Dietary quinoa (Chenopodium quinoa Willd.) polysaccharides ameliorate high-fat diet-induced hyperlipidemia and modulate gut microbiota

As the high nutritional and functional values of quinoa acknowledged, the increasing researches focus on the bioactivities and related mechanisms of its abundant carbohydrates. Herein, the beneficial effects of the soluble polysaccharide fraction from quinoa was investigated to lower the serum lipid of rats treated by high-fat diet (HFD) and call the disordered gut microbiota back. The polysaccharide faction was firstly extracted by ultrasonic-assisted extraction technology (yield of 9.65%) and characterized of the monosaccharide composition with glucose and arabinose (1.17:1, molar ratio). And then, the oral administration of quinoa polysaccharide of 300 mg·kg^-1·day^-1 and 600 mg·kg^-1·day^-1 for 8 weeks remarkably alleviated dyslipidemia by decreasing the levels of serum total triglyceride (TG), low density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), total glutamic pyruvic transaminase (ALT) and glutamic oxaloacetic transaminase (AST) in rats fed with HFD, as well as the reduced hepatic lipid accumulation. Meanwhile, the relative abundance of gut microbiota could be disordered by the long term of HFD. Nevertheless, dietary supplementation of quinoa polysaccharide could enhance species richness and regulate the gut microbiota community structure, reducing the ratio of Firmicutes and Bacteroides, the relative abundance of Proteobacteria. Meanwhile, Sequencing of 16S rRNA gene revealed that intake of quinoa polysaccharide decreased the relative abundances of Desulfovibrio and Allobaculum, which were positively correlated with serum lipid profiles and beneficial to lessen intestinal inflammation. Taken together, the present study demonstrated that quinoa polysaccharide supplementation could ameliorate the hyperlipidemia induced by HFD in association with modulating gut microbiota in a positive way.

Keywords: Gut microbiota; High-fat diet; Quinoa polysaccharides.