Effects of tobacco nitrate content on free radical levels in mainstream smoke

Mocniak, Leanne E; Bitzer, Zachary T.; Trushin, Neil; Richie, John P.

doi:10.1016/j.freeradbiomed.2022.08.006

Cited by 4 publications

(22 citation statements)

References 45 publications

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“…Cigarettes were smoked as reported previously. , In short, cigarettes were smoked on a single-port linear smoking machine (Human Puff Profile Cigarette Smoking Machine (CSM-HPP), CH Technologies, NJ) using the Canadian Intense (CI T-115:1999) smoking regimen (55 mL puff volume, 2 s duration, 30 s puff interval). Cigarettes were smoked to the 40 mm mark (two-thirds of the total 60 mm of tobacco filler), and the mainstream smoke was separated into gas and particulate phases using a CFP.…”

Section: Methodsmentioning

confidence: 99%

“…Free radicals were captured as reported previously . Briefly, mainstream smoke was passed through a CFP, located immediately downstream of the cigarette and before the pump, to collect particulate-phase radicals.…”

Section: Methodsmentioning

confidence: 99%

“…Free radicals were analyzed as previously reported using a Bruker eScan R spectrometer (Bruker-Biospin, Billerica, MA) operating in X-band. , CFPs were placed directly into the EPR cavity and analyzed using the following parameters at room temperature (22 °C): microwave frequency, 9.78 GHz; modulation frequency, 86.0 kHz; microwave power, 6.00 mW; scan range, 50 G; modulation amplitude, 3.24 G; sweep time, 5.24 s; time constant, 10.24 ms; conversion time, 10.24 ms. Total PP spin was determined by taking the double integral of the EPR signal and reported in arbitrary signal intensity units. EPR spectra of deoxygenated GP samples were obtained under the following instrument parameters at room temperature (22 °C): microwave frequency, 9.78 GHz; modulation frequency, 86.0 kHz; microwave power, 6.00 mW; scan range, 60 G; modulation amplitude, 0.36 G; sweep time, 5.24 s; time constant, 10.24 ms; conversion time, 10.24 ms. Total spin concentrations were determined by comparison to standard solutions of TEMPO in tert -butylbenzene.…”

Section: Methodsmentioning

confidence: 99%

“…All filtrates were diluted 10× and 20× in deionized water before analysis. The concentration of nitrate in the filtered supernatant was determined using a procedure adapted from the Microplate Nitrate test kit (NECi Superior Enzymes, Lake Linden, MI) . Total nitrate concentrations in the tobacco extracts were determined using a standard curve (1–100 ppm) obtained by reduction of known concentrations of sodium nitrate to nitrite using the nitrate reductase procedure outlined previously …”

Section: Methodsmentioning

confidence: 99%

“…Although there are still many unknowns, the generally accepted mechanism for free radical formation during smoking is a propagation cycle involving nitric oxide (NO), first presented by William Pryor in 1982 and reviewed in 1993. , The evidence supporting the steady-state formation of free radicals from NO led us to propose that the source of NO in tobacco smoke originates from the nitrate content in the tobacco blends. We recently investigated the impact of intrinsic nitrate levels in cigarettes made from individual tobacco varieties on the formation of free radicals in the mainstream smoke produced from cigarettes made with the corresponding tobacco variety . We demonstrated evidence that the levels of gas-phase (GP) free radicals in tobacco smoke are highly dependent on the intrinsic nitrate content of the unsmoked tobacco and suggested that NO is likely formed from the thermal decomposition of nitrate during smoking.…”

Section: Introductionmentioning

confidence: 99%

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Tobacco Nitrate and Free Radical Levels in the Mainstream Smoke of US Cigarette Brands

Mocniak

Trushin

Bitzer

et al. 2023

Chem. Res. Toxicol.

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Tobacco nitrate levels have been known to impact the levels of toxicants such as polyaromatic hydrocarbons and tobacco-specific nitrosamines (TSNAs) produced during smoking. Recent work in our group showed that the intrinsic nitrate levels in individual tobacco varieties also have a large influence on the formation of gas-phase (GP) free radicals in the mainstream smoke of cigarettes produced with a single tobacco variety. As tobacco nitrate content is a potential target for future regulatory policies, we investigated whether the levels of GP free radicals in the smoke from commercially available cigarettes is also dependent on the nitrate content in the corresponding tobacco blends. GP and particulate-phase (PP) free radical yields in mainstream smoke produced from 25 popular US cigarette brands were measured by electron paramagnetic resonance (EPR) spectroscopy. For each brand, we also measured levels of the TSNAs NNN (N′-nitrosonornicotine) and NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) via HPLC-MS and the nicotine content via GC-FID. Our results show that the intrinsic nitrate levels varied >15-fold and GP radicals varied 4-fold among the 25 brands tested. The GP radicals were correlated with intrinsic nitrate levels (r = 0.87, p < 0.001). NNK and NNN levels varied >8-fold and 12-fold, respectively. We found that NNK was moderately correlated to nitrate content (r = 0.42, p = 0.03) while the NNN was strongly correlated to the nitrate content (r = 0.65, p < 0.001). Nicotine levels varied the least (<3-fold) but showed a moderate negative correlation to nitrate content (r = −0.47, p = 0.02). No statistically significant correlation was observed between nicotine and TSNA levels in mainstream smoke. Overall, this demonstrates that the nitrate content of tobacco blends used in US cigarette brands impacts toxicant output in the mainstream smoke, although other proprietary variables (total ventilation, additives, filter type, etc.) may also modulate these results.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tobacco Nitrate and Free Radical Levels in the Mainstream Smoke of US Cigarette Brands

Mocniak

Trushin

Bitzer

et al. 2023

Chem. Res. Toxicol.

