Policosanol inhibits cholesterol biosynthesis and enhances low density lipoprotein processing in cultured human fibroblasts

Abstract

Policosanol is a mixture of aliphatic primary alcohols isolated and purified from sugar cane wax, that induces cholesterol-lowering effects in experimental models and human beings. When human lung fibroblasts were incubated with policosanol for 48 hours prior to the experiment, a dose dependent inhibition of 14C-acetate incorporation into total cholesterol was observed, whereas labeled mevalonate incorporation was not inhibited. Even when cholesterol synthesis was not strongly inhibited, low density lipoprotein (LDL) processing was markedly enhanced. Thus, LDL binding, internalization and degradation were significantly increased after policosanol treatment. In addition, despite the fact that'cholesterol generation was not inhibited at the lowest dose of policosanol assayed, LDL processing was significantly increased. The current data indicate that policosanol inhibits cholesterol synthesis at the earliest steps of the cholesterol biosynthetic pathway. On the other hand, this study suggests that the increase in LDL processing may be partially explained by the inhibition of cholesterol biosynthesis, even though an sterol-independent mechanism might be responsible for the enhancement of LDL-receptor activity.