Gliocladium sp. FO-1513 was found to produce novel inhibitors of acyl-CoA: cholesterol acyltransferase (ACAT). Two active compounds, designated glisoprenins A and B, were isolated from the culture broth of the producing strain by a conventional method. The IC50 values of glisoprenins A and B for ACAT activity were 46 and 61 microM in an enzyme assay using rat liver microsomes, and 1.2 and 0.57 microM in a J774 macrophage assay, respectively.