Secoisolariciresinol diglucoside ameliorates high fat diet-induced colon inflammation and regulates gut microbiota in mice

Secoisolariciresinol diglucoside (SDG) has a strong anti-inflammatory effect, which depends partly on the participation of gut microbiota. We studied the effect of SDG on colonic inflammation caused by a common poor diet, high-fat diet (HFD), and the regulation of gut microbiota as well as its metabolites. Considering the difference of sources, prices, and possible bioactivity, we compared the effects of a single compound and the extract of SDG on colon inflammation. The results displayed that both the single compound and the extract ameliorated morphologic damage of the colon and improved intestinal barrier integrity. In addition, SDG suppressed the mRNA expressions of inflammatory cytokines in the colon, and the inhibitory effect of a single compound was stronger than that of the extract. The results of 16S rRNA sequencing showed that SDG altered the diversity and composition of gut microbiota, particularly the abundance of inflammation-related bacteria, and the effect of the extract was greater than that of a single compound. The analysis of short-chain fatty acids (SCFAs) manifested the improved concentration with the intervention of SDG. These results confirmed that SDG, including a single compound and extract, exerted protective effects against colon inflammation, which might be partly explained by the gut microbiome. Our research could provide a positive nutritional intervention for chronic intestinal inflammation.