Theoretical studies of l-ascorbic acid (vitamin C) and selected oxidised, anionic and free-radical forms

2009 ◽  
Vol 910 (1-3) ◽  
pp. 61-68 ◽  
Author(s):  
Damian M. Bailey ◽  
William O. George ◽  
Mariusz Gutowski
Keyword(s):  
Ascorbic Acid ◽  
Free Radical ◽  
Vitamin C ◽  
Theoretical Studies

scholarly journals Pengaruh Perendaman Asam Askorbat dan Natrium Bisulfit pada Dua Varietas Bawang Merah (Allium ascalonicum L.) terhadap Sifat Fisikokimia dan Organoleptik Tepungnya (Effect of Ascorbic Acid Soaking and Sodium Bisulphite on Two Varieties of Shallot (Allium ascalonicum L.) on Physical and Organoleptical Character of Shallot Powder)

2016 ◽  
Vol 36 (03) ◽  
pp. 270 ◽  
Author(s):  
Ermi Sukasih ◽  
Setyadjit Setyadjit
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Free Radical ◽  
Vitamin C ◽  
Moisture Content ◽  
Acid Treatment ◽  
Total Phenolics ◽  
Ash Content ◽  
Sodium Bisulphite ◽  
Significant Data

Recently, there is an increase of shallot production in Indonesia. One alternative of flesh shallot processing is shallot powder making which can be used during the off season. The aim of the study was to observe the effect of immersion in ascorbic acid and sodium bisulphite on two varieties of shallot on physical and organoleptic characters of shallot powder. Drying was done using tray dryer. Experimental design used was factorial completely randomised design. The first factor was the type of immersion agent and duration time and the second factor was shallot varieties (Bima and Sembrani). Statistical mean test was using Tukey Honestly Significant (HSD). The result showed that the treatments significantly affected parameters such as moisture content, ascorbic acid, total phenol, anthocyanin, and antioxidant activity, free radical inhibition and color (chroma). From ranking test the best treatment was Bima variety with 0.2% ascorbic acid treatment for 30 min. Characteristic of the best treatment was with moisture content 4.03±0.79 % (w/w), ash content 4.45±0.13 % (w/w), fat content 1.24±0.64 % (w/w), protein content 15.56±0.28 % (w/w), 61.94±4.11 mg/100g, total phenolics 256.39±16.26 ppm, anthocyanins 50.70±2.31 ppm, quercetin 2612.40±408.94 ppm, antioxidant activity ekuivalent, 225.72±4.0 µg/mL, inhibition free radical 83.05±1.69 %, 85.02 hue value (yellowish red) and aroma score 3.2 (strong), brightness score 4.2 (bright) and color 1.25 (pale red). ABSTRAKKenaikan cukup signifikan pada produksi bawang merah terjadi di Indonesia. Salah satu alternatif pengolahan bawang merah segar adalah melalui pengolahan menjadi tepung sehingga tetap tersedia saat langka dan harganya tinggi. Penelitian ini bertujuan untuk melihat pengaruh perendaman asam askorbat dan natrium bisulfit pada dua varietas bawang merah terhadap sifat fisikokimia dan organoleptik tepung yang dihasilkan. Pengeringan dilakukan dengan tray dryer. Percobaan menggunakan rancangan acak lengkap faktorial, faktor pertama jenis bahan  dan lama perendaman dan faktor kedua adalah varietas bawang merah (Bima dan Sembrani). Analisis statistik menggunakan metode Tukey Honestly Significant Data (HSD). Hasil penelitian menunjukkan bahwa perlakuan berpengaruh nyata terhadap parameter kadar air, vitamin C, total fenolik, antosianin, aktivitas antioksidan, inhibisi radikal bebas dan warna (chroma). Berdasarkan uji peringkat diperoleh perlakuan terbaik adalah tepung bawang merah dari varietas Bima dengan perlakuan perendaman asam askorbat 0,2 % selama 30 menit. Karakteristik dari tepung bawang ini memiliki  kadar air 4,03 ± 0,79 % (bb), kadar abu 4,45 ± 0,13 % (bb), lemak 1,24 ± 0,64 % (bb) protein 15,56 ± 0,28 % (bb), vitamin C 61,94 ± 4,11 mg/100 g, total fenol 256,39 ± 16,26 ppm, antosianin 50,70 ± 2,31 ppm, kuersetin 2612,40 ± 408,94 ppm, aktivitas antioksidan ekuivalen 225,72 ± 4,07 µg/mL, inhibisi radikal bebas 83,05 ± 1,69 %, nilai oHue 85,02 (kuning kemerahan) dan skor aroma 3,2 (kuat), skor kecerahan 4,2 (terang) dan skor warna 1,25 (merah pucat).   Kata kunci: Asam askorbat; tepung bawang merah; perendaman; natrium bisulfit

scholarly journals Trying to Solve the Puzzle of the Interaction of Ascorbic Acid and Iron: Redox, Chelation and Therapeutic Implications

