Marine natural products: Chemistry and chemosystematics of the gorgonian genus Eunicea and exploratory studies of the secondary metabolites of marine fungi.

摘要

Secondary metabolites of the Caribbean gorgonian genus Eunicea were extensively investigated through the systematic collection and assortment based on thin layer chromatographic analysis. In addition, the chemical characters of Eunicea species were compared to the morphological classifications. In total, 792 individual colonies were collected from various locations. Based upon the TLC characters, 780 colonies were divided into 11 chemotypes which cover 8 of 12 taxonomically defined species and 4 new species.; Detailed chemical investigation resulted in the isolation of 39 new metabolites, along with 9 previously described compounds. Diterpenoids were the major group of metabolites, and cembranes were the most commonly encountered class. Other diterpenoids were dolabellanes, cubitanes, asperketals, fuscol and fuscol glycosides. Metabolites of three unprecedented classes were also isolated: C{dollar}sb{lcub}28{rcub}{dollar} reduced quinones, trisnorditerpenoids and a diterpene glycoside of the "extended eremophilane" class. The irregular diterpenoids cubitanes were determined to be formed by a photochemically induced 1,3-acyl migration of a cembrane precursor.; Several chemotypes were collected from more than one location. Each chemotype contained only one or two classes of very distinct metabolites. In the case where metabolites of a single class were isolated from more than one chemotype, there were great structural similarities among metabolites from the same chemotype, while metabolites from different chemotypes often showed very distinct patterns of functionalization.; Chemical characteristics of each chemotype were compared to the morphological classification. The chemical contents were clearly different between the Eunicea subgenera, Eunicea sensu strictu and Euniceopsis. Eunicea s.s. was a chemically homogeneous group, all containing cembrane lactones. In contrast, Euniceopsis showed species-specific distribution of metabolites. Comparison of chemical contents revealed that for the chemosystematics of the Eunicea, types and distributions of functional groups were as important characters as the carbon skeletons of metabolites.; One hundred twenty one marine fungal strains were either isolated from various habitats or obtained from mycologists. The fungi were cultivated in liquid media. Thirty eight extracts showed significant anti-microbial activities and/or cytotoxicity. Based upon the results of bioactivity tests, TLC analysis, and proton NMR spectroscopic analysis of the extracts, several strains were chemically investigated.; From Asteromyces cruciatus, gliovictin, a metabolite of the gliotoxin class was isolated. Also, several trichothecenes of the verrucarin and roridin classes were isolated from an unknown fungus. In addition, a few small-sized metabolites were isolated. The future of marine fungi for chemical investigation is discussed.