title: Reaction dynamics of excited 2-(3-benzoylphenyl)propionic acid (ketoprofen) with histidine.
abstract: Photoreaction dynamics of 2-(3-benzoylphenyl)propionic acid (ketoprofen, KP), one of nonsteroidal anti-inflammatory drugs, with histidine in a phosphate buffer solution (pH 7.4) was investigated with the laser flash photolysis. The deprotonated form of KP (KP(-)) was decarboxylated via UV laser excitation to form a carbanion. It was found that histidine accelerates the protonation reaction of the carbanion to 3-ethylbenzophenone ketyl biradical (3-EBPH) for the first time. The experimental results of the photoreaction of KP with alanine as well as the photoreaction of KP with 4-methylimidazole (a part of the side chain of histidine) in methanol, clearly showed that the protonated form of histidine is a key species for the protonation reaction of the carbanion. These series of the initial reactions should result in the occurrence of photosensitization in vivo. The reaction mechanism was discussed in detail.
authors.affiliation: Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo, Japan. suzuki.t.af@m.titech.ac.jp
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Okita
authors.forename: Yohei
authors.initials: Y
authors.lastname: Osanai
authors.forename: Teijiro
authors.initials: T
authors.lastname: Ichimura
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D007660:Ketoprofen / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D006639:Histidine; D007660:Ketoprofen