Study On The Extraction And Purification Of Prodelphinidins From Chinese Bayberry Leaves And Its Anti-obesity Effect

Proanthocyanidins are a kind of plant polyphenols,belonging to the aromatic secondary metabolites.Because of its polyhydroxyl group structure,the proanthocyanidins own strong antioxidant activity,and other functions associated with antioxidant activity.The proanthocyanidins are widely distributed in nature,such as pine bark and grape seed,and high content of component in many plants.The leaves of Chinese bayberry(Myrica rubra Sieb.Et Zucc.)in Zhejiang Province are found to be rich sources of proanthocyanidins,and the type is basically prodelphinidins,which have stronger antioxidation for its gallate ester structure.Obesity,which is a ubiquitous physiological condition with the development of social economy,is closely related to the level of oxidative stress in the body.Obesity brings a lot of inconvenience to daily life,but even more serious is that it can induce a series of cardiovascular diseases and have threatened the health and life of people.To avoid the harm done by the obesity,the scientists have always been committed to the development of drugs to lose weight.Currently,there are two types of weight-losing products on the market:one is Orlistat,a kind of synthetic drugs with less side effects;another kind is a variety of biological products with lots of uncertainty effects.The causes of obesity are diverse,and there are three aspects assosiated with food intake to control the fat we obtain:first,reducing the intake of high-energy food;second,controling and reducing the energy absorbed by the body;third,promoting the conversion of energy,and avoiding the energy stored in the body in the form of white fat.People can easily choose their food,such as meal replacements with low energy,but have to fall back on diet pills to control the absorption and storage of energy.In this study,the extract of proanthocyanidins was further purified to remove sugar.Obesity inhibition of proanthocyanidins extracted from bayberry leaves was analyzed,compared with Orlistat based on their effects on pancreatic lipase and phospholipase and also on SD rats model.Results were summarized as follows:The extraction of bayberry leaf proanthocyanidins of Biqi were processed by using acetone,n-hexane and dichloromethane,and then purified by HPD-500 macroporous resin.The sugar content of final sample fell to 0.5%from 24.7%,and the proanthocyanidins content rose to 54%from 26%.The influence on pancreatic lipase and phospholipase A1 of proanthocyanidins extract in vivo and in vitro were tested,compared with Orlistat.Pancreatic lipase and phospholipase A1 can decompose fat from food catalytically to glycerol and fatty acids for further use to reduce the absorption of energy.Therefore,inhibiting the activity of pancreatic lipase plays an important role in combating obesity.Data showed Orlistat and the purified proanthocyanidins extract inhibited the activities of pancreatic lipase and phospholipase A1 effectively both in vivo and in vitro.Body weights,visceral indexes,serum markers and other biological indicators assosiated with energy conversion of SD rats were detected after feeding for 2 months.In this study,normal rats were fed with high-fat diet,and those gained 10%weight more than others who were picked and continued to be fed with Orlistat and proanthocyanidins extracts along with high-fat diet.At the end of the study,all the SD rats were killed and their whole blood and livers,kidneys,epididymises and abdominal fat were collected for detection.Data showed that the purified proanthocyanidins extract achieved good results in all the indices,even better than Orlistat,which reduced the differentiation of white fat cells by inhibiting the expression of SIRT1,and confirmed the production of brown fat,which can consume energy rapidly,by inducing the expression of UCP1.The left sides of livers were cut and HE stained.Sections showed that the purified proanthocyanidins extract reduced the symptoms of fatty liver disease.The oil droplets in the liver were reduced remarkably and the histologic features of cirrhosis disappeared.In conclusion,the proanthocyanidins of bayberry leaves were a kind of natural products with good effect on regulating obesity both in vitro and in vivo.The wide material sources and low cost make it be a promising weight-losing product.