Amphirionin‑4 with Potent Proliferation-Promoting Activity on Bone Marrow Stromal Cells from a Marine Dinoflagellate <i>Amphidinium</i> Species

A linear polyketide, amphirionin-4 (<b>1</b>), has been isolated from cultivated algal cells of the marine dinoflagellate <i>Amphidinium</i> species. The structure was elucidated on the basis of detailed analyses of 1D and 2D NMR data, and the absolute configurations of C-4 and C-8 were determined using the modified Mosher’s method. Amphirionin-4 (<b>1</b>) exhibited extremely potent proliferation-promoting activity on murine bone marrow stromal ST-2 cells (950% promotion) at a concentration of 0.1 ng/mL