Release of nitric oxide together with carbon-centered radicals from N-nitrosamines by ultraviolet light irradiation.
Solutions of N-nitrosamines, N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosomorpholine and N-nitrosopyrrolidine in phosphate buffer (pH 7.4) were irradiated by ultraviolet (UV) light at room temperature. The N-nitrosamines were extensively degraded due to irradiation for 120 min in a time-dependent fashion as monitored by UV-absorption or high performance liquid chromatographic analysis. Carbon-centered radicals were generated from four N-nitrosamines during the short time irradiation of 10-60 s as monitored by electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrroline N-oxide and N-tert-butyl-alpha-phenylnitrone as spin traps. Nitric oxide (NO) was generated during the short time irradiation as monitored by ESR technique using cysteine-Fe(II) complex, N-methyl-D-glucamine dithiocarbamate and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. Significant amounts of nitrite (4-16%) from four N-nitrosamines and also a significant amount of nitrate (4%) was produced from N-nitrosodimethylamine during the irradiation time of 120 min. Released NO from the N-nitrosamines must be converted into nitrite through intermediary reactive nitrogen oxide species including nitrogen dioxide and dinitrogen trioxide in contact with dissolved oxygen.
Hiramoto
K
K
School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.
Ohkawa
T
T
Kikugawa
K
K
D002244:Carbon / Q000737:chemistry / Q000528:radiation effects*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry / Q000528:radiation effects*; D009569:Nitric Oxide / Q000737:chemistry / Q000528:radiation effects*; D009602:Nitrosamines / Q000737:chemistry / Q000528:radiation effects*; D010777:Photochemistry; D026361:Reactive Nitrogen Species / Q000737:chemistry / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays
D005609:Free Radicals; D009602:Nitrosamines; D026361:Reactive Nitrogen Species; D009569:Nitric Oxide; D002244:Carbon