In vitro simulated digestion of rosa roxburghii tratt fruit: Release and integrated bioaccessibility response of aqueous antioxidant constituents

Rosa roxburghii Tratt (RRT) is a natural plant endemic to Guizhou region of China. Its fruit is edible and nutritional. This study investigated the release of antioxidant constituents from RRT fresh fruit matrix during in vitro simulated oral, gastric, and intestinal digestions with and without digestive enzymes. Spectrophotometric and chromatographic experiments were deployed to determine the content of total phenols (TPC), total flavonoids (TFC), total triterpenoids (TTC), and six ingredients of interest. Antioxidant capacity was tested by using the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2 '-azino-bis-3-ethylbenzo-tiazolin- 6-sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP). A novel concept of integrated bioaccessibility response (IBR) was introduced for assessing the antioxidant capacity of RRT fruit matrices at each digestion time. Results showed that RRT fresh fruit consisted of a variety of antioxidant constituents in rich amount. IBR was a more judicious indicator to measure the systematic antioxidant capacity than any single response of TPC, TFC, TTC, DPPH, ABTS, and FRAP. The digestive enzymes and pH of the gastrointestinal digesting matrices played vital roles in the release, transformation and degradation of polyphenols. The release of triterpenoids was not sensitive to the digestive environment, but high acidity enhanced triterpenoids solubility from this food matrix.