Mixture Of Ascorbic Acid Research Articles

DNA-DNA interstrand cross-linking by 2,5-bis(1-aziridinyl)-3,6-bis(carbethoxyamino)-1,4-benzoquinone: covalent structure of the dG-to-dG cross-links in calf thymus DNA and a synthetic DNA duplex.

The products of the alkylation reaction of reduced 2,5-bis(1-aziridinyl)-3,6-bis(carbethoxyamino)-1,4-benzoquinone (AZQ, 1a) with duplex DNA were studied using calf thymus DNA and a synthetic oligodeoxynucleotide. Reaction of calf thymus DNA with a mixture of AZQ and ascorbic acid followed by enzymatic digestion of the sugar phosphate backbone afforded numerous AZQ-derived products including substances identified as monoadducts of AZQ with both dG and dA (with the former in greater abundance) and two diadducts, as would be expected for intrastrand or interstrand cross-links, with one containing two dG residues per AZQ and the other one each of dG and dA (with the former adduct in greater abundance). The nucleotide connectivity and covalent structure of the dG-to-dG interstrand cross-links were studied in greater detail using a synthetic DNA duplex containing the nucleotide sequence 5'-d(GGGCCC), where it appeared that the predominant interstrand cross-links bridged dG residues on opposite strands and were separated by two intervening base pairs [5'-d(GNNC)]. The covalent structure of this lesion was tentatively identified as 2b, in which the N7 atoms of two dG residues have been alkylated by the aziridine functions of AZQ, based upon the results of piperidine fragmentation and characterization of the enzymatic and acidic hydrolysates of the cross-linked DNA.

Resolution of ascorbic acid or catecholamine and indole alkaloid mixtures by pulse voltammetry at highly polished glassy carbon

AbstractMetallographic polishing of glassy carbon electrodes (GCEs) yields well‐defined oxidation peaks for two‐ and three‐component mixtures of ascorbic acid, dopamine (DA), catechol, and hydroquinone. Linear calibration plots of differential pulse voltammetric current versus concentration were obtained for each component at a range of 0.4 to 10 μM, Deterioration of voltammograms was observed when highly, polished GCE was aged in solution, resulting in positive shifts and broadening of the peaks. Lower limits of detection (LLD) in water at pH 7 were about 0.01 μM, for DA and 1 μM for AA. Highly polished GCEs were further applied to mixtures of naturally occurring indole alkaloids.

Matrix Modification with Metal Nitrates and Organic Compounds for the Determination of Germanium by Graphite-Furnace Atomic Absorption Spectrometry

A mixture of cobalt and aluminum nitrates proved to be useful as a matrix modifier for determination of germanium by graphite-furnace atomic absorption spectrometry. These metal nitrates acted as a thermal stabilizer for germanium in the furnace before atomization, and atomic absorption sensitivity for the analyte was improved by a factor of about 40 over that in the absence of metal nitrate. For the removal of chloride interference in the determination of germanium, a mixture of ammonium acetate with these metal nitrates was suitable as an additive, because chloride formation of aluminum was masked by acetate and the volatile ammonium chloride formed could be easily removed from the furnace. The tolerable concentration of coexisting chlorides was about 10 or more times greater than that in the absence of ammonium acetate. The sulfate interference could also be removed by the addition of a mixture of ascorbic acid and ammonium-EDTA with cobalt and aluminum nitrates. EDTA acted as a masking agent and the formed ammonium sulfate could be easily removed from the furnace. The tolerable concentration of coexisting sulfates was also about 200 times greater than that in the absence of these organic reagents.

