Okadaic acid

(R) -2-hydroxy-3- ((2S,5R,6R,8S) -5-hydroxy-8- ((R, E) -4- ((2R,4a'R,5R,6'S,8'R,8a'S) -8'-hydroxy-6'- ((1S,3S) -1-hydroxy-3- ((2S,3R,6S) -3-methyl-1,7-dioxaspiro[5.5]undecan-2-yl) butyl) -7'-methyleneoctahydro-3H,3'H-spiro[furan-2,2'-pyrano[3,2-b]pyran]-5-yl) but-3-en-2-yl) -10-methyl-1,7-dioxaspiro[5.5]undec-10-en-2-yl) -2-methylpropanoic acid