Bioactive compounds from aquatic and terrestrial sources.

The world of nature provides a never-ending set of fascinating problems for the chemist. Many of the most intriguing problems, however, concern compounds available in only truly minute quantities. One solution is to focus on bioassay-guided separations. In so doing one can isolate compounds with novel structures or unsuspected activities from almost any phylum, including tunicates, sponges, insects, or even the much-studied terrestrial plants, as exemplified in several recent studies in our laboratory involving activities ranging from antiviral and antimicrobial activity to cytotoxicity and immunomodulation. Moreover, newer spectroscopic techniques, especially fast atom bombardment mass spectrometry and tandem mass spectrometry, enhance one's ability to study compounds present in minute quantities, including those of importance to the host organism, such as neuropeptides in insects or marine invertebrates.

Isolation and structure determination of crisamicin A, a new antibiotic from Micromonospora purpureochromogenes subsp. halotolerans.

A new antibiotic, crisamicin A, with in vitro activity against Gram-positive bacteria, B16 murine melanoma cells, and herpes simplex, vaccinia, and vesicular stomatitis viruses, has been isolated from Micromonospora purpureochromogenes subsp. halotolerans. On the basis of 1H and 13C NMR spectroscopic, high resolution field desorption mass spectrometric, and circular dichroism studies of the antibiotic and several of its derivatives, the structure of crisamicin A has been assigned.