Abstract

Photoreaction of ketoprofen (KP), one of the widely used nonsteroidal anti-inflammatory drugs (NSAIDs), was studied with transient absorption spectroscopy in phosphate buffer solution (pH 7.4) in the presence of basic amino acids of histidine (His), lysine (Lys) and arginine (Arg). Deprotonated form of KP (KP(-)) excited with UV-light irradiation gave rise to carbanion through a decarboxylation reaction. It was found that carbanion abstracted a proton from the side chain of the protonated amino acids to yield 3-ethylbenzophenone ketyl biradical (EBPH); however, no reaction was observed with alanine. The relative yield of EBPH by the proton transfer reaction with His was ca. 40 times larger than that of the other two basic amino acids, suggesting that the proton-donating ability of His (protonated His) should be quite high. The information on the photoreaction mechanism of NSAIDs with basic amino acids was essential to understand primary reaction of excited NSAIDs in vivo causing photosensitization on human skin.

Links

Publisher Full Text

Authors

Suzuki T, Osanai Y, Isozaki T

Institution

Department of Chemistry and Biological Science, Aoyama Gakuin University, Kanagawa, Japan. suzuki@chem.aoyama.ac.jp

Source

Photochemistry and photobiology 88:4 pg 884-8

MeSH

Anti-Inflammatory Agents, Non-Steroidal
Arginine
Buffers
Free Radicals
Histidine
Humans
Hydrogen-Ion Concentration
Ketoprofen
Kinetics
Lysine
Photochemical Processes
Photosensitizing Agents
Protons
Solutions
Spectrum Analysis
Ultraviolet Rays
Water

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22372495