Acylated derivatives of the C-1' and/or C-11 hydroxy group(s) of penicillide were synthesized and their inhibitory activity against acyl-CoA:cholesterol acyltransferase (ACAT) was studied. Introduction of long acyl group into either or both hydroxy residue(s) decreased the inhibitory activity. A small acyl moiety such as acetyl or n-butyryl at the C-1' hydroxy group is responsible for potent inhibitory activity against ACAT. The 1'-O-acetyl-11-O-tetrahydropyranyl derivative (11-O-2''-tetrahydropyranylpurpactin A) showed high selectivity (cytotoxic dose vs. effective dose) in a cell assay using J774 macrophages.