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Heliyon Nov 2017A range of endemic species are chewed as a smokeless tobacco by several Aboriginal populations of Australia. In tobacco research, nicotine to nornicotine conversion is...
A range of endemic species are chewed as a smokeless tobacco by several Aboriginal populations of Australia. In tobacco research, nicotine to nornicotine conversion is important because nornicotine lowers tobacco quality and is detrimental to health. A diverse group of cytochrome P450 genes with different transcriptional regulations are involved in this conversion. The primary aims of this study were to quantify the pyridine alkaloids and investigate nicotine to nornicotine conversion in laboratory-grown Australian spp. Nicotine, nornicotine, anatabine, anabasine, myosmine and cotinine were quantified in fresh leaves of 24 out of the 26 recognised Australian taxa. Conserved regions of CYP82E related genes were PCR amplified in all studied taxa. The conversion process in fresh leaves was compared with that in leaves that underwent a simulated curing process for species that we identified as being high converters (, ) and low converters (). Agarose gel electrophoretic analysis of CYP82E related genes obtained from the PCR amplification of the cDNA in fresh versus leaves with simulated curing showed about a 3-fold increase in transcript accumulation levels in cured leaves of the high converter species, while the transcript accumulation in and maintained a steady basal level and increased by a small amount in . This suggests the presence of functional loci that are triggered by curing in only high converter species and indicates a potential risk for chewers of high converter species.
PubMed: 29264422
DOI: 10.1016/j.heliyon.2017.e00469 -
Journal of Chromatography. A Jan 2016The α3β4α5 nAChR has been recently shown to be a useful target for smoking cessation pharmacotherapies. Herein, we report on the development and characterization of...
Development and characterization of the α3β4α5 nicotinic receptor cellular membrane affinity chromatography column and its application for on line screening of plant extracts.
The α3β4α5 nAChR has been recently shown to be a useful target for smoking cessation pharmacotherapies. Herein, we report on the development and characterization of the α3β4α5 nicotinic receptor column by frontal displacement chromatography. The binding affinity of the nicotine and minor alkaloids found in tobacco smoke condensates were determined for both the α3β4 and α3β4α5 nicotinic receptors. It was demonstrated that while no subtype selectivity was observed for nicotine and nornicotine, anabasine was selective for the α3β4α5 nicotinic receptor. The non-competitive inhibitor binding site was also studied and it was demonstrated while mecamylamine was not selective between subtypes, buproprion showed subtype selectivity for the α3β4 nicotinic receptor. The application of this methodology to complex mixtures was then carried out by screening aqueous-alcoholic solutions of targeted plant extracts, including Lycopodium clavatum L. (Lycopodiaceae) and Trigonella foenum graecum L. (Fabaceae) against both the α3β4 and α3β4α5 nAChRs.
Topics: Alkaloids; Anabasine; Binding Sites; Chemistry Techniques, Analytical; Chromatography, Affinity; Fabaceae; Lycopodiaceae; Nicotine; Plant Extracts; Receptors, Nicotinic; Smoke
PubMed: 26774122
DOI: 10.1016/j.chroma.2015.12.065 -
Biomedicines Mar 2023Ulcerative colitis (UC) is an intractable disease that causes persistent colonic inflammation. Numerous studies have reported that smoking can afford clinical benefits...
Ulcerative colitis (UC) is an intractable disease that causes persistent colonic inflammation. Numerous studies have reported that smoking can afford clinical benefits in UC. This study aimed to elucidate whether nicotine, the main component in cigarettes, can exert pharmacological effects against experimental UC. To achieve this objective, we compared the effects of nicotine with those of structural nicotine analogs in a UC rodent model (Slc: Wistar rats, male, 9-week-old, and 220-250 g/rat). Nicotine, or a respective structural analog (nornicotine, cotinine, anabasine, myosmine, and anatabine), was administered intraperitoneally daily to rats ( = 6/group) exhibiting dextran sulfate sodium-induced experimental colitis. Examining the colon tissues of model rats, we compared disease severity, cytokine secretion, and α7 nicotine acetylcholine receptor (nAChR7) expression. We observed that nicotine administration induced weight loss at 2.35% in 10 days. Notably, the reduction in histological severity (score) of UC was more pronounced in rats treated with nicotine (score = 4.83, = 0.042) than in untreated rats (score = 8.17). Nicotine administration increased nAChR7 expression 6.88-fold ( = 0.022) in inflammatory sites of the colon, mainly by suppressing the production of interleukin (IL)-1β and IL-6. Moreover, the secretion of these cytokines was suppressed in lipopolysaccharide-stimulated rat macrophages (MΦ) treated with nicotine. In conclusion, nicotine better alleviates experimental UC than the examined structural analogs by activating nAChR7 expression and suppressing proinflammatory cytokines in MΦ.
