Earlier work (2) demonstrated that low, but not high, concentrations of ascorbate produce a swelling or lytic change in dilute suspensions of isolated liver mit.ochondria. This structural change shows both similarities to and differences from the phosphate-induced, electron transport-dependent swelling which has been rather extensively investigated (3-6). Both phenomena require O2 and can be pr...

Information on dimethyl nitrosamine (DMN)-induced toxicity on endocrine functions is still scanty. This study therefore investigated the outcomes of DMN-induced toxicity on endocrine (thyroid and reproductive) functions, as well as kallikrein-3 level, and effects of ascorbate treatments in male wistar rats. Thirty animals divided into six groups of five rats each were used. Group I animals were...

Peroxynitrite (ONOO(((-)))/ONOOH) is expected in vivo to react predominantly with CO(2), thereby yielding NO(2)(.) and CO(3) radicals. We studied the inhibitory effects of ascorbate on both NADH and dihydrorhodamine 123 (DHR) oxidation by peroxynitrite generated in situ from 3-morpholinosydnonimine N-ethylcarbamide (SIN-1). SIN-1 (150 micrometer)-mediated oxidation of NADH (200 micrometer) was ...

Yeast plasma membrane contains an electron transport system that maintains ascorbate in its reduced form in the apoplast. Reduction of ascorbate free radical by this system is comprised of two activities, one of them dependent on coenzyme Q6 (CoQ6). Strains with defects in CoQ6 synthesis exhibit decreased capacity for ascorbate stabilization compared with wild type or with atp2 or cor1 respirat...

Previously, we showed that in barley (Hordeum vulgare) leaves with heat-inactivated oxygen-evolving complexes, photosystem II (PSII) has access to a large pool of alternative electron donors. Based on in vitro data, we proposed that this donor was ascorbate, yet this hypothesis has not been substantiated in vivo. In this paper, with the aid of chlorophyll a fluorescence induced by short (5-ms) ...

PURPOSE To determine whether UVA-excited human lens chromophores can cause the oxidation of ascorbic acid in the absence of oxygen, and whether these oxidation products are capable of glycating lens proteins. METHODS The oxidation of ascorbic acid, mediated by UVA irradiation in the presence of aged human lens proteins, was measured in the absence of oxygen by the decrease in absorbance at 26...

Infection of tomato leaves with the necrotrophic fungus Botrytis cinerea resulted in substantial changes in enzymatic and non-enzymatic components of the ascorbate-glutathione cycle as well as in superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione transferase (GST), and l-galactono-gamma-lactone dehydrogenase (GLDH) activities. In the initial phase of the 5 d experiment CuZ...

We have isolated two cDNA clones encoding spinach (Spinacia oleracea) stromal and thylakoid-bound ascorbate peroxidase isoenzymes [Ishikawa, Sakai, Yoshimura, Takeda and Shigeoka (1996) FEBS Lett. 384, 289-293]. The gene (ApxII) encoding both chloroplastic ascorbate peroxidase isoenzymes was isolated and the organization of the gene was determined. Alignment between the cDNAs and the gene for c...

OBJECTIVE To compare the effects of three antioxidants (sodium ascorbate, sodium ascorbate combined with a surfactant, and catalase) on the microleakage of composite resin restorations after external tooth bleaching with 10% carbamide peroxide. MATERIALS AND METHODS Buccal cavities were prepared on the surface of 60 intact premolars, which were randomly divided into six groups. All cavities w...

This study addresses the dynamic interactions among alpha-tocopherol, caffeic acid, and ascorbate in terms of a sequence of redox cycles aimed at accomplishing optimal synergistic antioxidant protection. Several experimental models were designed to examine these interactions: UV irradiation of alpha-tocopherol-containing sodium dodecyl sulfate micelles, one-electron oxidations catalyzed by the ...