title: Evaluation of N-hydroxy-2-thiopyridone as a nonmetal dependent source of the hydroxyl radical (HO.) in aqueous systems.
abstract: N-hydroxy-2-thiopyridone (1), an established source of the hydroxyl radical (HO., Boivin, J., Crepon, E., and Zard, S. Z. (1990) Tetrahedron Lett. 31, 6869-6872), produced HO. under conditions directly applicable to biological studies. Generation of HO. by subjecting 1 to irradiation with visible light was monitored in the following "HO." assays: deoxyribose degradation, addition to dimethyl sulfoxide, and hydroxylation of salicylate and phenol. All four assays demonstrated the production of HO. from 1 (added as a sodium salt) under mild conditions in aqueous buffer systems. An improved analysis method was developed for the phenol assay. A time course analysis demonstrated that a flux of HO. is generated from 1 throughout the irradiation period, in contrast to the classical Fenton reaction of H2O2 with a transition metal in which a burst of HO. is generated in a short time period. While a thiyl radical is generated from 1 concurrent with HO. generation, this species does not contribute to, or interfere with, any of the HO. assays, suggesting that it is weakly reactive in aqueous buffers. Thus, irradiation of 1 can be used as an alternative, complementary, approach for the unequivocal generation of the biologically significant and reactive HO..
authors.affiliation: Department of Chemistry, University of California, Irvine 92717.
authors.forename: K M
authors.initials: KM
authors.lastname: Hess
authors.forename: T A
authors.initials: TA
authors.lastname: Dix
mesh_terms: D002849:Chromatography, Gas / Q000379:methods; D003855:Deoxyribose / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D005609:Free Radicals; D006861:Hydrogen Peroxide; D006878:Hydroxides; D017665:Hydroxyl Radical; D006900:Hydroxylation; D007501:Iron; D007700:Kinetics; D008027:Light; D008353:Mannitol; D019800:Phenol; D010636:Phenols / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D012459:Salicylates / Q000737:chemistry; D020156:Salicylic Acid; D013997:Time Factors
chemical_list: C045076:Fenton's reagent; D005609:Free Radicals; D006878:Hydroxides; D010636:Phenols; D011725:Pyridines; D012459:Salicylates; D017665:Hydroxyl Radical; D019800:Phenol; D008353:Mannitol; D003855:Deoxyribose; D006861:Hydrogen Peroxide; D007501:Iron; D020156:Salicylic Acid; D004121:Dimethyl Sulfoxide