Effects Of Oudemansiella Radicata Exopolysaccharide On Intestinal Microflora And Antioxidant Activities

Oudemansiella radicata also known as Xerula radicata belongs to Basidiomycota, Agaricomycetes, Agaricales, Physalacriaceae, Oudemansiella. Because of its attractive beneficial effects and rarity in nature, O. radicata is considered as one of precious mushrooms in China.Oudemansiella radicata has been reported to possess various biological properties, including anticancer, anti-aging and immunity enhancement. Fruit bodies of Oudemansiella radicata have focused much more attention than its exopolysaccharides(EPS). In this study, liquid culture medium components for producing EPS were optimized, and the EPS was extracted and used to study its effects on intestinal microflora and antioxidant activities. The main results were as follows.(1) The optimal carbon source and nitrogen source of liquid culture medium for producing EPS were glucose and yeast extract, respectively, by using single-factor experiment design. The optimal fermentation medium conditions were obtained by orthogonal tests, it contained 250 g potato, 20 g glucose, 3g yeast extract, 1g KH2PO4, and 2.5g MgSO4·7H2O in a volume of 1L. With the optimized fermentation medium condition, the yield of EPS was 2936.96mg/L, it was increased by 3.4 times comparing with the contral.(2) For investigate the effect of EPS on mice intestinal microflora and secretory immunoglobulin A(SIgA), lincomycin hydrochloride was used to construct mouse intestinal dysbacteriosis model. And then, sixty mice were randomly divided into five groups including one control group, one spontaneous recovery group and three different doses of EPS treatment groups. The mice of control group and spontaneous recovery group were administrated with distilled water, and each mouse of the three EPS treatment groups was given polysaccharide of O. radicata at the dose of 75mg/kg·bw, 150mg/kg·bw, and 300mg/kg·bw, respectively, by gastrogavage for 14 successive days. And then, the effects of EPS on intestinal microflora and intestinal mucosal SIg A were analyzed. Compared with the control group, the amount of Bifidobacterium, Lactobacillus and intestinal mucosal SIgA of other groups were decreased and the number of Escherichia coli and Enterococcus were increased. While, compared with the spontaneous recovery group the above indexes of each EPS treatment group renewed to some extent( p<0.05). The results of 16 S rDNA high-throughput sequencing showed that the intestinal bacteria diversity and abundance varied remarkably, among which natural recovery group occupied the highest value, followed by treatment groups and normal control group. Higher proportion of intestinal probiotics and less pathogenic bacteria in instestinal samples of EPS treatment groups were found.(3) The results showed that EPS could significantly increase superoxide dismutase(SOD) activity of blood in mice, and decrease content of malondialdehyde(MDA). EPS of Oudemansiella radicata also displayed strong DPPH· scavenging effect, reducing power and Fe3+ chelating capacity. The results confirmed the excellent antioxidant activity of EPS.