Nominine (2), a new indole diterpenoid biogenetically related to the aflavinines, has been isolated as the major organic-soluble component of the sclerotia of the fungus Aspergillus nomius (NRRL 13137). A. nomius is closely related to the common fungi A. flauus and A. parasiticus, both of which selectively allocate antiinsectan aflavinine derivatives to their sclerotia. This compound was identified primarily through NMR decoupling studies and selective INEPT experiments and by spectral comparison with aflavinine derivatives isolated from A. flauus. Nominine exhibits potent activity against the widespread crop pest Heliothis zea, causing 40% mortality and a 97% reduction in weight relative to controls when incorporated into a standard test diet at 100 ppm dry weight. The structures of the novel antifungal antibiotics pradimicins A, B, and C, elaborated by a new strain of Actinomadura hibisca, have been determined on the basis of chemical degradations and spectral analysis. Acid hydrolysis cleaved pradimicin A to yield D-xylose, 4,6-dideoxy-4-(methylamino)-D-galactose, an aromatic chromophore fragment, and D-alanine. Extensive homo- and heteronuclear 2D NMR experiments assisted by the degradation results allowed us to assign N-[[(5S,6S)-5-O-[4,6-dideoxy-4-(methylamino)-3-O-(β-D-xylopyranosyl)-β-D-galactopyranosyl]-5,6,8,13-tetrahydro-1,6,9,14-tetrahydroxy-11-methoxy-3-methyl-8,13-dioxobenzo[a]naphthacen-2-yl]carbonyl]-D-alanine for the structure of pradimicin A. Pradimicins B and C are desxylosyl and des-N-methyl analogues of pradimicin A, respectively.