Studies on the macrolides from marine dinoflagellate Amphidinium sp.: Structures of amphidinolides R and S and a succinate feeding experiment

Two new cytotoxic macrolides, amphidinolides R (1) and S (2), were isolated from the cultured marine dinoflagellate Amphidinium sp. and their structures including absolute configuration were elucidated on the basis of spectroscopic data as well as chemical experiments. In a feeding experiment of C-13-labeled succinic acid into a culture of Amphidinium sp., no enrichment of the C-13 NMR signal intensity of any carbon of amphidinolide J(3), the most abundant macrolide in this dinoflagellate, was observed. (C) 1997 Elsevier Science Ltd.