Biotin

Biotin (vitamin N, vitamin B7, R coenzyme) — water-soluble vitamin of group B. Biotin is a cofactor in metabolism of fatty acids, leucine and in the course of gluconeogenesis.

Biotin in products. Yeast, tomatoes, spinach, soy, an egg yolk, mushrooms, a liver are richest with biotin.

Effects of biotin

Biotin is a part of the enzymes regulating proteinaceous and fatty exchange has high activity. Participates in synthesis of glucokinase. Is a coenzyme of various enzymes including transcarboxymanhole. With participation of biotin reactions of activation and transfer of CO2 proceed.

Biotin in bodybuilding

Biotin is often applied in sport as plays a huge role in metabolism of amino acids, and also in the processes providing muscles with energy. Quite often deficiency of biotin serves as the reason of slow growth of muscle bulk. Shortage of biotin can arise owing to the habit extended among body builders there are eggs crude. In intestines of the person biotin takes up with other compound of egg white - avidany. As a result connection hard to digest which deprives reception of biotin of any sense is formed.

Doses and the mode of reception

The overdose of biotin doesn't arise even in case of the use of large numbers. The recommended doses - 30 mkg, in bodybuilding are required higher doses - 200 mkg and above.

Historical information

In 1916 Mr. Beytmen found out that at rats in whose diet as the only source of white served egg white the syndrome which is characterized by neuromuscular frustration, heavy dermatitis and alopetion develops. This syndrome didn't develop if rats were fed with boiled egg white, added to a forage barmy mushrooms, a liver or extracts from them. In 1936. The size and Tennis from an egg yolk allocated a factor, necessary for growth of barmy mushrooms, which they called biotin in a crystal look. Biotin was that substance which protected rats from toxic effect of egg white (Gyorgy, 1940). You can try Honluten.

In 1942 Du Vinio established a structural formula of biotin, soon after that it was synthesized.

At the same time actively investigated the nature of the antagonist of biotin who is present at egg white. In 1940 Mr. Eykin and ñîòð. for the first time allocated it and called avidiny. Avidin represents glikoproteid which connects biotin with high affinity, interfering thereby with its absorption.

Structure

Structural formula of biotin following:

In natural products in addition to free biotin three more of its forms are found: biotsitin (e - biotinil - L - a lysine), d-and l-sulfoksidy of biotin. Value of these substances as biotin substitutes for the person isn't known though they support proliferation of some microorganisms. Biotsitin can be a product of disintegration of a complex of biotin with protein as, carrying out a role of group, biotin is connected with a s-amino group of a remaining balance of a lysine of the corresponding enzyme.

Effect of biotin is interfered by a number of connections, including sulfon biotin, destiobiotin and some imidazolidon-carbonic acids. Antagonism between avidiny and biotin is described above.

Pharmacological action

Biotin has no side effect at the person even in case of acceptance of high doses within several months.

Physiological functions

At the person biotin plays an important role in carbohydrate and fatty exchange, participating in a carboxylation of four substrata: pyrogrape acid, atsetil-KOA, propionil-Koa R-metilkrotonil-KOA. The carboxylation proceeds in two stages: on the first C02 it is activated, kovalentno contacting biotin in the active center of enzyme, and then the activated C02 is transferred from biotin to the corresponding acceptor.

Symptoms of deficiency

At the majority of animals for procreation of deficiency of a biotin it is necessary or to destroy an intestinal microflora (which, apparently, synthesizes a biotin), or to feed them crude egg white, or to enter antagonists of a biotin. Deficiency of a biotin at the person is shown by a dermatitis, an atrophic glossitis, a hyperesthesia, mialgiya, appetite loss, slight anemia and changes of an ECG. Deficiency of a biotin was observed in some cases long consumption in a nutrition of crude eggs. Congenital defects of biotindependent enzymes which it is possible to compensate by introduction of high doses of a biotin (Baumgartner et al are described., 1984).

Symptoms of deficiency of a biotin were observed at children and adults with chronic inflammatory diseases of an intestine, is long receiving parenteral delivery without biotin additives. In such cases probably insufficient synthesis of a biotin an intestinal microflora was an additional factor. The avitaminosis was shown by the serious erythrosis and an alopecia reminding symptoms of deficiency of Zincum, but disappearing at reception even of small doses of a biotin. Biochemical confirmations of deficiency of a biotin are given only in the few works, but in one case a biotin reduced the raised egestion with urine of β-hydroxyisovaleric acid that indicated dysfunction of a biotindependent metilkrotonil-KOA-karboksilazy (Gillis et al., 1982).

The need

The approximate daily need for a biotin for the adult makes 30 mkg/days (tab. XIII.2). Americans on average consume a biotin in number of 100 — 300 mkg/days. Also the biotin synthesized by intestinal microflora is partially soaked up. At deficiency of a biotin in an organism and dosages from 2500 mkg to 15-20 thousand mkg are quite often applied to fight against its consequences.

Food sources

Offal (liver, kidneys), egg yolk, milk, fish and nuts are rich with biotin. Biotin is steady against heating, but rather quickly collapses in the alkaline environment.

Absorption, exchange and ekskretion

Biotin is easily soaked up in a GIT and appears in urine mainly in not changed look, and also in the form of metabolites: encore-norbiotina and biotin sulfoksid. The system of rings in a biotin molecule in an organism of mammals doesn't collapse. Application. High doses of biotin (5 — 10 mg/days) apply at seboreyn dermatitis at newborns, and also at genetic defects of biotindependent enzymes. At long parenteral food it is necessary to add the vitamin medicines containing biotin to nutritious solutions.