Structure and Stereochemistry of Amphidinolide N Congeners from Marine Dinoflagellate Amphidinium Species

Two highly potent cytotoxic 26-membered macrolides, isocaribenolide-I (I) and a chlorohydrin 2, together with known amphidinolide N (3), have been isolated from a free-swimming dinoflagellate Amphidinium species (KCA09053 and KCA09056 strains) collected off Iriomote Island, Japan. The structures of 1 and 2 were determined to be a congener of 3 with an isobutyl terminus and the chlorohydrin form of 3, respectively, by detailed analyses of spectroscopic data. The relative stereochemistries of 1 and 2 were elucidated by the conformational analyses based on NMR data.

Automated summary

Two highly potent cytotoxic 26-membered macrolides, isocaribenolide-I and a chlorohydrin 2, were isolated from a free-swimming dinoflagellate Amphidinium species collected off Iriomote Island, Japan. The structures of these compounds were determined to be congeners of known amphidinolide N, with different end groups and chlorohydrin forms.