Analysis of nicotinic acid

For more specific analysis, chromatographic methods have been developed. Using reverse-phase columns and uv detection, hplc methods have been appHed to the analysis of nicotinic acid and nicotinamide in biological fluids such as blood and urine and in foods such as coffee and meat. Derivatization techniques have also been employed to improve sensitivity (55). For example, the reaction of nicotinic amide with DCCI (AT-dicyclohexyl-0-methoxycoumarin-4-yl)methyl isourea to yield the fluorescent coumarin ester has been reported (56). After separation on a reversed-phase column, detection limits of 10 pmol for nicotinic acid have been reported (57). 

Pyka, A. Sliwiok, J. Use of traditional structural descriptors in QSRR analysis of nicotinic acid esters. J. Liq. Chromatogr. Relat. Technol. 2004, 27 (5), 785-798. 

Iwaki M, Murakami E, Kakehi K. Chromatographic and capillary electrophoretic methods for the analysis of nicotinic acid and its metabolites. J Chromatogr B Biomed Sci Appl 2000 747 229-40. 

Immobilized Lactobacillus arabinosus strain ATCC 8014 was used for analysis of nicotinic acid (31). The vitamin assay was performed with a pH-electrode and bacteria immobilized in agar. 

Pyka, A. Study of lipophilicity and application of selected topological indexes in QSAR analysis of nicotinic acid... 

TLC is used for the analysis of nicotinic acid and nicotinamides in pharmaceutical preparations, foods, and in biological materials (blood, urine, tissues). 

Analysis of nicotinic acid, nicotinamide, and its metabolites in biological materials, i.e., blood, plasma, urine, and tissues, is important in studies on biochemical pathways (Hengen and deVries, 1985). Finder et al. (1971) described several paper and thin-layer chromatographic systems useful for the differentiation of nucleotides in tissues derived from nicotinamide and nicotinic acid. Hengen and deVries (1985) provided a table summarizing the Rp values of nicotinic acid, nicotinamide, and various intermediates of NAD+ and NADP-I- synthesis for both paper and thin-layer chromatography. Haworth and Walmsley (1972) used two-dimensional TLC on silica gel for the identification of tryptophan metabolites in urine and resolved 32 compounds including nicotinic acid and nicotinamide. Kala et al. (1978) used silica gel TLC to examine urine for nicotinic acid and its metabolites after administration of nicotinyl alcohol. They... 

Hirayama and Maruyama (32) reported the HPLC measurement of a small amount of nicotinic acid in foodstuffs such as rice vinegar, crane vinegar, strawberry jam, orange jam, and apple jam. This method is applicable for variety of foods and performs excellent. The detection limit of nicotinic acid is about 0.01 mg/100 g food. A chromatogram is shown in Figure 9. The other HPLC methods for analysis of nicotinic acid are summarized in Table 3. 

Kitada, Y., Inone, M., Tamase, K., Imou, M., Hasuike, A., Sasaki, M., and Tanigawa, K., Analysis of nicotinic acid and nicotinamide in foods by ion-pair HPLC, Eiyo Shokuryo, 35, 121 124, 1982. 

Both nicotinic acid and nicotinamide have been assayed by chemical and biological methods. Owing to the fact that niacin is found in many different forms in nature, it is important to indicate the specific analyte in question. For example, if biological assay procedures are used, it is necessary to indicate whether the analysis is to determine the quantity of nicotinic acid or if niacin activity is the desired result of the analysis. If nicotinic acid is desired, then a method specific for nicotinic acid should be used. If quantitation of niacin activity is the desired outcome, then all compounds (bound and unbound) which behave like niacin will assay biologically for this substance (1). 

Owing to poor volatihty, derivatization of nicotinic acid and nicotinamide are important techniques in the gc analysis of these substances. For example, a gc procedure has been reported for nicotinamide using a flame ionisation detector at detection limits of - 0.2 fig (58). The nonvolatile amide was converted to the nitrile by reaction with heptafluorobutryic anhydride (56). For a related molecule, quinolinic acid, fmol detection limits were claimed for a gc procedure using either packed or capillary columns after derivatization to its hexafluoroisopropyl ester (58). 

Another selenium-containing molybdenum hydroxylase that has been isolated from Clostridium barkeri (identical to Eubacterium barkeri) is nicotinic acid hydroxylase (NAH). Clostridium barkeri was isolated initially as a fermentor of nicotinic acid and thus NAH is a key enzyme in the efficient fermentation of nicotinic acid as a source of carbon and energy. NAH contained selenium when purified from cells labeled with Se-selenite. However, this label was lost during denaturing gel electrophoresis and also on heating of the enzyme (Dilworth 1982). Exhaustive analysis of selenium-labeled alkylation products of NAH under various conditions revealed selenium was bound as a labile cofactor (Dilworth 1982), and not as seleno-cysteine. This report was the first to describe a selenium-dependent enzyme that did not contain selenium in the form of selenocysteine. 

Purity of nicotinic acid peak confirmed by photodiode array spectral analysis. 

