RADARIN-A, RADARIN-B, RADARIN-C, AND RADARIN-D - NEW ANTIINSECTAN AND CYTOTOXIC INDOLE DITERPENOIDS FROM THE SCLEROTIA OF ASPERGILLUS-SULPHUREUS

Four new indole diterpenoids, radarins A-D (3-6), have been isolated from the sclerotia of Aspergillus sulphureus by chromatographic separation of the CH2Cl2 extract. The structure of radarin A (3) was determined using extensive high-field 2D NMR experiments. Radarins B-D (4-6) were assigned by analysis of NMR data, spectral comparison to 3, and/or by chemical interconversion. Compound 3 has the most potent activity against the corn earworm Helicoverpa zea and exhibits significant cytotoxicity in assays against three human solid tumor cell lines.