Development of an Advanced Multicellular Intestinal Model for Assessing Immunomodulatory Properties of Anti-Inflammatory Compounds

Intestinal inflammation is the collective term for immune system-mediated diseases of unknown, multifactorial etiology, with often complex interactions between genetic and environmental factors. To mechanistically investigate the effect of treatment with compounds possessing immunomodulating properties in the context of intestinal inflammation, we developed an immunocompetent in vitro triculture intestinal model consisting of a differentiated intestinal epithelial layer (Caco-2/HT29-MTX) and immunocompetent cells (differentiated THP-1). The triculture mimicked a healthy intestine with stable barrier integrity. Lipopolysaccharide treatment triggered a controlled and reversible inflammatory state, resulting in significant impairment of barrier integrity and release of pro-inflammatory cytokines and chemokines, which are known hallmarks of intestinal inflammation. Treatment with known anti-inflammatory reference compounds (TPCA-1 and budenoside) prevented the induction of an inflammatory state; the decreasing triculture responses to this treatment measured by cytokine release, transepithelial electric resistance (TEER), and epithelial layer permeability proved the suitability of the intestinal model for anti-inflammatory drug screening. Finally, selected tobacco alkaloids (nicotine and anatabine (R/S and S forms)) were tested in the in vitro triculture for their potential anti-inflammatory properties. Indeed, naturally occurring alkaloids, such as tobacco-derived alkaloids, have shown substantial anti-inflammatory effects in several in vitro and in vivo models of inflammation, gaining increasing interest. Similar to the anti-inflammatory reference compounds, one of the tobacco alkaloids under investigation partially prevented the decrease in the TEER and increase in permeability and reduced the release of pro-inflammatory cytokines and chemokines. Taken together, these data confirm that our in vitro model is suitable for screening potential anti-inflammatory compounds in the context of intestinal inflammation.

Gas Chromatography-Mass Spectrometry Method for Simultaneous Detection of Nine Alkaloids in Tobacco and Tobacco Products by QuEChERS Sample Preparation

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.

Comparison of the content of tobacco alkaloids and tobacco-specific nitrosamines in 'heat-not-burn' tobacco products before and after aerosol generation

Standardized methods for collecting smoke and for measuring smoke components in heat not burn tobacco product (HTP) are yet to be established, and there is a lack of consensus as to whether the content of HTP cigarettes can be assayed in the same manner as for conventional cigarettes. Since HTPcigarettes do not generate ash when smoked, we compared the levels of tobacco alkaloids (TAs) and tobacco-specific nitrosamines (TSNAs) of HTP cigarettes before and after aerosol generation. HTP cigarettes were smoked according to two international standardization methods. The TAs and TSNAs contents of the cigarettes were analyzed by UPLC-Q-TOF and UPLC-MSMS, respectively. Smoking was found to significantly decrease the content of nicotine, nornicotine, anatabine, and anabasine by 53 ∼ 100% in all samples, and the maximum inhalable amounts of these entities were determined to be 4.24 mg/cig, 103.52 μg/cig, 258.72 μg/cig, and 33.03 μg/cig, respectively. By contrast, smoking significantly increased the content of NNK and NAB. we suggested that the reduced nicotine content minus the nicotine content remaining in the filter is an amount that could potentially be inhaled during smoking. The increase of NNK and NAB in HTP cigarette after aerosol generation is expected to be caused by the precursor, but more specific behavioral studies should be performed.

Liquid chromatography with tandem mass spectrometry method for the determination of nicotine and minor tobacco alkaloids in electronic cigarette refill liquids and second-hand generated aerosol

A liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of nicotine and seven minor tobacco alkaloids in both refill liquids for electronic cigarettes and their generated aerosol was developed and validated. The limit of detection and limit of quantification values were 0.3-20.0 and 1.0-31.8 ng/mL, respectively. Within-laboratory reproducibility was 8.2-14.2% at limit of quantification values and 4.8-12.7% at other concentration levels. Interday recovery was 75.8-116.4%. The method was applied to evaluate the compliance of commercial liquids (n = 95) with their labels and to assess levels of minor alkaloids. Levels of nicotine and its corresponding compounds were also evaluated in generated aerosol. About 47% of samples showed differences above ±10 % of the stated nicotine concentration. About 78% of the "zero nicotine" liquids showed traces in the range of 1.3 ± 0.1-254.0 ± 14.6 μg/mL. Nicotine-N'-oxides, myosmine, and anatabine were the most common minor alkaloids in liquids containing nicotine. Nicotine and N'-oxides were detected in all air samples when aerosol was generated from liquids containing nicotine. Nicotine average emissions from electronic cigarette (2.7 ± 0.9 μg/m3 ) were significantly lower (p < 0.01, t-test) with respect to conventional cigarette (30.2 ± 1.5 μg/m3 ).

