Degradation Products Of Ascorbic Acid Research Articles

A New Approach for Studying the Stability and Degradation Products of Ascorbic acid in Solutions

A New Approach for Studying the Stability and Degradation Products of Ascorbic acid in Solutions

Recent Advancements in Enhancing Antimicrobial Activity of Plant-Derived Polyphenols by Biochemical Means

Plants are a reservoir of phytochemicals, which are known to possess several beneficial health properties. Along with all the secondary metabolites, polyphenols have emerged as potential replacements for synthetic additives due to their lower toxicity and fewer side effects. However, controlling microbial growth using these preservatives requires very high doses of plant-derived compounds, which limits their use to only specific conditions. Their use at high concentrations leads to unavoidable changes in the organoleptic properties of foods. Therefore, the biochemical modification of natural preservatives can be a promising alternative to enhance the antimicrobial efficacy of plant-derived compounds/polyphenols. Amongst these modifications, low concentration of ascorbic acid (AA)–Cu (II), degradation products of ascorbic acid (DPAA), Maillard reaction products (MRPs), laccase–mediator (Lac–Med) and horse radish peroxidase (HRP)–H2O2 systems standout. This review reveals the importance of plant polyphenols, their role as antimicrobial agents, the mechanism of the biochemical methods and the ways these methods may be used in enhancing the antimicrobial potency of the plant polyphenols. Ultimately, this study may act as a base for the development of potent antimicrobial agents that may find their use in food applications.

Ascorbic Acid: A Review of its Chemistry and Reactivity in Relation to a Wine Environment

Extensive reviews of research are available on the use of ascorbic acid, and its consequent degradation pathways, in physiological conditions or food matrices. However, very little information can be found for wine-related systems. This review highlights the relevant chemistry and reactivity of ascorbic acid with a focus on its behavior and potential behavior in a wine environment. The review describes the use of ascorbic acid as a complementary antioxidant preservative to sulfur dioxide along with the metal-catalyzed and radical-dependent manner by which it achieves this role. The relevant degradation products of ascorbic acid in aerobic and anaerobic conditions are presented as well as the interaction of these degradation products with sulfur dioxide and other wine-relevant sulfur compounds. Limitations in existing knowledge, especially regarding the crossover between the antioxidant and pro-oxidant roles of ascorbic acid, are identified.

Use of Green Rooibos (Aspalathus linearis) Extract and Water-Soluble Nanomicelles of Green Rooibos Extract Encapsulated with Ascorbic Acid for Enhanced Aspalathin Content in Ready-to-Drink Iced Teas

Heat-induced changes in aspalathin, iso-orientin, and orientin content of ready-to-drink (RTD) green rooibos iced tea formulations were investigated. An organic-solvent-based aspalathin-enriched extract prepared from green rooibos was used "as-is" or encapsulated with ascorbic acid in a water-soluble nanomicelle-based carrier system. The common iced tea ingredients, ascorbic acid, and/or citric acid were added to the iced tea containing green rooibos extract. Only citric acid was added to the iced tea containing the nanomicelles. Heat treatments consisted of pasteurization (93 °C/5 min and 93 °C/30 min), normal-temperature sterilization (NTS; 121 °C/15 min), and high-temperature sterilization (HTS; 135 °C/4 min). Pasteurization had little or no effect on the flavonoid content. NTS and HTS induced significant losses in the flavonoids. The addition of citric and ascorbic acids improved the stability of the flavonoids, but encapsulation of green rooibos extract with ascorbic acid in nanomicelles did not offer additional stability. The only benefit of using the water-soluble nanomicelles was the improved clarity of the RTD product. Iso-orientin and orientin contents were substantially less affected than aspalathin by the heat treatments, partially because of conversion of aspalathin to these flavones, which countered losses. 5-Hydroxymethylfurfural (HMF), a known dehydration product of hexoses under mild acidic conditions and also a degradation product of ascorbic acid, was observed in formulations containing citric and/or ascorbic acids.

