Abstract: This study aimed to evaluate the anti-obesity effects of green tea polysaccharides (GTP), black tea polysaccharides (BTP) and oolong tea polysaccharides (OTP) in 3T3-L1 preadipocytes. The monosaccharide compositions of GTP, BTP and OTP were analyzed using gas chromatography, and the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to determine the effects of three tea polysaccharides (TPs) on the proliferation of 3T3-L1 preadipocytes. The cell cycle was determined by flow cytometry. The preadipocytes were differentiated into adipocytes using the traditional “cocktail” method and the differentiation rate was measured based on absorbance. The triglyceride (TG) content was measured to analyze lipid accumulation in adipocytes using the phosphoric acid oxidase peroxidase (GPO-PAP) method. The expression of transcription factors related to adipocyte differentiation was analyzed by real-time polymerase chain reaction (RT-PCR). The inhibition of the proliferation and differentiation of 3T3-L1 preadipocytes by three TPs were significantly different (P < 0.05). With the addition of 100 μg/mL TPs, the differentiation rates were (62.00 ± 6.61)% (GTP), (82.95 ± 4.25)% (BTP) and (97.24 ± 5.80)% (OTP). In addition, GTP, BTP and OTP could regulate the cell cycle, and the proportions of G0/G1 phase cells after 5 days were (68.52 ± 2.28)%, (67.11 ± 1.68)% and (59.69 ± 1.35)%, respectively. Further investigation of the total RNA extracted from the differentiated preadipocytes revealed that the addition of TPs (100 μg/mL) could regulate the expression of related cytokines. In this study, the inhibitory effect of GTP was more significant than those of BTP and OTP. Up-regulation of of adiponectin (ADP) expression activated the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, which regulates the expression of related adipocyte factors, and ultimately leading to inhibition of TG synthesis and 3T3-L1 preadipocyte differentiation.

Key words: tea polysaccharides (TPs), anti-obesity activity, 3T3-L1 preadipocytes, differentiation, gene expression