A quinone antibiotic isolated from Streptomyces rosa var. notoensis with activity against gram-positive bacteria, mycoplasmas and fungi. Within an organism, nanaomycin A is first reduced by flavin or NADH dehydrogenase then rapidly autooxidized leading to the production of singlet molecular oxygen (O2-). The increase in intracellular O2- results in inhibition of DNA, RNA and cell-wall peptidoglycan synthesis. Further, nanaomycin A may have antineoplastic properties resulting from a reduction in DNA methylation by inhibiting DNA methyltransferase 3B (DNMT3B) and reactivating the tumor suppressor gene RASSF1A.