Niacin phosphate

The FCC is to food-additive chemicals what the USP—NF is to dmgs. In fact, many chemicals that are used in dmgs also are food additives (qv) and thus may have monographs in both the USP—NF and in the FCC. Examples of food-additive chemicals are ascorbic acid [50-81-7] (see Vitamins), butylated hydroxytoluene [128-37-0] (BHT) (see Antioxidants), calcium chloride [10043-52-4] (see Calcium compounds), ethyl vanillin [121-32-4] (see Vanillin), ferrous fumarate [7705-12-6] and ferrous sulfate [7720-78-7] (see Iron compounds), niacin [59-67-6] sodium chloride [7647-14-5] sodium hydroxide [1310-73-2] (see lkaliand cm ORiNE products), sodium phosphate dibasic [7558-79-4] (see Phosphoric acids and phosphates), spearmint oil [8008-79-5] (see Oils, essential), tartaric acid [133-37-9] (see Hydroxy dicarboxylic acids), tragacanth [9000-65-1] (see Gums), and vitamin A [11103-57-4]. 

Niacin. Figure 2 Structure of the coenzymes NAD+ (nicotinamide-adenine dinucleotid) and NADP+ (nicotinamide-adenine dinucleotid phosphate). 

NADP can be converted to nicotinic acid adenine dinucleotide phosphate (NAADP), which has distinct functions in the regulation of intracellular calcium stores. The studies of these new roles of NAD(P) in metabolism are in their early stages, but they might soon help to better understand and explain the symptoms of niacin deficiency ( pellagra) [1]. 

Pyridoxamine phosphate serves as a coenzyme of transaminases, e.g., lysyl oxidase (collagen biosynthesis), serine hydroxymethyl transferase (Cl-metabolism), S-aminolevulinate synthase (porphyrin biosynthesis), glycogen phosphoiylase (mobilization of glycogen), aspartate aminotransferase (transamination), alanine aminotransferase (transamination), kynureninase (biosynthesis of niacin), glutamate decarboxylase (biosynthesis of GABA), tyrosine decarboxylase (biosynthesis of tyramine), serine dehydratase ((3-elimination), cystathionine 3-synthase (metabolism of methionine), and cystathionine y-lyase (y-elimination). 

These dehydrogenases use nicotinamide adenine dinucleotide (NAD ) or nicotinamide adenine dinucleotide phosphate (NADP )—or both—and are formed in the body from the vitamin niacin (Chapter 45). The coenzymes are reduced by the specific substrate of the dehydrogenase and reoxidized by a suitable electron acceptor (Figure 11-4). They may freely and reversibly dissociate from their respective apoenzymes. 

Although the structures for molecules having niacin activity are simple, the forms in which they act in human biochemistry are not so simple. Nicotinic acid and nicotinamide are precursors for three complex coenzymes in multiple oxida-tion/reduction (redox) reactions nicotinamide mononucleotide, NMN nicotinamide adenine dinucleotide, NAD+ and nicotinamide adenine dinucleotide phosphate, NADP. I shall use NAD+ as representative of the class. NADH is the corresponding reduced form. ... 

Nicotinate and nicotinamide, together referred to as niacin, are required for biosynthesis of the coenzymes nicotinamide adenine dinucleotide (NAD"") and nicotinamide adenine dinucleotide phosphate (NADP" ). These both serve in energy and nutrient metabolism as carriers of hydride ions (see pp. 32, 104). The animal organism is able to convert tryptophan into nicotinate, but only with a poor yield. Vitamin deficiency therefore only occurs when nicotinate, nicotinamide, and tryptophan are all simultaneously are lacking in the diet. It manifests in the form of skin damage (pellagra), digestive disturbances, and depression. 

Niacin is also known as vitamin PP or vitamin Bj. The term niacin describes two related compounds, nicotinic acid and nicotinamide (Figure 19.18), both with biological activity. Niacin is formed from the metabolism of tryptophan, and therefore it is not strictly a vitamin. It is a precursor of two cofactors nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are essential for the functioning of a wide range of enzymes involved in redox reactions. 

More recently [635], a unique extraction step in supplemented foods, by using hot water and a precipitation solution, following by HPLC-ELD/UV analysis has been performed for the simultaneous determination of pyridoxine, thiamine, riboflavin, niacin, pantothenic acid, folic acid, cyanoco-balamin, and ascorbic acid. The mobile phase consisting of phosphate buffer and methanol has been modified in order to perform ion-liquid chromatography by adding l-octanesulfonic acid sodium salt. Furthermore, triethylamine has been also added to improve peak symmetry. 

Niacin is a generic term which refers to two related chemical compounds, nicotinic acid (6.22) and its amide, nicotinamide (6.23) both are derivatives of pyridine. Nicotinic acid is synthesized chemically and can be easily converted to the amide in which form it is found in the body. Niacin is obtained from food or can be synthesized from tryptophan (60 mg of dietary tryptophan has the same metabolic effect as 1 mg niacin). Niacin forms part of two important co-enzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are co-factors for many enzymes that participate in various metabolic pathways and function in electron transport. 

Vitamin B6 occurs naturally in three related forms pyridoxine (6.26 the alcohol form), pyridoxal (6.27 aldehyde) and pyridoxamine (6.28 amine). All are structurally related to pyridine. The active co-enzyme form of this vitamin is pyridoxal phosphate (PLP 6.29), which is a co-factor for transaminases which catalyse the transfer of amino groups (6.29). PLP is also important for amino acid decarboxylases and functions in the metabolism of glycogen and the synthesis of sphingolipids in the nervous system. In addition, PLP is involved in the formation of niacin from tryptophan (section 6.3.3) and in the initial synthesis of haem. 

