title: Reductive activation of terpenylnaphthoquinones.
abstract: Four terpenylnaphthoquinones were found to enhance the rate of superoxide production in the presence of ascorbate as detected from the superoxide dismutase (SOD)-inhibitable initial oxygen consumption rates. Initial rates of oxygen consumption in the presence of ascorbate plus quinone increase with an increase in the half-wave reduction potentials of the quinones. These quinones also enhance the rate of Cyt(III)c reduction by xanthine/xanthine oxidase (X/XO) in both air- and nitrogen-saturated aqueous solutions at pH 7.4. Maximum rates of Cyt(III)c reduction in nitrogen and oxygen-saturated solutions (V(max)), in the presence of X/XO, increase with an increase in the half-wave reduction potentials of the quinones. SOD inhibits Cyt(III)c reduction rates in the presence of these quinones and X/XO in a manner which is also dependent on the quinone half-wave redox potential. The relative antineoplastic activity of two of these quinones follows the order in rates of oxygen consumption or Cyt(III)c reduction. This is consistent with an antineoplastic action of these quinones through the mechanism of redox cycling or possible interference or inhibition of mitochondrial respiration.
authors.affiliation: Department of Chemistry, University of Puerto Rico at Humacao, CUH Station, Humacao, PR 00791, USA. a_alegria@cuhac.upr.clu.edu
authors.forename: Antonio E
authors.initials: AE
authors.lastname: Alegria
authors.forename: Emelyn
authors.initials: E
authors.lastname: Cordones
authors.forename: Glysette
authors.initials: G
authors.lastname: Santiago
authors.forename: Yanira
authors.initials: Y
authors.lastname: Marcano
authors.forename: Sheila
authors.initials: S
authors.lastname: Sanchez
authors.forename: Marina
authors.initials: M
authors.lastname: Gordaliza
authors.forename: Maria Luz
authors.initials: ML
authors.lastname: Martín-Martín
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000737:chemistry*; D003574:Cytochrome c Group / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006736:Horses; D007700:Kinetics; D009285:Naphthoquinones / Q000737:chemistry*; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000737:chemistry; D013481:Superoxides / Q000737:chemistry; D013729:Terpenes / Q000737:chemistry*; D019820:Xanthine / Q000737:chemistry; D014969:Xanthine Oxidase / Q000737:chemistry
chemical_list: D003574:Cytochrome c Group; D009285:Naphthoquinones; D013729:Terpenes; D013481:Superoxides; D019820:Xanthine; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D001205:Ascorbic Acid