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The Hypolipidemic Effects of Pu-Erh Tea
Lan-Chi, Lin.
Graduate Institute of Food Science and Technology, National Taiwan University,
Taipei, Taiwan, R.O.C.
Abstract
Pu-Erh tea is a fermented tea produced in the Yunan district in China.
Recently, this tea has also gained popularity in Taiwan. In Pu-Erh tea,
the bioactive ingredients can be originated from the tea leaves and their
transformed products by the endogenous enzymes. Metabolites derived from
the fermentation microorganisms such as Aspergillus, and biotransformation
products originally derived from tea may also contribute to the potential
biological activities of Pu-Erh tea. A previous study has indicated that
Pu-Erh tea reduces plasma cholesterol and triacylglycerol in female Wistar
rats. Meanwhile, the adrenalin-induced lipolysis is also stimulated, These
findings suggest that uptake of Pu-Erh tea may ameliorate hypolipidemia and
obiesty.
In this study, the potential of an aqueous extract of Pu-Erh tea (PET) on
cholesterol biosynthesis in vitro and lipid metabolism in vivo were elucidated
With lovastatin as a positive control, the incorporation of 〔2-3H〕acetate
and R-〔2-14C〕mevalonic acid into cholesterol by the cultured human hepotoma
cells (HepG2) was chosen as the in vitro model to elucidate the potential of
PET to inhibite cholesterol synthesis. In animal study, male hamsters and
male Spsgue-Dawley rats fed with cholesterol (1.0 %,
w/w) were chosen as animal models to elucidate the potential of PET to inhibit
hepatic cholesterol synthesis, intestinal cholesterol absorption, and
enetrohepatic circulation of bile acids.
In vitro syudy showed that PET reduced cholesterol biosynthesis significantly
(40 mg/mL PET showed 56 % inhibition) with the action mechanism of PET being
similar to that of lovastatin (pre-mevalonate inhibition). In animal models,
the results showed that PET inhibited cholesterol biosynthesis when compared
to the control group. It is intresting because lovastatin is a product of
Aspergillus and Aspergillus has often been found in the preparation of Pu-Erh
tea. PET supplemention also reduced hepatic cholesterol
content and the levels of serum cholesterol ,TG and FFA (p<0.05).
The reduction of serum FFA and elevation of incorporation of isotope labelled
acetate into TG in adipose tissue of hamsters suggested that PET stimulated
insulin sensitivity. The fecal cholesterol secretion was increased in hamsters
and rats fed with 1%, 1.5% and 2% PET. Cholesterol absorption in the intestine
is decreased by reducing the solubility of cholesterol in mixed micelles. The
finding that PET contained catechins further supported the observations
in these two animal models.
In comlusion, PET reduced liver cholesterol content and serum levels of
cholesterol, TG, FFA. The fecal cholesterol contents were increased.
Meanwhile, PET had the effect to inhibit cholesterol biosynthesis in vitro
and in vivo.
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