Figure 1. Chemical structures of phenolic acids (1~9) and catechin (10~16). 1: gallic acid, 2: protocatechuic acid, 3: tannic acid, 4: p-hydroxylbenzoic acid, 5: vanillic acid, 6: chlorogenic acid, 7: caffeic acid, 8: p-coumaric acid, 9: ferulic acid, 10: epigallocatechin, 11: catechin, 12: epicatechin, 13: epigallocatechin gallate, 14: gallocatechin gallate, 15: epicatechin gallate, 16: catechin gallate.
(Courtesy: Lee et al., 2012)