Viridicatol is a fungal metabolite that has been found in various Penicillium species as well as Phoma. It suppresses the expression of COX-2 and inducible nitric oxide synthase (iNOS) and inhibits production of nitric oxide and prostaglandin E2 (PGE2) in LPS-stimulated RAW 264.7 and BV2 cells. It also inhibits NF-κB DNA-binding activity, nuclear translocation of NF-κB p65 and p50 heterodimers, and blocks degradation of inhibitor of kappa B α (IκBα) in the cytoplasm of LPS-stimulated RAW 264.7 and BV2 cells. Viridicatol inhibits the growth of F. graminearum in a disc assay. It also inhibits protein tyrosine phosphatase 1B (PTB1B) in vitro (IC50 = 64 μM).