Water-soluble vitamins biotin

The water soluble vitamin (+)-biotin was synthesized by M. Seki and co-workers from L-cysteine in only 11 steps using inexpensive reagents and mild reaction conditions." The key ring forming step was an intramolecular allylic amination Tsuji-Trost reaction using a nitrogen nucleophile) of a cis allylic carbonate. As expected with a soft nucleophile, the allylation took place with an overall retention of configuration. 

Although a water-soluble vitamin, biotin is sufficiently non-polar to exhibit good retention on reversed-phase columns. Depending on the pH of the mobile phase, biotin elutes from C8 and C18 columns well separated from other... 

The water soluble vitamin, biotin, acts as a cofactor for a set of enzymes that catalyze carboxylation, decarboxylation or transcarboxylation reactions (Moss and Lane, 1971). In plants we have characterized four biotin-containing enzymes each of which catalyze reactions required in lipid metabolic processes. These enzymes are the homomeric and heteromeric isozymes of acetyl-CoA carboxylase (ACCase), methylcrotonyl-CoA carboxylase (MCCase) and geranoyl-CoA carboxylase (GCCase). The studies of these biotin-containing enzymes has led to an interest in biotin biosynthesis, and we have cloned the gene coding for biotin synthase. 

W. R. Streit, C. M. Joseph, and D. A. Phillips, Biotin and other water-soluble vitamins are key growth factors for alfalfa rhizosphere colonization by Rhizobium meli-loti 1021. Molec. Plant Microbe Interact. 5 330 (1996). 

Water-soluble vitamins removed by hemodialysis (HD) contribute to malnutrition and vitamin deficiency syndromes. Patients receiving HD often require replacement of water-soluble vitamins to prevent adverse effects. The vitamins that may require replacement are ascorbic acid, thiamine, biotin, folic acid, riboflavin, and pyridoxine. Patients receiving HD should receive a multivitamin B complex with vitamin C supplement, but should not take supplements that include fat-soluble vitamins, such as vitamins A, E, or K, which can accumulate in patients with renal failure. 

The water-soluble vitamins generally function as cofactors for metabolism enzymes such as those involved in the production of energy from carbohydrates and fats. Their members consist of vitamin C and vitamin B complex which include thiamine, riboflavin (vitamin B2), nicotinic acid, pyridoxine, pantothenic acid, folic acid, cobalamin (vitamin B12), inositol, and biotin. A number of recent publications have demonstrated that vitamin carriers can transport various types of water-soluble vitamins, but the carrier-mediated systems seem negligible for the membrane transport of fat-soluble vitamins such as vitamin A, D, E, and K. 

Recently, Prasad et al. cloned a mammalian Na+-dependent multivitamin transporter (SMVT) from rat placenta [305], This transporter is very highly expressed in intestine and transports pantothenate, biotin, and lipoate [305, 306]. Additionally, it has been suggested that there are other specific transport systems for more water-soluble vitamins. Takanaga et al. [307] demonstrated that nicotinic acid is absorbed by two independent active transport mechanisms from small intestine one is a proton cotransporter and the other an anion antiporter. These nicotinic acid related transporters are capable of taking up monocarboxylic acid-like drugs such as valproic acid, salicylic acid, and penicillins [5], Also, more water-soluble transporters were discovered as Huang and Swann [308] reported the possible occurrence of high-affinity riboflavin transporter(s) on the microvillous membrane. 

On rare occasions an organic aciduria occurs not because of an enzyme deficiency but from a failure to transport or activate a water-soluble vitamin that serves as a cofactor for the reaction in question. Thus, congenital deficiencies in the metabolism of vitamin B12 commonly give rise to methylmalonic aciduria (Fig. 40-1, Table 40-2). Similarly, deficiencies of biotin metabolism can cause a severe organic aciduria (Table 40-2). It is very important to be aware of the defects of vitamin metabolism because the administration of large doses of these cofactors may completely prevent brain damage. 

During the course of the development of a new technical synthesis at Lonza for biotin (a water-soluble vitamin), the Rh-Josiphos-catalyzed diastereoselective hydrogenation of a tetrasubstituted C=C bond turned out to be a key step [40, 42, 81] (Fig. 37.19). 