Nicotine biosynthesis also involves the incorporation of nicotinic acid (Fig. 2.2) (Robins et al., 1987), and the availability of this moiety can be as important in nicotine accumulation as that of the putrescine-derived portion. However, the enz)une responsible for the condensation of N-methylpyrrolinium with decarboxylated nicotinic acid, nicotine s)mthase (Friesen and Leete, 1990), was measured at only a very low level of activity, quite inadequate to account for the rates of nicotine accumulation observed in cultures. The molecular analysis of low-nicotine mutants of N. tabacum suggested the presence of regulatory genes (Me 1 and Me 2) governing the expression of nicotine bios)mthesis (Hibi et al, 1994). 

Conversion of nicotinic acid to NAD is illustrated by the following experiment involving mice (Figure 9.63), The animals were injected with carbon-14-labeled nicotinic acid. The livers were removed at the indicated times — 0.33,1.0,3.0, and 10 minutes — and used for analysis of the radioactive metabolites. At 20 seconds, unchanged nicotirric acid (O) w as the major metabolite. At 1 to 3 minutes, there was a temporary accumulation of nicotinic acid ribonucleotide (V) and deamjdo-NAD (A). NAD ( ) was the major metabolite after 3 minutes. 

A new photometric determination of volatile bases in tobacco and tobacco smoke in terms of nicotine, which compares quantitatively with mass spectral and g.c. methods, has been developed.27 A colorimetric method for the estimation of nicotine alkaloids in tobacco by reaction with cyanogen bromide and 4,4 -di-aminostilbene-2,2 -disulphonic acid has also been reported.28 Dilute sulphuric acid extraction of nicotine and anabasine from autopsy tissue appears to be a more efficient method than extraction with acidified ethanol, aqueous oxalic acid, and steam distillation.29 Thin-layer chromatography has been effective in the analysis of nicotine and other alkaloids and drugs.30 Two reports on the isolation of anabasine from anabasine-lupinine mixtures have appeared.31 The P a values of some nicotine-type compounds have been determined.32... 

Bruckert, E., Labreuche, J., and Amarenco P., 2010. Meta-analysis of the effect of nicotinic acid alone or in combination on cardiovascular events and atherosclerosis. Atherosclerosis. 210 353-361. 

Prior to chromatographic analysis of foods, acid or alkaline pretreatment is used to liberate nicotinic acid (Hengen and deVries, 1985). Katsui (1972) described a method for determining nicotinic acid in coffee. After extraction with HCl and decoloration with lead carbonate, the solution was spotted on chromatographic paper and developed in a mobile phase of -butanol-ammonia-water (100 2 16). Spots were visualized using cyanogen bromide and benzidine. This procedure is probably applicable to TLC on cellulose. 

Ion exchange chromatography is still used for preparative purification of nicotinic acid and nicotinamide and their related compounds. Ion exchange systems can separate a large number of substances, but require long analysis times. 

Nicotinamide is present in pork, beef, chicken, and fish. 2-Py and 4-Py are the major metabolites of nicotinic acid and nicotinamide excreted in urine. The contents of 2-Py and 4-Py in blood are below the limit of detection (33). The HPLC methods for analysis of nicotinamide and the related compounds are summarized in Table 4. Shibata et al. (34) reported the simultaneous measurement of nicotinamide, 2-Py, and 4-Py. This method is commonly applicable not only to urine and pharmaceutical preparations but also biological materials and foods. Chromatograms of a reference mixture of isonicotinamide (used as an internal standard), nicotinamide, 2-Py, and 4-Py and of extracts of rat urine, human urine, rat liver, and of the extract of multivitamin preparations are shown in Figure 10. The detection limits for nicotinamide, 2-Py, and 4-Py were 4 pmol (552 pg), 10 pmol (1220 pg), and 2 pmol (304 pg), respectively, at a signal-to-noise ratio of 5 1. Daily urinary excretion of nicotinamide, 2-Py and 4-Py in rats, mice, guinea pigs, hamsters and humans is given in Table 5. 

A method for the separation and independent determination of nicotinic acid and nicotinamide, by which the analysis of mixtures containing only 1 part of one form of the vitamin in the presence of 100 parts of the other, has been described by Sweeney and Hall. In this method solutions con-... 

The equilibrium between neutral a and zwitterionic b forms in the case of nicotinic 6 and isonicotinic 7 acids has been studied by Halle in mixtures of DMSO and water (from 0 to 100%) (Scheme 4). The position of the equilibrium is very sensitive to the composition of the solvent and for more than 80% of DMSO, the a form essentially dominates the equilibrium in solution (96CJC613). An analysis of their data shows a perfect linear relationship (r = 1) between the In Kt of the two acids and moderate linear relationships between In Kt and the percentage of DMSO. Johnston has studied the equilibrium 2-hydroxypyridine/2-pyridone in supercritical fluids (propane at 393 K and 1,1-difluoroethane at 403 K) (89JPC4297). The equilibrium constant Kt (pyridone/hydroxypyridine) increases four-fold for a pressure increase of 40 bar in 1,1-difluoroethane. 

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