Chemical Composition and Evaluation of Nicotine, Tobacco Alkaloids, pH, and Selected Flavors in E-Cigarette Cartridges and Refill Solutions

INTRODUCTION

Electronic cigarette (e-cigarette) use is increasing dramatically in developed countries, but little is known about these rapidly evolving products. This study analyzed and evaluated the chemical composition including nicotine, tobacco alkaloids, pH, and flavors in 36 e-liquids brands from 4 manufacturers.

METHODS

We determined the concentrations of nicotine, alkaloids, and select flavors and measured pH in solutions used in e-cigarettes. E-cigarette products were chosen based upon favorable consumer approval ratings from online review websites. Quantitative analyses were performed using strict quality assurance/quality control validated methods previously established by our lab for the measurement of nicotine, alkaloids, pH, and flavors.

RESULTS

Three-quarters of the products contained lower measured nicotine levels than the stated label values (6%-42% by concentration). The pH for e-liquids ranged from 5.1-9.1. Minor tobacco alkaloids were found in all samples containing nicotine, and their relative concentrations varied widely among manufacturers. A number of common flavor compounds were analyzed in all e-liquids.

CONCLUSIONS

Free nicotine levels calculated from the measurement of pH correlated with total nicotine content. The direct correlation between the total nicotine concentration and pH suggests that the alkalinity of nicotine drives the pH of e-cigarette solutions. A higher percentage of nicotine exists in the more absorbable free form as total nicotine concentration increases. A number of products contained tobacco alkaloids at concentrations that exceed U.S. pharmacopeia limits for impurities in nicotine used in pharmaceutical and food products.

Vibrational circular dichroism and theoretical study of the conformational equilibrium in (-)-S-nicotine

We report an extensive study of the molecular and electronic structure of (-)-S-nicotine, to deduce the phenomenon that controls its conformational equilibrium and to solve its solution-state conformer population. Density functional theory, ab initio, and molecular mechanics calculations were used together with vibrational circular dichroism (VCD) and Fourier transform infrared spectroscopies. Calculations and experiments in solution show that the structure and the conformational energy profile of (-)-S-nicotine are not strongly dependent on the medium, thus suggesting that the conformational equilibrium is dominated by hyperconjugative interactions rather than repulsive electronic effects. The analysis of the first recorded VCD spectra of (-)-S-nicotine confirmed the presence of two main conformers at room temperature. Our results provide further evidence of the hypersensitivity of vibrational optical activity spectroscopies to the three-dimensional structure of chiral samples and prove their suitability for the elucidation of solution-state conformer distribution.

Nicotelline: a proposed biomarker and environmental tracer for particulate matter derived from tobacco smoke

Particulate matter (PM) derived from tobacco smoke contains numerous toxic substances. Since the PM and gas phase of tobacco smoke may distribute differently in the environment and substances in them may have different human bioavailability, multiple tracers and biomarkers for tobacco smoke constituents are desirable. Nicotelline is a relatively nonvolatile alkaloid present in tobacco smoke, and therefore, it has the potential to be a suitable tracer and biomarker for tobacco smoke-derived PM. We describe experiments demonstrating that nicotelline is present almost entirely in the PM, in both freshly generated cigarette smoke and aged cigarette smoke. An excellent correlation between the mass of nicotelline and the mass of the PM in aged cigarette smoke was found. We also describe experiments suggesting that the main source of nicotelline in tobacco smoke is dehydrogenation of another little-studied tobacco alkaloid, anatalline, during the burning process. We show that nicotelline metabolites can be measured in the urine of smokers and that nicotelline can be measured in house dust from homes of smokers and nonsmokers. We conclude that nicotelline should be useful as a tracer and biomarker for PM derived from tobacco smoke.