Characterization of psoralen-oleic acid cycloadducts and their possible involvement in membrane photodamage

By UVA irradiation of an ethanol solution of psoralen and oleic acid, four main photoproducts have been isolated and characterized: two have cis,cis structure; the other two are trans,cis. The same adducts have been isolated from the photoreaction of psoralen with beta-oleoyl-gamma-stearoyl-1-alpha-phosphatidylcholine followed by enzymatic hydrolysis with phospholipase A2. The four isomers stimulate protein kinase C to almost the same extent.