Mycalolide B (122752-21-0) is a novel marine natural product which binds to actin in a 1:1 molar ratio (Kd=13-20 nM).1It selectively and completely depolymerizes F-actin to G-actinviaa novel mechanism different from that of the cytochalasin D.2It is a novel and specific inhibitor of actomyosin ATPase.3