Napyradiomycin A1 is a fungal metabolite originally isolated from C. rubra and has diverse biological activities. It is active against S. aureus, M. luteus, B. anthracis, C. bovis, and M. smegmatis (MICs = 1.56-12.5 μg/ml). Napyradiomycin A1 is an estrogen receptor antagonist (IC50 = 4.2 μM in rat uterine homogenates). It also inhibits mitochondrial NADH:ubiquinone oxidoreductase (complex I) and succinate:ubiquinone oxidoreductase (complex II) activities in bovine heart homogenates (IC50s = 20 and 9.7 μM, respectively).