The evaluation of catechins reducing heterocyclic aromatic amine formation: Structure-activity relationship and mechanism speculation

The favorable inhibitory effect of tea polyphenols on heterocyclic aromatic amines (HAAs) has been confirmed in many past studies. The objective of this study was to investigate the structure-activity relationship of catechins that act as inhibitors of HAA formation in chemical models. Two kinds of quantitative structure-activity relationship models for catechin-inhibiting-HAA were established. We chose two kinds of HAAs including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and five catechins including epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC), epicatechin (EC), and catechin (C). The inhibitory effect of five catechins were in the following order: EGCG > ECG > EGC > C > EC. Thereinto, EGCG and ECG showed dramatically better inhibition on the formation of PhIP and MeIQx, especially EGCG. Further, the mechanisms of catechin-inhibiting-HAA were speculated by correlation analysis. The free radical-scavenging ability was predicted to be the most relevant to the inhibitory effect of ECG, EGC, EC and C on HAAs. Differently, the phenylacetaldehyde-trapping ability might be the more important mechanism of EGCG inhibiting PhIP in chemical model system. This study may bring a broader idea for controlling the formation of HAAs according to the structure of catechins.