In an investigation of the water-soluble vitamins in human skin,71 it was found that 15 individuals showed relatively small ranges (less than 2-fold) for vitamin B12, folic acid, and biotin about 2-fold ranges in the cases of riboflavin, niacin, and thiamine about a 4-fold range in the case of ascorbic acid, and more than a 5-fold range in the case of pantothenic acid. In another study72 it was found that the total choline content of normal skin varied in four individuals over approximately a 10-fold range 127 to 1200 ig. per gm. The variation in the free choline in the same individuals was relatively small. 

Fig. 3 Electropherogram of five water-soluble vitamines thiamine (cationic), nicotinamide (nonionic), biotin (anionic), ascorbic acid (anionic), and nicotinic acid (anionic) in 20 mM phosphate run buffer at pH 8.0.

The B-group is a heterogeneous collection of water-soluble vitamins, most of which function as co-enzymes or are precursors of co-enzymes. The B-group vitamins are thiamin, riboflavin, niacin, biotin, pantothenic acid, pyridoxine (and related substances, vitamin B6), folate and cobalamin (and its derivatives, vitamin B12). 

Vitamins are chemically unrelated organic compounds that cannot be synthesized by humans and, therefore, must must be supplied by the diet. Nine vitamins (folic acid, cobalamin, ascorbic acid, pyridoxine, thiamine, niacin, riboflavin, biotin, and pantothenic acid) are classified as water-soluble, whereas four vitamins (vitamins A, D, K, and E) are termed fat-soluble (Figure 28.1). Vitamins are required to perform specific cellular functions, for example, many of the water-soluble vitamins are precursors of coenzymes for the enzymes of intermediary metabolism. In contrast to the water-soluble vitamins, only one fat soluble vitamin (vitamin K) has a coenzyme function. These vitamins are released, absorbed, and transported with the fat of the diet. They are not readily excreted in the urine, and significant quantities are stored in Die liver and adipose tissue. In fact, consumption of vitamins A and D in exoess of the recommended dietary allowances can lead to accumulation of toxic quantities of these compounds. 

In general, vitamins appear to be at least as stable during UHT processing as during conventional pasteurization (Mehta 1980). Levels of the fat-soluble vitamins A, D, and E, as well as those of the water-soluble vitamins, riboflavin, nicotinic acid, pantothenic acid, and biotin in milk, are not decreased by UHT processing. Furthermore, no loss of... 

The fat-soluble vitamins are A, D, E, and K. The water-soluble vitamins are thiamine (vitamin Bj), riboflavin, nicotinic acid (niacin) and nicotinamide, pyridoxine (vitamin B6), pantothenic acid, biotin, para-aminobenzoic acid, choline, inositol, and other lipotropic agents, ascorbic acid (vitamin C), the riboflavonoids, folate, and vitamin B12 (see Figure 66.1 and Figure 66.2, and Table 66.1). 

The CP content of cottonseed meal may vary from 360 to 410g/kg, depending on the contents of hulls and residual oil. AA content and digestibility of cottonseed meal are lower than in soybean meal. Although fairly high in protein, cottonseed meal is low in lysine and tryptophan. The fibre content is higher in cottonseed meal than in soybean meal, and its ME value is inversely related to the fibre content. Cottonseed meal is a poorer source of minerals than soybean meal. The content of carotene is low in cottonseed meal, but this meal compares favourably with soybean meal in water-soluble vitamin content, except biotin, pantothenic acid and pyridoxine. 

Biotin (60), a water-soluble vitamin with widespread application in the growing market for health and nutrition, acts as a co-factor for carboxylase enzymes and its essential fatty acid synthesis. The key step in the chemical synthesis of biotin is the asymmetric reduction of the tetrasubstituted olefins 61 by in situ Rh(I)-4i catalyst (Scheme 12.1 S).79-83-85-86 Substrate-to-catalyst ratios of 2000 with diastereoselectivities of 99% de were achieved with Rh-4i at the multi-ton scale before production was terminated.87... 

Many cells require media supplemented with complex B vitamins, while other vitamins are presumably supplied by the addition of serum to culture media. Nevertheless, when serum-free media are employed, not only the water-soluble vitamins should be provided, but also the lipid-soluble ones, such as biotin, folic acid, niacin, panthotenic acid, thiamine, and ascorbic acid, as well as the vitamins B12, A, D, E, and K. 

Water-soluble vitamins. Water-soluble vitamins include vitamin C, and those of the B-complex group biotin, folate, niacin, pantothenic acid, riboflavin, thiamine, vitamin Bg and vitamin B12. They function mainly as coenzymes and prosthetic groups. 

