Jiashun Gong, Chunxiu Peng, Ting Chen, Bin Gao, and Hongjie Zhou
Abstract: Theabrownin (TB), one of the main bioactive components in pu-erh tea, has a signiﬁcant blood lipid-lowering effect in hyperlipidemic rats. Therefore, it was hypothesized that TB would regulate the activity of key enzymesinvolved in lipid metabolism and accelerate the catabolism of exogenous cholesterol in rats fed a high fat diet. A total of 90 Sprague–Dawley rats were randomly divided into a normal control group (Group I), a high fat diet group (Group II), and high-fat diet plus TB group (Group III). A total of 10 rats were selected from each group and killed at 15, 30, or 45 d after starting the study foranalysis. After feeding 45 d, the contents of TC, TG, and LDL-C levels in Group II were increased by 54.9%, 93.1%, and 134.3% compared with those in Group III, respectively, and the content of HDL-C in Group II was decreased by 55.7%. These effects were inhibited in the rats in Group III, which exhibited no signiﬁcant differences in these levels compared with Group I, indicating that TB can preventhyperlipidemia in rats fed a high fat diet. TB enhanced the activity of hepatic lipase and hormone-sensitive triglyceride lipase (HSL) and increased the HSL mRNA expression in liver tissue and epididymis tissue. The HL activity in serum of Group III was increased by 147.6% compared with that in Group II. The content of cholesterol and bile acid in the feces of rats was increased by 21.11- and4.08-fold by TB. It suggested that TB could promote the transformation and excretion of dietary cholesterol of rats in vivo. Keywords: hepatic lipase (HL), hormone-sensitive triglyceride lipase (HSL), hyperlipidemia, reaction mechanism,
Pu-erh tea, produced mainly in the Yunnan Province of China, is a traditional beverage in Hong Kong, Taiwan, and areas of southeast Asia.Sano and others (1986) noted that pu-erh tea signiﬁcantly reduced the plasma levels of cholesterol ester and triglyceride in rats (Sano and others 1986). Although pu-erh tea possesses lower levels of catechins than green, oolong, and black teas, it had remarkable effects, suppressing genotoxicity induced by nitroarenes (Ohe and others 2001), lowering the atherogenic index and increasing the highdensity lipoprotein (HDL)-total cholesterol ratio (Yang and Koo 1989). Wu and others (2007) reported that the water extract of pu-erh tea had a potential inhibitory effect on a direct-acting mutagen, NQNO, and on an indirect-acting mutagen, AFB1 , which requires metabolic activation (Wu and others 2007). However, what is the main bioactive component in pu-erh tea? Unfortunately, few reports haveinvestigated the components in pu-erh tea (Duh and others 2004). Our previous study showed that the rust-brown pigment in pu-erh tea, which can be dissolved in water but is not soluble in ethyl acetate, n-butyl alcohol or other organic solvents, had a signiﬁcant cholesterol-lowering effect (Gong and others 2007). The features of this pigment are very similar to theabrownin (TB) in black tea(Roberts and others
MS 20091124 Submitted 11/10/2009, Accepted 4/16/2010. Authors Gong, Chen, and Gao are with Faculty of Food Science and Technology, author Peng is with Horticultural Dept., and author Zhou is with Faculty of Pu-erh Tea, Yunnan Agricultural Univ., Kunming, 650201, P.R.China. Direct inquiries to author Gong (E-mail: email@example.com).
1957; Ruan and Cheng 1983; Bailey and others1991); therefore, it is also called pu-erh tea TB. The TB in black tea liquor was ﬁrst named by Ruan (1983). It was considered to be a rustbrown pigment, which can be dissolved in water but not soluble in ethyl acetate, n-butyl alcohol or other organic solvents, its chemical components are not clear. The total TB content in black tea ranges from 4% to 9%, with an average of 6.5% (Ruan and Cheng...