Structural Characteristics, Metabolic Differences, and Gut Microbiota Modulation of Flavonoid C-Glycosides and O-Glycosides from Lotus Leaf and Plumule

This study investigated the structural characteristics, bioavailability, and metabolism of lotus plumule flavonoid C-glycosides (LPF C-Gly), lotus plumule flavonoid O-glycosides (LPF O-Gly), and lotus leaf flavonoids (LLF). Through preparative chromatography isolation, we found that LLF primarily consisted of quercetin-O-glycosides, while LPF O-Gly was predominantly composed of quercetin and luteolin derivatives, and LPF C-Gly mainly contained apigenin and luteolin glycosides. In vitro digestion and fermentation tests demonstrated that during the digestion process, the antioxidant activity of LPF O-Gly decreased to a level comparable to that of LPF C-Gly. After 48 hours of fermentation, the retention rate of LPF C-Gly (89.19%) was significantly higher than that of LPF O-Gly (19.39%) and LLF (9.42%). Animal experiments demonstrated that LPF C-Gly exhibited significantly higher activity in urine during 12-24 h compared to LLF and LPF O-Gly，explain the stability of C-glycosides metabolism. It significantly enhanced the α-diversity of intestinal microbiota, increased the abundance of Bacteroidetes and Proteobacteria, inhibited pathogen colonization, and demonstrated significant microbiota-modulating effects. Our findings demonstrate that LPF C-Gly modulates gut health through the microbiota-metabolite axis, whereas LPF O-Gly acts as a systemic bioactive regulator during in vitro digestion and fermentation processes, highlighting their distinct roles in health modulation.