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N-Nitrosamines
Published in Roger O. McClellan, Critical Reviews in Toxicology, 2017
Klaus D. Brunnemann, Bogdan Prokopczyk, Mirjana V. Djordjevic, Dietrich Hoffmann
Figure 2 presents the formation of TSNA by nitrosation of secondary and tertiary amines. Tobacco alkaloids with a secondary amino group are nornicotine, anatabine, anabasine, and (likely also) cotinine acid; among those with a tertiary amino group is the major tobacco alkaloid nicotine (Figure 1). An earlier study had shown that at ambient temperature and at a range between pH 2 and 7, nicotine is nitrosated to N′-nitrosonornicotine (NNN), 4-(methyl-nitrosamino)-4-(3-pyridyl)-butanal (NNA) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).2 The rate of nicotine nitrosation is slow, as it is for tertiary amines in general.3,4 The rate-limiting step is the formation of the iminium intermediate (Figure 2). Adding thiocyanate, a catalyst present in physiological fluids especially of smokers, doubles the rate of N-nitrosation of nicotine.3 The nitrosation kinetics of the minor tobacco alkaloids nornicotine and anabasine follows those of aliphatic secondary amines. Despite the different rate constants for the N-nitrosation of nicotine and nornicotine, most NNN in tobacco stems from nicotine rather than from nornicotine.5
Genotoxic effect induced by dried nicotiana tabacum leaves from tobacco barns (kiln-houses) in chinese hamster lung fibroblast cells (V79)
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Daiana Dalberto, Caroline Cardoso Nicolau, Melissa Rosa De Sousa, Ana Letícia Hilário Garcia, Fernanda Boaretto, Jaqueline Nascimento Picada, Guilherme Maurício Soares De Souza, Paola Chytry, Johnny Ferraz Dias, Cleverson Costa Feistel, Alexandre Barros Falcão Ferraz, Ivana Grivicich, Juliana Da Silva
When dried leaves are processed, a lot of dust is generated releasing many compounds. Tobacco dust affects the respiratory tract in exposed individuals resulting in different forms of allergies, dizziness, and vomiting (Fiori et al. 2015; Riquinho and Hennington 2012; Saleeon et al. 2016; Umadevi 2003; Zaga et al. 2021). During the classification of the tobacco leaves, the producer has contact not only with nicotine but also with tobacco-specific nitrosamines (TSNAs) (Hoffmann et al. 1994; Hoffmann; Hoffmann and Hoffmann 1997) and polycyclic aromatic hydrocarbons (PAHs) (Alves et al. 2016; Hoffmann; Hoffmann and Hoffmann 1997). These compounds and some pesticides used in the cultivation of tobacco are classified as mutagenic, which lead to a significant contribution to human cancer (Hoffmann and Hoffmann and Hoffmann 1997; IARC (International Agency for Research on câncer) 2007). Tobacco-specific nitrosamines (TSNAs) are generated from alkaloids including nicotine, nornicotine, anatabine, and anabasine during the healing, fermentation, and aging processes of tobacco leaves. Polycyclic aromatic hydrocarbons (PAHs) are released during tobacco curing associated with the combustion process with the use of wood to produce heat (Alves et al. 2016; IARC (International Agency for Research on câncer) 2007; Umadevi 2003). Several studies demonstrated cytotoxicity, genotoxicity, and mutagenicity attributed to exposure to tobacco products, green tobacco, and occupational dust exposure (Da Silva et al. 2014; Gao, Prasad, and Zacharias 2014; Kahl et al. 2018; Moghbel et al. 2016); however, little is known regarding the cytotoxicity and genotoxicity induced by dry leaves of N. tabacum.