BIOCHEMISTRY - Textbook - Ostapchenko L. I. - 2012

Chapter 8. VITAMINS

8.3. Water-soluble vitamins

8.3.10. Vitamin-like substances

These are diverse chemical compounds that exhibit vitamin-like properties, yet are partially synthesized within the body and sometimes incorporated into tissue structures (Fig. 8.23).

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Fig. 8.23. Vitamin-like substances:

A - pangamic acid; B - Inositol; C - orotic acid

Vitamin P (bioflavonoids, polyphenols) is a group of compounds containing a diphenylpropane carbon "Skeleton" of chromone or flavone. Their structural hallmark is the presence of double bonds, as well as keto and hydroxy groups within the rings and sugar residues. This group includes catechins, leucoanthocyanins, flavanones, flavonols (such as rutin), and anthocyanins. Hesperidin (citrin), derived from citrus peel, is a representative flavanone. Rutin is obtained from buckwheat leaves, and catechin from tea leaves. The most important biological property of these compounds is their ability to maintain capillary elasticity and strength, reducing vascular permeability. Compounds with P-vitamin activity are widely distributed in nature and are found in the same foods as Vitamin C. One of the pathways through which they affect The Vascular System is via the Endocrine glands. Polyphenols can protect adrenaline from oxidation; adrenaline stimulates the Pituitary Gland, which in turn promotes the secretion of corticosteroids. Another aspect of vitamin P's capillary-protective action involves the inhibition of hyaluronidase activity. This leads to the accumulation of hyaluronic acid, which is essential for strengthening Connective Tissue and vessel walls.

Inositol (meso-inositol, myo-inositol). This hexahydric cyclic alcohol, a cyclohexane derivative, is widespread in both the animal and plant kingdoms. Most commonly, it occurs in plants in the form of phosphoric esters—phytin—and is formed through the cyclization of a glucose molecule. Phytin is a mixture of calcium and magnesium salts of inositol hexaphosphoric ester. Of the nine possible stereoisomers of inositol, meso-inositol—a compound first isolated from Muscle tissue—possesses biological activity. Inositol is essential for the growth of MICROORGANISMS AND THE normal development and functioning of animals. In humans, inositol deficiency is practically never observed. In the bodies of humans and animals, inositol is utilized for the synthesis of phosphoglycerides, specifically phosphatidylinositol, and exhibits a potent lipotropic effect.

Vitamin U (methylmethionine) is an active form of Methionine. It is found in large quantities in raw vegetable juices, especially cabbage juice. A crystalline preparation has been isolated from asparagus and fresh tomatoes that is a thousand times more active than cabbage juice. Methylmethionine has a stimulating effect on damaged mucous membranes of the gastrointestinal tract. This effect is likely due to the fact that methylmethionine serves as an active methyl group donor; it also participates in the synthesis of choline and creatine.

Vitamin B ₁₃ (orotic acid) is a pyrimidine derivative. This compound is capable of enhancing the growth of microorganisms and higher animals. In birds and mammals, orotic acid is synthesized from aspartic acid and carbamoyl phosphate during nucleic acid synthesis. When administered exogenously, it enhances anabolic processes and thereby stimulates the growth of plants and animals. Potassium orotate is used in the Treatment of Liver and Heart diseases, as well as certain types of anemia.

Vitamin B ₁₅ (pangamic acid) is an ester of α-gluconic acid and dimethylglycine. This acid improves Lipid METABOLISM and prevents fatty liver infiltration. It also promotes the synthesis of creatine phosphate, activates oxidative processes in the body, and exerts a detoxifying effect in poisonings caused by organochlorine compounds, tetracycline Antibiotics, alcohol, and narcotics.