Theoretical Study of Ibuprofen Phototoxicity

Klefah A.K. Musa and Leif A. Eriksson*
Department of Natural Sciences and rebro Life Science Center, rebro University, 701 82 rebro, Sweden
J. Phys. Chem. B, 2007, 111 (46), pp 13345–13352
DOI: 10.1021/jp076553e
Publication Date (Web): October 25, 2007
Copyright © 2007 American Chemical Society
*

 Corresponding author. E-mail:  leif.eriksson@nat.oru.se.

Abstract

The photochemical properties and degradation of the common nonsteroid anti-inflammatory drug ibuprofen is studied by means of hybrid density functional theory. Computed energies and properties of various species show that the deprotonated form dominates at physiological pH, and that the species will not be able to decarboxylate from a singlet excited state. Instead, decarboxylation will occur, with very high efficiency, provided the deprotonated compound can undergo intersystem crossing from an excited singlet to its excited triplet state. In the triplet state, the C−C bond connecting the carboxyl group is elongated, and the CO2 moiety detaches with a free energy barrier of less than 0.5 kcal/mol. Depending on the local environment, the decarboxylated product can then either be quenched through intersystem crossing (involving the possible formation of singlet oxygen) and protonation, or serve as an efficient source for superoxide anions and the formation of a peroxyl radical that will initiate lipid peroxidation.

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History

  • Published In Issue November 22, 2007
  • Received August 15, 2007
    Revised September 10, 2007

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