title: Reactivity of 2',7'-dichlorodihydrofluorescein and dihydrorhodamine 123 and their oxidized forms toward carbonate, nitrogen dioxide, and hydroxyl radicals.
abstract: The aim of this study was to investigate the oxidation of two common fluorescent probes, dichlorodihydrofluorescein (DCFH2) and dihydrorhodamine (DHR), and their oxidized forms, dichlorofluorescein and rhodamine, by the radical products of peroxynitrite chemistry, *OH, NO2*, and CO3*-. At pH 8.0-8.2, rate constants for the interaction of carbonate radical with probes were estimated to be 2.6 x 10(8) x M(-1) s(-1) for DCFH2 and 6.7 x 10(8) M(-1) s(-1) for DHR. Nitrogen dioxide interacted more slowly than carbonate radical with these probes: the rate constant for the interaction between NO2* and DCFH2 was estimated as 1.3 x 10(7) M(-1) s(-1). Oxidation of DHR by nitrogen dioxide led to the production of rhodamine, but the kinetics of these reactions were complex. Hydroxyl radical interacted with both probes with rate constants close to the diffusion-controlled limit. We also found that oxidized forms of these fluorescent probes reacted rapidly with carbonate, nitrogen dioxide, and hydroxyl radicals. These data suggest that probe oxidation may often be in competition with reaction of the radicals with cellular antioxidants.
authors.affiliation: Gray Cancer Institute, Mount Vernon Hospital, Northwood, Middlesex HA6 2JR, UK. wrona@gci.ac.uk
authors.forename: Marta
authors.initials: M
authors.lastname: Wrona
authors.forename: Kantilal
authors.initials: K
authors.lastname: Patel
authors.forename: Peter
authors.initials: P
authors.lastname: Wardman
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D002254:Carbonates / Q000737:chemistry*; D004058:Diffusion; D005452:Fluoresceins / Q000494:pharmacology*; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D009585:Nitrogen Dioxide / Q000737:chemistry*; D010100:Oxygen / Q000378:metabolism; D012235:Rhodamines / Q000737:chemistry / Q000494:pharmacology*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013997:Time Factors
chemical_list: D000975:Antioxidants; D002254:Carbonates; D005452:Fluoresceins; D005609:Free Radicals; D012235:Rhodamines; C065013:2',7'-dichlorodihydrofluorescein; C058319:dihydrorhodamine 123; D017665:Hydroxyl Radical; D009585:Nitrogen Dioxide; D010100:Oxygen