Abstract: The contents of triglyceride (TG) and total cholesterol (TG), the mRNA expression level of fatty acid synthase (FAS), sterol regulatory element binding protein 1c (SREBP-1c), cholesterol 7α-hydroxylase (CYP7A1) and ATP binding cassette transporter A1 (ABCA1), and the protein expression level of phospho-AMP-activated protein kinase (p-AMPK) were investigated for studying the effects of pigments from Pu-erh tea on lipid metabolism in HepG2 cell line cultured with normal or oleic acid enriched medium. The results showed that pigments from Pu-erh tea significantly decreased the contents of TG and TC in HepG2 cells cultured in oleic acid-enriched medium in a dose-dependent manner, although having no significant effect on HepG2 cells cultured in normal medium. The mRNA expression levels of FAS and SREBP-1c were significantly down-regulated, and the mRNA level of ABCA1 was significantly up-regulated, the mRNA expression level of CYP7A1 showed an increased tendency and the protein expression level of p-AMPK was significantly up-regulated after the treatment with pigments from Pu-erh tea for 24 hours in HepG2 cells cultured in oleic acid-enriched medium (P < 0.05). Therefore, pigments from Pu-erh tea could improve lipid metabolism in HepG2 cells cultured in oleic acid-enriched medium by regulating the mRNA levels of enzymes and transcription factors.

Key words: HepG2, lipid metabolism, Pu-erh tea, pigments