Spectroscopic detection of photoproducts in lecithin model system after 8-methoxypsoralen plus UV-A treatment

Photoreactions of 8-methoxypsoralen (8-MOP) in the presence of synthetic le cithins esterified at the beta-position with linoleic/oleic and gamma-palmi tic acid (PCd2/d1pal) have been studied. Following W-A (320-400 nm) irradia tion, the photoproducts separated by thin-layer chromatography are analysed by UV absorption spectroscopy, nuclear magnetic resonance and mass spectro scopy. The new isolated products are lecithin double cyclobutane adducts, P C-(8-MOP)(2), fatty acid-8-MOP split adducts from phosphatidylcholine and l ecithin adducts with photo-oxidized 8-MOP. The photolysis performed in the presence of 8-MOP is related to the previously reported lecithin cyclobutan e adducts with psoralen. A hypothetical scheme of lecithin photolysis under PUVA (psoralen + W-A) treatment is proposed. We suggest that photolysis of lecithin may have a significant role in the chain of reactions triggered i n cell membrane submitted to PUVA treatment. (C) 2000 Elsevier Science S.A. All rights reserved.