Increasing Effect of a Chitosan and Ascorbic Acid Mixture on Fecal Dietary Fat Excretion

Rats were fed for 2 weeks on five different high-fat diets containing cellulose (control) or chitosan with and without organic acids (i.e., ascorbic, lactic and citric acids) as the dietary fiber. The apparent fat digestibility in the chitosan-receiving groups was significantly lower than in the control group. The addition of ascorbic acid to chitosan caused a larger increase in the fecal fat excretion than otherwise, without considerably affecting the apparent protein digestibility.The effect is thought to have occurred because chitosan was so well dissolved and mixed with fat by the action of ascorbic acid that it encapsulated fine fat droplets on its gel after contacting the pancreatic juice in the samll intestine. The intake of a mixture of chitosan and ascorbic acid is suitable for reducing excess fat.

Carbon Film Electrodes from the Pyrolysis of Two Aromatic Anhydrides

Abstract Two new carbon film electrodes have been prepared from the low pressure pyrolysis of aromatic anhydrides onto quartz substrates. The anhydrides employed are safer and more volatile than those previously used for preparing carbon film electrodes. The voltammetric response of the film electrodes both in millimolar dopamine and in background electrolyte was studied. The differential pulse voltammetry response with a mixture of dopamine, homovanillic acid and ascorbic acid was studied. Also, the application of the electrode as an optically transparent carbon electrode was examined. The film electrodes had lower background current than glassy carbon, but the reversibility with dopamine was not ideal. These two new films appear to have utility similar to previously studied films, with the advantage of rapid and safe production.

Kalman filtering of data from first- and second-order kinetics

The Kalman filter algorithm was used to process data obtained in the simultaneous determination of species following first- and second-order kinetics. The performance of the algorithm in the quantification of chemical components from simulated data was assessed, and the influence of various parameters involved was estimated. The algorithm was applied to the resolution of cysteine—ascorbic acid and glutathione—ascorbic acid mixtures where the ascorbic acid followed pseudo first-order kinetics and the amino acids second-order kinetics in the reaction with the copper(II)—neocuproine system. Some features of the determinations (namely, afforded concentration ratios, accuracy and precision) are discussed.

Antioxidant Defenses of Baker′s Yeast against Free Radicals and Lipid Peroxides in Rat Brain

We examined through the electron spin resonance spectrometry/spin trapping technique the antioxidant activity of baker′s yeast Saccharomyces cerevisiae which is known to have both enzymatic and nonenzymatic antioxidants. The components in baker′s yeast were separated by differential filtration/centrifugation using centrifuge-type filter tubes, yielding four nonenzymatic thermostable fractions of varied molecular weights which scavenged 85-95% of 1,1-diphenyl-2-picrylhy-drazyl in organic solution, of hydroxyl and superoxide radicals in aqueous solution, and of lipid carbon-centered radicals induced by equimolar mixture of ascorbic acid and Fe(II) salt in rat brain homogenate. Baker′s yeast also inhibited the thiobarbituric acid-reactive substance formation in the cortex, midbrain, pons-medulla oblongata, cerebellum, hippocampus, and striatum. Partial characterization of the antioxidative defenses in baker′s yeast against free radicals and lipid peroxides in the brain confirmed the presence of superoxide dismutase, catalase, peroxidase, and glutathione.

INHIBITION of APPLE POLYPHENOLOXIDASE (PPO) BY ASCORBIC ACID, CITRIC ACID and SODIUM CHLORIDE

The inhibiting effect of ascorbic acid, citric acid and sodium chloride on Polyphenoloxidase (PPO) of Golden Delicious apple cubes was studied. Dipping in ascorbic acid (0.2-10 g/L range) and in NaCl (0.2-1 g/L range) solutions for 5 min increases the PPO activity. Citric acid solutions (0.2-10 g/L range) have little or no inhibition of PPO. A 90-100% PPO inhibition was obtained with a 5 min dip in mixtures of ascorbic acid and citric acid (10 + 2 g/L), and of ascorbic acid and sodium chloride (10 + 0.5 g/L).

Evaluation of the antioxidant actions of ferulic acid and catechins.

