Studies On Hypoglycemic Effects And The Mechanism Of Polysaccharides From Melastoma Dodecandrum Lour.

Objective:To extract and separate polysaccharide from Melastoma dodecandrum Lour.,the hypoglycemic effects and mechanism was investigated to provide the foundation for reasonable utilization.Methods:（1）The Melastoma dodecandrum Lour.was refluxed degreasing by ethanol 3 times after grinding,the residue was dried,the crude polysaccharide of Melastoma dodecandrum Lour.was precipitated with ethanol after 3 times water extraction.（2）The crude polysaccharide was further purified with DEAE-52 column,gradient eluted by 0.1-0.9 mol/L Na Cl,purified polysaccharide obtained by dialyzing,concentrating and freeze-drying.The purified polysaccharide was purified with Sepharose CL-4B chromatographic column,eluted by distilled water,the refined polysaccharide obtained after freeze-drying.（3）Study the in vitro antioxidant by DPPH free radical scavenging method as Vc used as positive control.Studied the hypoglycemic activity by inhibition ofα-glucosidase,α-amylase,pancreatic lipase as acarbose used as positive control,inhibition of glycogen phosphorylase as caffeine is positive group.（4）30 SD mice was divided into crude polysaccharide serum group,metformin serum group and blank serum group,dose of crude polysaccharide was 1g/kg,metformin was0.0525g/kg,the mice were given by intragastric administration for 5 days,twice per day.1h after the last administration,the blood was collected from the abdominal aorta and then centrifuged,inactivated and filtered to obtain the drug-containing serum.Ins-1 cells were cultured in vitro,and STZ/high fat and high sugar were used to establish the STZ toxicity and glycolipid toxicity model,metformin serum as the positive control,intervene by 4%,8%,12%serum of crude polysaccharide for 48 hours,cell vitality was been tested by CCK8 kits,study the the protective effect of polysaccharides serum on STZ and glycolipid toxicity of INS-1 cells.（5）120 kunming mice,intraperitoneal injection of STZ by dose of 160 mg/kg to establish DM model,mice were randomly divided into model group,metformin group,crude polysaccharide low,medium and high dose group,blank control group was also set.12mice/group.The mice were given saline,crude polysaccharide（0.25 g/kg,0.5g/kg and 1.0g/kg）,metformin（0.6g/kg）respectively for 21 days.The mice were weighed every 3 days,and fasting blood glucose was measured in 7 ^th,14^th,21^thday,test FBG,TG,TC,HDL-C,LDL-C,SOD,MDA,GSH-Px after the experiment to study the hypoglycemic effect and mechanism of polysaccharide of Melastoma dodecandrum Lour..Results:（1）Obtained the crude polysaccharide of Melastoma dodecandrum Lour..（2）Crude polysaccharide was isolated by DEAE-52,Sepharose CL-4B column and two kinds of polysaccharide（MDP1,MDP2）were got.（3）Crude polysaccharide,MDP1,MDP2 had the effect of free radical scavenging,inhibitation ofα-glucosidase,α-amylase,MDP1,MDP2had the effect of glycogen phosphorylase.（4）Compare with model group,cell proliferation of crude polysaccharide of Melastoma dodecandrum Lour.group was significantly increased.（5）The crude polysaccharide of Melastoma dodecandrum Lour.can reduce the blood glucose,TG,TC,LDL-C,increase HDL-C and increase the SOD,GSH-Px activities,decrease the content of MDA on STZ-induced Hyperglycemic Mice.Conclusion（s）:Polysaccharide of Melastoma dodecandrum Lour.has the effect of hypoglycemic,lowing lipid and antioxidation.The hypoglycemic effect may be related to free radical scavenging,inhibitation of glucose metabolism enzymes and antioxidation effect.