The Study On Characteristics Of Fermented Barley ?-Glucan And Its Regulation On Lipid Metabolism

Studies have found that barley?-glucan has many physiological and nutritional functions such as lowering cholesterol and blood lipids,regulating blood glucose and improving intestinal flora,especially in improving lipid metabolism.Our previous studies have found that?-glucan from barley fermented by lactic acid bacteria could inhibit the differentiation of 3T3-L1 preadipocytes more effectively than raw barley?-glucan(RBG).Moreover,the yield and content of?-glucan were changed to some extent after fermentation,which can be speculated that the structural changes of fermented barley?-glucan(FBG)might have a certain effect on its physiological activities.In this paper,FBG was obtained from lactobacillus plantarum dy-1 fermented barley extract,and the molecular structure,physicochemical properties and the lipid-lowering activity with its possible mechanisms in Caenorhabditis.elegans of FBG in comparison with RBG were studied.The main research contents and results are as follows:1.The effects of fermentation on the main structural changes of barley?-glucan were studied.By measuring the molecular weight,monosaccharide composition and glycosidic bond of barley?-glucan before and after fermentation,the structural characteristics of barley?-glucan were preliminarily determined.The results showed that the molecular weight of RBG was decreased from 1.13×10~5 g/mol(peak area:100%)to 6.35×10~4 g/mol(peak area:98.7%).In terms of microstructure,RBG wae mainly rod-shaped,and FBG was dominantly flaky.According to the results of infrared spectroscopy,monosaccharide composition,methylation and nuclear magnetic resonance analysis,RBG and FBG are polysaccharides predominanted by?-(1?3)and?-(1?4)linked glucose,and the ratio of the?-(1?3)residues to the?-(1?4)residues ranges from 1:2.50-1:2.70 to 1:2.24-1:2.27 after fermentation.2.The effects of fermentation on the main physicochemical properties of barley?-glucan were studied.By measuring the solubility,swelling,water/oil holding capacity,foaming and rheological properties of barley?-glucan,and their effects on glucose diffusion and adsorption capacity,cholesterol adsorption capacity,as well as their inhibitory effects on amylase,glucosidase and lipase activity to determine the main physicochemical properties and in vitro physiological activities of barley?-glucan after fermentation.The results showed that the fermentation improved the solubility,swelling,water/oil holding capacity of barley?-glucan and its ability to adsorb glucose and inhibited the activity of?-amylase,?-glucosidase and lipase,as well as the adsorption of cholesterol under acidic conditions.3.The effects of fermented barley?-glucan on the fat deposition and its mechanism of C.elegans were studied.A high-glucose model of nematodes was established to study the effects of barley?-glucan on the lifespan,locomotive behavior,fat deposition and lipid metabolism of nematodes before and after fermentation.The results showed that both RBG and FBG could significantly improve the locomotive behavior of nematodes,thereby increasing the energy consumption of nematodes and reducing the fat deposition in nematodes,and the effects of FBG were more significant.In addition,RBG and FBG played large roles in the regulation of nhr-49-mediated signaling pathway,TGF-daf-7 pathway,serotonin-mediated signaling pathway and TOR and hexosamine-mediated signaling pathways in the nematodes,with significant differences between RBG and FBG in the regulation of some specific gene expressions.