The physiological function of vitamin K

Is a fat-soluble vitamins. Because of its function to promote blood coagulation, it is also called coagulation vitamin. Common are vitamin K1 and K2. K1 is synthesized from plants such as alfalfa, spinach and other leafy plants; K2 synthesized by microorganisms. Human intestinal bacteria can also be synthesized vitamin K2. Modern synthetic vitamin K has been able to, such as vitamin K3, are commonly used in clinical. Vitamin K are 2 - methyl-1,4 - naphthoquinone derivatives. Vitamin K1 is a yellow oily, K2 is a light yellow crystal, are heat-resistant, but susceptible to ultraviolet radiation and the damage will be to dark to save. Synthetic K3 and K4 are water-soluble and can be used orally or by injection. The clinical use of anticoagulants pairs of coumarin, vitamin K and its chemical structure similar to confront the role of vitamin K can be used to combat thrombus formation. Of vitamin K and liver synthesis of four clotting factors (prothrombin, coagulation factor Ⅶ, Ⅸ and Ⅹ) is closely related to the absence of vitamin K1, then the liver synthesis of clotting factors for the above-mentioned four kinds of abnormal protein molecules, their catalytic role in blood clotting ability dropped significantly. Vitamin K is known to γ carboxylation reaction of glutamic acid cofactor. A lack of vitamin K clotting factors in the above mentioned γ-carboxylation can not be, in addition, these types of blood clotting factor reduction, there will be slow blood clotting and bleeding disorders. In addition, it is recognized that vitamin K dissolved in the lipid in the mitochondrial membrane plays a role in electron transfer, vitamin K can increase the intestinal peristalsis and secretion, the lack of vitamin K, decreased muscle tension and contraction, it can also affect the metabolism of some hormones . Such as the delay of glucocorticoid in the liver of the decomposition, while have a similar effect of hydrocortisone, long-term injection of vitamin K can increase the endocrine activity of the thyroid gland. A lack of vitamin K in clinical practice is common in biliary obstruction, steatorrhea, long-term use broad-spectrum antibiotics, as well as newborns, use of vitamin K can be corrected. But after a large dose of vitamin K also has a certain degree of toxicity, such as the neonatal injection of 30 mg / day qd for 3 days may cause hyperbilirubinemia.

Vitamin K in 1929, the Danish chemist Dam from animal liver and pock oil discovered and extracted. It is the yellow crystals, melting point 52 ~ 54 ℃, insoluble in water, soluble in ether and other organic solvents. A more stable chemical properties of vitamin K can be heat-acid-resistant, but susceptible to alkali and UV-decomposition. It is in the human body can promote blood coagulation. The human body without it, a clotting time longer would severe bleeding and even death. The strange thing is there is a person's intestinal bacteria for the body to manufacture vitamin continuously K, combined with liver, eggs, vegetables and more solid in content, therefore, most people are not lacking. Now has been able to artificially synthesized, and the clever chemists can change its "character" as the water-soluble, is conducive to the human body absorption, has been widely used for medical services.