Characterization of in vitro digestion and fermentation of Polygonatum sibiricum ethanol extract and implications for antioxidant and lipid‐lowering potential

BACKGROUND Polygonatum sibiricum is known to possess antioxidant and lipid‐regulating properties, but due to the presence of various macromolecular active ingredients such as saponins, it is difficult to digest. The mechanism by which it is digested, absorbed in the gastrointestinal tract and exerts functional activity is still unclear. RESULTS The results of in vitro digestion based on static INFOGEST showed that the content of saponin in P. sibiricum ethanol extract (PSE) gradually decreased during oral, gastric and intestinal digestion, with relatively stable degradation rate of saponin in the gastric digestion phase (18.3%) and the most significant degradation rate of saponin in the intestinal digestion phase (53.5%). Liquid chromatography–mass spectrometry identified 16 saponins in PSE; among these, 13 and 11 saponins were detected in gastric digestion for 2 h (S2) and intestinal digestion for 6 h (I6). In terms of antioxidant capacity, 2.5 mg mL −1 of I6 exhibited DPPH and hydroxyl radical scavenging rates of 72.22 and 52.47% ( P < 0.05), respectively, while ABTS + scavenging activity remained above 60% at all phases of digestion. For lipid‐lowering potential, PSE adsorbed oil at 690 g kg −1 , all samples bound sodium cholate and sodium bovine cholate, and cholesterol micelles increased significantly with concentration ( P < 0.05). In a mouse fecal fermentation model, PSE fermentation enriched Bifidobacterium and Lactobacillus , and reduced Enterococcus and Enterobacter . Meanwhile, total short‐chain fatty acids increased 82‐fold ( P < 0.01), with acetic acid rising from 32.03 ± 1.12 to 9427.23 ± 0.75 μg mL −1 . CONCLUSION P. sibiricum has changed saponin content and composition during digestion and fermentation in vitro , showing antioxidant and lipid‐lowering potential, and has an effect on specific flora. These findings provide a theoretical basis for the prospect of P. sibiricum as a functional food.