We have evaluated the abilities of ferulic acid, (+/-) catechin, (+) catechin and (-) epicatechin to scavenge the reactive oxygen species hydroxyl radical (OH.), hypochlorous acid (HOCl) and peroxyl radicals (RO2.). Ferulic acid tested at concentrations up to 5 mM inhibited the peroxidation of phospholipid liposomes. Both (+/-) and (+) catechin and (-) epicatechin were much more effective. All the compounds tested reacted with trichloromethyl peroxyl radical (CCl3 O2.) with rate constants > 1 x 10(6) M-1 s-1. A mixture of FeCl3-EDTA, hydrogen peroxide (H2O2) and ascorbic acid at pH 7.4, has often been used to generate hydroxyl radicals (OH.) which are detected by their ability to cause damage to the sugar deoxyribose. Ferulic acid, (+) and (+/-) catechin and (-) epicatechin inhibited deoxyribose damage by reacting with OH. with rate constants of 4.5 x 10(9)M-1 s-1, 3.65 x 10(9) M-1 s-1, 2.36 x 10(9) M-1 s-1 and 2.84 x 10(9) M-1 s-1 respectively. (-) Epicatechin, ferulic acid and the (+) and (+/-) catechins exerted pro-oxidant action, accelerating damage to DNA in the presence of a bleomycin-iron complex. On a molar basis, ferulic acid was less effective in causing damage to DNA compared with the catechins. A mixture of hypoxanthine and xanthine oxidase generates O2-. which reduces cytochrome c to ferrocytochrome c. (+) Catechin and (-) epicatechin inhibited the reduction of cytochrome c in a concentration dependent manner. Ferulic acid and (+/-) catechin had only weak effects. All the compounds tested were able to scavenge hypochlorous acid at a rate sufficient to protect alpha-1-antiproteinase against inactivation. Our results show that catechins and ferulic acid possess antioxidant properties. This may become important given the current search for "natural" replacements for synthetic antioxidant food additives.

Individual and simultaneous determination of uric acid and ascorbic acid by flow injection analysis

Flow injection methods for the individual and simultaneous determination of ascorbic acid and uric acid are proposed. A spectrophotometer and a miniamperometric detector are connected in sequence. The calibration graphs for uric acid obtained by measuring its absorbance at 293 nm and its current at +0.6 V are linear up to at least 80 and 70 μg/ml, respectively, with an rsd ( n = 10) of 1 % for both methods at mid-range concentrations. The calibration graph for ascorbic acid with amperometric detection is linear up to 80 mg/l. with an rsd ( n = 10) of 0.8% at 30 mg/l. The simultaneous determination of uric acid and ascorbic acid is based on measurement of the absorbance of uric acid at 393 nm and amperometric determination of both analytes at +0.6 V. The average relative errors of the analysis of binary mixtures of uric acid and ascorbic acid are 2.2 and 4.2%, respectively.

Inhibiting effect of ascorbic acid on the growth of human mammary tumor xenografts

The effect of ascorbic acid on the growth of a human mammary tumor in mice has been investigated using the 6-d subrenal capsule assay method. The results indicated that ascorbic acid administered in the drinking water significantly inhibited the growth of the tumor fragments implanted beneath the renal capsule of mice. Administration of a mixture of ascorbic acid and cupric sulfate orally or intraperitoneally significantly inhibited tumor growth in these mice, whereas neither alone was effective. These results support the hypothesis that certain oxidation or degradation products of ascorbic acid were active antineoplastic agents for the human mammary tumor studied. The activity of D-isoascorbic acid, an isomer of ascorbic acid, was similar to that of ascorbic acid. This suggests that the antitumor activity of ascorbic acid was not due to the metabolism of ascorbic acid as a vitamin, but due to its chemical properties.