PubMed: 36979901
DOI: 10.3390/biomedicines11030922 -
Addiction Science & Clinical Practice Sep 2019Tobacco use is a chronic relapsing disease, and remains the leading cause of preventable death in much of the world. Increasingly, tobacco use, chiefly cigarette...
Tobacco use is a chronic relapsing disease, and remains the leading cause of preventable death in much of the world. Increasingly, tobacco use, chiefly cigarette smoking, is being framed as a chronic disease, with periods of use and periods of abstinence. An implicit component of this conceptualization is that treatment-both counseling and pharmacotherapy-may be needed at various intervals for extended periods of time, perhaps over an individual's lifetime. This would mirror the treatment of other chronic conditions, such as diabetes, hypertension, or hyperlipidemia. Yet, clinical trials of tobacco dependence treatment still generally model outcome measures in terms of cessation, abstinence, or quitting, measured at discrete time points. This reinforces the notion that smoking, or tobacco dependence, is a dichotomous condition, and that one is either "cured," or not. Although the goal of treating tobacco dependence is to ensure long-term abstinence (i.e. "quitting"), this model is discordant with clinical reality, in which of periods of tobacco use are interspersed with periods of abstinence. Hence, the goal of treatment is to lengthen the duration of the latter, while shortening the duration of the former. In the clinical arena, this dichotomous model of tobacco use is reflected in electronic health records, where smoking is generally categorized as current, former, or never. We propose that clinicians move away from the dichotomous categorization of tobacco use, and adopt methods used to categorize the status of other chronic conditions. Specifically, biomarkers such as carbon monoxide, cotinine, and anabasine, measured at regular intervals, can provide clinicians with much clearer, clinically relevant and actionable assessments of current tobacco use by their patients. This can be done without making reference to dichotomous states such as current or former use of tobacco. In psychological terms, one can frame tobacco use in terms of states, attributes in specific situations at discrete moments in time, rather than the more durable traits.
Topics: Biomarkers; Chronic Disease; Humans; Patient Care Planning; Smoking Cessation; Tobacco Smoking; Tobacco Use Disorder
PubMed: 31474229
DOI: 10.1186/s13722-019-0159-z -
Bioscience, Biotechnology, and... Aug 2005Neonicotinoid insecticides, which act selectively on insect nicotinic acetylcholine receptors (nAChRs), are used worldwide for insect pest management. Studies that span... (Review)
Review
Neonicotinoid insecticides, which act selectively on insect nicotinic acetylcholine receptors (nAChRs), are used worldwide for insect pest management. Studies that span chemistry, biochemistry, molecular biology, and electrophysiology have contributed to our current understanding of the important physicochemical and structural properties essential for neonicotinoid actions as well as key receptor residues contributing to the high affinity of neonicotinoids for insect nAChRs. Research to date suggests that electrostatic interactions and possibly hydrogen bond formation between neonicotinoids and nAChRs contribute to the selectivity of these chemicals. A rich diversity of neonicotinoid-nAChR interactions has been demonstrated using voltage-clamp electrophysiology. Computational modeling of nAChR-imidacloprid interaction has assisted in the interpretation of these results.
Topics: Amino Acid Motifs; Anabasine; Animals; Insecta; Membrane Potentials; Models, Molecular; Receptors, Nicotinic
PubMed: 16116270
DOI: 10.1271/bbb.69.1442 -
Genes Nov 2019Nicotine, the most abundant pyridine alkaloid in cultivated tobacco ( L.), is a potent inhibitor of insect and animal herbivory and a neurostimulator of human brain...
