1- Water-soluble vitamins:
A- group transfer Coenzymes:
* Pyridoxal phosphate (vitamin B6) or pyridoxine or pyridoxamine
– Spoke at the transamination reactions and decarboxylation of amino acids (amino acid catabolism).
– Deficiency -> peripheral neuropathy and convulsion. Depression; nervousness
* Thiamin pyrophosphate or TPP (vitamin B)
– Spoke mainly in carbohydrate metabolism (carboxylation oxidative keto acid and pyruvic acid). It is necessary for proper nerve transmission.
– Deficiency -> Wernicke Korsakov syndrome; beriberi
* Coenzyme A (vitamin B5 or pantothenic acid)
Especially involved in the biosynthesis and? -oxidation Of fatty acids
* Coenzyme transfer carbonaceous groups (COO)
– Folic acid and vitamin B12 (cobalamin), which are also involved in DNA synthesis.
– Biotin (vitamin H)
B- Coenzymes redox:
* Vitamin PP (nicotinic acid) or vitamin B3 or niacin.
– It gives two coenzymes: NAD and NADP
– Deficiency -> Pellagra (three D: dermatitis, diarrhea and dementia).
* Vitamin B2 (riboflavin)
– Two coenzymes: FMN, FAD
– Deficiency -> cheilitis, glossitis.
* Vitamin C (ascorbic acid) is a coenzyme for oxidation-reduction reactions (hydroxylation of proline and lysine during collagen maturation, the synthesis of carnitine, the metabolism of tyrosine and catecholamine synthesis ).
It is also an antioxidant and a facilitating iron absorption. Vitamin C deficiency is responsible for capillary fragility (bruising, petechiae); of immunosuppression; scurvy, delayed wound healing, osteoporosis, bleeding and anemia.Dental disorders.
2- Fat-soluble vitamins:
A- Vitamin A (retinol):
– The 11-cis-retinal is the prosthetic group of rhodopsin (visual pigment of the retina)
– Beta-carotene is an antioxidant
– The rétinylphosphate serves as a donor / acceptor mannose units in the synthesis of glycoproteins
– Retinol and retinoic acid regulate growth of tissue differentiation
B- Vitamin D (cholecalciferol):
– The main source is the skin (UV)
– It is hydroxylated in the liver and then in the kidney to give the active form 1,25 (OH) D3
– Its main function is to increase the intestinal absorption of calcium
– Other: mineralization and bone resorption
– Glucocorticoids inhibit vitamin D
C- Vitamin E (tocopherol):
– Protection of the membranes and proteins against free radicals (antioxidants)
– The reduced vitamin C regenerates tocopherol
– Its sources: vegetables with green leaves and sprouts of grain.
– It plays a role in fertility (fertility vitamin)
D- Deficiencies & intoxication:
* Vitamin A: Night blindness (night blindness); xerophthalmia; hyperkeratosis of the skin
* Vitamin D: Rickets (in children); osteomalacia (in adults)
* Vitamin E: neuromuculaires disorders; myopathies with creatinuria; hemolytic anemia, retinal degeneration;Sterility (testicular atrophy).
* The vitamin K is needed in the post-translational carboxylation of glutamyl residues calciprotéines including blood coagulation factors VII, IX and X
NB: the intestinal flora provides vitamin K and pantothenic acid (vitamin B5)