Blood biomarkers of nicotine-induced toxicity in healthy males

Abstract

Background: Smoking enhances oxidative stress by causing an oxidant/antioxidant imbalance in the body leading to deleterious effects on various tissues and organs. 8-hydroxy-2′-deoxyguanosine (8-OHdG) is a predominant form of free radical-induced oxidative lesions, and is widely used as a biomarker of oxidative stress. Objectives: This study aimed to estimate blood 8-OHdG level in active, passive and non-smokers and its relation with some lifestyle determinants as well as to assess smoking effects on oxidant/antioxidant status. Participants and methods: The current work included 90 male participants who were classified into 3 groups; 20 non-smokers, 30 passive smokers, and 40 active smokers. Data were collected by answering a premade questionnaire. Peripheral venous blood samples were withdrawn then 8-OHdG, cotinine, superoxide dismutase (SOD), and total antioxidant capacity (TAC) levels were estimated in plasma using ELISA kits, while malondialdehyde (MDA) was estimated by colorimetry. Results: There were highly statistically significant higher levels of 8-OHdG, cotinine and MDA and lower levels of SOD and TAC in active smokers compared to both passive and non-smokers (p < 0.001) whereas, no statistically significant difference between passive and non-smokers was detected (p > 0.05). There were no significant differences between 8-OHdG level and smoking habits, age, exercise, tea and coffee consumption, and body mass index (BMI) among the 3 studied groups. Conclusion: Smoking induces oxidative stress not only through the production of reactive oxygen radicals and increasing blood 8-OHdG levels but also through weakening of the antioxidant defense systems. Further studies are required to reach a consensus on the background level of 8-OHdG and understand which factors determine it and to further differentiate between passive and non-smokers.