Nicotinamide adenine dinucleotide (NAD+ in its oxidized form) and its close analog nicotinamide adenine dinucleotide phosphate (NADP+) are composed of two nucleotides joined through their phosphate groups by a phosphoanhydride bond (Fig. 13-15a). Because the nicotinamide ring resembles pyridine, these compounds are sometimes called pyridine nucleotides. The vitamin niacin is the source of the nicotinamide moiety in nicotinamide nucleotides. 

Two vitamins, nicotinamide and pyridoxine (vitamin B6), are pyridine derivatives. Nicotinamide participates in two coenzymes, coenzyme I (65 R = H) which is known variously as nicotinamide adenine dinucleotide (NAD) or diphosphopyridine nucleotide (DPN), and coenzyme II (65 R = P03H2) also called triphosphopyridine nucleotide (TPN) or nicotinamide adenine dinucleotide phosphate (NADP). These are involved in many oxidation-reduction processes, the quaternized pyridine system acting as a hydrogen acceptor and hydrogen donor. Deficiency of nicotinamide causes pellagra, a disease associated with an inadequately supplemented maize diet. Nicotinic acid (niacin) and its amide are... 

Niacin, a water-soluble vitamin vital for oxidation by living cells, functions in the body as a component of two important coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). NAD and NADP are involved in the release of energy from carbohydrate, fat, and protein, and in the synthesis of protein, fat, and pentoses for nucleic acid formation. Milk is a poor source of preformed niacin, containing about 0.08 mg per 100 g. However, milk s niacin value is considerably greater than indicated by its niacin content (Horwitt et al. 1981). Not only is the niacin in milk fully available, but the amino acid tryptophan in milk can be used by the body for the synthesis of niacin. For every 60 mg of tryptophan consumed, the body synthesizes 1 mg of niacin. Therefore, the niacin equivalents in 100 g milk equal 0.856 mg including that from pre-... 

Niacin production of reduced nicotinamide adenine dinucleotide (phosphate) (NADPH) by ACTH via cyclic adenosine monophosphate (AMP)... 

In die physiological system, niacin and related substances maintain nicotinamide adenine diiuicleotide (NAD) and nicotinamide adenine ciinucleotide phosphate (NADP). Niacin also acts as a hydrogen and electron transfer agent in carbohydrate metabolism and furnishes coenzymes for dehydrogenase systems. A niacin coenzyme participates in lipid catabolism, oxidative deamination, and photo synthesis,... 

The niacin vitamers in foods include nicotinic acid and nicotinamide (Fig. 4), which occur in limited quantities in the free form, and their coenzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) (93,96). The nicotinic acid analog of NAD as well as nicotinamide and nicotinic acid mononucleotides also occur in nature. In addition, niacin occurs as nicotinyl esters bound to polysaccharides, peptides, and glycopep-tides, which are known as niacytin and niacynogens, respectively. In general, the niacin vitamers in cereal grains and other seeds are principally the nicotinic acid forms, whereas those in meat and fish are primarily the nicotinamide forms (94,95). 

Please note that other diet defiencies can lead to reduced metabolic rate including phosphates, niacin, selenium, and magnesium among others, such as Zinc. 

Figure 5.8 Separation of eleven water-soluble vitamins by MECC. Peaks 1, pyridoxamine 2, nicotinamide 3 pyridoxal 4, vitamin B6 5, vitamin B2 6, vitamin B12 7, vitamin B2 phosphate 8, pyridoxamine 5 -phosphate 9, niacin 10, vitamin Bi 11, pyridoxal 5 -phosphate. Conditions buffer, 50 mM SDS in 20 mAf phosphate-borate buffer, pH 9.0 applied voltage, 20 kV detection, UV absorbance at 210 nm. (Reprinted from Ref. 20 with permission.)...

NAD A Coenzyme Nicotinamide adenine dinucleotide (NAD) is one of the principal oxidation-reduction reagents in biological systems. This nucleotide has the structure of two D-ribose rings (a dmucleotide) linked by their 5 phosphates. The aglycone of one ribose is nicotinamide, and the aglycone of the other is adenine. A dietary deficiency of nicotinic acid (niacin) leads to the disease called pellagra, caused by the inability to synthesize enough nicotinamide adenine dinucleotide. 

What may be called the 3-deoxy-D-om6mo-heptulosonic acid 7-phosphate pathway is used in E. coli for the synthesis of (a) the aromatic amino acids of proteins and (b) p-aminobenzoate. In Neurospora this pathway is also used for the synthesis of niacin ( > since these organisms convert tryptophan to niacin by a pathway first observed in mammals, but E. coli synthesizes niacin by a different pathway. jt is clear at present, even on the basis of limited evidence, that plants use the 3-deoxy-D-oroWno-heptulosonic acid 7-phosphate pathway for the synthesis of a much more extensive series of products. 

Niacin is unusual among the vitamins in that it was discovered as a chemical compound, nicotinic acid produced by the oxidation of nicotine, in 1867 -long before there was any suspicion that it might have a role in nutrition. Its metabolic function as part of what was then called coenzyme II [nicotinamide adenine dinucleotide phosphate (NADP)] was discovered in 1935, again before its nutritional significance was known. 

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