Менадион

Описание

Vitamin K is a general term referring to a group of naphthoquinone derivatives required in the diet for blood clotting. Menadione is a fat-soluble vitamin that is essential for blood clotting. It is destroyed by irradiation during processing but has no appreciable loss during storage. It occurs in spinach, cabbage, liver, and wheat bran.

Химические свойства

Bright-yellow crystals with a very faint acrid odour. Insoluble in water; soluble in benzene (1 g/10 mL), ethanol (1 g/60 mL), and vegetable oils (1g/50 mL); moderately soluble in carbon tetrachloride and chloroform. Stable in air; decomposed by sunlight; destroyed by alkalis and reducing agents.

Физические свойства

Appearance: phylloquinone is a yellow oil at room temperature, but the other vitamers K are yellow crystals. Solubility: the vitamers K and MK and most forms of menadione are insoluble in water, slightly soluble in ethanol, and readily soluble in ether, chloroform, fats, and oils. Stability: the vitamers K are sensitive to light and alkali, but are relatively stable to heat and oxidizing environments.
Menadione, the formal parent compound of the menaquinone series does not occur naturally but is a common synthetic form called menadione (2-methyl-1,4- naphthoquinone). This compound forms a water-soluble sodium bisulfite addition product, menadione sodium bisulfite, whose practical utility is limited by its instability in complex matrices such as feeds. However, in the presence of excess sodium bisulfite, it crystallizes as a complex with an additional mole of sodium bisulfite (i.e., menadione sodium bisulfite complex), which has greater stability, therefore, is used widely as a supplement to poultry feeds. A third water-soluble compound is menadione pyridinol bisulfite (MPB).

Использование

Menadione is precursor to verious types of Vitamin K. It is of industrial importance as an intermediate in the synthesis of phylloquinone, and salts of its bisulfite adduct are used as stabilized forms in the animal feed industry. Commercially significant forms are menadione sodium bisulfite and menadione dimethyl pyrimidinol. Used as a micronutrient for livestock and pet foods.

прикладной

The primary known function of vitamin K is to assist in the normal clotting of blood, but it may also play a role in normal bone calcification. It is being incorporated into cosmetic preparations, particularly those used for treating dark circles. It could also be used in acne products, and there are studies underway on its efficacy for the treatment of spider veins.

Подготовка

Menadione can be prepared by oxidizing 2-methylnaphthalene with chromic acid or hydrogen peroxide.

Определение

ChEBI: Menadione is a member of the class of 1,4-naphthoquinones that is 1,4-naphthoquinone which is substituted at position 2 by a methyl group. It is used as a nutritional supplement and for the treatment of hypoprothrombinemia. It has a role as a nutraceutical, a human urinary metabolite, an angiogenesis inhibitor, an EC 3.4.22.69 (SARS coronavirus main proteinase) inhibitor and an antineoplastic agent. It is a member of 1,4-naphthoquinones and a vitamin K.

Показания

Vitamin K activity is associated with several quinones, including phylloquinone (vitamin K₁), menadione (vitamin K₃), and a variety of menaquinones (vitamin K₂). These quinones promote the synthesis of proteins that are involved in the coagulation of blood.These proteins include prothrombin, factor VII (proconvertin), factor IX (plasma thromboplastin). The vitamin K quinones are obtained from three major sources.Vitamin K is present in various plants, especially green vegetables. The menaquinones that possess vitamin K₂ activity are synthesized by bacteria, particularly gram-positive organisms; the bacteria in the gut of animals produce useful quantities of this vitamin.Vitamin K₃ is a chemically synthesized quinone that possesses the same activity as vitamin K₁.

Общее описание

Menadione is a prothrombogenic compound and belongs to the Vitamin K class of compounds, which are necessary for the biosynthesis of prothrombin and other blood clotting factors. It is used as a model quinone in cell culture and in vivo investigations. It is obtained as a catabolic product of phylloquinone and circulating precursor of tissue menaquinone-4 in rats.

Опасность

Irritant to skin and mucous membranes, especially the alcoholic solution.

Фармаколо?гия

The typical role of vitamin K is to maintain normal blood coagulation function. Its role is related to the metabolic processes.

Клиническое использование

Vitamin K deficiency results in increased bleeding time. This hypoprothrombinemia may lead to hemorrhage from the gastrointestinal tract, urinary tract, and nasal mucosa. In normal, healthy adults, deficiency is rare. The two groups at greatest risk are newborn infants and patients receiving anticoagulant therapy; hypoprothrombinemia preexists in these two groups. Any disease that causes the malabsorption of fats may lead to deficiency. Inhibition of the growth of intestinal bacteria from extended antibiotic therapy will result in decreased vitamin K synthesis and possible deficiency.

Побочные эффекты

Toxicity of vitamin K has not been well defined. Jaundice may occur in a newborn if large dosages of vitamin K are given to the mother before birth. Although kernicterus may result, this can be prevented by using vitamin K.

Профиль безопасности

Poison by ingestion, intraperitoneal, and subcutaneous routes. Experimental teratogenic effects. Questionable carcinogen with experimental tumorigenic data. Human mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.

Методы очистки

Recrystallise it from 95% EtOH, or MeOH after filtration. It forms bright yellow crystals which are decomposed by light. Its solubility in EtOH is 1.7% and in *C6H6 it is 10%. It IRRITATES mucous membranes and skin. [Fieser J Biol Chem 133 391 1940, Beilstein 7 IV 2430.]