Metabolomic insights into flavonoid migration and bioactivity enhancement in Apocynum venetum tea during hot-water brewing.

Apocynum venetum is a perennial shrub valued for its flavonoid-rich tea and medicinal properties. However, systematic evaluation of regional variation and hot-water brewing effects on flavonoid content and bioactivity remains limited. This study analyzed leaves from multiple regions as unprocessed tea (PT), brewed infusion (TS), and residues (TG) for flavonoid content, extraction efficiency, antioxidant activity, and metabolomic profiles. Shandong samples (P7, P6) exhibited higher total flavonoid contents (66.2, 68.6 mg/g) and extraction efficiencies (59.1%, 58.8%), with P7 exhibiting the strongest antioxidant activity. Metabolome analysis identified flavonoids as dominant metabolites, with phellodensin E enriched in infusions. KEGG enrichment revealed significant upregulation of quercetin-3-O-sulphate. In vivo bioactivity assays demonstrated that phellodensin E (20-25 μg/mL) and quercetin-3-O-sulphate (20 μg/mL) markedly reduced yolk-sac oxidative markers and neutrophil counts (P < 0.001), confirming strong antioxidant and anti-inflammatory effects. Overall, hot-water brewing provides a metabolomic basis for health-beneficial transformations in A. venetum tea.