Abstract
The increase in serum cholesterol level in a group of rats fed a high-cholesterol diet containing an ethanol extract of Adzuki bean seeds was significantly lower than that in a group of rats fed a control diet that did not contain the extract. Feces weight and cholesterol excretion were significantly higher in the Adzuki bean group. An in vitro micellization study showed that the solubility of cholesterol micellized by addition of an ethanol extract of Adzuki bean seeds at concentrations of 1.10mg/ml∼5.56mg/ml decreased in a concentration dependent manner. In addition, liver HMG-CoA reductase activity in rats fed the Adzuki bean seed extract was significantly lower than in the control. However, there was no significant difference in the level of HMG-CoA reductase mRNA expression. Furthermore, there were no significant differences in the levels of mRNA expression of genes associated with cholesterol metabolism, cholesterol 7α-hydroxylase, LDL receptor, LCAT, ACAT, hepatic cholesterol esterase, and SREBP2. These findings suggest that an ethanol extract of Adzuki bean seeds may inhibit increases in serum cholesterol by two mechanisms : inhibition of micellization of cholesterol in the gastrointestinal tract, leading to reduced absorption of cholesterol and its excretion in feces ; and a reduction in the activity of cholesterol synthase in the liver. It is also possible that the fatty acid metabolism system was affected, because the expression of SREBP1 was significantly lower.
