In this study, we investigated whether amination is a novel metabolic pathway of myricetin, one of the major dietary flavonoids found in fruits and vegetables, and whether the aminated metabolite of myricetin remains bioactive. We found that myricetin with a vic-trihydroxyl group on the B ring could chemically react with ammonia via the formation of myricetin quinone to generate the aminated product in vitro. As expected, the amination occurred on position 4′ of the B-ring of myricetin. The structure of this new product was confirmed based on 1D and 2D NMR and LC-MS spectra analysis, and subsequently named as 4′-NH2-myricetin. Using the synthetic 4′-NH2-myricetin as standard, we searched this compound in fecal samples collected from myricetin treated mice using LC-MS and confirmed 4′-NH2-myricetin as the metabolite of myricetin in mice for the first time. Furthermore, two metabolites of myricetin, the mono methylated myricetin and the microbial-derived metabolite 3,4,5-trihydroxyphenylacetic acid, were confirmed to be aminated in vivo based on LC-MS data analysis. After administration of different doses of myricetin, the amination of myricetin showed dose-dependent response. A similar trend was observed for the amination of the mono methylated myricetin, but not for the microbial-derived metabolite 3,4,5-trihydroxyphenylacetic acid. Interestingly, we observed that the aminated myricetin retained the anti-inflammatory activity of myricetin.

Amination as a novel metabolic pathway of myricetin in mice

2019 Fall National Meeting

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