Comparison of antioxidant enzymes in saliva of elderly smokers and non-smokers

Objectives: This study was designed to compare the levels of copper/zinc superoxide dismutase (Cu/Zn SOD), peroxidase (POx) and glutathione peroxidase (GSH‐Px) in saliva of smokers and those in saliva of non‐smokers. Methods: Unstimulated saliva samples were collected from 88 elderly males (65 years old or over) who visited a private dental clinic. Forty‐four subjects were current smokers (more than 20 cigarettes daily for at least 30 years) and 44 were non‐smokers. The levels of salivary thiocyanate, Cu/Zn SOD, GSH‐Px, and POx activity were measured using standard procedures. Results: The mean levels of salivary thiocyanate (SCN^?) and SOD were significantly higher (p < 0.01) in the smoking group than in the non‐smoking group, whereas the specific activity levels of POx and GSH‐Px were significantly higher (p < 0.05) in the non‐smoking group than in the smoking group. Significant correlation coefficients were found between the levels of SCN^? and SOD (r = 0.37, p < 0.001). In the non‐smoking group, a significant positive association was found between specific activity of POx and age (r = 0.33, p < 0.05). Conclusion: Measurement of SCN^? and Cu/Zn SOD in human saliva might be useful for estimating the level of oxidative stress caused by cigarette smoke. Despite increased H₂O₂ level as a defense system induced by SOD, detoxification of H₂O₂ might be deteriorated in the oral cavity of elderly smokers.