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Submitted: April ninth 2018Reviewed: October 1st 2018Published: December fifth 2018
Dwelling > Books > Vitamin C – an Replace on Present Makes use of and Features
Summary
chapter and creator information
1. Introduction
In 1970, Pauling [1] acknowledged that “Ascorbic acid is an essential food for human beings. People who receive no ascorbic acid (vitamin C) become sick and die.”
2. Vitamin C supply
Vitamin C is produced solely in non-humans as primate species, guinea pigs, fishes and birds [2]. Though many of the animals have the power to synthesis their wants of vitamin C, people endure from mutation within the DNA coding of gulonolactone oxidase which is the principle enzyme chargeable for ascorbic acid synthesis [3]. As a consequence of this mutation, the exterior complement of vitamin C turns into a should [4].
The principle supply of vitamin C for human beings is especially present in fruit and veggies. Citrus fruits and different varieties are significantly wealthy sources of vitamin C as; cantaloupe, water melon, berries, pineapple, strawberries, cherries, kiwi fruits, mangoes, and tomatoes. Moreover, greens are thought-about the principle supply of vitamin C resulting from its greater content material and availability for longer interval all year long resembling cabbage, broccoli, Brussels sprouts, bean sprouts, cauliflower, mustard greens, peppers, peas and potatoes [5].
3. Chemical construction of ascorbic acid – “vitamin c ph”
Though vitamin C is the generic title of l-ascorbic acid, it has many different chemical names as ascorbate and antiscorbutic vitamin. l-Ascorbic acid molecule is shaped of asymmetrical six-carbon atoms (C6H8O6) which is structurally associated to glucose (Determine 1) [7, 8]. Its molecular weight is 176 with a melting level of 190–192°C (with decomposition) and exhibits a density of roughly 1.65 g/cm3. l-Ascorbic acid is freely soluble in water (300 g/L at 20°C), troublesome in alcohol (20 g/L at 20°C) and insoluble in chloroform, ether and benzene. It kinds a transparent colorless to barely yellow answer. It has two pKa values: 4.2 and 11.6. The pH of a 5% (w/v) answer in water is 2.2–2.5 [9].
The chemical construction of ascorbic acid determines its bodily and chemical properties. It’s a weak, water soluble, unstable natural acid which might be simply oxidized or destroyed in mild, cardio situation (oxygen), excessive temperature, alkali, humidity, copper and heavy metals. Ascorbic acid is normally discovered within the type of white or barely yellowish crystalline powder. Its crystalline type is chemically secure in dryness. Nevertheless L-ascorbic acid is extremely soluble in water, it exhibits nice issue to be soluble in alcohol, chloroform, ether and benzene. In water, it kinds clear colorless barely yellow answer which is quickly oxidized [8, 10].
There are various derivatives of ascorbic acid as sodium l-ascorbate (sodium ascorbate), calcium l-ascorbate (calcium ascorbate), zinc-ascorbate, 6-palmityl-l-ascorbic acid (ascorbyl palmitate) and ascorbyl monophosphate calcium sodium salt (sodium calcium ascorbyl phosphate) [128, 129].
Ascorbic acid is obtained from sodium ascorbate by cation alternate. Whereas sodium ascorbate outcomes from reacting methyl-d-sorbosonate (or ketogulonic acid methyl ester) with sodium carbonate. Calcium ascorbate is produced by the interplay of ascorbic acid with calcium carbonate in water and ethanol, which it’s then remoted and dried. Ascorbyl palmitate is ready by response of ascorbic acid with sulfuric acid adopted by esterification with palmitic acid. Sodium calcium ascorbyl phosphate resulted from the response of ascorbic acid (alone or together with sodium ascorbate) with calcium hydroxide and sodium trimetaphosphate. The earlier ascorbic acid derivatives have superior properties compared to ascorbic acid as the sunshine resistance, pores and skin irritation [128, 129].
4. Vitamin C metabolism
Vitamin C features rely primarily on its principal character as a lowering agent and the outcomes of its oxidation mechanisms both reversible or irreversible [130, 131]. These reactions rely solely on the pH adjustments and never on the presence of air or oxidizing brokers [132].
Ascorbic acid undergoes a 3-step oxidation course of. To start with, ascorbic acid can reversibly oxidize into dehydroascorbic acid on the publicity to copper, low alkaline media and warmth [11].
Dehydroascorbic acid is a really quick half-life (couple of minutes) product which might both reversibly or irreversibly oxidize within the tissues. In pH 4.0, odd temperatures and aqueous media, dehydroascorbic acid might be oxidized irreversibly into 2,3-diketo-l-glutonic acid (diketogulonic acid). Nevertheless, the dehydroascorbic acid oxidation begins in gentle acidic media (pH 4.0), it requires a impartial or alkaline media to progress extra quickly. The resultant diketogulonic acid is a stronger lowering agent, not diminished by glutathione or H2S and never an anti-ascorbutic agent. It was discovered that under pH 4.0, diketogulonic acid losses its lowering property. In acidic media and the presence of H2S, dehydroascorbic acid may also reversibly grow to be ascorbic acid. Ascorbic acid and dehydroascorbic acid have the identical anti-ascorbutic impact [133, 134].
The third oxidation product is l-threonic acid and oxalic acid which proceed solely in alkaline media (pH 7–9) [11]. All reversible adjustments might be achieved within the presence of H2S and glutathione in impartial or alkaline media. Typically, carbon dioxide could also be the results of vitamin C oxidation at excessive doses [132].
In human beings, ascorbic acid is reversibly oxidized into dehydroascorbic acid, which might be diminished again to ascorbic acid or hydrolyzed to diketogulonic acid after which oxidized into oxalic acid, threonic acid, xylose, xylonic acid and lyxonic acid. Additional oxidation (decomposition) could happen by the oxidizing brokers in meals. In keeping with the oxidation-reduction reactions, ascorbic acid is the diminished type of vitamin C whereas dehydroascorbic acid is the oxidized type of vitamin C. The l-isomer of ascorbic acid is the one lively type. Different isomers as d-ascorbic acid, d-isoascorbic acid and l-isoascorbic acid are current. These stereoisomers don’t have any impact within the therapy of scurvy [128, 129].
The absorbed and the unabsorbed types of ascorbic acid might be excreted in conjugated or non-conjugated sample. Ascorbic acid could endure restricted conjugation with sulfate to type ascorbate-2-sulphate, which is excreted within the urine. Unchanged ascorbic acid and its metabolites are excreted within the urine. Within the presence of intestinal flora, excessive doses of ascorbic acid (unabsorbed half) can oxidized into carbon dioxide which is the principle excretory mechanism of vitamin C in guinea pigs, rats and rabbits. There exists equilibrium between ascorbic acid and dehydroascorbic acid, depending on the redox standing of the cells [12].
5. Vitamin C bioavailability
The bioavailability is a measure of the effectivity of gastrointestinal tract absorption [13].