Extracts of samples of a Caribbean tunicate (ascidian, sea squirt) of the family Didemnidae inhibit in vitro at low concentrations the growth of DNA and RNA viruses as well as L1210 leukemic cells. The active compounds isolated from the tunicate, didemnins A, B, and C, are depsipeptides, and didemnin B (a derivative of didemnin A) is the component active at the lowest concentration in inhibiting viral replication in vitro and P388 leukemia in vivo.
Extracts of marine species from Baja California and theCaribbean have been examined on shipboard for a variety of bioactlvities and their constituents studied there by gas chromatography! mass spectrometry. A very high proportion of the extracts has been shown to be cytotoxic, a high proportion to be antibacterial or antifungal and a surprisingly large number to be antiviral. Many of these activities have been confirmed in more extensive assays against tumor cells, pathogenic microorganisms and a battery of viruses. A number of the compounds responsible for the activities have been identified, including several new compounds. Of special current interest are the didemnins, depsipeptides isolated from a didemnid tunicate, which inhibit a number of RNA and DNA viruses and exhibit potent cytotoxicity vs. tumor cell lines.
Four new prenylated bis-indolyl benzenoid metabolites (ochrindoles A-D; 1-4) were isolated from antiinsectan organic extracts of the sclerotia of Aspergillus ochraceus (NRRL 3519). The structures of these compounds were determined primarily through HMBC, selective INEPT, and NOESY experiments. These compounds displayed moderate activity in feeding assays against the corn earworm Helicoverpa zea and the driedfruit beetle Carpophilus hemipterus. Compounds 1-4 also exhibited activity against Gram-positive bacteria.
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