Comparison of salivary antioxidant enzyme activity between ex-smokers and subjects who had never smoked

Smoke contains oxidants such as oxygen-free radicals which are probably the major cause of damage to biomolecules. A decrease of salivary antioxidant enzymes was detected in habitual smokers. However, the effects of cigarette smoke on salivary antioxidant enzymes may persist after withdrawal from smoking. The objective of this study was to assess salivary superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in ex-smokers in comparison with that of subjects who had never smoked. The test group included 25 ex-smokers (13 males and 12 females; mean age: 48 ± 8 years) who had given up smoking for at least one year but for no more than 2 years, and a control group consisting of 25 subjects (14 males and 11 females; mean age: 50 ± 12 years) who had never smoked. Salivary samples were collected and SOD and GSH-Px activity was measured. Student’s t-test was used to evaluate differences between groups and significant differences were observed for p < 0.05. A significant decrease (p < 0.05) of GSH-Px (14.5 ± 2) was observed in the test group compared to the control group (30 ± 4). However, SOD was very similar in the two groups: 0.9 ± 0.3 in the test group and 0.8 ± 0.3 in the controls and no significant difference was detected (p> 0.05). Detoxification of hydrogen peroxide by the GSHPx was altered even after withdrawal from smoking, while the production of hydrogen peroxide, that is mediated by SOD, was not modified.