Three new metabolites, vibralactones D—F (1—3) were isolated from cultures of the basidiomycete Boreostereum vibrans . The relative configuration of 1 was established on the basis of X-ray diffraction analysis, while the absolute configurations of 1—3 were assigned using a modified Mosher's method. Compound 1 showed weak inhibitory activities against isozymes of 11β-hydroxysteroid dehydrogenases (HSD) with IC₅₀ values of 85.7 μ M (human HSD1), 295.2 μ M (mouse HSD1), and 87.1 μ M (human HSD2).