Contribution of Nicotine and Nornicotine toward the Production of N′-Nitrosonornicotine in Air-Cured Tobacco (Nicotiana tabacum)

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• 作者：Bin Cai ; Huihua Ji ; Franklin F. Fannin ; Lowell P. Bush
• 刊名：Journal of Natural Products
• 出版年：2016
• 出版时间：April 22, 2016
• 年：2016
• 卷：79
• 期：4
• 页码：754-759
• 全文大小：335K
• 年卷期：0
• ISSN：1520-6025

文摘

N′-Nitrosonornicotine (6) is a potent and organ-specific carcinogen found in tobacco and tobacco smoke in substantial amounts. Nicotine (1) and nornicotine (2) are proposed to be the precursors of 6 in tobacco. Since 1 can be rapidly demethylated to 2 in tobacco, to distinguish between the direct formation of 6 from these potential precursors is difficult. A gas chromatography/thermal energy analyzer method using two columns in series was developed to separate the enantiomers of 6, N′-nitrosoanabasine (7), and N′-nitrosoanatabine (8). Tobacco lines with different combinations of three nicotine demethylases inhibited were grown in the field. Air-cured leaves were analyzed for the enantiomeric composition of four main alkaloids and their corresponding tobacco-specific nitrosamines. The percentage of (R)-6 of total 6 varied from 7% to 69% in mutant lines. The measured 6 had the same enantiomeric composition as 2, rather than 1, even when the level of 2 was reduced to 0.6% of 1 in a triple mutant line. The pattern of the enantiomeric composition of 1, 2, and 6 demonstrated that the direct formation of 6 from 1, if it occurs, is negligible in air-cured tobacco. Since (S)-6 is more highly carcinogenic than its R form, the reduction of (S)-2 should be a priority for the reduction of 6.