(2E,4E,6E,8E)-10-({(3R,4S,5S,6R)-5-methoxy-4-[2-methyl-3-(3-methylbut-2-en-1-yl)oxiran-2-yl]-1-oxaspiro[2.5]oct-6-yl}oxy)-10-oxodeca-2,4,6,8-tetraenoic acid