Nicotinamide, synthesis

As mentioned in Chapter 1 the same Rhodococcus rhodochrous catalyses the last step in Lonza s >3500 tonnes/year nicotinamide synthesis [94, 111, 112]. Lonza has further developed this technology and currently synthesises a number of relevant fine chemical building blocks with nitrile hydratases [94, 113]. 

Besides its role in nicotinamide synthesis, tryptophan pyrrolase is interesting in another respect. The enzyme is absent in embryonic liver, and in adults hepatic activity is increased by the administration of tryptophan. The developmental biochemistry and the induction of tryptophan are discussed in the section on the biochemistry of growth. 

An inborn error in which there is defective intestinal and renal transport of neutral amino acids, one of these being tryptophan. This amino acid is normally converted to the vitamin, nicotinamide. The clinical features of Hartnup disease are similar to the nicotinamide deficiency disease, pellagra, being due to the low amounts of tryptophan available for nicotinamide synthesis. The disease can be diagnosed by the presence of large amounts of indole compounds in the urine, which result from the action of gut bacteria on the unabsorbed dietary tryptophan. 

Synthesis of 4,6-disubstituted-2-picolines and their corresponding nicotinamides has been developed using (3-arninocrotoriitrile (52) and a, P-unsaturated compounds, where = aryl (51). 

Key intermediates in the industrial preparation of both nicotinamide and nicotinic acid are alkyl pyridines (Fig. 1). 2-Meth5l-5-ethylpyridine (6) is prepared in ahquid-phase process from acetaldehyde. Also, a synthesis starting from ethylene has been reported. Alternatively, 3-methylpyridine (7) can be used as starting material for the synthesis of nicotinamide and nicotinic acid and it is derived industrially from acetaldehyde, formaldehyde (qv), and ammonia. Pyridine is the principal product from this route and 3-methylpyridine is obtained as a by-product. Despite this and largely due to the large amount of pyridine produced by this technology, the majority of the 3-methylpyridine feedstock is prepared in this fashion. 

During the 1950s and 1960s Hafner used Konig salts, derived from the reaction of A -methyl aniline with Zincke salt 1, for azulene synthesis. The Zincke reaction also achieved prominence in cyanine dye synthesis and as an analytical method for nicotinamide determination. ... 

Zincke salts have played an important role in the synthesis of NAD /NADH coenzyme analogs since a 1937 report on the Zincke synthesis of dihydropyridine 7 for use in a redox titration study.The widely utilized nicotinamide-derived Zincke salt 8, first synthesized by Lettre was also used by Shifrin in 1965 for the preparation and study of NAD /NADH analogs. In 1972, Secrist reported using 8 for synthesis of simplified NAD analogs such as 10 for use in spectroscopic studies (Scheme 8.4.4). Subsequent utilization of 8 is discussed later in this article. 

Most foods of animal origin contain nicotinamide in the coenzyme form (high bioavialability). Liver and meat are particularly rich in highly bioavailable niacin. Most of the niacin in plants, however, occurs as nicotinic acid in overall lower concentrations and with a lower bioavailability. The major portion of niacin in cereals is found in the outer layer and its bioavailability is as low as 30% because it is bound to protein (niacytin). If the diet contains a surplus of L-tryptophan (Ttp), e.g., more than is necessary for protein synthesis, the liver can synthesize NAD from Trp. Niacin requirements are therefore declared as niacin equivalents (1 NE = 1 mg niacin = 60 mg Trp). 

Rice bran is the richest natural source of B-complex vitamins. Considerable amounts of thiamin (Bl), riboflavin (B2), niacin (B3), pantothenic acid (B5) and pyridoxin (B6) are available in rice bran (Table 17.1). Thiamin (Bl) is central to carbohydrate metabolism and kreb s cycle function. Niacin (B3) also plays a key role in carbohydrate metabolism for the synthesis of GTF (Glucose Tolerance Factor). As a pre-cursor to NAD (nicotinamide adenine dinucleotide-oxidized form), it is an important metabolite concerned with intracellular energy production. It prevents the depletion of NAD in the pancreatic beta cells. It also promotes healthy cholesterol levels not only by decreasing LDL-C but also by improving HDL-C. It is the safest nutritional approach to normalizing cholesterol levels. Pyridoxine (B6) helps to regulate blood glucose levels, prevents peripheral neuropathy in diabetics and improves the immune function. 

The most important product of the hexose monophosphate pathway is reduced nicotinamide-adenine dinucleotide phosphate (NADPH). Another important function of this pathway is to provide ribose for nucleic acid synthesis. In the red blood cell, NADPH is a major reducing agent and serves as a cofactor in the reduction of oxidized glutathione, thereby protecting the cell against oxidative attack. In the syndromes associated with dysfunction of the hexose monophosphate pathway and glutathione metabolism and synthesis, oxidative denaturation of hemoglobin is the major contributor to the hemolytic process. 