Formation of Pigment Precursor (+)-1′′-Methylene-6′′-hydroxy-2H-furan-5′′-one-catechin Isomers from (+)-Catechin and a Degradation Product of Ascorbic Acid in a Model Wine System

The present study investigates the contribution of ascorbic acid to the formation of pigment precursors in model white wine systems containing (+)-catechin as the oxidizable phenolic substrate. The two main colorless products in these systems were structurally characterized as isomers of (+)-catechin substituted at either C6 or C8 on the A ring with a furan-type unit, namely, (+)-1''-methylene-6''-hydroxy-2H-furan-5''-one-6-catechin and (+)-1''-methylene-6''-hydroxy-2H-furan-5''-one-8-catechin. A known degradation product of ascorbic acid, L-xylosone, was separately prepared and, when reacted with (+)-catechin, generated the same (+)-furanone-catechin isomers as in model white wine systems. Incubation of these isomers in wine-like conditions yielded yellow xanthylium cation pigments. This study has shown that undesirable spoilage reactions (yellow coloration) can occur from a breakdown product of ascorbic acid-L-xylosone.

Formation of furan and methylfuran from ascorbic acid in model systems and food

Previous model studies have suggested ascorbic acid as one of the major sources of furan, a possibly hazardous compound found in thermally processed foods (e.g. canned products, jars). The study showed that about 2 mmol mol−1 furan was obtained when dry-heating ascorbic acid, while much lower amounts were formed upon pressure cooking, i.e. 58 µmol mol−1 at pH 4 and 3.7 µmol mol−1 at pH 7. Model reactions also generated 2-methylfuran (MF). However, the MF levels were generally very low with the exception of the binary mixture ascorbic acid/phenylalanine (1 mmol mol−1). Studies with 13C-labelled ascorbic acid indicated that furan comprises an intact C4 unit, mainly C-3 to C-6, generated by splitting off two C1 units, i.e. CO2 and formic acid. Possible intermediates are 2-deoxyaldoteroses, 2-furoic acid and 2-furaldehyde, which are known as ascorbic acid degradation products. The mechanism of furan formation from ascorbic acid was validated based on the labelling pattern of furan and the identification of 13CO2 and H13COOH. Furan formation is significantly slowed down in binary mixtures, e.g. the presence of erythrose led to 80% less furan under roasting conditions. This is most likely due to competing reactions in complex systems, thus disfavouring furan formation. The mitigation effect is because furan, contrary to MF, is formed without recombination of ascorbic acid fragments. Therefore, furan levels are definitely much lower in foods than expected from trials with pure ascorbic acid. Consequently, conclusions should be drawn with much caution from model reactions, avoiding extrapolation from oversimplified model systems to food products.

Isolation, purification and characterization of histidino-threosidine, a novel Maillard reaction protein crosslink from threose, lysine and histidine

We isolated a novel acid-labile yellow chromophore from the incubation of lysine, histidine and d-threose and identified its chemical structure by one and two-dimensional NMR spectroscopy combined with LC-tandem mass spectrometry. This new cross-link exhibits a UV absorbance maximum at 305 nm and a molecular mass of 451 Da. The proposed structure is 2-amino-5-(3-((4-(2-amino-2-carboxyethyl)-1 H-imidazol-1-yl)methyl)-4-(1,2-dihydroxyethyl)-2-formyl-1 H-pyrrol-1-yl)pentatonic acid, a cross-link between lysine and histidine with addition of two threose molecules. It was in part deduced and confirmed through synthesis of the analogous compound from n-butylamine, imidazole and d-threose. We assigned the compound the trivial name histidino-threosidine. Systemic incubation revealed that histidino-threosidine can be formed in low amounts from fructose, glyceraldehyde, methylglyoxal, glycolaldehyde, ascorbic acid, and dehydroascorbic acid, but at a much higher yield with degradation products of ascorbic acid, i.e. threose, erythrose, and erythrulose. Bovine lens protein incubated with 10 and 50 mM threose for two weeks yielded 560 and 2840 pmol/mg histidino-threosidine. Histidino-threosidine is to our knowledge the first Maillard reaction product known to involve histidine in a crosslink.

Role of ascorbic acid in stratum corneum lipid models exposed to UV irradiation.