Nicotine, the most abundant pyridine alkaloid in cultivated tobacco ( L.), is a potent inhibitor of insect and animal herbivory and a neurostimulator of human brain function. Nicotine biosynthesis is controlled developmentally and can be induced by abiotic and biotic stressors via a jasmonic acid (JA)-mediated signal transduction mechanism involving members of the APETALA 2/ethylene-responsive factor (AP2/ERF) and basic helix-loop-helix (bHLH) transcription factor (TF) families. AP2/ERF and bHLH TFs work combinatorically to control nicotine biosynthesis and its subsequent accumulation in tobacco leaves. Here, we demonstrate that overexpression of the tobacco NtERF32, NtERF221/ORC1, and NtMYC2a TFs leads to significant increases in nicotine accumulation in T2 transgenic K326 tobacco plants before topping. Up to 9-fold higher nicotine production was achieved in transgenics overexpressing NtERF221/ORC1 under the control of a constitutive GmUBI3 gene promoter compared to wild-type plants. The constitutive 2XCaMV35S promoter and a novel JA-inducible 4XGAG promoter were less effective in driving high-level nicotine formation. Methyljasmonic acid (MeJA) treatment further elevated nicotine production in all transgenic lines. Our results show that targeted manipulation of NtERF221/ORC1 is an effective strategy for elevating leaf nicotine levels in commercial tobacco for use in the preparation of reduced risk tobacco products for smoking replacement therapeutics.
Topics: Acetates; Alkaloids; Anabasine; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Helix-Loop-Helix Motifs; Nicotine; Oxylipins; Plant Growth Regulators; Plant Leaves; Plants, Genetically Modified; Promoter Regions, Genetic; Pyridines; Nicotiana; Tobacco Products; Transcription Factors
PubMed: 31739571
DOI: 10.3390/genes10110930 -
Marine Drugs Oct 2019Three major forms of the nicotinic agonist toxin anabaseine (cyclic iminium, cyclic imine and the monocationic open-chain ammonium-ketone) co-exist in almost equal...
Three major forms of the nicotinic agonist toxin anabaseine (cyclic iminium, cyclic imine and the monocationic open-chain ammonium-ketone) co-exist in almost equal concentrations at physiological pH. We asked the question: Which of these forms is pharmacologically active? First, we investigated the pH dependence of anabaseine inhibition of [H]-methylcarbamylcholine binding at rat brain α4β2 nicotinic acetylcholine receptors (nAChRs). These experiments indicated that one or both monocationic forms interact with the orthosteric binding site for ACh. However, since they occur at equal concentrations near physiological pH, we employed another approach, preparing a stable analog of each form and examining its agonist activities and binding affinities at several vertebrate brain and neuromuscular nAChRs. Only 2-(3-pyridyl)-1,4,5,6-tetrahydropyrimidine monohydrogen chloride (PTHP), the cyclic iminium analog, displayed nAChR potencies and binding affinities similar to anabaseine. The cyclic imine analog 2,3'-bipyridyl and the open-chain ammonium-ketone analog 5-methylamino-1-(3-pyridyl)-1-pentanone (MAPP), displayed ≤1% of the activity predicted if the one form was solely active. The lower potency of weakly basic 2,3'-bipyridyl can be explained by the presence of a small concentration of its monocationic form. Since the open chain ammonium-ketone monocationic form of anabaseine has some structural similarity to the neurotransmitter GABA, we also tested the ability of anabaseine and its 1,2-dehydropyrrolidinyl analog myosmine to activate a mammalian GABA receptor, but no activity was detected. We conclude that the monocationic cyclic iminium is the form which avidly binds and activates vertebrate nAChRs.
Topics: Anabasine; Animals; Binding Sites; Brain; Cell Line; Humans; Nicotinic Agonists; Rats; Receptors, GABA; Receptors, Nicotinic; Structure-Activity Relationship
PubMed: 31671780
DOI: 10.3390/md17110614 -
Phytochemistry Feb 2020Nicotinic acetylcholine receptor (nAChR) subtype-selective pharmacological profiles of tobacco alkaloids are essential for understanding the physiological effects of...
