Nair J, Nair U J, Ohshima H, Bhide S V, Bartsch H
Unit of Environmental Carcinogens and Host Factors, International Agency for Research on Cancer, Lyon, France.
IARC Sci Publ. 1987(84):465-9.
In order to evaluate endogenous nitrosation in the oral cavity of chewers of betel quid with tobacco (BQT) or without tobacco (BQ), saliva samples were collected from healthy male volunteers after chewing sequentially (i) unmodified BQT or BQ, (ii) BQT or BQ to which proline has been added, and (iii) BQT or BQ to which proline and ascorbic acid had been added. Samples were collected over 20 min and analysed for N-nitrosoproline (NPRO), tobacco-specific nitrosamines (TSNA) and areca nut-specific nitrosamines using gas chromatography-thermal energy analysis, arecoline and nicotine using gas chromatography-nitrogen phosphorus-specific detector, and for nitrite and thiocyanate. When results were expressed as a ratio of NPRO (ng/ml) to nicotine (micrograms/ml), all BQT chewers had increased NPRO contents after chewing BQT with proline. For BQ chewers, when the results were expressed as a ratio of NPRO (ng/ml) to arecoline (micrograms/ml), a similar increase in NPRO content was observed. However, the presence of ascorbic acid inhibited the increased nitrosation in only four out of ten BQT chewers and in five out of ten BQ chewers; in the rest of the samples, its presence enhanced the levels of NPRO. N'-Nitrosoanatabine (NAT) and N-nitrosoguvacoline (NGCO) levels decreased significantly in saliva of chewers of BQT in the presence of ascorbic acid, suggesting inhibition of their formation. In-vitro nitrosation of BQT/BQ with proline and proline plus ascorbic acid showed a similar pattern of nitrosation at salivary pH. The study confirmed previous results that certain nitrosamines are formed during the chewing of BQT/BQ.
为了评估咀嚼含烟草槟榔（BQT）或不含烟草槟榔（BQ）的人群口腔内的内源性亚硝化作用，从健康男性志愿者处收集唾液样本，这些志愿者依次咀嚼（i）未添加物质的BQT或BQ，（ii）添加了脯氨酸的BQT或BQ，以及（iii）添加了脯氨酸和抗坏血酸的BQT或BQ。在20分钟内收集样本，并使用气相色谱 - 热能分析法分析其中的N - 亚硝基脯氨酸（NPRO）、烟草特异性亚硝胺（TSNA）和槟榔特异性亚硝胺，使用气相色谱 - 氮磷特异性检测器分析槟榔碱和尼古丁，同时分析亚硝酸盐和硫氰酸盐。当结果表示为NPRO（纳克/毫升）与尼古丁（微克/毫升）的比值时，所有BQT咀嚼者在咀嚼添加了脯氨酸的BQT后，NPRO含量均增加。对于BQ咀嚼者，当结果表示为NPRO（纳克/毫升）与槟榔碱（微克/毫升）的比值时，也观察到NPRO含量有类似增加。然而，抗坏血酸的存在仅在十分之四的BQT咀嚼者和十分之五的BQ咀嚼者中抑制了亚硝化作用的增加；在其余样本中，其存在提高了NPRO的水平。在抗坏血酸存在的情况下，BQT咀嚼者唾液中的N'-亚硝基新烟草碱（NAT）和N - 亚硝基古豆碱（NGCO）水平显著降低，表明其形成受到抑制。BQT/BQ与脯氨酸以及脯氨酸加抗坏血酸的体外亚硝化作用在唾液pH值下呈现出类似的亚硝化模式。该研究证实了先前的结果，即在咀嚼BQT/BQ过程中会形成某些亚硝胺。
