The Effect And Mechanism Studies Of Grifola Frondosa Polysaccharide On Alleviating Obesity

With the improvement of people’s living standards,the trend of high calorie diet is growing.However,the accelerated pace of life would lead to lack of exercises,which directly induce occurrence of obesity.Obesity will not only affect the appearance,but also do harm to the health.Therefore,obesity has attracted more and more attentions of scholars.The drugs,used for control of weight in clinical practice,could cause some toxic and side effects and harm the body.It is very necessary to find natural bioactive extract with weight reduction function and explore the agents in application.In this thesis,Grifola frondosa was considered as the research object.The crude polysaccharide extract of G.frondosa was obtained by the optimization of the extraction process.The two single molecular weight polysaccharides were obtained by deproteinization,Named GFI and GFII.,GFI.is composed of arabinose,mannose,glucose and galactose by GC-MS with a molar ratio of 1.1:1.8:1:7.1;GFII.is composed of arabinose,mannose,glucose and galactose,with a molar ratio of 1:3.9:5.4:4.2.Furthermore,the fat metabolism regulation effect and mechanism of G.frondosa polysaccharide were studied in this subject.The research details are as follows:(1)The effects of G.frondosa polysaccharides on the proliferation and cytotoxicity of Hep G2 cells were verified by in vitro detections.In the concentration range of 1-1000μg/m L,the survival rate of Hep G2 cells was more than 85%,and it had no toxic effect on cells.Subsequently,different doses of G.frondosa polysaccharides were used to treated liver injured cell and 70 μg/m L is the optimal dose.At the same time,we found that G.frondosa polysaccharides could reduce the contents of triglycerides in cells,increase the antioxidant capacity of cells,and reduce cell damage.The assay of oil red O stain vertified that G.frondosa polysaccharides could reduce the contents of lipid in cells.(2)The anti-obesity effects of G.frondosa polysaccharide in vivo showed that the polysaccharide could inhibit the weight growth of obese rats.The weight increases of low,medium and high doses of GFⅡ were 11.28%,6.82% and 8.57%,respectively,which were lower than those of the model rats of 22.88%.The detection of blood lipid indexes in rats showed that GFⅡ could reduce the contents of TG,TC,LDL-C in serum and increase the contents of HDL-C.The detection of body fat showed that GFⅡ could reduce the storage of fat around kidney and testis.Liver samples were taken and HE staining was performed for pathological analysis.The appearance obversion showed that the rat liver was hypertrophic induced by high fat,and yellow fat infiltration appeared on the surface.Pathological analysis showed that the adipocytes became smaller and the inflammatory reaction decreased after the treatments of GFⅡ.(3)The expression of energy metabolism related factors in rat liver was further studied by fluorescent quantitative PCR and Western blotting to explore the mechanism of weight loss of G.frondosa polysaccharide.It was found that GFⅡ could activate AMPK signaling pathway,up-regulate the expression of p-AMPK,p-ACC and CPT-1 in obese rats,promote fatty acid oxidation,inhibit the expression of SREBP1 c,ACC and FAS,reduce fat biosynthesis,and play a role in weight loss.In addition,GFⅡ can also eliminate leptin resistance and restore leptin to normal level and regulate the energy balance in the body as same as inhibit the expression of neuropeptide Y and produce satiety.