title: Electron spin resonance study of radiosterilization of antibiotics: ceftazidime.
abstract: Fundamental information on radiosterilization of ceftazidime was obtained by electron spin resonance (ESR) measurement of free radicals produced in gamma-ray-irradiated ceftazidime at 4.2-295 K. Three types of free radicals are produced by gamma-irradiation. The first one shows septet lines in an ESR spectrum and decays at 230 K: it is assigned as a .C(CH3)2COOH radical. The second one shows triplet lines and decays at 293 K: it is assigned as iminoxyl radicals (> C = N-O.). The third one shows a broad singlet line and survives even at 295 K. The plausible assignment of this spectrum is discussed. It is concluded that an O-C bond of the gamma-irradiated ceftazidime is ruptured, producing the iminoxyl radicals and .C(CH3)2COOH radicals. The yields of free radicals increase linearly with the increasing dose of gamma-irradiation up to 10 kGy at 295 K as well as 77 K. Half of the radicals that show a broad singlet line survive at 295 K upon storage of the irradiated ceftazidime for 159 days. It is concluded that the ESR measurement of free radicals gives a good method for discrimination of irradiated antibiotics from non-irradiated ones and an estimation of an irradiation dose.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Nagoya University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Miyazaki
authors.forename: T
authors.initials: T
authors.lastname: Kaneko
authors.forename: T
authors.initials: T
authors.lastname: Yoshimura
authors.forename: A S
authors.initials: AS
authors.lastname: Crucq
authors.forename: B
authors.initials: B
authors.lastname: Tilquin
mesh_terms: D002442:Ceftazidime / Q000737:chemistry / Q000528:radiation effects*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D005720:Gamma Rays; D013242:Sterilization
chemical_list: D005609:Free Radicals; D002442:Ceftazidime