Velmurugan Balaiya, Bhuvaneswari Vaidhyanathan, Nagini Siddavaram
Department of Biochemistry Faculty of Science, Annamalai University, Annamalainagar-608 002, Tamil Nadu, India.
Asia Pac J Clin Nutr. 2003;12(4):488-94.
We investigated the chemopreventive effect of S-allylcysteine (SAC), a water-soluble garlic constituent against gastric carcinogenesis induced in male Wistar rats by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and saturated sodium chloride (S-NaCl). The animals were divided into four groups of six animals. Rats in groups 1 and 2 were administered MNNG (200 mg/kg body weight) on days 0 and 14 as well as S-NaCl (1 mL/rat) three days during weeks 0 to 3, and thereafter placed on basal diet until the end of the experiment. Rats in group 2 in addition received SAC (200 mg/kg body weight) three times per week starting on the day following the first exposure to MNNG and continued until the end of the experimental period. Group 3 animals were given SAC alone as in group 2. Group 4 animals received basal diet and tap water throughout the experiment and served as the untreated control. The animals were sacrificed after an experimental period of 21 weeks. Measurement of lipid peroxidation and antioxidants of the glutathione redox cycle in the stomach tissue, liver and venous blood was used to monitor the chemopreventive potential of SAC. All animals that received MNNG and S-NaCl alone, developed tumours, identified histologically as squamous cell carcinomas. In the tumour tissue, diminished lipid peroxidation was accompanied by increase in reduced glutathione (GSH) and GSH-dependent enzymes, whereas in the liver and circulation, enhanced lipid peroxidation was associated with antioxidant depletion. Administration of SAC suppressed the incidence of MNNG+S-NaCl-induced gastric tumours as revealed by the absence of carcinomas. SAC ameliorated MNNG-induced decreased susceptibility of the gastric mucosa to lipid peroxidation, whilst simultaneously increasing the antioxidant status. In the liver and blood, SAC reduced the extent of lipid peroxidation and significantly enhanced antioxidant activities. We suggest that SAC exerts its chemopreventive effects by modulating lipid peroxidation and enhancing GSH-dependent antioxidants in the target organ as well as in the liver and blood.
我们研究了S-烯丙基半胱氨酸（SAC）的化学预防作用，SAC是大蒜中的一种水溶性成分，可预防雄性Wistar大鼠由N-甲基-N'-硝基-N-亚硝基胍（MNNG）和饱和氯化钠（S-NaCl）诱导的胃癌发生。将动物分为四组，每组六只。第1组和第2组的大鼠在第0天和第14天给予MNNG（200 mg/kg体重），并在第0至3周的三天内给予S-NaCl（1 mL/只大鼠），此后给予基础饮食直至实验结束。第2组大鼠从首次接触MNNG后的第二天开始，每周额外接受三次SAC（200 mg/kg体重），并持续至实验期结束。第3组动物与第2组一样单独给予SAC。第4组动物在整个实验过程中接受基础饮食和自来水，作为未处理的对照。实验21周后处死动物。通过测量胃组织、肝脏和静脉血中脂质过氧化和谷胱甘肽氧化还原循环的抗氧化剂来监测SAC的化学预防潜力。所有单独接受MNNG和S-NaCl的动物均发生肿瘤，经组织学鉴定为鳞状细胞癌。在肿瘤组织中，脂质过氧化减少伴随着还原型谷胱甘肽（GSH）和GSH依赖性酶的增加，而在肝脏和循环系统中，脂质过氧化增强与抗氧化剂耗竭有关。给予SAC可抑制MNNG+S-NaCl诱导的胃肿瘤发生率，表现为无癌发生。SAC改善了MNNG诱导的胃黏膜对脂质过氧化敏感性降低的情况，同时提高了抗氧化状态。在肝脏和血液中，SAC降低了脂质过氧化程度，并显著增强了抗氧化活性。我们认为，SAC通过调节脂质过氧化并增强靶器官以及肝脏和血液中GSH依赖性抗氧化剂来发挥其化学预防作用。
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