Intestinal toxicity evaluation of polygala total saponins in mice according to toxicological evidence chain (TEC) concept

Background Polygalae Radix a widely used tranquilizing traditional Chinese medicine, is limited by gastrointestinal adverse effects. The Polygala total saponins are identified as its major toxic constituents. Methods To clarify the toxicity of PTS and elucidate its underlying toxic mechanism, this study performed five key experiments: First, we observed the toxic manifestations of PTS in male ICR mice and collected serum and intestinal tissue samples after administration. Second, we obtained toxicological evidence through histopathological examination and serum biochemical analysis. Third, we detected the protein and mRNA expression levels of tight junctions (TJs) in intestinal tissues, as well as the content of short-chain fatty acids (SCFAs) in feces. Fourth, we analyzed fecal microbial community structure using 16S rRNA gene sequencing after PTS exposure. Fifth, we explored the potential toxic mechanisms using metabolomics and transcriptomic analysis. Results Three days after PTS administration (i.g., 120 and 240 mg/kg/d), mice exhibited obvious intestinal damage. The main mechanisms underlying PTS-induced intestinal toxicity involved disrupted digestive and absorptive functions, enhanced intestinal inflammation, impaired intestinal barrier integrity (including compromised tight junctions), and severe intestinal microbiota dysbiosis. Notably, intestinal microbiota dysbiosis was closely correlated with body weight loss and intestinal barrier injury in PTS-treated mice. Further analysis revealed that PTS significantly reduced the abundance of multiple genera within the Lachnospiraceae family and tended to decrease short-chain fatty acid (SCFA) levels. Mechanistically, PTS promoted intestinal inflammation at least partially by upregulating arachidonic acid metabolism. Conclusion This study interprets the mechanism of intestinal toxicity of PTS from the perspectives of metabolites, DEGs, and microbiota. This helps us refine the toxicological evidence chain (TEC) of PTS and further understand its toxicity mechanism.