| Abstract
| - An extensive chemical study of the secondary metabolites found in the crude organic extract of the gorgonian octocoral Pseudopterogorgia kallos has led to the isolation of seven new cembranolides, bipinnatins K-Q (2-8), and one known compound, bipinnatin E (9). The molecular structures of compounds 2-8, many of which contain unusual structural features, were assigned mainly by 2D NMR spectroscopic methods and X-ray crystallographic analysis. The discovery of compounds 2-8 may lend support to previously proposed mechanisms for the biosynthesis of recently isolated bioactive natural products from the same gorgonian specimen. The in vitro cytotoxicity of bipinnatins 4, 6, and 7 against the NCI tumor cells MCF breast cancer, NCI-H460 non-small cell lung cancer, and SF-268 CNS cancer was evaluated. However, only bipinnatin Q (6) displayed significant cytotoxic activity. Some of the compounds isolated proved to be inhibitors of acetylcholine receptors.
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