Alleviating effects of noni fruit polysaccharide on hepatic oxidative stress and inflammation in rats under a high-fat diet and its possible mechanisms

Non-alcoholic fatty liver disease is associated with gut microbiota, oxidative stress, and inflammation. We aimed to investigate the possible mechanism by which noni fruit polysaccharide (NFP) improved hepatic oxidative stress and inflammation in rats under a high-fat diet (HFD) by modulating short-chain fatty acids (SCFAs), the intestinal barrier, and gut microbiota. Hepatic oxidative stress, inflammation, and gut dysbiosis in rats were induced through HFD feeding for 4 weeks, followed by intervention with NFP treatment (100 mg per kg bw) for 5 weeks. The results showed that NFP reduced body weight gain and improved lipid metabolism, hepatic oxidative stress, and inflammation in rats under a HFD. Aside from these beneficial effects, NFP positively affected the SCFA production and reversed the HFD-induced gut dysbiosis as indicated by improved microbiota diversity and composition. The levels of Lactobacillus, Ruminococcaceae_UCG_014, Parasutterella, [Eubacterium]_coprostanoligenes_group, and Ruminococcus_1 improved, whereas the levels of Prevotella_9, Collinsella, Bacteroides, and Turicibacter decreased. Furthermore, NFP maintained the colonic barrier integrity (increased the mRNA relative expression of CCL5, ZO-1, and occludin in the colon, and decreased the serum CCL5 level), and decreased the serum lipopolysaccharide level. Thus, NFP may modulate the gut microflora and SCFA production and reduce the permeability of the colonic barrier and metabolic endotoxemia, thereby alleviating hepatic oxidative stress and inflammation in rats under a HFD.