School of Health Sciences, Massey University Wellington, New Zealand.
Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Neurotoxicology. 2019 Dec;75:123-128. doi: 10.1016/j.neuro.2019.09.010. Epub 2019 Sep 16.
Monoamine oxidase inhibitors have been hypothesised to be important in tobacco dependence, reinforcing the brain's response to nicotine by delaying the degradation of neurotransmitters by monoamine oxidases. The development of electronic cigarettes has provided an alternative nicotine delivery system, which is widely viewed as less toxic than tobacco smoke. However, significant data gaps remain. This paper reports the results of measurements of monoamine oxidase inhibitory activity in a small sample of commercially available, flavoured e-liquids.
Twelve e-liquids were tested for monoamine oxidase inhibitory activity, using the kynuramine assay and monoamine oxidase enzymes (human, recombinant). Control samples of carrier liquids, propylene glycol and glycerol, and nicotine were also tested.
Four e-liquids contained high levels of inhibitory activity, four more were moderately inhibitory. The remaining four e-liquids were mildly inhibitory, while the carrier liquids, and nicotine were inactive at relevant concentrations. The active compounds in the e-liquids were subsequently identified as vanillin and ethyl vanillin. Under some conditions of use, the sampled e-liquids with the highest concentrations of monoamine oxidase inhibitory activity have the potential to expose consumers to physiologically significant levels of MAO inhibitory activity.
While only a small sample of e-liquids was tested, the findings suggest that some flavours have pharmacological actions, with potential to enhance the response to nicotine or to other drugs. The public health implications of these preliminary findings on addiction and smoking cessation warrant exploration and further research.
单胺氧化酶抑制剂被认为在烟草依赖中具有重要作用，通过延迟单胺氧化酶对神经递质的降解来增强大脑对尼古丁的反应。电子烟的发展提供了一种替代尼古丁的输送系统，被广泛认为比烟草烟雾毒性更小。然而，仍存在显著的数据空白。本文报告了对一小部分市售调味电子烟液中单胺氧化酶抑制活性的测量结果。
使用犬尿氨酸测定法和单胺氧化酶酶（人、重组）对 12 种电子烟液进行了单胺氧化酶抑制活性测试。还测试了载液、丙二醇和甘油以及尼古丁的对照样品。
四种电子烟液含有高水平的抑制活性，四种具有中等抑制活性。其余四种电子烟液具有轻度抑制活性，而载液和尼古丁在相关浓度下没有活性。电子烟液中的活性化合物随后被鉴定为香草醛和乙基香草醛。在某些使用条件下，含有最高浓度单胺氧化酶抑制活性的抽样电子烟液有可能使消费者暴露于具有生理意义的 MAO 抑制活性水平。
尽管仅测试了一小部分电子烟液，但这些发现表明，某些口味具有药理作用，有可能增强对尼古丁或其他药物的反应。这些初步发现对成瘾和戒烟的公共卫生影响值得探讨和进一步研究。
