Topopyrone D is a naphthochromene that is 4H-naphtho[2,3-g]chromene-4,6,11-trione substituted by hydroxy groups at positions 5, 7 and 9 and a methyl group at position 2. It is isolated from fungal strains Phoma and Penicillium and acts as an inhibitor of the enzyme topoisomerase I. It has a role as an antimicrobial agent, an antineoplastic agent, an antiviral agent, an EC 5.99.1.2 (DNA topoisomerase) inhibitor and a Penicillium metabolite. It is a naphthochromene, a member of phenols and a member of p-quinones.