Hypocholesterolemic effect of emodin by simultaneous determination of in vitro and in vivo bile salts binding.

Emodin is an active anthraquinone derivative from Rheum palmatum and some other Chinese herbs and it is traditionally used for treating a variety of diseases. In this study, we investigated the hypocholesterolemic effects and mechanism of emodin on hypercholesterolemia rats. In vitro, capability of emodin binding to sodium deoxycholate which is one kind of bile salts (BAs) was evaluated by detection of surplus content of sodium deoxycholate. In vivo, hypocholesterolemic effects were assessed by determining total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) level of serum and TC, TG level of the liver. Oil red O staining was employed to determine lipid droplet of the liver. The mechanism was explored by BAs in feces, the liver and small intestine. Furthermore, cholesterol 7α-hydroxylase (CYP7A1) activity was measured to evaluate cholesterol's transforming to BAs. The results indicated that TC level of emodin group apparently decreased comparing with model group (p<0.05). Emodin could bind to BAs both in vivo (p<0.05) and in vitro. CYP7A1 activity in emodin group apparently increased comparing with model group (p<0.05). Data suggested that emodin had the potential value for treatment of hypercholesterolemia. The underlying mechanism is probably associated with binding capability to BAs and subsequent increasing expression of CYP7A1.