myosmine and nornicotine

Recent studies in rodents suggest that non-nicotine constituents of tobacco smoke (e.g., minor tobacco alkaloids) may promote tobacco consumption-either through their own pharmacological effects or by augmenting the effects of nicotine. However, there is scant information on the behavioral pharmacology of minor tobacco alkaloids in primate species.. The present studies were conducted to determine whether the minor tobacco alkaloids nornicotine, anabasine, anatabine, myosmine, and cotinine exhibit nicotine-like behavioral effects in squirrel monkeys.. Initial experiments were conducted to determine the effects of nicotine (0.032-1.0 mg/kg) and the minor tobacco alkaloids nornicotine (1-1.8 mg/kg), anabasine (0.1-1.0 mg/kg), anatabine (10-32 mg/kg), myosmine (0.32-1.8 mg/kg), and cotinine (10-180 mg/kg) on food-maintained performance (n = 4). Next, the ability of tobacco alkaloids to substitute for the α4β2-selective nicotinic agonist (+)-epibatidine in drug discrimination experiments was evaluated in a separate group of monkeys (n = 4).. Results show that nicotine and each minor tobacco alkaloid except cotinine (a) produced dose-related decreases in food-maintained responding; (b) substituted for (+)-epibatidine and, in additional experiments, produced additive effects when combined with nicotine; (c) induced emesis or tremor at doses that reduced food-maintained responding and had (+)-epibatidine-like discriminative-stimulus effects; and (d) based on correlation with reported receptor binding affinities, likely produced their behavioral effects through α4β2 receptor mechanisms.. Selected minor tobacco alkaloids have nicotinic-like effects that may contribute to tobacco consumption and addiction.

Topics: Alkaloids; Anabasine; Animals; Behavior, Addictive; Behavior, Animal; Cotinine; Dose-Response Relationship, Drug; Male; Nicotiana; Nicotine; Pyridines; Saimiri; Smoke

Nornicotine is a natural alkaloid produced by plants in the genus Nicotiana and is structurally related to nicotine. Importantly, nornicotine is the direct precursor of tobacco-specific nitrosamine N'-nitrosonornicotine, which is a highly potent human carcinogen. Microbial detoxification and degradation of nicotine have been well characterized; however, until now, there has been no information on the molecular mechanism of nornicotine degradation. In this study, we demonstrate the transformation of nornicotine by the nicotine-degrading strain Shinella sp. HZN7. Three transformation products were identified as 6-hydroxy-nornicotine, 6-hydroxy-myosmine, and 6-hydroxy-pseudooxy-nornicotine by UV spectroscopy, high-resolution mass spectrometry, nuclear magnetic resonance, and Fourier transform-infrared spectroscopy analyses. The two-component nicotine dehydrogenase genes nctA1 and nctA2 were cloned, and their product, NctA, was confirmed to be responsible for the conversion of nornicotine into 6-hydroxy-nornicotine as well as nicotine into 6-hydroxy-nicotine. The 6-hydroxy-nicotine oxidase, NctB, catalyzed the oxidation of 6-hydroxy-nornicotine to 6-hydroxy-myosmine, and it spontaneously hydrolyzed into 6-hydroxy-pseudooxy-nornicotine. However, 6-hydroxy-pseudooxy-nornicotine could not be further degraded by strain HZN7. This study demonstrated that nornicotine is partially transformed by strain HZN7 via nicotine degradation pathway.

Topics: Alkaloids; Biotransformation; Cloning, Molecular; Insecticides; Nicotine; Oxidoreductases Acting on CH-NH Group Donors; Rhizobiaceae; Spectrum Analysis

Insurance agencies might request laboratories to differentiate whether a deceased has been a smoker or not to decide about refunding of his nonsmoker rate. In this context, the question on a solid proof of tobacco alkaloids and major metabolites in tissues came up. Currently, an appropriate assay is still lacking to analyze tissue distribution in smokers or nonsmokers. Nicotine (NIC), nornicotine (NNIC), anatabine (ATB), anabasine (ABS), and myosmine (MYO) are naturally occurring alkaloids of the tobacco plant; most important phase I metabolites of NIC are cotinine (COT), norcotinine (NCOT), trans-3'-hydroxycotinine (HCOT), nicotine-N'-oxide (NNO), and cotinine-N-oxide (CNO). An analytical assay for their determination was developed and applied to five randomly selected autopsy cases.. Homogenates using 500 mg aliquots of tissue samples were analyzed by liquid chromatography/tandem mass spectrometry following solid phase extraction. The method was validated according to current international guidelines.. NIC, COT, NCOT, ABS, ATB, and HCOT could be detected in all tissues under investigation. Highest NIC concentrations were observed in the lungs, whereas highest COT concentrations have been found in the liver. MYO was not detectable in any of the tissues under investigation.. The assay is able to adequately separate isobaric analyte pairs such as NIC/ABS/NCOT and HCOT/CNO thus being suitable for the determination of tobacco alkaloids and their phase I metabolites from tissue. More autopsy cases as well as corresponding body fluids and hair samples will be investigated to differentiate smokers from nonsmokers.

