Nicotinic acid, analysis

Caf,Tb,Tp,hypoX,X,UA,tri-gonellin,nicotinic acid Analysis coffee Aminex 50W-X4, NH4+ 440x6 NH -formate buffer(pH 3.65) in 25 EtOH 10,15,38... 

Caf.Tb.Tp.hypoX.trigonel-lin,nicotinic acid Analysis in coffee Zipax SCX 1000x2.1 aq. HN03(pH 1.56) 40... 

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). 

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). 

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). 

The infrared technique has been described in numerous publications and recent reviews were published by Davies and Giangiacomo (2000), Ismail et al. (1997) and Wetzel (1998). Very few applications have been described for analysis of additives in food products. One interesting application is for controlling vitamin concentrations in vitamin premixes used for fortification of food products by attenuated total reflectance (ATR) accessory with Fourier transform infrared (FTIR) (Wojciechowski et al., 1998). Four vitamins were analysed - Bi (thiamin), B2 (riboflavin), B6 (vitamin B6 compounds) and Niacin (nicotinic acid) - in about 10 minutes. The partial least squares technique was used for calibration of the equipment. The precision of measurements was in the range 4-8%, similar to those obtained for the four vitamins by the reference HPLC method. 

The first biochemical analysis of a selenium-containing XDH was reported in 1999 by Andreesen s group. This preparation was specific for xanthine and did not hydroxylate nicotinic acid. Moreover, the enzyme contained FAD, acid-labile sulfur, iron, and a dinucleotide molybdenum cofactor. Most intriguing was the near-equimolar presence of tungsten and molybdenum. It should be noted that the culture medium contained nearly equimolar levels of these metals, making one wonder whether the specificity of this enzyme for metal may be relaxed (i.e., can use Mo or W). Selenium was also found in the preparation and could be released by treatment with cyanide indicating it was also a labile cofactor. This further confirmed the chemical nature of the cofactor from the NAH enzyme from the same strain. ... 

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. 

K Shibata, T Shimono. Nicotinic acid and nicotinamide. In AP De Leenheer, WE Lambert, HJ Nelis, eds. Modern Chromatographic Analysis of Vitamins. 2nd ed. New York Marcel Dekker, 1992, pp 285-317. 

Alkaloids of the Celastraceae.—The structures of eleven new alkaloids of this family, all related to nicotinic acid, have been elucidated, largely by interconversions and degradations and by spectral study and analysis.28-30... 

A meta-analysis was performed on randomized trials assessing lipid-lowering therapy in 698 patients with PAD who were treated with a variety of therapies, including diet, cholestyramine, probucol, and nicotinic acid, for four months to three years (8). There was a significant difference in total mortality [0.7% in the treated patients, as compared with 2.9% in the patients given placebo (p = NS)], with an additional reduction in disease progression, as measured by angiography and the severity of claudication. 

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. 

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. 

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. 

Fig. 8-87. Analysis of water-soluble vitamins. - Separator column Spherisorb ODS 2 (5 pm) eluent (A) 0.1 mol/L KOAc (pH 4.2 with HOAc), (B) water/methanol/acetonitrile (50 10 40 v/v/v) gradient linear, 6% B in 30 min to 100% B flow rate 2 mL/min detection UV (254 nm) injection volume 50 pL solute concentrations 5 nmol each of ascorbic acid (1), nicotinic acid (2), thiamine (3), pyridoxine (4), nicotinic add amide (5), p-aminobenzoic add (6), cyanocobala-mine (7), and riboflavine (8).

Casal S., Oliveira M., Alves M.R. and Ferreira M.A. (2000a) Discriminate analysis of roasted coffee varieties for trigonelline, nicotinic acid and caffeine content. J. Agric. Food Chem. 48 (8), 3420—4. 

The concept utilised was based on a retrosynthetic analysis comprising a nicotinic acid derivative (41) and a dihydroxychromone. The nicotinic acid moiety was prepared by lithiation of nicotinaldehyde followed by treatment with trimethyltin chloride. After benzoylation of the chromone noreugenin to protect the free phenolic group the compound was brominated to yield (42) and the two compounds formed were reacted with the nicotinic derivative to give a C-C bond with either the 6 or 8 of the chromone to give a compound such as (43) from which isoschumanniophytine or schumanniophytine respectively could be easily obtained by debenzoylation and lactonisation. 

The method was used successfuUy to analyse a variety of compounds, including p-bromoacetanilidide, p-nitroanilidide, nicotinic acid sodium notropentacyanoferrate (III), 1,2,3-benzotriazole and blood. The absolute accuracy of the analysis is 0.1%. One operator can perform 30 analyses during an 84t ift. 

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. 

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