Nicotinic acetylcholine receptor (nAChR) subtype-selective pharmacological profiles of tobacco alkaloids are essential for understanding the physiological effects of tobacco products. In this study, automated electrophysiology was used to functionally characterize the effects of distinct groups of tobacco alkaloids on human α4β2 and α7 nAChRs. We found that, in tobacco alkaloids, pyridine as a hydrogen bond acceptor and a basic nitrogen atom at a distance of 4-7 Å are pharmacophoric elements necessary for molecular recognition by α4β2 and α7 nAChRs with various degrees of selectivity, potency, and efficacy. While four alkaloids-nicotine, nornicotine, anabasine and R-anatabine-potently activated α4β2, they were also weak agonists of α7 nAChRs. Nicotine was the most potent agonist of α4β2, while anabasine elicited the highest activation of α7. None of the tobacco alkaloids enhanced nAChR activity elicited by the endogenous ligand acetylcholine; therefore, none was considered to be a positive allosteric modulator (PAM) of either α4β2 or α7 nAChRs. In contrast, we identified tobacco alkaloids, such as the tryptophan metabolite 6-hydroxykynurenic acid, that decreased the activity of both α4β2 and α7 nAChRs. Our study identified a class of alkaloids with positive and negative effects against human α4β2 and α7 nAChRs. It also revealed human α4β2 to be the principal receptor for sensing the most abundant alkaloids in tobacco leaves.
Topics: Alkaloids; Biological Products; Dose-Response Relationship, Drug; Humans; Ligands; Molecular Structure; Phytochemicals; Receptors, Nicotinic; Structure-Activity Relationship; Nicotiana; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 31865001
DOI: 10.1016/j.phytochem.2019.112187 -
Food and Chemical Toxicology : An... Oct 2019Within the traditional pharmacopeia, tobacco (Nicotiana spp.) is often cited as an efficient pesticide. This activity is generally attributed to nicotine, but tobacco...
Within the traditional pharmacopeia, tobacco (Nicotiana spp.) is often cited as an efficient pesticide. This activity is generally attributed to nicotine, but tobacco plants contain other alkaloids that could potentially contribute to this effect. In this study, we tested methanolic extracts of N. glutinosa, N. glauca, N. debneyi, and N. tabacum (putrescine N-methyltransferase line, burley TN90 and Stella, Virginia ITB 683 and K326), selected according to alkaloid content. Their antiparasitic activity was evaluated in bioassays against adult fleas (Ctenocephalides felis), blowfly (Lucilia cuprina) larvae, nematodes (Caenorhabditis elegans), and ticks (Rhipicephalus sanguineus larvae and adults, Ixodes ricinus nymphs). None of the extracts killed fleas and blowfly larvae effectively at the concentrations tested. Only N. tabacum K326 and N. glutinosa exhibited moderate anthelmintic activity. All extracts significantly repelled R. sanguineus ticks, but not I. ricinus, and the nicotine-rich extracts rapidly knocked down all tick species and stages at high concentrations. The link between nicotine and tick knockdown was confirmed by successfully testing the pure alkaloid at concentrations found in the tobacco extracts. In contrast, repellent activity could not be correlated to the individually tested alkaloids (nicotine, nornicotine, anabasine, anatabine), although anatabine and nornicotine were active in the tick bioassay at high concentrations.
Topics: Animals; Antiparasitic Agents; Biological Assay; Female; Insecta; Nematoda; Plant Extracts; Plant Leaves; Ticks; Nicotiana
PubMed: 31276744
DOI: 10.1016/j.fct.2019.110660 -
Analytical Sciences : the International... Aug 2019One method based on QuEChERS sample preparation is presented in this study, which leads to simultaneously detect nine alkaloids in tobacco and tobacco products....
One method based on QuEChERS sample preparation is presented in this study, which leads to simultaneously detect nine alkaloids in tobacco and tobacco products. Nicotine, nornicotine, myosmine, N-methyl anabasine, β-nicotyrine, anabasine, anatabine, isonicotenine and cotinine can all be found in fresh tobacco leaves, cigars, Virginia-type and blended-type cigarettes. The samples were purified via a certain proportion of adsorbents consisting of anhydrous magnesium sulfate, PSA and carbon after extracting, then centrifuged and filtered before analyzing by GC-MS. The matrix effects were all among 88 - 105%. The limit of detection of all were within the range of 0.0065 - 0.1509 μg/g and limit of quantification were among 0.0217 - 0.5031 μg/g. The recovery rates were higher than 89%. This is the first time that the QuEChERS sample preparation method has been applied for tobacco alkaloids, where more varieties of alkaloids could be quantified regarding sensitivity and reproducibility.
Topics: Alkaloids; Gas Chromatography-Mass Spectrometry; Solid Phase Extraction; Nicotiana; Tobacco Products
PubMed: 30930354
DOI: 10.2116/analsci.19P063