The effects of ascorbic acid on Stratum corneum lipid models following ultraviolet irradiation were studied adding iron ions as transition metal catalysts. Lipid peroxidation was quantified by the thiobarbituric acid assay. The qualitative changes were studied on a molecular level by mass spectrometry. To elucidate the nature of free radical involvement we carried out electron paramagnetic resonance studies. The influence of ascorbic acid on the concentration of hydroxyl radicals was examined using the spin trapping technique. Moreover, we checked the vitamin's ability to react with stable radicals. Ascorbic acid was found to have prooxidative effects in all lipid systems in a concentration dependent manner. The degradation products of ascorbic acid after its prooxidative action were detected. The concentration of the hydroxyl radicals in the Fenton assay was decreased by ascorbic acid. The quantification assay of 2,2-diphenyl-1-picrylhydrazyl hydrate showed reduced concentration levels of the stable radical caused by ascorbic acid. Considering human skin and its constant exposure to UV light and oxygen, an increased pool of iron ions in irradiated skin and the depletion of co-antioxidants, the administration of ascorbic acid in cosmetic formulations or in sunscreens could unfold adverse effects among the Stratum corneum lipids.

Degradation of Ascorbic Acid in Aqueous Solution

An HPLC method, for the simultaneous determination of the degradation products of ascorbic acid, was employed to investigate the degradation of ascorbic acid in aqueous solution at different pH values. After ascorbic acid aqueous solutions were heated at 100 °C for 2 h, four main degradation products, furfural, 2-furoic acid, 3-hydroxy-2-pyrone, and an unidentified compound, were separated and determined. In an acid aqueous solution, ascorbic acid was converted to 2-furoic acid and 3-hydroxy-2-pyrone via dehydroascorbic acid under aerobic conditions, whereas under anaerobic conditions, ascorbic acid degraded to furfural. Low pH conditions favored the formation of furfural, 2-furoic acid, and 3-hydroxy-2-pyrone; at extremely low pH (i.e., pH 1), the formation of furfural dominated. In an alkaline aqueous solution, the unknown compound became the main degradation product of ascorbic acid; at pH 10, only very small amounts of furfural and 3-hydroxy-2-pyrone with no 2-furoic acid were detected. Our results su...

Structural elucidation of a novel lysine-lysine crosslink generated in a glycation reaction with L-threose

A novel lysine-lysine crosslink was isolated from a reaction containing L-threose (a degradation product of ascorbic acid) and N-α acetyllysine. The compound, after chromatographic purification, had a relative molecular mass of 628 as determined by fast atom bombardment spectrometry. Structural analysis by NMR spectroscopy (1H,13C, COSY, HETCOR and DEPT) suggests that the compound is composed of 3 threose residues and 2 N-α-acetyllysines with an empirical formula of C28H45N4O12. The compound, referred to as threosidine (2,5-dihydroxy-5,6,7,8-tetrahydro 1,7-naphthyridinium as the core molecule) has an absorption maximum at 328 nm with an excitation and emission maxima at 328 nm and 402 nm respectively. Threosidine was stable upon acid hydrolysis, and it was not found in the reactions containing threose and amino acids other than N-α-acetyllysine. Threosidine was also not found in the reactions containing N-α-acetyllysine and sugars other than threose.

Glycation mediated crosslinking between α-crystallin and MP26 in intact lens membranes

With advancing age, progressive crosslinking occurs between lens crystallin proteins and other lenticular components. This crosslinking may be involved in the development of senile cataracts. Experiments were conducted to determine whether non-enzymatic glycation could be involved in the crosslinking between lens α-crystallin and MP26, an abundant lens fiber cell membrane intrinsic protein. In vitro crosslinking of α-crystallin and MP26 of bovine lens membranes was observed in presence of two degradation products of ascorbic acid (ASA), dehydroascorbic acid (DHA) and threose. Alkali-washed bovine lens membranes, isolated after glycation with DHA and threose, contained both α-crystallin and MP26, as determined by immunoblot and double immunocytochemical labeling studies. In contrast, membranes incubated without these glycating compounds contained only MP26. SDS-PAGE analysis of [ 125I]α-crystallin incubated with lens membranes in the presence of threose showed a higher amount of radioactivity in high molecular weight aggregates than in the aggregates produced when α-crystallin and threose were incubated without membranes. A slot-blot immunoassay of alkali-washed human lens membranes showed a higher amount of covalently bound α-crystallin in aged, cataractous or diabetic lens membranes than was present in lens membranes from young normal donors. Based on the in vitro results, we hypothesize that non-enzymatic glycation is one of the in vivo mechanisms in the crosslinking of α-crystallin to lens membrane proteins, such as MP26. This crosslinking may contribute significantly to the development of age-related and diabetic cataracts.