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Free Radicals in Little Cigar Mainstream Smoke and the Potential Influence of Flavoring Chemicals on Free Radical Production

Mocniak,

Bitzer,

Goel

et al. 2024

Chem. Res. Toxicol.

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Implementation of the Tobacco Control Act in 2009 banned characterizing flavors in cigarettes (except menthol and tobacco), but substitution has occurred by the continued availability of alternative flavored products (i.e., flavored little cigars). Little is known about how flavorants in noncigarette tobacco products impact human health. Thus, we investigated the impact of flavorants on free radical production in the mainstream smoke of little cigars. Gas- and particulate-phase free radical yields in mainstream smoke generated from 12 commercial little cigar brands and research little cigars and cigarettes were measured via electron paramagnetic resonance spectroscopy using the International Organization of Standardization (ISO) smoking protocol. Flavorants were extracted from unsmoked little cigars and analyzed by gas chromatography–mass spectroscopy. Gas- and particulate-phase radical yields from little cigars ranged from 13.5 to 97.6 and 0.453–1.175 nmol/unit, respectively. Comparatively, research cigarettes yielded an average of 4.9 nmol gas-phase radicals/unit and 0.292 nmol particulate-phase radicals/unit. From the products, 66 flavorants were identified, with each brand containing 4–24 individual flavorants. The free radical content was strongly correlated with the number of flavorants present in each cigar (r = 0.74, p = 0.01), indicating that highly flavored little cigars may produce higher levels of toxic free radicals. The presence of the flavorant ethyl methylphenylglycidate (strawberry) was associated with >2-fold higher levels of GP radicals (p = 0.001). Our results show that free radical delivery from little cigars is greater than that from research cigarettes and provide empirical evidence for the harmfulness of flavored tobacco products. Additionally, it demonstrates that flavorants present in combustible tobacco products can influence the levels of free radicals produced. Therefore, future tobacco product standards should consider little cigars.

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The impact of different preceding crops on soil nitrogen structure and nitrogen cycling in tobacco-planting soil

Liu,

Xue,

Han

et al. 2024

Sci Rep

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Soil nitrogen content, structure, and nitrogen cycling play a crucial role in tobacco growth quality, with different preceding crops having varying impacts on tobacco cultivation soil. This study conducted using field experiments, employed three treatments with different preceding crops, namely tobacco, barley, and rapeseed, to investigate the effects of different preceding crops on soil nitrogen structure and the expression levels of soil nitrogen cycling-related functional genes in tobacco cultivation soil. The results indicated that different preceding crops had varying effects on the content of different nitrogen forms in tobacco cultivation soil. Ammonium nitrogen and nitrate nitrogen were the two nitrogen forms which were most influenced by preceding crops, with the ammonium nitrogen content in soils following barley and rapeseed preceding crops increasing by 82.88% and 63.56%, respectively, compared to sole tobacco cultivation. The nitrate nitrogen content in tobacco cultivation soil was 26.97% higher following barley preceding crops and 24.39% higher following rapeseed preceding crops compared to sole tobacco cultivation. Simultaneously, different preceding crops also affected the expression levels of nitrogen cycling-related genes in tobacco cultivation soil. In the nitrification process, amoA was significantly impacted, with its expression reduced by 64.39% and 72.24% following barley and rapeseed preceding crops, respectively, compared to sole tobacco cultivation. In the denitrification process, except for the narG gene, all other genes were subjected to varying degrees of inhibition when preceded by barley and rapeseed crops. Correlation analysis between soil nitrogen structure and the expression levels of nitrogen cycling-related genes revealed that increased nitrogen levels suppressed the expression of Arch-amoA. Additionally, ammonium nitrogen strongly influenced the expression levels of most soil nitrogen cycling functional genes. In conclusion, preceding crops alter soil nitrogen structure, possibly due to changes in soil microorganisms, and different preceding crops modified the expression levels of nitrogen cycling-related genes in tobacco cultivation soil, consequently affecting the proportions of various nitrogen forms in the soil.

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Effects of tobacco nitrate content on free radical levels in mainstream smoke

Cited by 4 publications

References 45 publications

Tobacco Nitrate and Free Radical Levels in the Mainstream Smoke of US Cigarette Brands

Tobacco Nitrate and Free Radical Levels in the Mainstream Smoke of US Cigarette Brands

Free Radicals in Little Cigar Mainstream Smoke and the Potential Influence of Flavoring Chemicals on Free Radical Production

The impact of different preceding crops on soil nitrogen structure and nitrogen cycling in tobacco-planting soil

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