(1R-(1alpha(Z),2beta(1E,3S*),3alpha))-9-(3-Hydroxy-2-(3-hydroxy-1-octenyl)-5-oxocyclopentyl)-7-nonenoic acid 1a,1b Dihomoprostaglandin E2 1a,1b-Dihomo-PGE2 1a,1b-Dihomoprostaglandin E2 26198-80-1