Study On Anti-obesity Activity Of Black Tea Extract And Its Mechanism

With the change in diet and living habits,obesity has become a global public health problem.The anti-obesity function of tea received recognition to a certain extent,but the activity of reducing weight varies from different varieties of tea to different kind of functional components.This study researched the anti-obesity activity and its mechanism of three kind of black tea extracts.Isolated black tea total water extract,tea polyphenols and tea polysaccharide from coarse keemun black tea with hot water and organic solvent,tested the main ingredient and content by ultraviolet spectrophotometry,HPLC,GC methods,etc.;carried out the prevent obesity animal experiments with male SD rats,detected the body weight,lee's index,visceral fat weight,biochemical profile,fat cells morphology and quantity,fecal fatty acid component and content to research those weight-loss activity;differentially expressed genes screened by gene expressional profiles microarray,which used to preliminary explored the anti-obesity mechanism from the regulation on fat metabolism pathways.The results are as follows:The black tea total water extract contains 14.84%total phenols,27.31%total sugar;black tea polyphenols extract contains 52.60%tea polyphenols(including 12.38%EGC,28.81%EC,8.16%EGCG,3.25%ECG);black tea polysaccharide extract contains 33.85%total sugar,20.92%uronic acid,16.45%protein,3.91%nucleic acid,the monosaccharide composition including 8.62 mol%rhamnose,6.21%fucose,23.15 mol%arabinose,7.29 mol%xylose,8.40 mol%mannose,22.50 mol%galactose,23.85 mol%glucose.In animal experiments,compared with model control group,the black tea total water extract,tea polyphenols and tea polysaccharide extract had the effect of reducing body weight,Lee's index,fat weight,fat index(the best one was total water extract high dose group,which could decrease body weight 13.71%,Lee's index 5.70%,fat weight 44.63%,fat index 35.52%),fat cell size,serum TG,hepatic TC,MDA content,and elevating the serum HDLC,adiponectin,hepatic SOD content,fecal excretion of fatty acid,shown that the three kind of black tea extracts could control body weight,reduce lipid accumulation,inhibit fat cell enlargement,increase fatty acid discharge,had the anti-obesity activity.There are 13 differentially expressed genes in rat fat and liver tissue of black tea polyphenols,polysaccharide and their mix groups compared with the model control group,the liver tissue has five up-regulated differentially expressed genes and two down-regulated genes,meanwhile the fat mass has three up-regulated differentially expressed genes and three down-regulated genes,which affected the fat metabolic pathways,such as fatty acid degradation,glycerolipid and glycerophospholipid metabolism,bile and pancreatic secretion,AMPK signaling pathway,steroid hormone secretion,etc.,consequently suppressed fat formation,restrained the accumulation of fat,promoted the decomposition of fat,so as to achieve the effect of anti-obesity.