Decaisnea insignis Seed Oil Inhibits Trimethylamine-N-oxide Formation and Remodels Intestinal Microbiota to Alleviate Liver Dysfunction in l -Carnitine Feeding Mice

Elevated circulating level of the intestinal microbiota-derived l -carnitine metabolite trimethylamine- N -oxide (TMAO) has recently been linked to many chronic diseases. The purpose of our study was to investigate the effects of omega-7-enriched Decaisnea insignis seed oil (DISO) on reducing TMAO formation to prevent the l -carnitine-induced hepatic damage in mice. Feeding of mice with 3% l -carnitine in drinking water clearly increased the serum and urinary levels of TMAO ( p < 0.05 vs Normal), whereas the serum and urinary TMAO formation was sharply reduced by DISO administration ( p < 0.05). Meanwhile, DISO resulted in strong inhibition against the elevation of hepatic injury marker (AST, ALT, and ALP) activities and dyslipidemia (TC, TG, LDL-C, and HDL-C), as well as liver inflammatory cytokine (IL-1, IL-6, TNF-α, and TNF-β) release in l -carnitine-fed mice ( p < 0.05). As revealed by 16S rDNA gene sequencing, DISO significantly inhibited the l -carnitine-induced elevations in the abundance of Firmicutes, Proteobacteria, and Erysipelotrichaceae and the increases in the proportion of Lactobacillus and Akkermansia, revealing that DISO attenuated the l -carnitine-caused gut dysbiosis. These findings suggested that DISO could alleviate liver dysfunction in l -carnitine-fed mice, which might be due to the protection against TMAO formation by modulating the gut microbiota.