Research On The Bioactivity Of Glycosaminoglycan From Oastrea Rivularis

Ostrea rivularis is an edible shellfish with extremely high nutritional value.It is one of the four largest shellfish in my country.Ostrea rivularis are rich in protein,polysaccharides,vitamins and minerals.As one of the most important active ingredients of marine shellfish,polysaccharides have relatively mature functional studies.A large number of studies have shown that glycosaminoglycans(GAG)extracted from marine shellfish have a variety of biological activities,such as hypoglycemic,hypolipidemic and antioxidant activities.Howere,the current functions of GAG extract from ostrea rivularis are mainly focused on immune regulation and anti-tumor activity.In this paper,ostrea rivularis was selected as the experimental raw material,and suitable preparation methods were used to extract GAG of ostrea rivularis.Preliminary research on the hypoglycemic and anticoagulant activities of GAG from ostrea rivularis.And through animal experiments,explore the lipid-lowering activity of GAG from ostrea rivularis and its mechanism of action and its effect on the intestinal flora.Provide a theoretical basis for the exploration of the GAG biological activity of ostrea rivularis and the development and utilization of related health foods.The main research results of this paper are as follows.(1)The hypoglycemic and anticoagulant activities of GAG from ostrea rivularis was explored through vitro experiments.The results of hypoglycemic activity experiments show that GAG from ostrea rivularis has a certain inhibitory effect on α-glucosidase activity.The inhibitory effect is the best when the concentration is 0.4 mg/m L,the inhibition rate reaches to 43.68%.When 0.4mg/m L GAG from ostrea rivularis reaction time is 10 minutes,the inhibition rate reaches 66.7%.Judging from the kinetic test indicat that GAG from ostrea rivularis inhibits α through anti-competition.The activity of glucosidase has the effect of lowering blood sugar.The results of in vitro anticoagulant activity experiments show that when the concentration of GAG from ostrea rivularis is 1mg/m L,the anticoagulant time is basically the same as that of 0.1 mg/m L heparin sodium.GAG from ostrea rivularis can make blood clotting and recalcification time Increase,showing a very good endogenous anticoagulant effect.(2)To explore the hypolipidemic effect and mechanism of GAG from ostrea rivularis by feeding a high-cholesterol diet induces a high-fat zebrafish model.The results showed that TG,TC,LDL-c levels in serum and liver of zebrafish in the GAG experimental group were significantly decreased,and HDL-c level was significantly increased,which indicating that GAG from ostrea rivularis can effectively improve lipid metabolism disorder of high-lipid zebrafish.The influence of GAG on the expression of key genes in lipid metabolization-related signaling pathways was analyzed through transcriptome high-throughput sequencing and RT-q PCR.The results showed that the hypolipidemic mechanism of GAG from ostrea rivularis was mainly through the following pathways:(1)The expression of lipid metabolism synthesis genes,such as pparγ,SCD,hmgra and acat2 were inhibited,thereby inhibiting lipid biosynthesis and accumulation.(2)The expression of ketone body formation rate-limiting enzyme HMGCS gene was down-regulated,which promoted the production of ketone body during the catabolism of fatty acids and reduced the accumulation of fatty acids.(3)Fatty acids combine with fatty acid translocator CD36 and fatty acid binding enzymes FABP2 and FABP6 to keep fatty acids soluble,further transport them to various organelles that require energy,and promote the excretion of fatty acids.(4)The direct rate-limiting enzyme Hmgcr gene expression of cholesterol is downregulated,reducing the synthesis of cholesterol,while up-regulating the expression levels of abcg5 and cyp7a1 genes,thereby increasing the conversion of cholesterol to bile acids.(3)The regulating effect of GAG from ostrea rivularis on the gut microbiota of high-cholesterol zebrafish was studied through the 16 s DNA high-throughput sequencing methods.The results showed that intervention of GAG from ostrea rivularis for 4 weeks can effectively improve the diversity and abundance of the gut microbiota and the evenness of gut microbiota distribution in the highcholesterol zebrafish.GAG from ostrea rivularis improves the relative abundance of beneficial bacteria such as Bacteroidetes,Verrucomicrobia,Acidobacteria and Sphingomonas,which promotes the catabolism of cholesterol and inhibits the reproduction of pathogenic bacteria and the activity of harmful enzymes.At the same time,GAG from ostrea rivularis reduces the relative abundance of harmful bacteria such as Proteobacteria,Cohaesibacter and Vibrio,thereby reducing the possibility of disease and improving inflammation.In addition,it also reduced the F/B ratio,which may also be a way to regulate lipid metabolism disorders.