Rapid assessment of early glycation products by mass spectrometry

In order to detect the early glycation products, we have reacted a model peptide (t-boc-lys-ala-ala) with L-threose (a degradation product of ascorbic acid) and analyzed the reaction products by a combination of HPLC and mass spectrometry. Amino group modification, as observed by a fluorescamine assay, indicated complete modification after 3 days of incubation with a 10-fold excess of threose. As much as 60% of the adducts were acid labile and only 4% of the adducts could be observed by amino acid analysis. However, Fast atom bombardment mass spectrometry (FABMS) of the samples incubated for 6 hr showed relative molecular masses consistent with the formation of adducts corresponding to the addition of one and two molecules of L-threose to the peptide. Likewise, samples incubated for 12 hr showed peptide adducts with two and three L-threoses. The number of threose molecules added to the peptide was also confirmed from the FABMS analysis by using [1-13C]-threose as the glycating agent.

Ascorbic Acid Glycation: the Reactions of l-Threose in Lens Tissue

l-Threose is a significant degradation product of ascorbic acid at pH 7·0 in the presence of oxygen. When compared to several other ascorbate-derived degradation products, it had the greatest ability to glycate and crosslink lens proteins in vitro. To determine whether l-threose was formed in the lens, the sugars in a TCA-soluble extract from human lenses were reduced to polyols with NaBH4, acetylated and analysed by gas-liquid chromatography. The threitol levels measured were 3·4 ± 0·8 μg per lens (n = 4). GC-MS measurements made after reduction with NaBD4 indicated that threitol, but little or no threose, was originally present in the human lens. Rat lenses were incubated with [1-13C]D-threose for 24 hr, and considerable d-threitol formation was seen by NMR spectroscopy. Analysis of the lenses after medium removal showed that only [1-13C]threitol was present within the lenses indicating a rapid reduction of threose within the lens, presumably by aldose reductase. Assays with human recombinant aldose reductase and with human lens cortical and nuclear extracts all exhibited sorbinil-inhibitable aldose reductase activity with l-threose as substrate. This was confirmed by incubating a preparation of [1-14C]l-tetrose (a mixture of 40% L-threose and 45% l-erythrose) with both the pure aldose reductase and crude lens extracts followed by the subsequent identification of the [1-14C]l-threitol formed by thin layer chromatography.l-Threose degrades very slowly in 0·1 M phosphate buffer at pH 7·0, but the addition of a four-fold excess of Nα-acetyl-l-lysine accelerated the rate of disappearance of threose 30-fold, indicating a rapid glycation reaction. When [1-14C]L-tetrose was incubated with a complete bovine lens homogenate, a linear incorporation into protein was observed over a 24 hr period. Increasing levels of lens extract exhibited increasing incorporation into protein. These data confirm a rapid reactivity of l-threose with lens protein and argue that glyeation would occur in vivo in spite of the presence of aldose redactuse.

Ascorbic Acid: A Jaffé Interference

Abstract The effects of ascorbate, the interference of the Jaffé reaction was individually studied by polarography, spectrophotometry, and thin-layer chromatography. Ascorbate was incubated in 28.4 mmol dm−3 picrate blank solution in 0.51 mol dm−3 NaOH at 25.00 ± 0.02 °C and the reactivity of test solution containing ascorbate : picrate was investigated. Picramic acid formed in all ascorbate: 28.4 mmol dm−3 picrate test solutions which explained the observed positive interference of ascorbic acid. No fluorescent product was formed in ascorbate : picrate test solutions. The reactivity of ascorbate : picrate test solutions confirmed that ascorbate was a powerful reducing agent. 2-Furaldehyde which has been listed as one of the degradation products of ascorbic acid, is not identified under the experimental conditions.

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.

