On the Stability of Vitamin C Radicals

1986 ◽  
Vol 41 (11) ◽  
pp. 1315-1318 ◽  
Author(s):  
M. Eckert-Maksić ◽  
P. Bischof ◽  
Z. B. Maksić
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Energy Partitioning ◽  
Mndo Method ◽  
Biochemical Processes ◽  
Stable Species ◽  
The Stability ◽  
Semiempirical Mndo ◽  
Partitioning Technique

Stability of vitamin C (ascorbic acid - AA) radicals is considered by the semiempirical MNDO method. It is found that AA⨪ is thermodynamically the most stable species. Interestingly, the AA⨪ radical is more stable than the parent AA. This finding is of great importance in view of omnipresence and versatility of the vitamin C in biochemical processes. The origin of the pronounced stability of AA⨪ is elucidated by a particular form of the energy partitioning technique.

On the Structure of Lead(II) Complexes in Aqueous Solutions. I. Trinuclear Clusters

1995 ◽  
Vol 60 (4) ◽  
pp. 527-536 ◽  
Author(s):  
Martin Breza ◽  
Alena Manová
Keyword(s):  
Quantum Chemistry ◽  
Aqueous Solutions ◽  
Electronic Structures ◽  
Mndo Method ◽  
Model Systems ◽  
Trinuclear Clusters ◽  
The Stability ◽  
Semiempirical Mndo

Using semiempirical MNDO method of quantum chemistry the optimal geometries and corresponding electronic structures of [Pb3(OH)n]6-n model systems as well as of their hydrated [Pb3(OH)n(H2O)8-n]6-n analogues (n = 4, 5) are investigated. The most stable trinuclear lead(II) complexes present in aqueous solutions correspond to cyclo-(μ3-OH)(μ2-OH)3Pb32+, Pb(μ-OH)2Pb(μ-OH)2Pb2+, cyclo-(μ3-OH)2(μ2-OH)3Pb3+, Pb(OH)(μ-OH)2Pb(μ-OH)Pb(OH)+ and Pb(OH)(μ-OH)2Pb(μ-OH)2Pb+ systems. The key role of OH bridges (by vanishing direct Pb-Pb bonds) on the stability of individual isomers is discussed.

scholarly journals ELECTROCHEMICAL EVALUATION OF THE STABILITY OF ASCORBIC ACID IN WHEY FROM CHEESE AND RICOTTA

2017 ◽  
Vol 14 (27) ◽  
pp. 51-55
Author(s):  
Lucélia HOEHNE ◽  
Adriano GENNARI ◽  
Eduardo Miranda ETHUR ◽  
Maurício HILGEMANN ◽  
Claucia Fernanda Volken SOUZA ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Cyclic Voltammetry ◽  
Vitamin C ◽  
Antioxidant Capacity ◽  
Electrochemical Techniques ◽  
Factors Affecting ◽  
Oxidative Reactions ◽  
Antioxidant Evaluation ◽  
The Stability ◽  
Electrochemical Evaluation

Ascorbic acid has aroused particular interest due to its antioxidant capacity, which can prevent oxidative reactions. Cyclic voltammetry stands out as one of the main electrochemical techniques for antioxidant evaluation. The cheese and ricotta whey are subproducts of the dairy, and have several components that allow its use in various foods. The enrichment of subproducts with essential substances in food may make its use even more attractive by industries. Therefore, the aim of this study was to evaluate the stability of ascorbic acid in cheese and ricotta whey using cyclic voltammetry. For this, the cheese and ricotta whey were collected from a dairy industry of the Vale do Taquari-RS and were fortified with ascorbic acid and its stability was evaluated according to the electrochemical profiles of the samples. With the data obtained, it was concluded that one of the factors affecting directly the stability of ascorbic acid was the pH, but more studies are needed to evaluate other interfering stability of vitamin C.

