A new sorbicillinoid polyketide, dihydrotrichodimerol (2), along with known trichodimerol (1), and rezishanones C (3) and D (4) were isolated by bioassay-guided fractionation from an unidentified fungal strain. Dihydrotrichodimerol (2) specifically activated peroxisome proliferator-activated receptor gamma with an ED50 value of 80 ng/ml as measured by a transactivation assay using a chimeric hPPAR/GAL4 system without affecting peroxisome proliferator-activated receptors alpha and sigma. On the other hand, compounds 1 and 2 suppressed the production of tumor necrosis factor-alpha and nitric oxide in LPS-stimulated RAW264.7 cells to a similar extent.