Topics: Alkaloids; Anabasine; Animals; Brain Chemistry; Cattle; Chickens; Chromatography, Liquid; Ganglionic Stimulants; Humans; Liver; Lung; Muscle, Skeletal; Nicotiana; Nicotine; Pyridines; Smoking; Solid Phase Extraction; Swine; Tandem Mass Spectrometry; Tissue Distribution

While nicotine is the primary addictive compound in tobacco, other tobacco constituents including minor alkaloids (e.g., nornicotine, anabasine) may also contribute to tobacco addiction by mimicking or enhancing the effects of nicotine. Further evaluating the behavioral effects of minor alkaloids is essential for understanding their impact on tobacco addiction and informing development of tobacco product standards by the FDA.. This study compared the addiction-related effects of nicotine and the minor alkaloids nornicotine, anabasine, myosmine, anatabine, and cotinine on intracranial self-stimulation (ICSS) thresholds in rats.. Acute injection of nicotine produced reinforcement-enhancing (ICSS threshold-decreasing) effects at low to moderate doses, and reinforcement-attenuating/aversive (ICSS threshold-increasing) effects at high doses. Nornicotine and anabasine produced similar biphasic effects on ICSS thresholds, although with lower potency compared to nicotine. Myosmine only elevated ICSS thresholds at relatively high doses, while anatabine and cotinine did not influence ICSS thresholds at any dose. None of the alkaloids significantly influenced ICSS response latencies, indicating a lack of nonspecific motoric effects.. These findings indicate that some minor tobacco alkaloids can either fully (nornicotine, anabasine) or partially (myosmine) mimic nicotine's addiction-related effects on ICSS, albeit at reduced potency. These findings emphasize the need for further study of the abuse potential of minor alkaloids, including evaluation of their effects when combined with nicotine and other tobacco constituents to better simulate tobacco exposure in humans. Such work is essential for informing FDA regulation of tobacco products and could also lead to the development of novel pharmacotherapies for tobacco addiction.

Topics: Alkaloids; Anabasine; Animals; Brain; Cotinine; Male; Nicotine; Pyridines; Rats; Self Stimulation

An efficient nicotine-degrading fungus was isolated from tobacco leaves and identified as Aspergillus oryzae 112822 based on morphological characteristics and sequence analysis of 18S rDNA, 5.8S rDNA and the internal transcribed spacer (5.8S-ITS region). When the strain was cultured in a medium with tobacco leaf extract for 40 h, the maximum amount of cell growth was 3.6 g l(-1) and nicotine degradation was 2.19 g l(-1). The intermediates of nicotine degradation by resting cells were isolated by preparative TLC or semi-preparative HPLC, and identified by TLC, MS, NMR, Fourier-transform (FT)-IR and GC-MS analysis. The pathway for nicotine degradation in A. oryzae 112822 was proposed to be from nicotine to 2,3-dihydroxypyridine through the intermediates nornicotine, myosmine, N-methylnicotinamide and 2-hydroxy-N-methylnicotinamide. The ring of 2,3-dihydroxypyridine was opened between the 2- and 3-hydroxy positions to yield succinic acid. N-methylnicotinamide and 2,3-dihydroxypyridine were satisfactorily verified as metabolites of nicotine degradation. This is the first elucidation of a pathway for nicotine degradation in fungi.

Topics: Alkaloids; Aspergillus oryzae; Biodegradation, Environmental; DNA, Ribosomal; DNA, Ribosomal Spacer; Gas Chromatography-Mass Spectrometry; Metabolic Networks and Pathways; Models, Biological; Niacinamide; Nicotiana; Nicotine; Plant Leaves; Pyridines; RNA, Ribosomal, 18S

Nicotine or nornicotine enriched with stable isotopes in either the N'-methyl group or the pyrrolidine-N were fed to Nicotiana plumbaginifolia suspension cell cultures that do not form endogenous nicotine. The metabolism of these compounds was investigated by analysing the incorporation of isotope into other alkaloids using gas chromatography-mass spectroscopy (GC-MS). Nicotine metabolism primarily resulted in the accumulation of nornicotine, the N'-demethylation product. In addition, six minor metabolites appeared during the course of nicotine metabolism, four of which were identified as cotinine, myosmine, N'-formylnornicotine and N'-carboethoxynornicotine. While cotinine was formed from [(13)C,(2)H(3)-methyl]nicotine without dilution of label, N'-formylnornicotine was labelled at only about 6% of the level of nicotine and N'-carboethoxynornicotine was unlabelled. Feeding with [1'-(15)N]nornicotine resulted in incorporation without dilution of label into both N'-formylnornicotine and N'-carboethoxynornicotine. This pattern strongly indicates that, while nornicotine and cotinine are derived directly from nicotine, N'-formylnornicotine and N'-carboethoxynornicotine are metabolites of nornicotine. Thus, it is directly demonstrated that N'-formylnornicotine is not an intermediate in nicotine demethylation.

Topics: Alkaloids; Cell Culture Techniques; Cells, Cultured; Cotinine; Gas Chromatography-Mass Spectrometry; Methylation; Nicotiana; Nicotine; Nitrogen Isotopes

To determine the effects of nicotine alkaloids on the microcirculation of a variety of tissues, we infused equimolar concentrations (10(-4)-10(-1) M) of 1-nicotine (N), nor-nicotine (NN), dihydro-metanicotine (DHN) in the skeletal muscle, in a skin flap chamber, and in a saline-perfused mesentery preparation of the rat (WistHan). The qualitative and quantitative responses to these equimolar concentrations were measured by modern microcirculatory techniques. Our data showed that 1-nicotine and its alkaloids differ significantly in dose-dependency, maximal vasoactivity, tissue specificity, and microvascular localization. In conclusion, the small differences in the chemical structure of the pyridine ring which distinguishes the alkaloids cause significantly different microvascular effects.

Topics: Alkaloids; Animals; Dose-Response Relationship, Drug; Female; Insecticides; Male; Mesentery; Microcirculation; Muscles; Nicotine; Organ Specificity; Rats; Rats, Inbred Strains; Skin; Stereoisomerism; Vasoconstriction