Structural and Morphological Characteristics of Hybrid Nanomaterials Type Ascorbic Acid-hydrotalcite Used for Stimulating Salivary Secretion

2018 ◽  
Vol 69 (5) ◽  
pp. 1244-1246
Author(s):  
Georgeta Zegan ◽  
Loredana Golovcencu ◽  
Eduard Radu Cernei ◽  
Elena Mihaela Carausu ◽  
Daniela Anistoroaei
Keyword(s):  
Drug Delivery ◽  
Ascorbic Acid ◽  
Vitamin C ◽  
Morphological Analysis ◽  
Interlayer Space ◽  
Morphological Characteristics ◽  
Salivary Secretion ◽  
Morphological Characterization ◽  
Hybrid Nanomaterial ◽  
The Stability

A new hybrid nanomaterial type vitamin C/ZnAl-hydrotalcite, acting as drug delivery system for ascorbic acid, was developed in order to use it for stimulating salivary secretion. The synthesis of this nanomaterial was achieved using a simple coprecipitation method for intercalation of ascorbate anions in the ZnAl-hydrotalcite gallery. The stability of vitamin C was significantly increased after its incorporation into the interlayer space. Structural and morphological characterization techniques revealed an alteration of the pristine nanomaterial type ZnAl-hydrotalcite when vitamin C was loaded in its matrix. Structural and morphological analysis showed that ascorbate anions were intercalated in the interlayer of ZnAl-hydrotalcite having no effect on the hydroxide lattice of hydrotalcite, so this new nanomaterial can be used for the intended purpose.

scholarly journals Strawberry Puree Functionalized with Natural Hydroxytyrosol: Effects on Vitamin C and Antioxidant Activity

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5829
Author(s):  
Alejandra Bermúdez-Oria ◽  
Yougourthane Bouchal ◽  
África Fernández-Prior ◽  
Blanca Vioque ◽  
Juan Fernández-Bolaños
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Vitamin C ◽  
Functional Food ◽  
Dehydroascorbic Acid ◽  
Model System ◽  
Human Diet ◽  
Low Concentrations ◽  
High Concentrations ◽  
The Stability

The natural antioxidant hydroxytyrosol (HT) was used to functionalize a strawberry puree. The effect of the antioxidant on the stability of the two bioactive forms of vitamin C (ascorbic acid-AA and dehydroascorbic acid-DHAA) in strawberry puree stored at 4 °C, compared with the effect on a model system of AA in water, was investigated. In the absence of HT, the concentration of vitamin C in strawberry puree decreased but not in the model system. Low concentrations of HT in strawberry puree (0.05 and 0.1 mg HT/g puree) stabilized vitamin C and improved its antioxidant activity. However, at high concentrations of HT (from 0.5 mg HT/g puree), although the antioxidant activity improved, degradation of vitamin C occurred. Therefore, the concentration of HT used to obtain a functionalized strawberry puree it is very important. An adequate concentration increases the antioxidant activity and protects vitamin C from degradation, developing a functional food. However, an inadequate concentration of HT affects the vitamin C content, which is essential for the human diet because it cannot be biosynthetized by the organism.

scholarly journals Studies on the Stability of Vitamin C at Elevated Concentrations in Canned Tropical Fruit Juices and Nectars

1969 ◽  
Vol 48 (4) ◽  
pp. 327-336
Author(s):  
Abdul R. Rahman ◽  
J. Anziani ◽  
E. Díaz Negrón
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Room Temperature ◽  
Fruit Juices ◽  
The Other ◽  
Tropical Fruit ◽  
The Stability ◽  
Different Levels

Studies were conducted to determine the stability of vitamin C at elevated concentrations in canned tropical fruit juices and nectars. Canned guava nectar, as well as juices of orange, tomato, and pineapple were fortified with ascorbic acid at seven different levels ranging from the original content present in the samples to about 300 mg. per 100 ml. Half of the samples were stored at room temperature and the other similar half at 100°F. for a period of 6 months. The results indicated that the losses of vitamin C were higher in the samples stored at 100°F. than in those stored at room temperature—regardless of the level of concentration. However, in the guava nectar the percentage of vitamin C destruction was relatively higher at lower concentrations and lower at higher concentrations at both temperatures. No such pattern could be observed in the juices. But the losses of vitamin C in the juices at all levels of concentration ranged below 30 percent at room temperature and below 40 percent at 100°F. This is relatively less than the losses that occurred in the guava nectar.

