Kurgat Caren, Kibet Joshua, Cheplogoi Peter
Department of Chemistry, Egerton University, P.O Box 536, Egerton, 20115 Kenya.
Chem Cent J. 2016 Jul 15;10:43. doi: 10.1186/s13065-016-0189-5. eCollection 2016.
Consensus of opinion in literature regarding tobacco research has shown that cigarette smoke can cause irreparable damage to the genetic material, cell injury, and general respiratory landscape. The alkaloid family of tobacco has been implicated is a series of ailments including addiction, mental illnesses, psychological disorders, and cancer. Accordingly, this contribution describes the mechanistic degradation of major tobacco alkaloids including the widely studied nicotine and two other alkaloids which have received little attention in literature. The principal focus is to understand their energetics, their environmental fate, and the formation of intermediates considered harmful to tobacco consumers.
The intermediate components believed to originate from tobacco alkaloids in mainstream cigarette smoke were determined using as gas-chromatography hyphenated to a mass spectrometer fitted with a mass selective detector (MSD) while the energetics of intermediates were conducted using the density functional theory framework (DFT/B3LYP) using the 6-31G basis set.
The density functional theory calculations conducted using B3LYP correlation function established that the scission of the phenyl C-C bond in nicotine and β-nicotyrine, and C-N phenyl bond in 3,5-dimethyl-1-phenylpyrazole were respectively 87.40, 118.24 and 121.38 kcal/mol. The major by-products from the thermal degradation of nicotine, β-nicotyrine and 3,5-dimethyl-1-phenylpyrazole during cigarette smoking are predicted theoretically to be pyridine, 3-methylpyridine, toluene, and benzene. This was found to be consistent with experimental data presented in this work.
Clearly, the value of the bond dissociation energy was found to be dependent on the π-π interactions which plays a primary role in stabilizing the phenyl C-C in nicotine and β-nicotyrine and the phenyl C-N linkages in 3,5-dimethyl-1-phenylpyrazole. This investigation has elucidated the energetics for the formation of free radicals and intermediates considered detrimental to human health in cigarette smoking.Graphical abstractSome molecular alkaloids of tobacco the plant.
文献中关于烟草研究的共识表明，香烟烟雾会对遗传物质、细胞损伤和整体呼吸道状况造成不可修复的损害。烟草的生物碱家族与一系列疾病有关，包括成瘾、精神疾病、心理障碍和癌症。因此，本论文描述了主要烟草生物碱的降解机制，包括广泛研究的尼古丁以及另外两种在文献中很少受到关注的生物碱。主要重点是了解它们的能量学、环境归宿以及对烟草消费者有害的中间体的形成。
使用与配备质量选择检测器（MSD）的质谱仪联用的气相色谱法测定主流香烟烟雾中被认为源自烟草生物碱的中间成分，同时使用密度泛函理论框架（DFT/B3LYP）并采用6-31G基组对中间体的能量学进行研究。
使用B3LYP相关函数进行的密度泛函理论计算表明，尼古丁和β-烟碱中苯基C-C键的断裂以及3,5-二甲基-1-苯基吡唑中C-N苯基键的断裂分别为87.40、118.24和121.38千卡/摩尔。理论预测，吸烟过程中尼古丁、β-烟碱和3,5-二甲基-1-苯基吡唑热降解的主要副产物为吡啶、3-甲基吡啶、甲苯和苯。这与本研究中呈现的实验数据一致。
显然，发现键离解能的值取决于π-π相互作用，π-π相互作用在稳定尼古丁和β-烟碱中的苯基C-C以及3,5-二甲基-1-苯基吡唑中的苯基C-N键方面起主要作用。本研究阐明了吸烟过程中对人体健康有害的自由基和中间体形成的能量学。
图形摘要
烟草植物的一些分子生物碱
