title: Quinone-enhanced ascorbate reduction of nitric oxide: role of quinone redox potential.
abstract: The quinones 1,4-naphthoquinone (NQ), methyl-1,4-naphthoquinone (MNQ), trimethyl-1,4-benzoquinone (TMQ) and 2,3-dimethoxy-5-methyl-1,4-benzoquinone (UQ-0) enhance the rate of nitric oxide (NO) reduction by ascorbate in nitrogen-saturated phosphate buffer (pH 7.4). The observed rate constants for this reaction were determined to be 16+/-2,215+/-6,290+/-14 and 462+/-18 M-1 s-1, for MNQ, TMQ, NQ and UQ-0, respectively. These rate constants increase with an increase in quinone one-electron redox potential at neutral pH, E1(7). Since NO production is enhanced under hypoxia and under certain pathological conditions, the observations obtained in this work are very relevant to such conditions.
authors.affiliation: Department of Chemistry, University of Puerto Rico at Humacao, CUH Station, Humacao, PR 00791. ae_alegria@webmail.uprh.edu
authors.forename: Antonio E
authors.initials: AE
authors.lastname: Alegria
authors.forename: Sheila
authors.initials: S
authors.lastname: Sanchez
authors.forename: Ingrid
authors.initials: I
authors.lastname: Quintana
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism*; D016227:Benzoquinones / Q000494:pharmacology*; D009285:Naphthoquinones / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D016227:Benzoquinones; D009285:Naphthoquinones; D009589:Nitrogen Oxides; D009569:Nitric Oxide; C004532:quinone; C039900:nitroxyl; D009609:Nitrous Oxide; D001205:Ascorbic Acid