In intact HepG2 cells, FR194738 concentration-dependently inhibits the incorporation of [ 14 C]acetate into free cholesterol and cholesteryl ester, with IC 50 s of 4.9 and 8.0 nM, respectively. FR194738 induces intracellular [ 14 C]squalene accumulation. It increases the incorporation of [ 14 C]acetate into squalene, an intermediate of cholesterol synthesis. FR194738 potently inhibits squalene epoxidase (SE) in HepG2 cell homogenate and liver microsomes in dogs and rats. The inhibitory effect of FR194738 in comparison to the HMG-CoA reductase inhibitors, Simvastatin, Fluvastatin and Pravastatin, on cholesterol biosynthesis in HepG2 cells is examined. Among these compounds, FR194738 is the most potent, with an IC 50 of 2.1 nM. The IC 50 s of Simvastatin, Fluvastatin and Pravastatin are 40, 28 and 5100 nM, respectively. FR194738 inhibits hamster liver microsomal squalene epoxidase activity in a concentration-dependent manner with an IC 50 of 14 nM.
