Biosynthetic study of amphidinolide B

The biosynthetic origins of amphidinolide B (1) were investigated on the ba sis of C-13-NMR data of C-13-enriched samples obtained by feeding experimen ts with [1-C-13], [2-C-13], and [1,2-C-13(2)] sodium acetates in cultures o f a dinoflagellate Amphidinium sp. These incorporation patterns suggested t hat 1 was generated from three successive polyketide chains, an isolated C- 1 unit from C-2 of acetates, six branched C-1 units from C-2 of acetates, a nd an "m-m" and an "m-m-m" unit derived only from C-2 of acetates. The labe ling patterns of amphidinolide B (1) were different from those of amphidino lide H (2), a 26-membered macrolide closely related to 1.