Organogenesis in tissue culture of Solanum melongena cv. Florida Market

Cell suspension cultures were initiated from pith callus of eggplant, Solanum melongena cv. Florida Market on Murashige and Skoog (MS) medium supplemented with 13.5 μM 2,4-dichlorophenoxyacetic acid (2,4-D). The effects of mineral salts (MgSO 4, KNO 3, CaCl 2), sucrose and 2,4-D were studied on aggregate formation in suspension cultures. Aggregates from a cell suspension when cultured on an MS agar medium supplemented with various concentrations and combinations of indole-3-acetic acid (IAA) and γ,γ-isopentenyl adenine (2iP) differentiated into green nodules, but they failed to develop into organized shoots on the same medium. Upon transfer of these green nodules to MS medium supplemented with 0.1 μM ascorbic acid (autoclaved with the medium) alone or in combination with 49 μM 2iP, developed further into organized leafy shoots. This suggests that some degradation product of ascorbic acid might be responsible for inducing leafy shoots. Based on leaf morphology and chromosome analysis, regenerated plants were identified as tetraploids.

Ascorbic acid and fat content in the red and white muscle of carp, catla catla

1. 1. Ascorbic acid, the degradation products of ascorbic acid and total fat content were analysed in the red and white muscles of lateral musculature of riverine major carp Catla catla. 2. 2. The white muscles are characterized by low fat, high iodine number and high water content. 3. 3. The white muscle contain 2·5-3 times more ascorbic acid; about twelve times less dehydroascorbic acid and one-two times less diketogulonic acid than the red muscles. 4. 4. Post-mortem changes and cold storage of these muscle altered the relative proportions of the above substance in varying amounts. 5. 5. The data on the relative ratios of ascorbic acid and its metabolites, as well as ascorbic acid oxidase activity, suggested that ascorbic acid oxidation is higher in red muscle than in white muscle.

Ascorbic acid and copper in linoleate oxidation. II. Ascorbic acid and copper as oxidation catalysts

Both ascorbic acid and copper were strong prooxidants in the oxidation of linoleate in a buffered (pH 7.0) aqueous dispersion at 37 degrees C. Minimum concentrations at which catalytic activity was detected were 1.3 x 10(-7) m for copper and 1.8 x 10(-6) m for ascorbic acid. For concentrations up to 10(-3) m, the increase in rate of oxidation with increase in concentration of catalyst was greater for ascorbic acid than for copper. Ascorbic acid had maximum catalytic activity at 2.0 x 10(-3) m, but was still prooxidant at the highest concentration tested (5.0 x 10(-2) m). Dehydroascorbic acid was a weaker prooxidant than ascorbic acid. Further degradation products of ascorbic acid were not prooxidant. In early stages of the oxidation autocatalytic behavior was observed with copper, but not with ascorbic acid. Ascorbic acid functioned as a true catalyst, i.e., it accelerated the reaction but it was not oxidized simultaneously with the linoleate. It is proposed that the dehydroascorbic acid radical initiates the linoleate oxidation reaction.

Thin-layer chromatographic separation of the oxidative degradation products of ascorbic acid

Thin-layer chromatographic separation of the oxidative degradation products of ascorbic acid

Determination of Degradation Products of Ascorbic Acid

Summary The 2,4-dinitrophenylhydrazine test for ascorbic acid was used to determine both ascorbic and gulonic acid in milk. Data are presented in support of the validity of the test and simplification of procedure. Comparisons are also made with the 2,6-dichlorophenolindophenol reduction procedure. Interpretation of the observed phenomena is made in view of other known facts found in the literature. One- to two-day-old raw milk was found to contain small quantities of gulonic acid. Immediately following pasteurization, the gulonic acid content was also found to be low, but upon storage at 40° F. it increased considerably. Analysis of nonfat dry milk failed to reveal any gulonic acid, regardless of source of the powder, and only questionable amounts were found in evaporated milk. Temperature of storage had a decided effect on the decomposition of dehydroascorbic acid and the rate of oxidation of the resulting gulonic acid in sterile milk. The oxidation of gulonic acid was generally found to proceed rapidly at elevated temperatures. Evidence is presented that exposure to sunlight and copper catalyzed the oxidation of gulonic acid, but not nearly to the same extent as elevated temperatures. The rate of formation of gulonic acid under these conditions was greater than its oxidation.