Photolysis of NSAIDs. IV. Photoproducts of zomepirac determined by LC-ESI-MS.
A sample of 10 mm zomepirac in methanol was photo-irradiated with a Hanovia 200 W high-pressure quartz Hg lamp for 14 days. In total, four photoproducts were observed from the HPLC chromatogram. The preparative HPLC included an YMC-Pack Pro C18 column (250 x 20 mm i.d.), a mobile phase of CH3CN-CH3OH-1%HOAc (10:60:30, v/v/v), and UV detection at 254 nm. The most probable structures of the four photoproducts were determined by LC-MS. Two major photoproducts were separated, and their structures were further confirmed by the spectroscopic methods. A reaction scheme of zomepirac was proposed that the photochemical reaction routes occur mainly via bond fission between carbonyl-pyrrolyl groups (alpha-cleavage of a ketone), and decarboxylation followed by oxidation with singlet oxygen to produce an aldehyde.
Wang
Ching-Chiung
CC
Graduate Institute of Pharmacognosy Science, Pharmacy College, Taipei Medical University, Taipei 110, Taiwan, Republic of China.
Chen
Fu-An
FA
Chen
Chih-Jui
CJ
Chao
Su-Hui
SH
Wu
An-Bang
AB
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003653:Decarboxylation; D007659:Ketones / Q000737:chemistry; D008027:Light; D010084:Oxidation-Reduction; D010782:Photolysis; D026082:Singlet Oxygen / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014046:Tolmetin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007659:Ketones; D026082:Singlet Oxygen; C020549:zomepirac; D014046:Tolmetin