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)