Ameliorative effects of Trichosanthes kirilowii Maxim. seed oil on hyperlipidemia rats associated with the regulation of gut microbiology and metabolomics.

The mechanisms underlying the ameliorative effects of polyunsaturated fatty acids (PUFAs) on metabolic disorders induced by a high-fat diet (HFD) remain poorly unclear. In this study, we investigated the anti-hyperlipidemic effects of Trichosanthes kirilowii Maxim. (T. kirilowii) seed oil rich in conjugated linolenic acid in HFD-induced hyperlipidemic rats, by the gut microbiome, cecum bile acids (BAs), and serum metabolomics. The results showed that T. kirilowii seed oil improved dyslipidemia, hepatic steatosis, oxidative stress, and inflammatory responses in HFD-induced rats. Meanwhile, T. kirilowii seed oil inhibited sterol regulatory element-binding protein 1c (SREBP-1c) mediated fatty acid synthesis and upregulated cholesterol 7-alpha hydroxylase (CYP7A1) mediated hepatic cholesterol metabolism to exert hypolipidemic effects. The administration of high dose T. kirilowii seed oil (THD) improved gut microbiota dysbiosis, increased the relative abundance of beneficial bacteria Romboutsia and unidentified_Oscillospiraceae, and decreased the relative abundance of Christensenellaceae_R-7 group, Phascolarctobacterium, and Bacteroides in HFD-induced rats. T. kirilowii seed oil reduced the accumulation of cecum primary BAs in HFD-induced rats. In addition, THD reversed the HFD-induced changes in 24 serum metabolites including leucine, isoleucine, acetylcarnitine, and glucose. Metabolic pathway enrichment analysis of the differential metabolites revealed that valine, leucine and isoleucine metabolism, butanoate metabolism, citrate cycle, and glycolysis were potential metabolic pathways involved in the anti-hyperlipidemic effects of T. kirilowii seed oil. In conclusion, this study found that dietary T. kirilowii seed oil alleviated gut microbiota dysbiosis and improved metabolic disorders in hyperlipidemic rats. This provides new insights into the anti-hyperlipidemic mechanism by which other families of PUFAs are derived from different plants.