Structure elucidation of catechins for modulation of starch digestion

- The fine structure of catechins affected the inhibitory activity of α-amylase.
- Catechins interacted with the catalytic residues of the active site of α-amylase with hydrogen bonds and Van der Waals forces.
- Galloylated catechins presents good affinity to bind to human α-amylase.

This study investigated interactions of six type catechins monomers with human pancreatic α-amylase and the structural requirements for inhibitory activity. The in vitro and in silico results showed that inhibitory effects of catechins followed the order: (+)-gallocatechin-3-O-gallate > (−)-epicatechin-3-O-gallate > (−)-epigallocatechin-3-O-gallate > (−)-epicatechin > (−)-epigallocatechin > (+)-catechin. The A, B and C rings of catechins affected the activity by interact with the catalytic residues of the active site of α-amylase forming a phenols-protein complex, including hydroxyl on the 3-position or 5-position of A-C rings, number of hydroxyl substation on the B-ring or C ring, or 2,3-cis/trans isomerism. The galloylated catechins has higher binding affinity with α-amylase than non-galloylated catechins. The results showed that biological activity of catechins against α-amylase, which supported catechins monomer is a promising ingredient as a development strategy of health food for regulation of energy balance and reduction of related diseases risk.