Repression of acyl-CoA:cholesterol acyltransferase by a traditional herbal medicine (Kampo medicine), Ogi-Keishi-Gomotsu-To-Ka-Kojin.

Ogi-Keishi-Gomotsu-To-Ka-Kojin (OKGK) is a traditional herbal medicine (Kampo medicine) which has been found to ameliorate hypercholesterolemia and hypertriglyceridemia in rats and rabbits. In the present study, the effect of OKGK on acyl-CoA:cholesterol acyltransferase (ACAT) was studied in order to elucidate the mechanism of its antihypercholesterolemic action. Oral administration of OKGK to rats fed a cholesterol-enriched diet for 4 weeks markedly repressed the increase in ACAT activity in the small intestine. In contrast, OKGK did not influence hepatic ACAT activity. These results indicate that OKGK selectively inhibits ACAT activity in the small intestine relative to that in the liver, resulting in a reduction of cholesterol absorption, followed by a decrease in serum cholesterol.