title: Photoreaction of skin-sensitizing trimethyl psoralen with lipid membrane models.
abstract: The concerted photoreaction between trimethyl psoralen (TMP) and isomeric model compounds of oleic acid methyl ester (OAME) and eadilic acid methyl ester (EAME) are explored using density functional theory. The S(1) surfaces all reveal large barriers (25-31 kcal/mol) to reach the decay channels, whereas the S(2) surfaces differ considerably between the furan and pyrone side adducts. For the pyrone side adducts, a small barrier to reach the intersection between the S(1) and S(2) states is found, followed by a small second barrier on the S(1) surface to the low-lying decay channel. For the furan-side adducts, no such intersection between S(1) and S(2) is seen, which thus prevents these products from being formed in high yields. The photoinduced cycloaddition is more favorable between OAME and the pyrone side double bond of TMP than for any of the other systems, which agrees with the experimental findings that this is formed in the highest yield. The computed UV absorption spectra of TMP and the TMP(pyrone)-OAME cycloadduct agree well with the experimental spectra.
authors.affiliation: Department of Natural Sciences and Orebro Life Science Center, Orebro University, Orebro, Sweden.
authors.forename: Xiao Yi
authors.initials: XY
authors.lastname: Li
authors.forename: Leif A
authors.initials: LA
authors.lastname: Eriksson
mesh_terms: D003198:Computer Simulation; D005663:Furans / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry* / Q000528:radiation effects*; D008567:Membranes, Artificial; D008956:Models, Chemical; D015394:Molecular Structure; D009829:Oleic Acids / Q000737:chemistry; D017319:Photosensitizing Agents / Q000737:chemistry*; D011753:Pyrones / Q000737:chemistry; D014307:Trioxsalen / Q000737:chemistry*
chemical_list: D005663:Furans; D008563:Membrane Lipids; D008567:Membranes, Artificial; D009829:Oleic Acids; D017319:Photosensitizing Agents; D011753:Pyrones; C005576:methyl oleate; D014307:Trioxsalen