Department of Anatomy and Cell Biology, The Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel.
J Physiol Pharmacol. 2009 Nov;60 Suppl 5:127-32.
Cigarette smoke (CS) is associated with a variety of human pathologies including cardiovascular disease and cancer. Oral squamous cell carcinoma (OSCC) is the most common malignancy of the head and neck. The major inducer of OSCC is exposure to tobacco. Recent studies demonstrated that oxidative and nitrosative stress contributes to the development of oral carcinogenesis through DNA damage. All salivary reactive nitrogen species (RNS) analyzed from OSCC patients are significantly higher in comparison with healthy subjects. Our findings show that CS and external RNS addition induced reduction in alpha-amylase activity and produced some excited carbonyl formation, but to a much less extant than CS. The addition of epigallocatechine-3-gallate (EGCG) to saliva produced no protective effect against damage to alpha-amylase activity. Our proposed mechanism for the decrease in alpha-amylase activity is the formation of adducts at SH groups of the alpha-amylase active site. In this case, EGCG was unable to counteract this phenomenon, as it does not reduce the concentration of disulfides, and does not alter the amount of protein-SH moieties. However, EGCG did reduce the levels of excited carbonyl formation. Our results indicate that although RNS are abundant in CS, a significant decrease in amylase activity is due to other components in CS, probably aldehydes, reacting with the thiol group of proteins by the Michael addition reaction.
香烟烟雾（CS）与多种人类病理有关，包括心血管疾病和癌症。口腔鳞状细胞癌（OSCC）是头颈部最常见的恶性肿瘤。OSCC 的主要诱因是接触烟草。最近的研究表明，氧化和硝化应激通过 DNA 损伤促进口腔癌变的发展。与健康受试者相比，从 OSCC 患者中分析的所有唾液反应性氮物种（RNS）都显着升高。我们的研究结果表明，CS 和外部 RNS 加合物诱导的α-淀粉酶活性降低，并产生了一些激发的羰基形成，但程度远低于 CS。将表没食子儿茶素没食子酸酯（EGCG）添加到唾液中对α-淀粉酶活性的损伤没有保护作用。我们提出的α-淀粉酶活性降低的机制是在α-淀粉酶活性部位的 SH 基团形成加合物。在这种情况下，EGCG 无法对抗这种现象，因为它不会降低二硫化物的浓度，也不会改变蛋白质-SH 部分的数量。但是，EGCG 确实降低了激发的羰基形成水平。我们的结果表明，尽管 CS 中含有丰富的 RNS，但淀粉酶活性的显着降低是由于 CS 中的其他成分，可能是醛，通过迈克尔加成反应与蛋白质的巯基反应。
