ABSTRACT
Objective:To compare the anti-obesity effect of green tea and black tea polyphenols and investigate their molecular mechanisms. Method:Rats were divided randomly into four groups:control group,high-fat group,high-fat diet with green tea polyphenols(GTP) supplement group,and high-fat diet with black tea polyphenols(BTP) supplement group. Body weight was determined every 2 w. After 3 months,the changes of epididymal fat tissues weight and serum lipids were observed. Expressions of those genes associated with adipocyte differentiation in epididymal fat tissues of rats were measured by real-time transcription-polymerase chain reaction,including pref-1,aP2,TNF-?,leptin,PPAR-?,C/EBP-? . Results:Both GTP and BTP prevented the increase of body weight and fat induced by high-fat diet and profoundly down-regulated those adipocyte-specific genes,including aP2,TNF-?and leptin. In addition,GTP also up-regulated the pre-adipocye marker — pref-1 and reduced the expression of transcription factor,peroxisome proliferators-activated receptor(PPAR-?) . Conclusion:Tea polyphenols could prevent obesity by reversing the adipocyte differentiation,and GTP possessed stronger inhibitory effect than BTP.
ABSTRACT
Objective: To investigate the effect of (-) epigallocatechin gallate (EGCG) and black tea polyphenols on the lipid metabolism related gene expression profile of human hepatocellular carcinoma HepG2 cells. Method: The total RNA was isolated from HepG2 cells treated with EGCG (5? mol/L), black tea polyphenols (5?g/ml) or 0.1%DMSO (control) for 8 h and was hybridized to Human 14k cDNA microarray for gene expression profile analysis. Real-time RT-PCR was conducted to confirm microarray data. Results: A total of 13 and 29 genes related to lipid metabolism showed differential change after EGCG or black tea polphenols treatment respectively, of which six genes showed consistent expression. The results of real-time PCR were consistent with the microarray data. Conclusion: The mechanism(s) by which EGCG and black tea polyphenols exerts its effects on lipid metabolism are comprehensive. The novel target identified in this study may provide new evidence for further investigation in the hypolipidemic effects of tea polyphenols.