Vitamins of the B Complex

The vitamin B complex contains a number of factors which are closely associated in their distribution in nature and have related functions in intermediate metabolism. Of the eleven factors which are available in pure form, five have been shown to be constituents of coenzymes, namely, thiamine, riboflavin, niacinamide, pyridoxine, and pantothenic acid. It seems likely that other B vitamins may be found to function in a similar manner. Two members of the B complex, choline and inositol, appear to have lipotropic activity, and two others, folic acid and vitamin B12, have antianemic properties. Deficiency of vitamins of the B complex is one of the most frequently encountered syndromes of malnutrition in man. 

In view of the common distribution of many of the B vitamins in foods, deficiency of several factors is more often observed than deficiency of a single vitamin. In view of the interrelationship of these vitamins in metabo- 

Thiamine, or vitamin Bi, is a water-soluble compound which is rapidly broken down by moist heat in neutral or alkaline solutions into its constituent pyrimidine and thiazole rings. The ready destructability of thiamine is important in human nutrition, since much may be lost in the preparation of food. Some of the biochemical methods used in evaluating thiamine nutrition are based on reactions with the thiazole and pyrimidine portions of the thiamine molecule. The thiochrome method is widely used in assaying biological materials for thiamine, while determination of the urinary excretion of pyramine (a pyrimidine-like compound) has been used to assist in assessment of nutritional status. 

Thiamine is excreted in the urine, the amount being dependent on dietary intake and the relative saturation of the tissue stores. Determination of thiamine excretion in the urine, especially after a test dose of thiamine has been administered, is one of the methods used in evaluating nutritive status relative to this vitamin. After intramuscular injection of 1 mg. of thiamine, persons who are adequately nourished excrete at least 100 fig. in the subsequent 4 hr., whereas patients with signs of thiamine deficiency usually excrete less than 50 /xg. during this period. Estimation of the concentration of thiamine in blood has also been used in nutritional appraisal. Mean 

Ferrebee, N. Weissman, D. Parker, and P. S. Owen, The Thiamin Content of Human Tissue, in The Role of Nutritional Deficiency in Nervous and Mental Disease, Williams and Wilkins Co., Baltimore, 1943, p. 42. 

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The water-soluble vitamins comprise the B complex and vitamin C and function as enzyme cofactors. Fofic acid acts as a carrier of one-carbon units. Deficiency of a single vitamin of the B complex is rare, since poor diets are most often associated with multiple deficiency states. Nevertheless, specific syndromes are characteristic of deficiencies of individual vitamins, eg, beriberi (thiamin) cheilosis, glossitis, seborrhea (riboflavin) pellagra (niacin) peripheral neuritis (pyridoxine) megaloblastic anemia, methyhnalonic aciduria, and pernicious anemia (vitamin Bjj) and megaloblastic anemia (folic acid). Vitamin C deficiency leads to scurvy. 

The water-soluble vitamins of the B complex act as enzyme cofactors. Thiamin is a cofactor in oxidative... 

Vitamins are essential nutrients, which must be supplied exogenously. They are organic compounds with indispensable biological activities as coenzymes in a multitude of cellular metabolic processes. Vitamin A, retinoids (vitamin A-derivatives), carotenoids, vitamin D, vitamin E, and vitamin K are fat-soluble, vitamin C and vitamins of the B-complex are water-soluble. This is of importance for gastrointestinal absorption in oral supplementation as well as the transdermal penetration for topical applications. 

Apart from pantothenic acid, which has been attributed loads of helpful effects in skin care and occurs quite frequently as dexpanthenol in cosmetic and medical formulations, the other vitamins of the B-complex are so far not known for specific positive results on skin, neither topically nor systemically. Nevertheless, some ideas for applications might eventually lead to new treatment options. 

Calculate the percent composition of thiamine (a vitamin of the B complex family), C12H17N4OSCI. 

Biotin is a water-soluble vitamin of the B complex (vitamin Bio, also called vitamin H), and is found in many foods, especially eggs and liver. Biotin is involved in the action of four carboxylases ... 

A deficiency of vitamin Bg alone is uncommon, and it is more usual to expect the problem to occur in association with deficits in other vitamins of the B-complex. As with other water-soluble vitamins that function as coenzymes, the relative affinity of the coenzyme for a given apoenzyme and the extent to which a particular holoenzyme-catalyzed reaction is essential are reflected in the progressive symptomatology of deficiency of the vitamin. Investigations of the consequences of vitamin Bg deficiency in the human use... 

Thiazole is known to occur naturally in various forms. The most widely recognized thiazole lies in the essential vitamin Bi or thiamin in the form of its thiazolium salt. It is a water-soluble vitamin of the B complex. Thiamin pyrophosphate is the essential coenzyme in the enzymatic decarboxylation of pyruvate to aldehyde. 

