A compound of formula (I) treating or preventing an elevated blood lipid level-related disease and inhibiting the activities of acyl-CoA:cholesterol-O-acyltransferase(ACAT) and 3-hydroxy-3-methylglutaryl CoA(HMG-CoA) reductase: wherein, R1 is R5 R6CO group; R2 is H or R6CO group; R3 is H, CH3, R5 or R6CO group; R4 is H, OH, OR5 or R6COO group; R5 is a C2-5 alkyl group substituted with a phenyl group optionally having one or more substituents selected from the group consisting of C1-3 alkyl, OH, Cl and NO2; a C1-5 alkyl group substituted with a naphthyl group optionally having one or more substituents selected from the group consisting of C1-3 alkyl, OH, Cl and NO2; a C10-18 alkyl; or a C10-18 alkenyl group; and R6 is a C10-18 alkenyl group; or an aryl group optionally having one or more substituents selected from the group consisting of C1-3 alkyl, OH, Cl or NO2.