Viridicatol is a polar metabolite first isolated from Penicillium cyclopium and P. viridicatum by Birkinshaw and collaborators in 1963. Viridicatol is a 2,3-dihydroxyquinoline which, like its analogue viridicatin, exists in equilibrium with its keto-tautomer. Viridicatol acts as an anti-inflammatory agent by suppressing the expression of pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, via inhibition of the nuclear factor-kappa B (NF-κB) pathway in LPS stimulated cells. Further, viridicatol is a selective inhibitor of PTP1B, a potential drug target for the treatment of type 2 diabetes and obesity.