Medicines ◽  
2020 ◽  
Vol 7 (8) ◽  
pp. 45
Author(s):  
George J. Kontoghiorghes ◽  
Annita Kolnagou ◽  
Christina N. Kontoghiorghe ◽  
Loukia Mourouzidis ◽  
Viktor A. Timoshnikov ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Free Radical ◽  
Vitamin C ◽  
Metal Binding ◽  
Binding Capacity ◽  
Pharmaceutical Preparations ◽  
Normal Growth ◽  
Iron Complex ◽  
Main Function ◽  
Therapeutic Implications

Iron and ascorbic acid (vitamin C) are essential nutrients for the normal growth and development of humans, and their deficiency can result in serious diseases. Their interaction is of nutritional, physiological, pharmacological and toxicological interest, with major implications in health and disease. Millions of people are using pharmaceutical and nutraceutical preparations of these two nutrients, including ferrous ascorbate for the treatment of iron deficiency anaemia and ascorbate combination with deferoxamine for increasing iron excretion in iron overload. The main function and use of vitamin C is its antioxidant activity against reactive oxygen species, which are implicated in many diseases of free radical pathology, including biomolecular-, cellular- and tissue damage-related diseases, as well as cancer and ageing. Ascorbic acid and its metabolites, including the ascorbate anion and oxalate, have metal binding capacity and bind iron, copper and other metals. The biological roles of ascorbate as a vitamin are affected by metal complexation, in particular following binding with iron and copper. Ascorbate forms a complex with Fe3+ followed by reduction to Fe2+, which may potentiate free radical production. The biological and clinical activities of iron, ascorbate and the ascorbate–iron complex can also be affected by many nutrients and pharmaceutical preparations. Optimal therapeutic strategies of improved efficacy and lower toxicity could be designed for the use of ascorbate, iron and the iron–ascorbate complex in different clinical conditions based on their absorption, distribution, metabolism, excretion, toxicity (ADMET), pharmacokinetic, redox and other properties. Similar strategies could also be designed in relation to their interactions with food components and pharmaceuticals, as well as in relation to other aspects concerning personalized medicine.

scholarly journals Essential Features for Antioxidant Capacity of Ascorbic Acid (Vitamin C)

2021 ◽  
Author(s):  
Kelton L. B. Santos ◽  
Vitor A. N. Bragança ◽  
Larysse V. Pacheco ◽  
Sirlene S. B. Ota ◽  
Christiane P. O. Aguiar ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Antioxidant Capacity ◽  
Fruits And Vegetables ◽  
Functional Group ◽  
Cellular Level ◽  
Theoretical Chemistry ◽  
Molecular Characteristics ◽  
Theoretical Studies ◽  
Citrus Species

Abstract Vitamin C or ascorbic acid is an indispensable micronutrient for human health found principally on citrus species such as lemon and orange fruits, and vegetables. It was involved in the production of proteins such as collagen. Its biochemical mechanism is related to its antioxidant capacity, however its function at the cellular level is still unclear. Several theoretical studies about antioxidant and redox mechanisms for ascorbic acid were suggested, however no derivative was proposed. Thereby, an electronic study of antioxidant capacity for ascorbic acid derivatives was performed using theoretical chemistry at the DFT/ B3LYP/6-311++(2d,2p) level of theory. Simplified derivatives show that enol hydroxyls are more important than any other functional group. The vicinal enolic hydroxyl on β-position are more important for antioxidant capacity of ascorbic than hydroxyl on α-position. According to our molecular modifications, the keto-alkene compound showed the best values when compared to ascorbic acid in some molecular characteristics. New promising structural derivatives related to ascorbic acid can be developed in the future.

Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode

1979 ◽  
Vol 44 (11) ◽  
pp. 3395-3404 ◽  
Author(s):  
Pavel Posádka ◽  
Lumír Macholán
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Oxygen Electrode ◽  
Ascorbate Oxidase ◽  
Current Response ◽  
Reaction Conditions ◽  
Long Term Storage ◽  
Oxidase Enzyme ◽  
Optimal Reaction

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.

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