Chakradeo P P, Nair J, Bhide S V
Carcinogenesis Division, Tata Memorial Centre, Parel, Bombay, India.
Cancer Lett. 1994 Nov 11;86(2):187-94. doi: 10.1016/0304-3835(94)90077-9.
The endogenous formation of N-nitroso compounds in tobacco users, namely chewers of tobacco + lime, betel quid with tobacco, and without tobacco, was determined by N-nitrosoproline test. Twenty-four- or six-hour urine samples were collected from volunteers for 3 days: day 1 without proline, day 2 after ingesting 100 mg proline three times a day and day 3 after ingesting 100 mg proline together with 100 mg ascorbic acid three times a day. The urine samples were analysed for the following N-nitrosamino acids: N-nitrosoproline, N-nitrososarcosine, N-nitrosopropionic acid, N-nitrosobutyric acid, N-nitrosothiozolidine-4-carboxylic acid, and N-methyl nitrosothiozolidine-4-carboxylic acid using gas chromatography-thermal energy analyser. It was observed that chewers of tobacco + lime excreted high basal levels of N-nitrosoproline on day 1 as compared with betel quid chewers with tobacco and without tobacco and those in the 'no habit' group. Levels of N-nitrosoproline on day 2 were 15.14 +/- 4.51 microns/mole creatinine in the tobacco + lime group, 3.55 +/- 1.22 microns/mole creatinine in the betel quid tobacco group, 4.72 +/- 1.35 microns/mole creatinine in the betel quid group while levels were 3.34 +/- 0.83 microns/mole creatinine in the 'no habit' group. A decrease in the N-nitrosoproline levels was observed in all the four groups on ingestion of ascorbic acid. This preliminary study suggests that there is a statistically significant increase in endogenous nitrosation in tobacco + lime chewers as compared with those with no habit, and ascorbic acid has an anti-nitrosating action in vivo.
通过N-亚硝基脯氨酸试验测定了烟草使用者（即咀嚼烟草加石灰者、含烟草的槟榔咀嚼者和不含烟草的槟榔咀嚼者）体内N-亚硝基化合物的内源性形成。从志愿者身上收集24小时或6小时的尿液样本，持续3天：第1天不摄入脯氨酸，第2天每天摄入3次100毫克脯氨酸，第3天每天摄入3次100毫克脯氨酸和100毫克抗坏血酸。使用气相色谱-热能分析仪对尿液样本分析以下N-亚硝基氨基酸：N-亚硝基脯氨酸、N-亚硝基肌氨酸、N-亚硝基丙酸、N-亚硝基丁酸、N-亚硝基硫代唑烷-4-羧酸和N-甲基亚硝基硫代唑烷-4-羧酸。观察到，与含烟草和不含烟草的槟榔咀嚼者以及“无此习惯”组相比，咀嚼烟草加石灰者在第1天排出的N-亚硝基脯氨酸基础水平较高。第2天，烟草加石灰组中N-亚硝基脯氨酸的水平为15.14±4.51微摩尔/摩尔肌酐，含烟草的槟榔咀嚼组为3.55±1.22微摩尔/摩尔肌酐，槟榔咀嚼组为4.72±1.35微摩尔/摩尔肌酐，而“无此习惯”组的水平为3.34±0.83微摩尔/摩尔肌酐。在所有四组中，摄入抗坏血酸后N-亚硝基脯氨酸水平均下降。这项初步研究表明，与无此习惯者相比，咀嚼烟草加石灰者体内的内源性亚硝化作用在统计学上有显著增加，并且抗坏血酸在体内具有抗亚硝化作用。
