An optode was designed for an indirect determination of ascorbic acid by using neocuproine, which has been coated on transparent triacetylcellulose film as a membrane. The proposed method is based on the oxidation of ascorbic acid to dehydroascorbic acid with the Cu(II) and neocuproine reagent. The increase in the absorbance value of the optode at the maximum wavelength of 455 nm was related ...

Ascorbic acid and glutathione (GSH) are important determinants of the intracellular redox state, and both are known to accelerate the decomposition of S-nitrosoglutathione (GSNO), an endogenous adduct of nitric oxide (NO). The implications of these observations for GSNO bioactivity are not yet clear. We investigated the effect of ascorbic acid and GSH on GSNO bioactivity by using a bioassay wit...

It has been amply documented that L-ascorbic acid added to the medium of a cell culture increases oxidative damage, and this effect of L-ascorbic acid has been ascribed to the generation of reactive oxygen intermediates in the medium during its auto-oxidation. We have here questioned whether such an effect is exerted inside the cell as well, and if so, what its mechanism is. To assess thiol oxi...

L-ascorbic acid (Vitamin C) and peptide are both useful compounds for collagen biosynthesis in cosmeceuticals (cosmetic and pharmaceutical fields). The instability of these compounds, however, limit their application in these industries. In this report, we describe the development of a novel compound, Stabilized Ascorbyl Pentapeptide (SAP), which physically is much more stable than L-ascorbic a...

The effect of L(+)ascorbic acid and/or sodium nitrate in nitric oxide production by hepatocytes in vitro was studied. It was demonstrated that the compounds added into an incubation medium stimulated nitric oxide production in hepatocytes. The highest concentration of nitric oxide was assayed after the incubation of the cells with sodium nitrate and L(+)ascorbic acid. It was found that the addi...

A detailed study of the oxidation of L-ascorbic acid by dioxygen and nitrite in water at pH 5.8 and 7.0, catalyzed by the octasulfophenyltetrapyrazinoporphyrazine complex of cobalt(II), was carried out using conventional spectrophotometric, low-temperature and high-pressure stopped-flow techniques. The Co(II) complex activates L-ascorbic acid through an intramolecular one-electron oxidation ste...

A simple and sensitive flow injection fluorometric method for the determination of ascorbic acid is described. Perylenebisimide-linked nitroxide (PBILN) is used as a fluorescent reagent, which permits the selective determination of ascorbic acid. The fluorescence of the perylenebisimide moiety in PBILN is quenched by the nitroxide moiety, which is linked to the perylenebisimide. When a stream o...

The medium used contained 3g of substrate, 150ml of 1/15M phosphate buffer and 150ml of sterile distilled water. 0.5g (dry weight) of the adapted cells was added to the medium and the whole was incubated at 30•‹ for 20 hours. For detecting the intermediate products, paper chromatography was chiefly used. For developing the nonvolatile acids, n-butanol-acetic acid-water (4:1:1) was used and the ...

The bioactivity of nitric oxide (.NO) depends, in part, on its interaction with superoxide. Usually, superoxide dismutase (SOD) preserves .NO bioactivity by limiting the availability of superoxide. Ascorbic acid also effectively scavenges superoxide, but the extent to which this interaction is necessary for intact .NO bioactivity is not known. Therefore, the present study examined the effect of...