Voltammetric techniques have been considered as important methods among the analytical techniques used for the identification and determination of trace concentrations of many biological molecules such as L-ascorbic acid (AA). L-ascorbic acid is an electro-active molecule, though it is difficult to determine its value directly with a majority of electrodes made of carbon and transition metals, ...

Ascorbic acid was measured in 125 plasma samples by an automated colorimetric method involving dichlorophenolindophenol and by a "high-performance" liquid-chromatographic procedure with electrochemical detection. The two methods gave comparable results for samples with ascorbate concentrations of 1 to 20 mg/L (r = 0.97). We also measured the amount of total ascorbate (ascorbic acid + dehydroasc...

objective: polyphenol oxidase or ppo (ec 1.14.18.1) is considered the enzyme responsible for quality deterioration and browning in different fruits during postharvest period. the objective of this study was to evaluate the antibrowning (inhibition of polyphenol oxidase activity) effect of cysteine, ascorbic acid, citric acid, kojic acid and glycine at two different ph (6 and 7) in  hawthorn. me...

The L-gulono-γ-lactone oxidase gene (Gulo) encodes an essential enzyme in the synthesis of ascorbic acid from glucose. On the basis of previous findings of bone abnormalities in Gulo (-/-) mice under conditions of ascorbic acid insufficiency, we investigated the effect of ascorbic acid insufficiency on factors related to bone metabolism in Gulo (-/-) mice. Four groups of mice were raised for 4 ...

In exploring the mechanism of biosynthesis of ascorbic acid by the rat, King and his coworkers (Musulin, Tully, Longenecker & King, 1939; Longenecker, Musulin, Tully & King, 1939; Longenecker, Fricke & King, 1940) observed that rats treated with Chloretone (1:1:1-trichloro-2methylpropan-2-ol) excreted more ascorbic acid than did the controls. By employing Chloretonized rats and isotopically lab...

Received: December 28, 2013; Revised; January 25, 2014; Accepted: March 2, 2014 . Abstract: A major problem in the micro propagation of litchi is the secretion of polyphenols into the medium by the tissues once excised. This secretion undergoes oxidation to produce substances that kill the tissues. The first visual symptom of deterioration is skin browning which has been reported to appear due ...

The reaction of 2,3-diketo-L-gulonic acid (DKG), which is one of the important intermediate products in the degradation of L-ascorbic acid (ASA) in both food and biological systems, in an aqueous solution was studied. The formation of a small amount of the γ-lactone, dehydro-L-ascorbic acid (DASA), from DKG was observed. This strongly suggests the chemical possibility of a reverse reaction in D...

A recent finding from this laboratory indicated that the incubation in vitro of purified xanthine oxidase with trace amounts of l-ascorbic acid resulted in a marked inhibition of the enzymatic activity (1, 2). Since the physiological mode’of action of Z-ascorbic acid is still obscure, it seemed desirable to determine whether ascorbic acid would, in the intact animal, exert a similar effect on x...

abstract effect of different concentrations of salicylic acid on postharvest life of kiwifruit (actinidia deliciosa) cultivar hayward at 0 ±.5 °c and 90-95% rh was studied. fruits were treated with salicylic acid (0, 1 and 2 mmol/l-1) and stored at 0±.5°c for 16 weeks. fruit quality attributes assessment including firmness, total acidity, soluble solid content, ascorbic acid, antioxidant activi...

BACKGROUND Ascorbic acid demonstrates a cytotoxic effect by generating hydrogen peroxide, a reactive oxygen species (ROS) involved in oxidative cell stress. A panel of eleven human cancer cell lines, glioblastoma and carcinoma, were exposed to serial dilutions of ascorbic acid (5-100 mmol/L). The purpose of this study was to analyse the impact of catalase, an important hydrogen peroxide-detoxif...