Ammoniation of Dietary Flavonoids Containing a Pyrogallol Group With Amino Acids at 37°C

ABSTRACT New research shows that flavonoids containing a pyrogallol group in ring B react with amino acids at 37°C, forming ammoniated derivatives and aldehydes. Despite this, studies on these reactions and the activity of the resulting ammoniated flavonoids (NH 2 ‐flavonoids) are scarce. This study investigates the amination of (+)‐dihydromyricetin (DMY), (−)‐epigallocatechin (EGC), and (−)‐epigallocatechin gallate (EGCG) by reaction systems involving the composite amino acid or single phenylalanine using UPLC‐QTOF‐MS/MS. Amino acid‐induced ammoniation occurs on both the flavonoids and their degradation products, forming unstable N ‐DMY, N ‐EGC, and N ‐EGCG. A method was developed to synthesize these NH 2 ‐flavonoids and their structures were confirmed with MS, NMR, and CD. Compared to the original flavonoids, N ‐DMY, N ‐EGC, and N ‐EGCG have reduced antioxidant, anticancer, and antibacterial activities. This provides a new sight that flavonoids may regulate physiological functions by affecting amino acid levels. Moreover, the pharmacokinetics, metabolism, and broader biological activities of N ‐DMY, N ‐EGC, N ‐EGCG and other NH 2 ‐flavonoids needs to be studied in future work.