Isolation of marine metabolites from Symbiodinium species of dinoflagellates.

摘要

The initial scope of this project was to determine if the symbiotic dinoflagellate, Symbiodinium sp., produces palytoxin, the highly lethal and complex compound originally found in the zoanthid, Palythoa spp. Through the examination of cell extracts made, this compound was not found. Instead, other secondary metabolites were isolated and their structures elucidated. The following is a summary of accomplishments. (1) The conditions to grow several strains of Symbiodinium organisms were investigated for the necessary extensive culturing required for cellular extraction. As a result, an isolate from Palythoa sp. obtained in Puerto Rico was successfully cultured. Previously, sustaining cultures of Palythoa symbionts was deemed very difficult. (2) During the above studies, the morphological changes of Symbiodinium were discovered and documented. Through the maintenance and enlargement of Symbiodinium strains, colonial cells had morphed into swimming cellular types. This finding will provide important information for the controversial taxonomical question about the Symbiodinium species. (3) Through the extraction process, several sterols were isolated and characterized. They include: 4alpha-methyl-24xi-ethylcholest-22-dien-3-beta-ol, 24xi-ethylcholest-4,22-dien-3-one, 24xi-ethylcholest-4-en-3-one as well as the novel 24xi-ethylcholest-22-dien-2,3 diol. The latter's rare 2,3 diol structure is similar to ecdysterone which is found in zoanthids, suggesting a possible biosynthetic link. (4) The structural analysis of symbiopolyolides, which are ubiquitously found in Symbiodinium organisms and have a complex polyoxygenated carbon chain resembling palytoxin, was accomplished.