mycalolide B

Mycalolide B is a macrolide natural product isolated from marine sponges, notable for being a potent and selective inhibitor of actomyosin ATPase. It binds tightly to actin in a 1:1 molar ratio (Kd = 13–20 nM), selectively and completely depolymerizing F-actin into G-actin via a unique severing and sequestration mechanism distinct from cytochalasins. This compound inhibits ATP-induced contraction and Mg2+-ATPase activity, displays strong cytotoxicity against certain leukemia cell lines (IC50 10–50 nM), and serves as a valuable tool for studying actin-dependent cellular functions. Mycalolide B is used primarily in preclinical research and is not approved for clinical use[1][3][4][6].

Other names

(E,3R,4R,5S,6R,9S,10S)-4-acetyloxy-1-[formyl(methyl)amino]-11-[(10S,11R,13E,16S,20S,21R,22S,24E)-16-hydroxy-10,22-dimethoxy-11,21-dimethyl-12,18-dioxo-3,7,19,27-tetraoxa-29,30,31-triazatetracyclo[24.2.1.12,5.16,9]hentriaconta-1(28),2(31),4,6(30),8,13,24,26(29)-octaen-20-yl]-10-methoxy-3,5,9-trimethylundec-1-en-6-yl] (2R)-2,3-dimethoxypropanoate((E)-4-acetyloxy-1-(formyl(methyl)amino)-11-((13E,24E)-16-hydroxy-10,22-dimethoxy-11,21-dimethyl-12,18-dioxo-3,7,19,27-tetraoxa-29,30,31-triazatetracyclo(24.2.1.12,5.16,9)hentriaconta-1(28),2(31),4,6(30),8,13,24,26(29)-octaen-20-yl)-10-methoxy-3,5,9-trimethylundec-1-en-6-yl) 2,3-dimethoxypropanoate