| The purpose of this study was to investigate the effects of Chinese yam extract on the growth and metabolism,extracellular polysaccharide synthesis,structure and biological activity of Grifola frondosa.The contents include:the effects of Chinese yam extract on the growth metabolism and polysaccharide synthesis of Grifola frondosa;Based on UHPLC-MS metabolomics,the components of ethanol extract from Chinese yam and their effects on the fermentation metabolism of Grifola frondosa were analyzed.The Physicochemical indexes,structural characteristics and antioxidant activity of Grifola frondosa polysaccharide were determined.To explore the relieving effect of Grifola frondosa polysaccharide on D-galactose induced aging mice.The specific research results are as follows:When the addition amount of 75%Chinese yam ethanol extract was 9 g/L,the promotion effect on the biomass and synthesis of extracellular polysaccharide was the best,which was 46.71%and 52.03%higher than that of the control group（0 g/L）（P<0.01）.The activities of glucokinase（GK）,phosphoglucose-mutase（PGM）and UDP-glucose pyrophosphorylase（UDPG）in the experimental group were significantly increased（P<0.05）,and reached the maximum on the 7th day of fermentation,while the activity of phosphoglucose-isomerase（GPI）was significantly decreased（P<0.05）.The results showed that the ethanol extract of Chinese yam could promote the growth of Grifola frondosa,regulate the key enzyme activity of polysaccharide synthesis,and promote the synthesis of polysaccharide.Based on ultra high performance liquid chromatography-mass spectrometry（UHPLC-MS）,the components of yam ethanol extract and its effect on the fermentation metabolism of Grifola frondosa were studied.The analysis showed that the alcohol extract of yam contained p-hydroxybenzyl alcohol,p-hydroxybenzaldehyde and allantoin,which could promote the growth of Grifola frondosa.A total of 55 differential metabolites were obtained by multivariate statistical analysis.The results of metabolic pathway showed that the alcohol extract of yam could enhance the process of starch and sucrose metabolism,TCA cycle,amino sugar and nucleotide sugar metabolism,galactose metabolism,purine metabolism and pyrimidine metabolism in Grifola frondosa cells,These are conducive to the synthesis of Grifola frondosa polysaccharide.The physicochemical properties,structure and antioxidant activity of exopolysaccharides in control group（GFP）and experimental group（YGFP）were determined.The results showed that the total sugar contents of GFP and YGFP were71.15±0.68%and 73.46±0.36%,respectively,and the contents of protein and uronic acid were low.GFP and YGFP are mainly composed of glucose,mannose,galactose and arabinose but have different molar ratios.The number average molecular weight（Mn）of GFP was 26.71 KDa,and the weight average molecular weight（Mw）was 71.15 KDa.The Mn of YGFP was 31.32 KDa,and the Mw was74.41 KDa.The scavenging rates of GFP and YGFP on DPPH,ABTS+,superoxide anion and hydroxyl radical increased with the increase of polysaccharide concentration,and the IC50values of YGFP were lower than those of GFP,indicating that the antioxidant activity of YGFP was stronger than that of GFP.Therefore,Chinese yam alcohol extract can improve the antioxidant activity of Grifola frondosa polysaccharide in vitro after participating in Grifola frondosa fermentation.GFP and YGFP have a good mitigation effect on inflammation and oxidative stress in D-galactose-induced aging mice.The results showed that high dose of GFP（GFPH）and high dose of YGFP（YGFPH）could significantly decrease the contents of interleukin（IL-6）,IL-1βand tumor necrosis factor-α（TNF-α）in serum of mice（P<0.01）,and significantly increase the content of IL-10（P<0.01）.SOD level in serum of mice in GFPH and YGFPH groups was significantly increased（P<0.05）,CAT and GSH-Px level in serum and liver of mice in YGFPH group were significantly increased（P<0.01）,MDA level was significantly decreased（P<0.05）;In addition,YGFPH also significantly decreased the activities of acetylcholinesterase（Ach E）and nitric oxide synthase（NOS）in the brain of mice（P<0.01）.The results of pathological section showed that the intervention of Grifola frondosa polysaccharide protected liver and brain tissue.Therefore,Grifola frondosa polysaccharide can reduce tissue damage by regulating inflammation and oxidative stress in mice.GFP and YGFP can regulate intestinal flora of aging mice.The results showed that GFPH and YGFPH groups could significantly up-regulate the relative abundance of Firmicutes and Bacteroidetes（P<0.01）,and reduce the F/B ratio of intestinal flora in aging mice.Up-regulating the relative abundance of beneficial bacteria,including Lactobacillus,Alistipes,Akkermansia,etc.Down-regulated relative abundance of Dubosiella,Corynebacterium and other harmful bacteria;Spearman correlation analysis showed that the contents of SOD,CAT,GSH-Px and IL-10 in serum were positively correlated with the abundance of beneficial bacteria and negatively correlated with the harmful bacteria,while the contents of MDA,IL-1β,IL-6 and TNF-αwere negatively correlated with the abundance of beneficial bacteria and positively correlated with the harmful bacteria.Studies have shown that Grifola frondosa polysaccharide can significantly improve the intestinal flora disorder and promote the stability of intestinal environment in aging mice.In conclusion,the ethanol extract of Chinese yam can regulate the growth and metabolism of Grifola frondosa,promote the synthesis of polysaccharides,and enhance the activity of polysaccharides.This study provides theoretical support for the development of anti-aging products related to Grifola frondosa polysaccharide,and provides a new technical idea for the deep processing of agricultural products in Guizhou. |
