Biosynthetic Study of Amphidinolide W

The biosynthetic origins of amphidinolide W (1) were investigated on the basis of 13C-NMR data of 13C-enriched samples obtained by feeding experiments with [1-13C], [2-13C], and [1,2-13C2] sodium acetate in cultures of a strain Y-42 of the dinoflagellate Amphidinium sp. These incorporation patterns suggested that 1 was generated from a hexaketide chain, two acetate units, four isolated C1 units from C-2 of acetates, and four branched C1 units from C-2 of acetates. The acetate-incorporation patterns for C-1–C-2–(C-21) and C-8–C-18–(C-23, C-24) of 1 corresponded well to those for C-1–C-2–(C-27) and C-5–C-15–(C-28, C-29) of amphidinolide H (2) isolated from this strain.