title: Separation and structure determination of nicardipine photoproducts by LC-ESI-MS.
abstract: A sample of 0.104 M nicardipine in methanol was photoirradiated with a Philips 400 W UV lamp for 3 h in a photochemical chamber. A total of four major photoproducts were found from the HPLC chromatogram. The same sample was used for taking LC-MS, while eight major photoproducts were observed and the structures elucidated by analyzing the CID patterns of their respective mass spectra. A reaction scheme of nicardipine is proposed that the photochemical reactions occur mainly via oxidation of 1,4-dihydropyridine moiety, following the stepwise photo-reduction of the m-nitro group and demethylation of the ester group at 5-position of the pyridine ring.
authors.affiliation: Taipei Medical University, Taipei 11031, Taiwan, ROC.
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Chen
authors.forename: Mau-Chih
authors.initials: MC
authors.lastname: Hsieh
authors.forename: Su-Hui
authors.initials: SH
authors.lastname: Chao
authors.forename: E E
authors.initials: EE
authors.lastname: Chang
authors.forename: Po-Yu
authors.initials: PY
authors.lastname: Wang
authors.forename: An-Bang
authors.initials: AB
authors.lastname: Wu
mesh_terms: D002121:Calcium Channel Blockers / Q000737:chemistry* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D009529:Nicardipine / Q000031:analogs & derivatives / Q000737:chemistry* / Q000302:isolation & purification*; D010777:Photochemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D002121:Calcium Channel Blockers; D009529:Nicardipine