title: Free radicals properties of gamma-irradiated penicillin-derived antibiotics: piperacillin, ampicillin, and crystalline penicillin.
abstract: The aim of this work was to determine the concentrations and properties of free radicals in piperacillin, ampicillin, and crystalline penicillin after gamma irradiation. The radicals were studied by electron paramagnetic resonance (EPR) spectroscopy using an X-band spectrometer (9.3 GHz). Gamma irradiation was performed at a dose of 25 kGy. One- and two-exponential functions were fitted to the experimental data, in order to assess the influence of the antibiotics' storage time on the measured EPR lines. After gamma irradiation, complex EPR lines were recorded confirming the presence of a large number of free radicals formed during the irradiation. For all tested antibiotics, concentrations of free radicals and parameters of EPR spectra changed with storage time. The results obtained demonstrate that concentration of free radicals and other spectroscopic parameters can be used to select the optimal parameters of radiation sterilization of β-lactam antibiotics. The most important parameters are the constants τ (τ (1(A),(I)) and τ (2(A),(I))) and K (K (0(A),(I)), K (1(A),(I)), K (2(A),(I))) of the exponential functions that describe free radicals decay during samples storage.
authors.affiliation: Department of Biophysics, School of Pharmacy and Laboratory Medicine, Medical University of Silesia in Katowice, Jedności 8, 41-200, Sosnowiec, Poland, swilczynski@sum.edu.pl.
authors.forename: Sławomir
authors.initials: S
authors.lastname: Wilczyński
authors.forename: Barbara
authors.initials: B
authors.lastname: Pilawa
authors.forename: Robert
authors.initials: R
authors.lastname: Koprowski
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Wróbel
authors.forename: Marta
authors.initials: M
authors.lastname: Ptaszkiewicz
authors.forename: Jan
authors.initials: J
authors.lastname: Swakoń
authors.forename: Paweł
authors.initials: P
authors.lastname: Olko
mesh_terms: D000667:Ampicillin / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D005609:Free Radicals / Q000032:analysis*; D005720:Gamma Rays; D046032:Microscopy, Energy-Filtering Transmission Electron; D010406:Penicillins / Q000737:chemistry; D010878:Piperacillin / Q000737:chemistry; D013242:Sterilization
chemical_list: D000900:Anti-Bacterial Agents; D005609:Free Radicals; D010406:Penicillins; D000667:Ampicillin; D010878:Piperacillin