Vit. C what is it?!
Question:
Vit. C what is it?
Ascorbic & Ascorbate ascid or vit C is present in citrus fruits; sour fruits. Green Mangos dont have them, but pepper has high Vit C. why? what is Vit C anyway?
Answers:
Vitamin C or L-ascorbate is an essential nutrient for higher primates, and a small number of other species. The presence of ascorbate is required for a range of essential metabolic reactions in all animals and in plants and is made internally by almost all organisms, humans being one notable exception. It is widely known as the vitamin whose deficiency causes scurvy in humans.
The pharmacophore of vitamin C is the ascorbate ion. In living organisms, ascorbate is an antioxidant, as it protects the body against oxidative stress, and is a cofactor in several vital enzymatic reactions.
As a nutrient, its uses and the daily requirement are matters of on-going debate. As a food additive, vitamin C is used as an antioxidant preservative and an acidity regulator. Several E numbers account for the vitamin, depending on its chemical structure: E300 as ascorbic acid, E301 as the salt sodium ascorbate, E302 as the salt calcium ascorbate, E303 as the salt potassium ascorbate, E304 for the esters ascorbyl palmitate and ascorbyl stearate, and E315 for the stereoisomer erythorbic acid.
Vitamin C is purely the L-enantiomer of ascorbate; the opposite D-enantiomer has no physiological significance. Both forms are mirror images of the same molecular structure. When L-ascorbate, which is a strong reducing agent, carries out its reducing function, it is converted to its oxidized form, L-dehydroascorbate. L-dehydroscorbate can then be reduced back to the active L-ascorbate form in the body by enzymes and glutathione.
L-ascorbate is a weak sugar acid structurally related to glucose which naturally occurs either attached to a hydrogen ion, forming ascorbic acid, or to a metal ion, forming a mineral ascorbate.
In humans, vitamin C is a highly effective antioxidant, acting to lessen oxidative stress, a substrate for ascorbate peroxidase, as well as an enzyme cofactor for the biosynthesis of many important biochemicals. Vitamin C acts as an electron donor for eight different enzymes:
* Three participate in collagen hydroxylation. These reactions add hydroxyl groups to the amino acids proline or lysine in the collagen molecule (via prolyl hydroxylase and lysyl hydroxylase), thereby allowing the collagen molecule to assume its triple helix structure and making vitamin C essential to the development and maintenance of scar tissue, blood vessels, and cartilage.
* Two are necessary for synthesis of carnitine. Carnitine is essential for the transport of fatty acids into mitochondria for ATP generation.
* The remaining three have the following functions:
o dopamine beta hydroxylase participates in the biosynthesis of norepinephrine from dopamine.
o another enzyme adds amide groups to peptide hormones, greatly increasing their stability.
o one modulates tyrosine metabolism.
Biological tissues that accumulate over 100 times the level in blood plasma of vitamin C are the adrenal glands, pituitary, thymus, corpus luteum, and retina. Those with 10 to 50 times the concentration present in blood plasma include the brain, spleen, lung, testicle, lymph nodes, liver, thyroid, small intestinal mucosa, leukocytes, pancreas, kidney and salivary glands.
While plants are generally a good source of vitamin C, the amount in foods of plant origin depends on: the precise variety of the plant, the soil condition, the climate in which it grew, the length of time since it was picked, the storage conditions, and the method of preparation.
The following table is approximate and shows the relative abundance in different raw plant sources. The amount is given in milligrams per 100 grams of fruit or vegetable and is a rounded average from multiple authoritative sources:
Plant source Amount
(mg / 100g)
Kakadu plum 3150
Camu Camu 2800
Rose hip 2000
Acerola 1600
Amla 720
Jujube 500
Baobab 400
Blackcurrant 200
Red pepper 190
Parsley 130
Seabuckthorn 120
Guava 100
Kiwifruit 90
Broccoli 90
Loganberry 80
Redcurrant 80
Brussels sprouts 80
Lychee 70
Cloudberry 60
Persimmon 60
Plant source Amount
(mg / 100g)
Papaya 60
Strawberry 60
Orange 50
Lemon 40
Melon, cantaloupe 40
Cauliflower 40
Grapefruit 30
Raspberry 30
Tangerine 30
Mandarin orange 30
Passion fruit 30
Spinach 30
Cabbage raw green 30
Lime 20
Mango 20
Potato 20
Melon, honeydew 20
Mango 16
Tomato 10
Blueberry 10
Pineapple 10
Plant source Amount
(mg / 100g)
Pawpaw 10
Grape 10
Apricot 10
Plum 10
Watermelon 10
Banana 9
Carrot 9
Avocado 8
Crabapple 8
Peach 7
Apple 6
Blackberry 6
Beetroot 5
Pear 4
Lettuce 4
Cucumber 3
Eggplant 2
Fig 2
Bilberry 1
Horned melon 0.5
Medlar 0.3