Coenzyme A is derived from four subunits. On the left is a two-carbon unit derived from 2-mercaptoethanamine. This unit is in turn joined by an amide bond to the carboxyl group of 3-aminopropanoic acid (/3-alanine). The amino group of /S-alanine is joined by an amide bond to the carboxyl group of pantothenic acid, a vitamin of the B complex. Finally, the —OH group of pantothenic acid is joined by a phosphoric ester bond to the terminal phosphate group of ADP ... 

Other heterocyclic rings appear in biological systems. Thiamin (131) contains a thiazole ring as well as a pyrimidine ring, and it is an essential component of the human diet. Thiamin is a water-soluble vitamin of the B complex (vitamin Bj). Although humans cannot synthesize thiamin, many bacteria synthesize it and use it in the form of thiamin pyrophosphate. Bacillus subtilis produces thiamin by a biosynthetic route, but it also synthesizes the thiazole unit (142) found in 131 from the amino acid glycine (133 see Chapter 27, Section 27.3.2) and l-deoxy-d-xylulose-5-phosophate, 132.2 (See Chapter 28, Section 28.1, for an introduction to sugars such as xylulose.)... 

Vitamins are a well-known group of compounds that are essential for human health. Water-soluble vitamins include folate (vitamin B9) to create DNA. Folate also plays an important role in preventing birth defects during early pregnancy. Thiamine is the first vitamin of the B-complex (vitamin Bl) that researchers discovered. It allows the body to break down alcohol and metabolize carbohydrates and amino acids. Like many other B vitamins, riboflavin (vitamin B2) helps the body to metabolize carbohydrates, proteins, and fat. Niacin (vitamin B3) protects the health of skin cells and keeps the digestive system functioning properly. Pantothenic acid (vitamin B5) and biotin allow the body to obtain energy from macronutrients such as carbohydrates, proteins, and fats. Vitamin B6 (pyridoxine) acts as a coenzyme, which means it helps chemical reactions to take place. It also plays a vital role in the creation of nonessential amino acids. 

Thiamine (vitamin Bj) is water-soluble, essential vitamin of the B complex. 

Fig. 2 Ball and stick representations (Mercury 3.5) of the crystal structure of MEMKEU, the phosphate of thiamin, a vitamin of the B complex, wherein sulfur forms two chalcogen bonds dotted blue lines) thanks to the entrance of chloride and phosphate anions on the extended covalent bonds at sulfur SENGOH, 2-phenyl-l,2-2//-benzisoselenazole-3-one wherein selenium forms one directional chalcogen bond. CSD Refcodes and the Normalized contacts Nc, see onwards) are given. Color code gray, carbon sky-blue, nitrogen red, oxygen ocher, phosphorus light yellow, sulfur green, chlorine dark yellow, selenium...

Absorption of fat is seriously impaired in man in the absence of bile from the intestinal tract, for example, in obstructive jaundice, although splitting of fat to fatty acids and glycerol proceeds normally. In sprue, idiopathic steatorrhea, and the celiac syndrome, fat is also poorly absorbed, although there is no decrease in available bile and the enzymatic breakdown to fatty acids is unimpaired. It has been suggested that a defective phosphorylating mechanism, due to deficiency of one or more vitamins of the B complex, may account for poor absorption in the sprue syndrome. Folic acid may be one of the factors involved. 

A water-soluble vitamin of the B complex, obtained in the diet from plant sources. It is a component of thiamine pyrophosphate, a cofactor required for the enzyme, trans-ketolase (qv), and also for the decarboxylation of a-oxoacids (e.g. the conversion of pyruvate to acetyl CoA). 

Acted upon by yeasts, molds, or bacteria in a controlled aerobic or anaerobic process in the manufacture of such products as alcohols, acids, vitamins of the B-complex group, or antibiotics. 

Besidual Vitamins of the B Complex.— At least a dozen different accessory food factors have been referred to the B group in natural food sources, especially yeast. These include Bg, a thermo-labile avian growth factor (Williams and Waterman) Bg, an alkali-labile rat growth factor (Readers) and Bg, a thermo-stable and alkali-stable rat growth factor (Carter) H, an anti-dermatitic factor (Kuhn), identified with factor Y (Chick and Copping) and vitamin Bg. Rats require at least six different factors from the B complex including thiamine, riboflavin and adermine. 

A search was made for the preventive factor in liver. Addition to the maternal diet of iodine, manganese, liver ash, casein, cod liver oil, and wheat germ oil were not preventive, but a mixture of 5 crystalline vitamins of the B-complex riboflavin, thiamin, niacin, pyridoxin, and pantothenic acid, prevented the abnormalities. Further experiments showed that in this mixture the riboflavin alone had preventive power (112). This result... 

The vitamins of the B complex include thiamine (vitamin Bj), riboflavin (vitamin B2), nicotinic acid (niacin), pantothenic acid (vitamin B5), pyridoxine (vitamin B ), cyanocobalamin (vitamin B12), biotin, lipoic acid, and folic acid. 

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