Spirastrellolide A: revised structure, progress toward the relative configuration, and inhibition of protein phosphatase 2A.

[structure: see text] The structure of spirastrellolide A, a novel macrolide isolated from the marine sponge Spirastrella coccinea, has been revised to accommodate new MS and chemical transformation data. Relative configurations of three major fragments of the molecule have been elucidated from ROESY and coupling constant data. Spirastrellolide A has been shown to be a potent and fairly selective inhibitor of protein phosphatase 2A.