Organ iodine compounds

The atomic groups present in an iodine-containing organic molecule interact with each other, which leads to electronic displacements in covalent chemical bonds and inevitably affects the physical and chemical properties of the organic compound. ^{[1] The} mutual influence of С-I atoms is determined by their electronegativity . Electronegativity is a property that characterizes the ability of an atom of an element to attract electrons. The chemical bond С-I is formed by elements with different electronegativity, which is why the electron displacement occurs, as a result of which the negative charge δ ^{- is} concentrated on the more electronegative iodine atom, and the partial positive charge δ ⁺ is formed on the carbon atom. The variety of chemical forms of iodine compounds, the ease of transition between different valence compounds, and the easy volatility of free iodine determine the diversity of the class of iodine organic substances. Two groups of substances also belong to organic iodine compounds: iodonium compounds having some chemical similarity with ammonium compounds, and iodine compounds containing an oxygen atom bound to iodine. In nature, stable compounds of trivalent iodine were not found, although it cannot be ruled out that some of them are intermediate products of iodine metabolism .

The unique properties of iodine and its compounds allow this element to be present in trace amounts in all objects of animate and inanimate nature, without exception. Iodine compounds in different valence states have a different migration ability and effect on living organisms, therefore, when considering the fate of a microelement in the biosphere, it is necessary to take into account both its valence states in specific objects of the biosphere and possible redox transformations under the considered conditions. In humans and animals, iodine is present both in the form of inorganic compounds - iodides , and organic iodine - thyroglobulin, iodinated amino acids - monoiodothyronine and diiodothyronine, iodine-containing hormones (up to 65% iodine) - thyroxine and triiodothyronine , as well as intermediate products of their metabolism. In circulating blood, about 75% of the iodine is in the form of organic compounds, and the rest is represented by an iodide ion. Obviously, covalently bound “organic iodine” plays a significant role in the exchange of iodine.

Iodine Organization

Such a thing as “organization of iodine” is inherent in all living beings. For example, in the human thyroid gland enzymatic addition of inorganic iodine to the amino acids of the protein - thyroglobulin (iodination) occurs every second. As a result of the hydrophilic substitution reaction, iodide (I ^- ) is inserted instead of hydrogen into the tyrosine amino acid molecule, forming a strong bond with carbon (C - I), and a partial positive charge is formed on the carbon atom. Thanks to the covalent bound form, “organic iodine” is able to exhibit diverse biological properties and effects, including through iodine-containing hormones - thyroxine and triiodothyronine, which are involved in the regulation of all metabolic processes in the human body. In addition to the thyroid gland, the processes of “iodine organization” are less carried out in the mammary and salivary glands , as well as in other tissues and organs. At birth, all mammals, including humans, consume mainly organic iodine associated with the proteins of mother’s milk. This is associated with the extremely important positive balance of iodine in the body of pregnant and lactating women. In other living organisms, organic iodine is also present in the form of mono - and diiodotyrosines. Especially a lot of them in marine hydrobionts, such as sea sponges , hedgehogs , algae , etc.

In humans, there are two different mechanisms of absorption , absorption and metabolism of inorganic and organic iodine. Ultimately, these mechanisms determine the effectiveness and safety of various approaches to the prevention of iodine deficiency. It should be noted that the opinion expressed by many foreign and domestic researchers about the main regulatory role of liver deiodinases in the absorption and metabolism of organic iodine is greatly simplified and controversial. Confirmation of this is an undeniable fact of the high iodine content in Japanese urine (1.5-10 mg / l ion iodide), which is possible only in case of absorption and metabolism of "organic iodine". For reference: WHO takes a normal iodine level of 150 mcg / L. The efficiency of consumption of organic iodine is determined by the complex system of its distribution and accumulation in the body, the coordinated work of not only liver deiodinases, but also deiodinases in tissues and organs, which determine the optimal level of iodine metabolism in general, as well as the work of the “iodine pump”, which determines the speed and amount of digestion thyroid gland iodine. In the 40-50s of the XX century, abroad and in the USSR, numerous attempts were made to use iodized proteins in medicine, pharmaceutical and food industries, as well as agriculture. But, despite the positive results obtained, this approach did not find further practical application for the following main reasons:

• The strong scatter of the mass content of organic iodine, as well as the presence of large residual amounts of inorganic iodine in the iodinated proteins (in the form of iodides and molecular iodine) did not allow normalization of organic iodine during food fortification.
• The use of chemical methods of protein iodination led to their change and contamination by reaction products (including organochlorine compounds and molecular iodine), which caused numerous side effects when used.
• The lack of industrial biotechnological equipment and processes (ultra- and nanofiltration, sublimation, chromatography, etc.) did not allow us to ensure the physicochemical properties and purity of the obtained iodinated proteins, especially on an industrial scale.

Iodine-containing organic compounds are used as radiopaque substances . Among them, water-soluble compounds and iodinated oils are distinguished. The water-soluble organic iodine compounds used for this purpose are triiodobenzoates (verographin, urographin, iodamide, triombrast) and are used in urography, angiography, and cholegraphy. Liquid organic compounds of iodine mixed with viscosity carriers (perabrodil, ioduron B, propyl iodone, chitrast) are used for bronchography. Iodized oils (iodolipol, iodatol, lipiodol) are used for bronchography, lymphography, fistulography, metrosalpingography. Dimeric and non-ionic water-soluble radiopaque compounds have been developed that have a less pronounced side effect (iopamidol, iopromide, omnipack, etc.) ^[2] .

At the beginning of the XXI century, a number of enterprises began to produce iodinated proteins (Tireiod, Iodkasein, Bioiod , Yoddar), which began to be increasingly used for the enrichment of food products (dairy, meat, confectionery and bakery products). Particularly relevant is the aspect of how these new products meet the requirements of the concept of “organic iodine”.

• STRUCTURE AND REACTIVITY. MUTUAL INFLUENCE OF ATOMS IN A MOLECULE, ELECTRONIC EFFECTS OF SUBSTITUTES.
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