Characteristic Analysis of Peptide Fraction Extracted from Dendrobium aphyllum After In Vitro Gastrointestinal Digestion and Fermentation by Human Fecal Microbiota

To characterize the digestive properties of an antioxidative peptide fraction (DA-P peptide) extracted from Dendrobium aphyllum and its effects following fermentation, DA-P peptide was used as a substrate for artificially stimulated in vitro gastrointestinal digestion and fermentation by human fecal microbiota. After in vitro digestion, the reducing power and DPPH- and ABTS- free radical-scavenging capabilities of DA-P peptide were significantly improved. During fermentation, changes in pH, peptide contents, and enzyme activities were evaluated and the results were well-correlated with each other; DA-P peptide lowered the pH value of the fermentation environment and stimulated the proliferation and metabolism of intestinal flora, indicating that DA-P peptide enhanced colon health. Thus, DA-P peptide showed antioxidative activities after gastrointestinal digestion and beneficial effects on intestinal flora when fermented by gut microbiota. Our results provide a foundation for studies of D. aphyllum peptide, which has not been widely examined.