Nair J, Ohshima H, Friesen M, Croisy A, Bhide S V, Bartsch H
Carcinogenesis. 1985 Feb;6(2):295-303. doi: 10.1093/carcin/6.2.295.
In order to evaluate exposure of betel quid chewers to N-nitroso compounds, saliva and urine samples were collected from chewers of betel quid with or without tobacco, from tobacco chewers, from cigarette smokers and from people with no such habit, and were analysed for the presence of N-nitrosamines by gas chromatography coupled with Thermal Energy Analyzer and alkaloids derived from betel nut and tobacco by capillary gas chromatography fitted with nitrogen-phosphorous selective detector. The levels of the betel nut-specific nitrosamines, N-nitrosoguvacoline and N-nitrososoguvacine (the latter being detected for the first time in saliva), ranged from 0 to 7.1 and 0 to 30.4 ng/ml, respectively. High levels of tobacco-specific nitrosamines were detected in the saliva of chewers of betel quid with tobacco and in that of chewers of tobacco, ranging from 1.6 to 59.7 (N'-nitrosonornicotine), 1.0 to 51.7 (N'-nitrosoanatabine) and 0 to 2.3 [4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone] ng/ml. Urinary concentrations of certain N-nitrosamino acids, including N-nitrosoproline, were determined as a possible index of exposure to nitroso compounds and their precursors in the study groups: no clear difference was observed. The betel nut-specific alkaloid, arecoline, was present at high levels in the saliva of betel quid chewers with or without tobacco. Nicotine and cotinine were also detected in saliva and urine of chewers of tobacco and of betel quid with tobacco. In order to assess whether N-nitroso compounds are formed in vivo in the oral cavity during chewing or in the stomach after swallowing the quids, the levels of N-nitroso compounds in betel quid extracts were determined before and after nitrosation at pH 7.4 and 2.1. The results indicate that N-nitroso compounds could easily be formed in vivo. The possible role of N-nitroso compounds in the causation of cancer of the upper alimentary tract in betel quid chewers is discussed.
为了评估嚼槟榔者对N-亚硝基化合物的暴露情况，从嚼含烟草或不含烟草槟榔的人群、嚼烟草者、吸烟者以及无此类习惯的人群中采集唾液和尿液样本，采用气相色谱-热能分析仪分析样本中N-亚硝胺的存在情况，并采用配备氮磷选择性检测器的毛细管气相色谱法分析槟榔和烟草中的生物碱。槟榔特有的亚硝胺N-亚硝基古豆碱和N-亚硝基高古豆碱（后者首次在唾液中检测到）的含量分别为0至7.1 ng/ml和0至30.4 ng/ml。在嚼含烟草槟榔者和嚼烟草者的唾液中检测到高水平的烟草特有的亚硝胺，其中N'-亚硝基去甲烟碱含量为1.6至59.7 ng/ml，N'-亚硝基假木贼碱含量为1.0至51.7 ng/ml，4-(甲基亚硝胺基)-1-(3-吡啶基)-1-丁酮含量为0至2.3 ng/ml。测定了研究组中某些N-亚硝基氨基酸（包括N-亚硝基脯氨酸）的尿液浓度，作为接触亚硝基化合物及其前体的可能指标：未观察到明显差异。槟榔特有的生物碱槟榔碱在嚼含烟草或不含烟草槟榔者的唾液中含量较高。在嚼烟草者和嚼含烟草槟榔者的唾液和尿液中也检测到了尼古丁和可替宁。为了评估N-亚硝基化合物是在咀嚼过程中口腔内体内形成还是在吞咽槟榔后胃内形成，测定了槟榔提取物在pH 7.4和2.1条件下亚硝化前后的N-亚硝基化合物水平。结果表明，N-亚硝基化合物可在体内轻易形成。讨论了N-亚硝基化合物在嚼槟榔者上消化道癌症病因中的可能作用。
