Structural, in vitro digestion, and fermentation characteristics of lotus leaf flavonoids

[Display omitted] •Flavonoids in lotus leaf mainly existed in the form of flavonol-3-O-glycosides.•Lotus leaf flavonoids kept almost stability in gastric and intestinal fluids.•LLF stimulated growth of Actinobacteria and Firmicutes, inhibited Proteobacteria.•Supplementation of soluble starch improved utilization of LLF by intestinal flora.•Carbon source could promote the utilization of flavonoids by gut microbiota. Bioaccessibility and bioactivity of flavonoids in lotus leaves are related to their characteristics in gastrointestinal digestion and colonic fermentation. The aim of this study is to investigate the stability of lotus leaf flavonoids (LLF) in simulated gastrointestinal digestion, and its modulation on gut microbiota in vitro fermentation. Results showed that LLF mainly consisted of quercetin-3-O-galactoside, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, and kaempferol-3-O-glucoside. These flavonoids kept stability with only a small fraction degraded in simulated gastric and intestinal fluids. In vitro fermentation, LLF stimulated the growth of Actinobacteria and Firmicutes, inhibited the growth of Proteobacteria, and induced the production of fermentation gases and short-chain fatty acids. Interestingly, supplementation of soluble starch significantly improved the utilization of LLF by the intestinal flora. These results revealed that LLF shaped a unique biological web with Lactobacillus and Bifidobacterium spp. as the core of the biological network, which would be more beneficial to gut health.