Inhibition of starch digestion by flavonoids: Role of flavonoid-amylase binding kinetics

In this study, kinetics of binding between alpha-amylase and green tea flavonoids were investigated by fluorescence quenching (FQ). Their effect on alpha-amylase inhibition was evaluated. Whereas epicatechin (EC) and epigallocatechin (EGC) exhibited slow binding kinetics (in the order of minutes), epicatechin gallate (ECG) and epigallocatechin gallate (ECGC) exhibited very rapid binding (in the order of seconds) with Human Salivary alpha-amylase (HSA) and Porcine Pancreatic a-amylase (PPA). EGCG reached maximum inhibition of HSA and PPA with short incubation time whereas maximum inhibition of HSA and PPA by EC was reached only after 45 to 60 min of incubation. Similar results with ECG and EGC, but not in line with FQ kinetics, highlighted possible interferences of starch-flavonoid interaction in the binding and inhibition process. These results suggest that incubation times of enzymes and flavonoids shall be evaluated prior to enzyme inhibition testing in order to ensure consistent and reliable results.

Automated summary

The study found that epicatechin and epigallocatechin had slow binding kinetics, while epicatechin gallate and epigallocatechin gallate had very rapid binding with salivary and pancreatic amylase. The maximum inhibition of enzymes by different flavonoids occurred at varying incubation times.