Abstract: Objective: In order to improve the digestive bioaccessibility of bamboo leaf flavonoids, this study aimed to clarify the protective effect of pectin on bamboo leaf flavonoids during simulated in vitro gastrointestinal digestion. Methods: The concentrations of isoorientin, orientin, isovitexin and vitexin from bamboo leaves at different stages of digestion in the presence and absence of pectin were determined by ultra-high performance liquid chromatography (UPLC). Results: Compared with the undigested samples, direct digestion (without pectin) significantly decrease in the concentrations of the four C-glycosylflavones (P < 0.05). Moreover, oral, gastric and intestinal digestion had different effects on the flavonoid concentrations. It was highlighted that the bioaccessibility of these flavonoids was significantly improved by pectin treatment (P < 0.05). Especially, the bioaccessibility of isovitexin and vitexin was increased by 75.1% and 80.2%, respectively. Moreover, principal component analysis and cluster analysis demonstrated different cluster tendencies for the four bamboo leaf flavonoids after treatments. Conclusion: Pectin is useful to enhance the bioaccessibility of bamboo leaf C-glycosylflavones, indicating its promising application in functional food products containing these flavonoid compounds.

Key words: bamboo leaf flavonoids, pectin, ultra-high performance liquid chromatography, in vitro gastrointestinal digestion, cluster analysis