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Dietary Bioactive Components (Poster Session)

(P26-059-25) Amination as a Novel Metabolic Pathway of Dietary Flavonoids to Detoxify Ammonia

Monday, June 2, 2025
11:45 AM - 12:45 PM ET
Location: Poster Board C-85

    Presenting Author(s)

  • Shengmin Sang, PhD

    Distinguished Professor
    North Carolina Agricultural and Technical State University
    Kannapolis, North Carolina, United States

    • Co-Author(s)

  • SZ

    Shuwei Zhang, PhD

    North Carolina A&T State University
    Kannapolis, North Carolina, United States

Disclosure(s):
Shengmin Sang, PhD: No relevant financial relationship(s) with ineligible companies to disclose.


Objectives: Ammonia is a primary waste product of cellular metabolism in vivo and, when its concentration is elevated in the brain, it can disrupt neurotransmission and induce oxidative stress. This study aimed to explore whether amination represents a novel metabolic pathway for dietary flavonoids to detoxify ammonia.

Methods: In vitro experiments involved reacting three flavonoids with a vic-trihydroxyl structure, baicalein (on the A-ring), myricetin, and epigallocatechin 3-gallate (EGCG) (on the B-ring), with ammonia under controlled conditions. Major aminated products were purified and structurally characterized using LC/MS and 1D/2D NMR spectroscopy. In vivo, mice were administered the flavonoids via oral gavage, and biological samples, including feces, urine, plasma, and brain tissue, were collected at specific time points. Flavonoids and their aminated derivatives in these samples were analyzed and quantified using LC/MS.

Results: All three flavonoids reacted rapidly with ammonia in vitro. Myricetin and EGCG formed mono-aminated products at position 4´ of the B-ring, while baicalein produced both mono- and di-aminated products at positions 5 and 6 of the A-ring. These aminated derivatives were purified and structurally characterized. In vivo, aminated products of all three flavonoids were detected in the feces and urine of treated mice. Plasma analysis revealed dose-dependent increases in the aminated forms of myricetin and its mono-methylated metabolite (from 100 mg/kg to 400 mg/kg). Significant levels of 6-NH2-baicalein were found across all biological samples, with higher concentrations in feces and urine compared to 5-NH2-baicalein. Notably, the concentration of 6-NH2-baicalein in the brain was nearly identical to that of baicalein itself.

Conclusions: This study demonstrates that flavonoids with a vic-trihydroxyl structure can trap and detoxify ammonia both in vitro and in vivo. The detection of aminated flavonoid in the brain highlights flavonoids' potential to cross the blood-brain barrier and detoxify ammonia in the central nervous system.

Funding Sources: This work was supported by funding from NIH grant R01DK131753 to S. Sang.