Concentration Of Corosolic Acid In Sea Buckthorn Leaf And The Hypoglycemic Mechanism

Diabetes is a chronic disease,which is caused by genetic and environmental factors,with high blood sugar as the main sign.The common symptoms of diabetes are more drink,more food,more urine and weight loss.Corosolic acid is called "plant insulin",the content in the sea buckthorn leaf is 0.055%.In this study,we used sea buckthorn leaf as material.First,we removed water soluble impurities through water extraction,and then removed alcohol soluble impurities by low alcohol.Finally,with hot ethanol to extract and concentrate corosolic acid in sea buckthorn leaf,then used high performance liquid chromatography to measure corosolic acid content of crude extract from sea buckthorn,the result was 2.14%.We tested the hypoglycemic efficacy of different doses of crude extract from sea buckthorn by the models of diabetic rats.In the test,56 SD rats were randomly divided into 7 groups:blank control group,model group,low dose group,middle dose group,high dose group,metformin group and corosolic acid group.In addition to the blank control group,other groups were fed with high energy diet with intraperitoneal injection of alloxan,then established diabetic rat models,while the stomach perfused of the subjects being tested.At last,through the changes of indexes,we detected the effect of the crude extract from sea buckthorn and explored the hypoglycemic mechanism.Detection indicators included:fasting blood glucose(FBG),organ index,liver glycogen,glucokinase,glucose-6-phosphatase,superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),catalase(CAT)and the content of malondialdehyde(MAD).We dissected the rats,took out and fixed the pancreas and the liver by stationary liquid,and then separately observed the morphological changes of pancreatic and hepatic tissues under light microscope,scanning electron microscope and transmission electron microscope.The results showed that in addition to the low dose,the middle and high dose crude extract from sea buckthorn,metformin,and corosolic acid significantly decreased the fasting blood glucose level of diabetic rats,in which the reduced hypoglycemic effect of metformin group and the corosolic acid group was better than that of the middle dose group and high dose group.From viscera index,glucose metabolism and antioxidant enzymes could be found,crude extract from sea buckthorn,metformin and corosolic acid were able to reduce the damage of pancreas,liver and kidney of diabetic rat in various degrees.They could also accelerate the utilization of blood glucose,inhibit the transformation of non sugar substances and the decomposition of glycogen,while improve glucose metabolism in diabetic rats.Besides,they could improve the activity of antioxidant enzyme and remove too many free radicals in the body.The rat pancreatic tissue pathological science observations showed that,compared with the model group,the diabetes rats of middle and high dose group had the following characteristics:pancreatic islet volume increased,islet cells increased and uniform distribution,mitochondria structure of acinar cell was normal,crest was neat and without necrosis.So the rat liver tissue pathological science observations showed that,compared with the model group,in the middle and high dose group,the liver tissue and liver cord,arrangement of the liver sinusoids,swelling degree of the liver cells,cytoplasmic lipid vacuoles status and mitochondrial structure all were improved of diabetes rats.As a result,the pathological changes of the liver was reduced.The indexes of diabetic rats in the low dose group were better than those of the model group,but the treatment effect was less than that in the middle and high dose group.In summary,our study results showed that the crude extract from sea buckthorn had obviously hypoglycemic effect on diabetic rats induced by alloxan.The hypoglycemic mechanism including the following two aspects:firstly,the crude extract from sea buckthorn could regulate body sugar metabolism and key enzymes activity,speed up the metabolism of blood glucose utilization and inhibit the decomposition of hepatic glycogen and transformation of non sugar substances.Secondly,the crude extract from sea buckthorn could enhance the body's antioxidant capacity,clean up too much free radicals in the body,and reduce the damage of organs such as the pancreas and the liver.The results of this study lay a theoretical foundation for the research and development of the sea buckthorn as health care products and medicine.