Pellagra Nicotinic acid

It was explained above how an antipellagra factor was included in the vitamin B2 complex. However, it was demonstrated that vitamin B2 (riboflavin), isolated from the vitamin B2 complex, did not show antipellagra activity in rats. As a result, the antipellagra factor separated from the vitamin B2 complex was called vitamin Bg [5]. Consequently, the factor that cures human pellagra is clearly different from this vitamin Bg. Thus, as the cure factors for black tongue disease of the dog, which resembles human pellagra, nicotinic acid and nicotinamide were isolated. 

Pellagra and Nicotinic Acid Metabolism 271 Clinicopathology of Pellagra Nicotinic Acid Deficiency Nicotinic Acid Metabolism Pathogenesis of Pellagra... 

Pella r, Nia.cin Deficiency. It was 220 years after the first description of pellagra that nicotinic acid was discovered to be the cure for black tongue in dogs (14), a condition suggested by a veterinarian in North Carolina to be similar to human pellagra (15). 

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]. 

Niacin Nicotinic acid, nicotinamide Coenzyme in oxidation and reduction reactions, functional part of NAD and NADP Pellagra—photosensitive dermatitis, depressive psychosis... 

Niacin was discovered as a nutrient during studies of pellagra. It is not strictly a vitamin since it can be synthesized in the body from the essential amino acid tryptophan. Two compounds, nicotinic acid and nicotinamide, have the biologic activity of niacin its metabolic function is as the nicotinamide ring of the coenzymes NAD and NADP in oxidation-reduction reactions (Figure 45-11). About 60 mg of tryptophan is equivalent to 1 mg of dietary niacin. The niacin content of foods is expressed as mg niacin equivalents = mg preformed niacin + 1/60 X mg tryptophan. Because most of the niacin in cereals is biologically unavailable, this is discounted. 

Niacin, which refers to nicotinic acid and nicotinamide, is the metabolic precursor to three nicotinamide coenzymes. These are essential for the activity of a large number of enzymes catalyzing redox reactions. Pellagra is a niacin deficiency disease. 

Oxidation of nicotine with chromic acid led to the isolation of pyridine-3-carboxylic acid, which was given the trivial name nicotinic acid. We now find that nicotinic acid derivatives, especially nicotinamide, are biochemically important. Nicotinic acid (niacin) is termed vitamin B3, though nicotinamide is also included under the umbrella term vitamin B3 and is the preferred material for dietary supplements. It is common practice to enrich many foodstuffs, including bread, flour, corn, and rice products. Deficiency in nicotinamide leads to pellagra, which manifests itself in diarrhoea, dermatitis, and dementia. 

Nicotine forms a number of metabolites in the body, mainly in the liver. Approximate 75% of nicotine is oxidized to cotinine, which is the primary nicotine metabolite. Cotinine can be measured in the blood, urine, and saliva and this is used as a measure of nicotine exposure in tobacco users and in those exposed to secondhand smoke. The oxidation of nicotine also produces nicotinic acid. Nicotinic acid is vitamin B3 and has the common name niacin. Niacin deficiency results in a disease called pellagra, which is found in certain malnourished populations. Pellagras symptoms include dermatitis, diarrhea, sensitivity to light, and dementia. 

FIGURE 13-17 Structures of niacin (nicotinic acid) and its derivative nicotinamide. The biosynthetic precursor of these compounds is tryptophan. In the laboratory, nicotinic acid was first produced by oxidation of the natural product nicotine—thus the name. Both nicotinic acid and nicotinamide cure pellagra, but nicotine (from cigarettes or elsewhere) has no curative activity. 

Niacin (nicotinic acid, nicotinamide) has the active forms NAD and NADPH. It functions in electron transfer. A deficiency of niacin causes pellagra, which is characterized by der matitis, diarrhea, and dementia. There is no known toxicity for this vitamin. High doses of niacin are used to treat hyperlipidemia. 

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... 

In 1937, Elvehjem and coworkers demonstrated that nicotinic acid cured canine "blacktongue." In the same year it was found to cure human pellagra, a terrible disease characterized by weakness, indigestion, and loss of appetite followed by dermatitis,... 

The daily requirement for an adult is about 7.5 mg. The amount is decreased by the presence in the diet of tryptophan, which can be converted partially to nicotinic acid (Chapter 25).d e Tryptophan is about 1 /60 as active as nicotinic acid itself. The one-time prevalence of pellagra in the southern United States was a direct consequence of a diet high in maize whose proteins have an unusually low tryptophan content. 

VITAMIN B2 (Riboflavin). Some earlier designations for this substance included vitamin G, lactoflavin, hepatoflavin, ovoflavin, veidoflavin. The chemical name is 6,7-dimcthyl-9-d-l ribityl isolloxazine. Riboflavin is a complex pigment with a green fluorescence. Riboflavin deficiency frequently accompanies pellagra and the typical lesions of both nicotinic acid and riboflavin deficiency are found in that disease. See also Niacin. 

A deficiency syndrome is not well-defined in humans. Since pyridoxine deficiency often produces nicotinic acid deficiency, pellagra-like clinical manifestations may occur.29 The recommended daily allowance is 1.5 to 2 mg.112... 

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. 

Niacin Nicotinic acid Coenzyme in oxidation and Pellagra-photosensitive... 

After it had been established that pellagra was a nutritional deficiency disease, the next problem was to discover the missing nutrient. Additional dietary protein was shown to be beneficial, thus it was concluded that pellagra was because of a protein deficiency. This view, and later that it was more specifically from a deficiency of tryptophan, was held for some time. In 1938, Spies and coworkers showed that nicotinic acid would cure pellagra thereafter it was gradually accepted that it was a niacin deficiency disease. 

Nicotinic acid was discovered and named as a product of the chemical oxidation of nicotine in 1867. When it was later discovered to he the pellagra-preventing vitamin, it was not assigned a number among the B vitamins because its chemistry was already known. Niacin is generally placed between vitamins B2 and Bg, although it is incorrect to call it vitamin B3, which was at one time assigned to pantothenic acid (Section 12.1). 

There is confusion in the literature because of the North American usage of the name niacin to mean specifically nicotinic acid, whereas the amide is known as niacinamide. The name niacin was coined in the late 1940s when the role of deficiency in the etiology of pellagra was realized, and it was decided that dietary staples should be fortified with the vitamin. It was felt that nicotinic acid was not a suitable name for a substance that was to be added to foods, both because of its phonetic (and chemical) relationship to nicotine and because it is an acid. 

NICOSIDE NICO-SPAN NICOSYL NICOTAM-IN NICOTENE NICOTIL NICOTINE ACID NICOTINIC ACID NICOTINIPCA NICOTINOYL HYDRAZINE NICOTINSAEURE (GER.MAN) NICOVASAN NICOVASEN NICOVEL NICYL NIPELLEN PELLAGRAMIN PELLAGRA PREVENTIVE FACTOR PELLAGRIN PELONIN PEVITON... 

Animals and yeasts can synthesize nicotinamide from tryptophan via hydroxyanthranilic acid (52) and quinolinic acid (53, Fig. 6A) (31), but the biosynthetic capacity of humans is limited. On a diet that is low in tryptophan, the combined contributions of endogenous synthesis and nutritional supply of precursors, such as nicotinic acid, nicotinamide, and nicotinamide riboside, may be insufficient, which results in cutaneous manifestation of niacin deficiency under the clinical picture of pellagra. Exogenous supply of nicotinamide riboside was shown to promote NAD+-dependent Sir2-function and to extend life-span in yeast without calorie restriction (32). 

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