scholarly journals The effect of selected substances on the stability of standard solutions in voltammetric analysis of ascorbic acid in fruit juices

2019 ◽  
Vol 17 (1) ◽  
pp. 655-662
Author(s):  
Radosław Kowalski ◽  
Artur Mazurek ◽  
Urszula Pankiewicz ◽  
Marzena Włodarczyk-Stasiak ◽  
Monika Sujka ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Room Temperature ◽  
Nutritive Value ◽  
Fruit Juices ◽  
Optimum Concentration ◽  
Voltammetric Analysis ◽  
The Stability ◽  
Standard Solutions

AbstractThe objective of the study was to identify suitable additives stabilizing standard solutions of ascorbic acid (AA) that would not cause interference in the analytical process with the use of voltammetry in the determination of the AA content in food products. In addition, the effect of various conditions of storage of selected fruit juices and drinks on the concentration of vitamin C was studied. The study demonstrated that AA degradation was inhibited the most effectively by tartaric acid and its optimum concentration was set to 200 mg L-1. Analysis of selected fruit juices stored in various temperature conditions confirmed that an elevation of temperature and extension of the time of storage caused a decrease in the content of vitamin C in the analyzed samples, while closing the packages caused a limitation of the changes in concentration of this vitamin. On the basis of literature data and of the results obtained in the present study it can be concluded that fruit juices should be stored at a temperature lower than room temperature to retain their nutritive value.

scholarly journals Factors Affecting the Stability of Vitamin C in Tropical Fruit Juices and Nectars

1969 ◽  
Vol 48 (1) ◽  
pp. 1-12
Author(s):  
Abdul R. Rahman ◽  
J. Anziani ◽  
J. R. Cruz-Cay
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Fruit Juices ◽  
Tropical Fruit ◽  
Factors Affecting ◽  
Synthetic Vitamin ◽  
The Stability ◽  
And Storage

Studies were conducted on the effect of certain factors such as temperature, pH, degrees Brix, concentration of vitamin C, and storage in sealed as well as in open containers, on the stability of vitamin C in tropical fruit juices and nectars. They were fortified with different quantities of synthetic vitamin C (1-ascorbic acid) ranging between 10 and 4,000 mg. per 100 ml.

Ascorbic acid-independent synthesis of collagen in mice

2006 ◽  
Vol 290 (6) ◽  
pp. E1131-E1139 ◽  
Author(s):  
Kelly K. Parsons ◽  
Nobuyo Maeda ◽  
Mitsuo Yamauchi ◽  
Albert J. Banes ◽  
Beverly H. Koller
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Critical Role ◽  
Model Organism ◽  
Deficient Diet ◽  
Biochemical Processes ◽  
Ascorbic Acid Biosynthesis ◽  
Independent Synthesis ◽  
Proline Hydroxylation

The mouse has become the most important model organism for the study of human physiology and disease. However, until the recent generation of mice lacking the enzyme gulanolactone oxidase (Gulo), the final enzyme in the ascorbic acid biosynthesis pathway, examination of the role of ascorbic acid in various biochemical processes using this model organism has not been possible. In the mouse, similar to most mammals but unlike humans who carry a mutant copy of this gene, Gulo produces ascorbic acid from glucose. We report here that, although ascorbic acid is essential for survival, its absence does not lead to measurable changes in proline hydroxylation. Vitamin C deficiency had no significant effect on the hydroxylation of proline and collagen production during tumor growth or in angiogenesis associated with tumor or mammary gland growth. This suggests that factors other than ascorbic acid can support proline hydroxylation and collagen synthesis in vivo. Furthermore, the failure of Gulo−/− mice to thrive on a vitamin C-deficient diet therefore suggests that ascorbic acid plays a critical role in survival other than the maintenance of the vasculature.

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

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