Isolation and structure determination of a cholesterol esterase inhibitor from Ganoderma lucidum.

Bioassay-guided fractionation of a methanol extract of Ganoderma lucidum gave a pure cholesterol esterase inhibitor. On the basis of spectroscopic analysis and comparison with data from the literature, the structure of this compound was identified as 5α,8α-epidioxyergosta-6,22-dien-3β-ol (compound I). This compound inhibited cholesterol esterase activity with an IC50 value of 42 ?M. Lineweaver-Burk plot analysis revealed that compound I is a noncompetitive inhibitor. The findings of this study suggest that compound I may be the active principle of the hypocholesterolemic effect of Ganoderma lucidum.