title: Terephthalic acid: a dosimeter for the detection of hydroxyl radicals in vitro.
abstract: Hydroxylation reactions of aromatic compounds have been used to detect hydroxyl radicals produced by gamma irradiation and ultrasound. The present study investigated the suitability of terephthalic acid (THA) as a hydroxyl radical dosimeter for general use in biologically relevant reactions. Hydroxyl radicals were generated by: (1) irradiating THA with a 254 nm ultraviolet light; (2) irradiating with gamma rays from a cesium source; and (3) generating hydroxyl radicals with 1 mM H2O2 and 10 microM Cu+2. In each of the three experiments, a fluorescent product was generated which exhibited identical fluorescent excitation and emission spectra. THA is non-fluorescent, eliminating the problem of a high initial background. Because THA has four identical ring hydrogens, only one mono-hydroxylated isomer was formed. The hydrogen peroxide reaction was dependent on the presence of a metal and cupric ions were effective in enhancing the reaction. With a Cu+2 concentration of 10 microM, the reaction was linear between 0-30 mM H2O2. Catalase abolished the reaction at a concentration of 100 micrograms/ml and the effects could still be observed at 10 ng/ml, consistent with the very high rate at which catalase destroys hydrogen peroxide. Tertbutyl- hydroperoxide did not generate any fluorescence in this system which makes THA a very specific detector of hydroxyl radicals.
authors: Department of Surgery, University of Texas Medical School, Houston 77030.
authors: J C
authors: JC
authors: Barreto
authors: G S
authors: GS
authors: Smith
authors: N H
authors: NH
authors: Strobel
authors: P A
authors: PA
authors: McQuillin
authors: T A
authors: TA
authors: Miller
mesh_terms: D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000737:chemistry; D006878:Hydroxides / Q000737:chemistry*; D010795:Phthalic Acids / Q000737:chemistry*; D017382:Reactive Oxygen Species; D013050:Spectrometry, Fluorescence
chemical_list: D005609:Free Radicals; D006878:Hydroxides; D010795:Phthalic Acids; D017382:Reactive Oxygen Species; C011363:terephthalic acid; D006861:Hydrogen Peroxide