolong tea) processed from the same fresh leaves on pancreatic α-amylase activity were studied using potato starch and cooked potato as substrates. The results showed that, with the both substrates, low concentration of TP significantly increased α-amylase activity while high concentration inhibited it by non-competitive fashion. In addition, the extents of enzymatic activation and inhibition were different when TP was pre-incubated with α-amylase or starch, respectively. The interaction of TP with enzyme/starch led to decreased antioxidant capacity. Results also showed that all the three types of teas significantly enhanced α-amylase activity for a wide range of concentrations (0.34-27.14 mg/mL), and green tea showed the highest activation effect. It is concluded that high concentration of TP exhibits mild inhibitory effect against α-amylase, while green tea, black tea and oolong tea enhance α-amylase activity, which may be due to other constituents in the tea, enhancing α-amylase activity that counteracts the inhibitory effect of TP.