Potent inhibitor, in vivo and in vitro, of mammalian, fungal and Saccharomyces cervisiae squalene synthase. Squalene synthase is the first committed enzyme in sterol synthesis, catalyzing the reductive condensation of farnesyl pyrophosphate to form squalene. As a squalene synthase inhibitor, zaragozic acid produces lower plasma cholesterol levels in primates. Treatment of rats with zaragozic acid A caused an increase in hepatic low density lipoprotein (LDL) receptor mRNA levels.