DNA base damage by β-lactam, tetracycline, bacitracin and rifamycin antibacterial antibiotics

Several antibacterial antibiotics have been shown to participate with transition metal ions in chemical reactions leading to the formation of reactive oxygen species. An important host defence mechanism for dealing with invading bacteria involves the production of reactive oxygen species, such as superoxide, hydrogen peroxide and hypochlorous acid, by phagocytic cells. The production of reactive oxygens by redox cycling antibacterial antibiotics has led us to suggest that a ‘phagomimetic’ contribution may also be made in vivo. Here we show that four structurally different antibacterial antibiotics, in the presence of added copper salt, bring about oxidative modification to bases in DNA detected using gas chromatography-mass spectrometry. The drug most damaging to DNA was rifamycin SV which was more active than a reference mixture of hydrogen peroxide and ascorbic acid.

Degradation of heme by a soluble peptide of heme oxygenase obtained from rat liver microsomes by mild trypsinization.

A tryptic peptide of heme oxygenase obtained after solubilization of rat liver microsomes by mild trypsin treatment was purified. The purified peptide gave only a single protein band with a molecular mass of 28 kDa on SDS/PAGE. The tryptic peptide, like the native heme oxygenase, readily bound with substrate heme forming a hemeprotein transiently. The absorption spectra of the ferric, ferrous, ferrous-CO and ferrous-O2 forms of the resulting complex resembled those of the corresponding forms of the complex of heme and the native enzyme. Ferric heme bound to the tryptic peptide was quantitatively decomposed to biliverdin on incubation with a mixture of ascorbic acid and desferrioxamine, indicating that the tryptic peptide still retained catalytic activity. These observations suggest that heme oxygenase has two domains, a hydrophilic and a hydrophobic domain, and that the two domains are folded almost independently of each other. An NADPH-cytochrome-P-450 reductase system composed of NADPH and detergent-solubilized NADPH-cytochrome-P-450 reductase readily reduced the ferric heme bound to the tryptic peptide, but failed to transfer the second electron required for rapid heme degradation, suggesting that the hydrophobic domain of heme oxygenase is important for receiving the second electron from the reductase.

Electrochemistry and detection of some organic and biological molecules at conducting poly(3-methylthiophene) electrodes

Electrodes modified by the electrodeposition of poly(3-methylthiophene) were used as chemical sensors for some organic and biological molecules of industrial and medicinal interest. The electrochemical behaviors of ferri/ferrocyanide, catechol, ascorbic acid, hydroquinone, dopamine epinephrine, acetaminophen, p-aminophernol and NADH were examined by cyclic voltammetry. The results showed that the proposed modified surface catalyzes the oxidation of these compounds. Differential pulse and square wave techniques were used for the analysis of binary mixture of ascorbic acid with catechol, NADH, dopamine and p-aminophenol. Voltammetric peak resolution was also demonstrated for a ternary mixture of ascorbic acid, catechol and p-aminophenol. Polymer coated electrode was also used in an amperometric detector for flow injection analysis of most of the aforementioned compounds. The responses of the polymer electrode were 4–10 times larger as compared to those of platinum. The modified electrode displayed excellent response stability for successive injections and detection limits were 10 ppb for catechol, dopamine, epinephrine, NADH and p-aminophenol, 1 ppb for acetaminophen and 100 ppb for ascorbic acid. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, film thicknesses were shown to be a factor affecting both the current magnitudes and oxidation peak potential of NADH.

THE DETERMINATION OF Se ENVIRONMENTAL BACKGROUND VALUE IN NATURAL RIVER WATER USING MIXED MATRIX MODIFIER-STPF

A method is described for the determination of the Se in river water after precorncentration by stabilized temperature platform furnace and Zeeman background correction. A mixture of platinum and ascorbic acid was proved to be an adequte and powerful matrix modifier for the determination. Thermal pretreatment temperature of 1200°C can be used with the proposed modifier and concentration can be obtained directly via calibration curve without using the standard-addition technique. The method is sensitive, reliable and relatively simple, with the chracteristic mass, detection limit and recovery, 19.5pg/0.0044A.S., 1.55μg/L and 85.0-110.0%, respectively.