Human CYPs are multicomponent enzyme systems, requiring at a minimum the CYP enzyme component and a reductase component to be functional. The reductase requires a reduced nicotinamide cofactor, typically NADPH, and this cofactor must be regenerated to provide a steady supply of reducing equivalents for the reductase. Regeneration is accomplished with a separate substrate and enzyme. Glucose-6-phosphate and glucose-6-phosphate dehydrogenase have been widely used for this purpose. The overall complexity of the reaction mixtures and their cost have been barriers to the widespread use of recombinant human CYPs for metabolite synthesis in the past. 

The procedure given is essentially that described by Taylor and Crovetti.3 Nicotinamide-1-oxide (m.p. 275-276° dec.) has also been prepared by the alkaline hydrolysis of nicotinonitrile-1-oxide 4 and by the action of ammonium hydroxide on methyl nicotinate-l-oxide.6 The melting point of the product prepared by the latter synthesis is reported to be 282-284° dec. 

The asymmetric reduction of prochiral functional groups is an extremely useful transformation in organic synthesis. There is an important difference between isolated enzyme-catalyzed reduction reactions and whole cell-catalyzed transformations in terms of the recycling of the essential nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] cofactor. For isolated enzyme-catalyzed reductions, a cofactor recycling system must be introduced to allow the addition of only a catalytic amount (5% mol) of NAD(P)H. For whole cell-catalyzed reductions, cofactor recycling is automatically achieved by the cell, and the addition of a cofactor to the reaction system is normally not required. 

Early investigators assumed that human erythrocytes could convert nicotinic acid, but not the amide, into NAD (H3, H8). There are later reports to the contrary, i.e., that nicotinamide, but not the acid, produced increased synthesis of NAD-active material (L3). To resolve these discrepancies, standards for assaying nicotinic acid activity were prepared by mixing equal weights of the acid and amide, because these... 

H3. Handler, P., and Kohn, H. I., The mechanism of cozymase synthesis in the human erythrocyte a comparison of the role of nicotinic acid and nicotinamide. J. Biol. Chem. 150, 447-452 (1943). 

L3. Leder, H. G., and Handler, P., Synthesis of nicotinamide mononucleotide by human erythrocytes in vitro. J. Biol. Chem. 189, 889-899 (1951). 

Group-transfer reactions often involve vitamins3, which humans need to have in then-diet, since we are incapable of realizing their synthesis. These include nicotinamide (derived from the vitamin nicotinic acid) and riboflavin (vitamin B2) derivatives, required for electron transfer reactions, biotin for the transfer of C02, pantothenate for acyl group transfer, thiamine (vitamin as thiamine pyrophosphate) for transfer of aldehyde groups and folic acid (as tetrahydrofolate) for exchange of one-carbon fragments. Lipoic acid (not a vitamin) is both an acyl and an electron carrier. In addition, vitamins such as pyridoxine (vitamin B6, as pyridoxal phosphate), vitamin B12 and vitamin C (ascorbic acid) participate as cofactors in an important number of metabolic reactions. 

To facilitate its application in organic synthesis, we developed a lyophilized cell powder of Sphingomonas sp. HXN-200 as a biohydroxylation catalyst. Hydro-xylation of A-benzyl-piperidine with such catalyst powder showed 85% of the activity of a similar hydroxylation with frozen/thawed cells, shown in Figure 15.6. The fact that rehydrated lyophilized cells are able to carry out such a reduced nicotinamide adenine dinucleotide (NADH)-dependent hydroxylation indicates that these cells are capable of retaining and regenerating NADH at rates equal to or exceeding the rate of hydroxylation. To our knowledge, this is the first example of the use of lyophilized cells for a cofactor-dependent hydroxylation. 

As expected, in vitro transcription assays involving PARP-1, NAD, and PARC illustrate these predicted outcomes (Kim et al, 2004). Even when driven by a transcriptional activator, such as estradiol-bound estrogen receptor, transcription is repressed when PARP-1 is added to chromatin templates. The repression is reversed by NAD+, and the NAD+-dependent effects are reversed by PARC (Kim et al, 2004). This system for transcriptional control shifts new importance onto the enzymes responsible for synthesis of NAD+ in the nucleus, such as nicotinamide mononucleotide adenylyltransferase-1 (Magni et al, 2004). Because NAD+ facilitates the decompaction of chromatin and the derepression of transcription, nuclear NAD+ biosynthetic enzymes may play critical roles as cofactors. 

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