Studies On The Lipid-lowering,Anti-obesity Effect And Mechanism Of Pu-erh Tea

Pu-erh tea is becoming a research hotspot because it’s potential lipid-lowering and anti-obesity functions in21st century. In this doctoral dissertation, firstly, the effect of Pu-erh tea as food additives on lipid-lowering and anti-obesity was investigated in obese rats. Then, Pu-erh tea had been separated into four different components with different organic solvent to seek main functional consitituents on the lipid-lowering and anti-obesity effect. Meanwhile, the enzymes activity relating to fat metabolism, the change of fat metabolism major product also had been researched systematically in animals that treated with Pu-erh tea or its consitituents.The mechanism of lipid-lowering and anti-obesity effect was disscussed combining with the experiment on3T3-L1fat cells metabolism of Pu-erh tea.The preliminary experiment results of Pu-erh tea preventing obesity and hyperglycemia showed that three experimental Pu-erh teas all have good effect on inhibiting the rat weight gain, reducing serum level of triglyceride, total cholesterol, and improving the level of high-density lipoprotein cholesterol. The effect of pu-erh ripe tea was superior to the pu-erh raw tea which produced with the same raw material. The effect of Pu-erh tea was positive correlation with storage time. In addition, Pu-erh tea has obvious effect on reducng the level of low-density lipoprotein cholesterol and atherosclerosis index, the subsequent experiments had demonstrsted that there was an obvious dosage-dependent effect of Pu-erh tea on preventing obesity and hyperlipidemia. From these results, the primary conclusion has come that Pu-erh tea has potential effects of preventing obesity, hyperlipidemia, and antiatherosclerosis.The lipid-lowering and anti-obesity experimental results of Pu-erh tea showed that the pu-erh has significant effect in nutritional obese rats and the effect showed dosage-dependent manne. The effect was better than green tea and fu-zhuan brick tea, and in close proximity to the diet-control group. In addition, the experiments results also demonstrated that the Pu-erh tea can significantly improve serum antioxidant enzymes activities of superoxide dismutase and glutathione peroxidase in the obese rat, reduce the accumulation of lipid peroxidation product such as malondialdehyde, improve the antioxidation index of obese rat, so as to lower the risk of disease related to atherosclerosis.The lipid-lowering and anti-obesity experimental results of Pu-erh tea different fractions demonstrated that the total water extracts, ethyl acetate extracts and the residue fraction, not including the n-butanol extracts, of Pu-erh tea had displayed obvious effects on reducing the body weight and body fat of obese ICR mice, the same effect was observed in blood and liver lipid indexes of ICR mice, meanwhile, these extracts can suppress effectively the accumulation of fat in adipocyte, revealing the good lipid-lowering and anti-obesity efficacy of Pu-erh tea. Furthermore, the lipid-lowering and anti-obesity effect of Pu-erh tea was superior to the L-carnitine, and the effect of ethyl acetate extracts surplus the residue fraction were better than the total water extracts of Pu-erh tea, but the effect of n-butanol extracts was unconspicuous. So the main functional components on lipid-lowering and anti-obesity effect in Pu-erh tea maybe exist in ethyl acetate extracts and/or the residue fraction.The studies on the lipid-lowering and anti-obesity mechanism of Pu-erh tea indicated that the enzyme activity of fatty acid synthase, the contents of free fatty acid and serum leptin were decreased, and the lipase activity was increased in liver and adipocyte with a dose-dependent manner when obese ICR mice were treated with ethyl acetate extracts. The results of experimental cell research also showed that the Pu-erh tea ethyl acetate extracts had exerted the dose-dependent manner and timeliness on reducing the vitality and proliferation speed of3T3-L1preadipocyte; promoting the lipolysis of3T3-L1mature fat cells and reducing the number and size of mature fat cells, so as to reduce triglyceride contents in3T3-L1adipocyte.