植物油脂中のトコフェロールの熱分解に対する没食子酸，大豆レシチン，あるいはカテキンとアスコルビン酸との混合物の効果

植物油脂中のトコフェロールの熱分解に対する没食子酸，大豆レシチン，あるいはカテキンとアスコルビン酸との混合物の効果

ROLE OF NATURAL ANTIOXIDANTS OR BIOAVILABILITY OF IRON FORTIFICATION ADDED TO MILK

We measured the effect of alfa-tocoferol VitE), taurine (Tau) and ascorbic acid (AA) on iron bioavailability when added to whole powdered cow's milk fortified with 10mg Fe/L as FeSO4. It was compared with an iron fortified infant formula. Three iron absorption studies were done using a double isotope technique. The preparations were labelled extrinsically with 55Fe and 59Fe. Subjects were 45 voluntary women (age = 35-45 y old). A reference dose of ferrous ascorbate was given to every subject to allow comparisons among groups. Iron absoption was measured in blood according to Eakins and Brown. Geometric mean of iron absorption from fortified cow's milk was 4,9%; no changes were found when VitE (20mg/L) or Tau (50mm/L) were added (5,4% and 5,5%, respectively). However, the addition of AA increased iron absorption up to 9,4% (p < 0.01). This value was not modified when mixtures of AA + VitE and AA + VitE + Tau were tested (10,6% and 9,3%, respectively). Iron absorption from the infant formula was 18.1%. Ascorbic acid improves the absorption of iron added to milk. VitE and Tau do not explain the high iron bioavailability of modified infant formula used as control.

Degradation Kinetics of Thiamine in Aqueous Systems at High Temperatures

High temperature thermal destruction kinetics of thiamine (Bl) were studied in water and in an aqueous mixture of thiamine, ascorbic acid and Maillard color forming compounds glucose and glycine. The thiamine content of test samples sealed in glass ampoules and capillary tubes subjected to various time-temperature treatments was analyzed by HPLC. The study indicated that the two sample heating techniques (ampoule and capillary) were comparable; the destruction of thiamine could be described by first order reaction rate kinetics, and the destruction behavior was dependent on the presence of other compounds (ascorbic acid and color precursors). The activation energy and reference rate constant (ko) at 121.1°C for thiamine destruction using the Arrhenius approach ranged from 103–118 kj/mole and 0.0060-0.0067min1 in water, and 71.1–73.4 kj/mole and 0.0066-0.0069min 1in the mixture, respectively. Similar analyses using the TDT approach yielded z and Dovalues of 26.4–30.6 C° and 350–394min in water and 42.4-43.8 C° and 338–354min in the mixture, respectively.

First Derivative Spectrophotometric Method for Determination of Ascorbic Acid and Analgin in Combination

Abstract A spectrophotometric method is presented for the determination of Ascorbic Acid and Analgin in prescence of each other using a first dervative spectrophotometry. By measuring the absolute value of the first-order contribution of both drugs in prescence of each other. The concentration of both drugs can be calculated without interference from each other. The method was proved using synthetic mixtures of Ascorbic Acid and Analgin in prescence of each other.

Evolution of phenolic acids and aldehydes during the different production process of “Fino” Sherry wine

The separation and determination of phenolic acids and aldehydes in “Fino” sherry wine, using high-perfomance liquid chromatography (HPLC), has enabled a study to be carried out of their evolution during the initial process in “fino” sherry wine production. A continuous extraction method with ethyl ether at pH 2 was chosen, by which the greatest reprodubility in the extraction of these compounds is achieved from must as well as from the wine. For stabilization of the must samples, a mixture of ascorbic acid (0.2%) and DMF (15%) was used, preventing the evolution of colour and the beginning of fermentation. These methods have permitted the study of changes in the content of the phenolic acids and aldehydes during the different stages of “fino” wine making.