Assays nicotine

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... 

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). 

As with many of the vitamins, biological assays have an important historical role and are widely used. For example, microbiological assays use l ctobacillusplantarum ATCC No. 8014 (57,59) or l ctobacillus arabinosus (60). These methods are appropriate for both nicotinamide and nicotinic acid. Selective detection of nictonic acid is possible if l euconostoc mesenteroides ATCC No. 9135 is used as the test organism (61). The use of microbiological assays have been reviewed (62). 

Salminen, O., Whiteaker, P., Grady, S.R., Collins, A.C., McIntosh, J.M., Marks, M.J. The subunit composition and pharmacology of alpha-Conotoxin Mil-binding nicotinic acetylcholine receptors studied by a novel membrane-binding assay. Neuropharmacology. 48 696, 2005. 

Nishiyama and Kuninori [65] described a combination method of assay for penicillamine using HPLC and postcolumn reaction with 6,6 -dithiodi(nicotinic acid). Thiols were separated by HPLC on a reversed-phase column (25 cm x 4.6 mm) packed with Fine Sil 08-10, with 33 mM KH2PO4 (adjusted to pH 2.2 with H3PO4) or 33 mM sodium phosphate (pH 6.8) as the mobile phase. Detection was by postcolumn derivatization with 6,6 -dithiodi(nicotinic acid), and measurement of the absorbance of the released 6-mercaptonicotinic acid was made at 344 nm. The detection limit for penicillamine was 0.1 nmol. A comparison was made with a... 

Smoking researchers may have to wait for more robust genetic assays before the issue is finally settled [30], but pharmacological inhibitors of CYP2A6 reduce smoking [31] and it seems likely that an inherited defect in nicotine metabolism would have the same effect. 

Recently nicotinic acid has been found to lower serum cholesterol in hypercholesteremia, and also in normal persons and rabbits (A3, F2). It was shown that the hypercholesteremia, induced by a 48-hour fast, could be completely corrected by giving the animals large doses of nicotinic acid during the fast. In contrast to nicotinic acid, nicotinamide does not lower the cholesterol level (M10). Several explanations are offered for the action of nicotinic acid (1) it inhibits cholesterol biosynthesis, (2) it interferes with coenzyme A, and (3) it involves a hitherto unknown pharmacologic effect. The renewed clinical interest in nicotinic acid induced us to look for a more specific and sensitive assay for nicotinic acid (B7, M8). 

We have developed a direct assay for vitamin Be in blood, serum, urine, cerebrospinal fluid, and tissue, based on the ciliate, Tetrahymena pyriformvs. The techniques are essentially those described for nicotinic acid (see Section 4.1), except that vitamin Be is omitted from the basal medium both nicotinic acid and its amide are added each at 0.1 mg/100 ml of basal medium. The method for blood, serum, urine, cerebrospinal fluid, and tissues is given below. 

To illustrate the principles of an equilibrium dialysis experiment, we will describe the binding of [ H] acetylcholine to the nicotinic acetylcholine receptor (nAChR) in native membranes from Torpedo electro-plax. The data obtained from such an experiment are shown in Figure 10-7 where they are compared with data obtained from a centrifugation assay described below (Protocol 4.2). 

Anderson DJ, Puttfarcken PS, Jacobs 1, Faltynek C (2000) Assessment of nicotinic acetylcholine receptor-mediated release of [ H]-norepinephrine from rat brain slices using a new 96-well format assay. Neuropharmacology 39 2663-2672 Anney RJ, Olsson CA, Lotfi-Miri M, Patton GC, Williamson R (2004) Nicotine dependence in a prospective population-based study of adolescents the protective role of a functional tyrosine hydroxylase polymorphism. Pharmacogenetics 14 73-81 Auerbach A, Akk G (1998) Desensitization of mouse nicotinic acetylcholine receptor channels. 

Kyerematen GA, Taylor LH, deBethizy JD, Vesell ES (1988a) Pharmacokinetics of nicotine and 12 metabolites in the rat. Application of a new radiometric high performance liquid chromatography assay. Drug Metab Dispos 16 125-129... 

Assays of acetyl- and butyrylcholine esterases inhibition, as well as of modulation of calcium channels and nicotinic receptors have been conducted in vivo. Moreover, their interaction with the active center of acetylcholine esterase has been simulated by molecular dynamics. For synthesized compounds the IC50 of acetylcholine esterase inhibition was about 9 X M, and for the most active the value was four to five times... 

Weak acid/strong base titration is used in the pharmacopoeial assays of benzoic acid, citric acid, chlorambucil injection, mustine injection, nicotinic acid tablets and undecanoic acid. 

Dawson DA et al (1988) Evaluation of the developmental toxicity of nicotine and cotinine with frog embryo teratogenesis assay Xenopus. Teratog Carcinog Mutagen 8 329-338... 

Rao, T. S., Correa, L. D., Reid, R. T., Lloyd, G. K. Evaluation of anti-nociceptive effects of neuronal nicotinic acetylcholine receptor (nAChR) ligands in the rat tail-flick assay, Neuropharmacology 1996, 35, 393-405. 

Sullivan, J. P., Briggs, C. A., Donnelly-Roberts, D., Brioni, J. D., Radek, R. J., McKenna, D. G., Campbell, J. E., Arneric, S. P., Decker, M. W. (+)-Epibatidine can differentially evoke responses mediated by putative subtypes of nicotinic acetylcholine receptors (nAChR) ligands in the rat tail-flick assay, Med. Chem. Res. 1994, 4, 502-516. 

The amino acids believed to be involved in GTF are the constituents of the naturally occurring tripeptide glutathione (256). Anderson et al. have reported a complex of glutathione/nicotinic acid and chromium(III) to be particularly active in their in vitro assay.1198 The complex was described as being purified by HPLC, but the details of the preparation are not available. 

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