Grafting of methylmethacrylate on to the plant seed galactomannans using potassium persulphate/ascorbic acid redox pair

2006 ◽  
Vol 66 (11) ◽  
pp. 1306-1318 ◽  
Author(s):  
Vandana Singh ◽  
Ashutosh Tiwari ◽  
Pankaj Shukla ◽  
Shailendra Pratap Singh ◽  
Rashmi Sanghi
Keyword(s):  
Ascorbic Acid ◽  
Potassium Persulphate ◽  
Plant Seed ◽  
Redox Pair

scholarly journals [11C]Ascorbic and [11C]dehydroascorbic acid, an endogenous redox pair for sensing reactive oxygen species using positron emission tomography

2016 ◽  
Vol 52 (27) ◽  
pp. 4888-4890 ◽  
Author(s):  
V. N. Carroll ◽  
C. Truillet ◽  
B. Shen ◽  
R. R. Flavell ◽  
X. Shao ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Positron Emission Tomography ◽  
Ascorbic Acid ◽  
Reactive Oxygen ◽  
Dehydroascorbic Acid ◽  
Emission Tomography ◽  
Oxygen Species ◽  
Redox Pair ◽  
Positron Emission

We report the radiosynthesis of an endogenous redox pair, [11C]ascorbic acid and [11C]dehydroascorbic acid and their application to ROS sensing.

scholarly journals The research determines appropriate parameters in the synthesis process of syringic acid grafted chitooligosaccharides

2019 ◽  
Vol 22 (3) ◽  
pp. 317-323
Author(s):  
Hoai Van Bui ◽  
Nghiep Dai Ngo
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Pathogenic Bacteria ◽  
Syringic Acid ◽  
Synthesis Process ◽  
Mass Ratio ◽  
Synthesis Time ◽  
Redox Pair ◽  
Ft Ir ◽  
Grafting Degree

Introduction: The aim of this study is to determine appropriate parameters in the synthesis of syringic acid onto chitooligosaccharides (COSs) with an ascorbic acid/hydrogen peroxide redox pair in order to obtain the derivative with the highest grafting degree. Methods: In this study, syringic acid grafted COSs, catalysed by an ascorbic acid/hydrogen peroxide redox pair were investigated. The synthesis conditions were investigated, including the mass ratio between syringic acid and COSs, pH, temperature and synthesis time. Characteristics of the derivative were evaluated by Thin Layer Chromatography (TLC), Ultraviolet-Visible (UV-vis) and Fourier Transform Infrared (FT-IR) spectroscopy. The activities of COSs and derivative were evaluated by antimicrobial ability. Results: The results showed, that the best conditions for the synthesis were the mass ratio between syringic acid and COSs at 0.5:1, pH 5, temperature 27oC, for 6 hours with grafting degree at 32%. The TLC assay showed, that free ascorbic acid and syringic acid are not present in the product. The UV-vis and FT-IR data confirmed, that syringic acid was successfully conjugated onto COSs. Furthermore, the antibacterial assay showed that syringic acid grafted onto COSs had minimum inhibitory concentration against foodborne pathogenic bacteria at 1%. Conclusion: The syringic acid onto chitooligosaccharides were successfully synthesized by free radical mediated grafting method with an ascorbic acid/hydrogen peroxide redox pair. The grafting degree of syringic acid onto COSs was greatly affected by many factors, including COSs, syringic acid, pH, as well as temperature and time of reaction. Moreover, the new derivative showed enhanced antibacterial capabilities, as compare to free COSs.  

Modification of guar gum through grafting of 4-vinyl pyridine using potassium peroxymonosulphate/ascorbic acid redox pair

2007 ◽  
Vol 106 (2) ◽  
pp. 1353-1358 ◽  
Author(s):  
Abhishek Srivastava ◽  
Jasaswini Tripathy ◽  
Madan Mohan Mishra ◽  
Kunj Behari
Keyword(s):  
Ascorbic Acid ◽  
Guar Gum ◽  
Redox Pair ◽  
Vinyl Pyridine ◽  
Potassium Peroxymonosulphate

Ređuktone und Reduktonate, I Das Redoxpaar Dehydroascorbinsäure-Ascorbinsäure und ihre Anionen / Reductones and Reductonates, I The Redox Pair Dehydroascorbic Acid-Ascorbic Acid and Anions

1977 ◽  
Vol 32 (5) ◽  
pp. 562-568 ◽  
Author(s):  
Rudolf Matusch
Keyword(s):  
Aqueous Solution ◽  
Ascorbic Acid ◽  
Nmr Spectroscopy ◽  
Oxidation Rate ◽  
Lactone Ring ◽  
Dehydroascorbic Acid ◽  
Hydroxyl Group ◽  
Redox Pair ◽  
Measurable Amount ◽  
Dehydro Ascorbic Acid

On the basis of NMR spectroscopy (1H and 13C) it can be shown that in water, dimethylsulfoxide and p-dioxane only the tautomer 1 of L-ascorbic acid is found in a measurable amount. Upon formation of the mono-anion la deprotonation occurs on the hydroxyl group attached to C-3; in addition the hydroxyl group on C-2 is deprotonated in case of the di-anion 1b. Both anions do not open the lactone ring.After oxidation with iodine in aqueous solution only the dimer of dehydroascorbic acid is detected. This is hydrolized with a half-life of three hours to the monomeric dehydro ascorbic acid dihydrate 7. In dimethylsulfoxide the oxidation rate is decreased, and therefore the formation of the monomeric non-hydratized dehydroascorbic acid 10 can be monitored. This undergoes ringclosure relatively fast to give the half-ketal 13, the reaction of which via 14 leads to the optical active dimeric dehydroascorbic acid 6. The L-ascorbic acid acetonide 15 is oxidised by iodine to 16 which undergoes racemization via the enol 17 to give 18. This forms an equilibrium with compound 19.

Comparative Study of Ascorbic Acid Levels in Gastric Secretion, Blood, Urine and Saliva

1951 ◽  
Vol 18 (2) ◽  
pp. 224-229 ◽  
Author(s):  
Joseph T. Freeman ◽  
Roberta Hafkesbring
Keyword(s):  
Ascorbic Acid ◽  
Gastric Secretion ◽  
Comparative Study

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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