Modulation effect of black rice dietary fiber on the metabolism and fermentation of cyanidin-3-glucoside in an in vitro human colonic model

Black rice (Oryza sativa L.) is a great source of anthocyanins and dietary fiber and possesses various health-promoting properties. The modulating effect of insoluble dietary fiber (IDF) from black rice on the fermentation of cyanidin-3-O-glucoside (Cy3G) in an in vitro human colonic model, together with the possible microbiota-mediated mechanisms, was investigated. The combined Cy3G and IDF fermentation can promote the biotransformation of Cy3G into phenolic compounds such as cyanidin and protocatechuic acid with stronger antioxidant activities and increase the total production of SCFAs during the fermentation of Cy3G. 16S rRNA sequencing analysis revealed that the addition of IDF modulated the microbiota structure and bloomed Bacteroidota and Prevotellaceae-related genera, which were positively correlated with metabolites of Cy3G, thus potentially regulating the microbial metabolism of Cy3G. The work is of great significance for elucidating the material basis of the health benefits of black rice.

Automated summary

Black rice is a food rich in anthocyanins and dietary fiber, which has various health-promoting effects. The study investigated the modulating effect of insoluble dietary fiber from black rice on the fermentation of cyanidin-3-O-glucoside in a human colonic model, as well as the possible microbiota-mediated mechanisms. The results showed that the combined fermentation of cyanidin-3-O-glucoside and insoluble dietary fiber promoted the transformation of cyanidin-3-O-glucoside into phenolic compounds with stronger antioxidant activities, and increased the production of short-chain fatty acids. The addition of insoluble dietary fiber also modulated the microbiota structure, leading to the growth of bacteria that are positively correlated with metabolites of cyanidin-3-O-glucoside, potentially regulating its microbial metabolism.