Many of the water-soluble vitamins are present in foods bound to proteins, and their release may require either the action of gastric acid (as for vitamin B12, Section 10.7.1) or specific enzymic hydrolysis [e.g., the action of conjugase to hydrolyze folate conjugates (Section 10.2.1) and the hydrolysis of biocytinto release biotin (Section 11.2.3)]. 

Ramaswamy K (1999) Intestinal absorption of water-soluble vitamins focus on molecular mechanism ofthe intestinal biotin titLnspottprocess. AmericanJournalofPhysiology 277, C603-4. 

Water soluble vitamins (Bi, B2, Be, B12, C, folacin, biotin, niacin, pantothenate) generally wash out of foods easily, and also wash out of the body relatively easily, (hence, are less easily stored in the body—an exception is vitamin B12 which is stored excellently, particularly in the liver). One may thus become depleted relatively quickly of most water soluble vitamins. Fortunately, so many foods are rich in them. Toxicity reactions, on the other hand, are more likely with fat-soluble vitamins, as they are so well-stored and are not eliminated easily from the body. 

Vitamins are divided into two major categories. They are fat-soluble (A, D, E and K) and water-soluble vitamins (B-complex and vitamin C). B complex vitamins include thiamine (Bi), riboflavin (B2), pantothenic acid (B3), niacin (B5), pyridoxine (Be), biotin (By), folic acid (B9), and cobalamin (Biy). Inositol, cholic and para-aminobenzoic acid are vitamin-like substances sometimes classified as part of the B complex, but no convincing evidence has been shown so far to be included as vitamins. All the fat-soluble vitamins and some B vitamins exist in multiple forms. The active forms of vitamin A are retinol, retinal and retinoic acid and vitamin D is available as ergocalciferol (D2) and cholecalciferol (D3). The vitamin E family includes four tocopherols and four tocotrienols but a-tocopherol being the most abundant and active form. The multiple forms of vitamins are interconvertible and some are interchangeable. 

Vitamins are classified into two categories Fat-soluble Vitamins (A, D, E, K) and Water-soluble Vitamins (All B, Biotin, Folic acid and Ascorbic acid). 

Some itamirLS are water soluble, while others are fat soluble. This classification is valuable as it indicates whether the vitamin is likely to be absorbed similarly to lipids or like other water-soluble nutrients. The fat-soluble vitamins are A, D, E, and K. The water-soluble vitamins arc ascorbic acid, biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B i, and vitamin B 2. The classification is also valuable, as it helps chemists decide on the best way to extract and analyze a particular vitamin in foods and biological tissues. Aside from having some bearing on the path ways of absorption and distribution throughout the body, the question of whether a particular vitamin is fat soluble or water soluble has little or no relevance to its function in the body. 

Biotin is a water-soluble vitamin. It is a cofactor for four ATP-dependent carboxylases acetyl-CoA carboxylase, pyruvate carboxylase, propionyl-CoA carboxylase, and p-methylcrotonyl-CoA carboxylase. Biotin occurs covalently bound to the enzymes via the terminal amino group of a lysine residue. With the normal and continual turnover of these enzymes in the body, the biotin is released, but then utilized again as a cofactor when the enzymes are re-synthesized. The structure of biotin is shown in Figure 9.32,... 

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 ... 

The potential of PBI LC-MS in the analysis of various vitamins was explored by Careri et al. [99-100]. The fat-soluble vitamins A, D, and E were analysed in food and multivitamin preparations [99]. Absolute detection limits in SIM mode were 0.6-25 ng after fast leversed-phase separation using a 97% aqueous methanol as mobile phase. Mass spectra in El, positive-ion and negative-ion Cl were obtained and discussed. The mass-spectral and quantitative performance of PBI LC-MS in the analysis of eleven water-soluble vitamins was also explored [100]. Detection limits were determined in SIM mode under positive-ion Cl, and were below 15 ng for ascorbic acid, nicotinamide, nicotinic acid, and pyridoxal, around 100 ng for dehydroascorbic acid, panthothenic acid, and thiamine, and above 200 ng for biotin, pyridoxamime, and pyridoxine. Riboflavine was not detected. 

Additional cofactors derived from water-soluble vitamins are involved in a variety of metabolic reactions. These include NADPH (derived from the vitamin niacin), biotin, pyridoxal phosphate (derived from vitamin Be), tetrahy-drofolate (derived from the vitamin folate), vitamin B12, and vitamin C. 

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