35 海洋共生藻由来の新規マクロリド化合物Amphidinolide JとKの構造(口頭発表の部)

抄録

Amphidinolides are a series of cytotoxic macrolides isolated from the laboratory-cultured dinoflagellates Amphidinium sp., which are symbionts of Okinawan marine flatworms Amphiscolops sp. Further investigation on search for other cytotoxic components of this dinoflagellate has been continuously progressed by us to isolate two novel 15- and 19-membered macrolides, amphidinolides J (1) and K (2), possessing cytotoxic activity against L1210 and KB cells in vitro (IC_<50> values, 1:2.7 and 3.9μg/mL, respectively; 2:1.65 and 2.9μg/mL, respectively). The planar structure of amphidinolide J (1) was deduced by detailed analysis of the ^1H and ^<13>C NMR data aided with 2D NMR spectra and synthesis of three ozonolysis products firmly established the absolute stereochemistry of six chiral centers of 1 to be 3R,9R,10R,13R,14R, and 15R. Amphidinolide K (2) was isolated as a minor constituent and its gross structure was elucidated on the basis of extensive 2D NMR investigations (^1H-^1H COSY, HSQC, HMBC, HOHAHA, and NOESY) using limited quantity of the sample. The dinoflagellate Amphidinium sp. is quite unique because it produces a number of cytotoxic macrolides possessing a variety of carbon-skeletons; they, however, have similar structural characteristics (e.g., odd-numbered macrocyclic lactone ring and the presence of exo-methylene units), appearing to be biogenetically related to one another.