Antioxidant capacity and biomarkers of oxidative stress in saliva of khat-chewing patients: a case-control study

Objectives. The aim of this study was to investigate the antioxidant levels and biomarkers of oxidative stress in saliva from khat-chewing patients compared with controls. Study Design. Saliva samples were collected from 51 chronic khat chewers and 46 age- and sex-matched controls. Concentrations of oxidative stress biomarkers (malonyl-dialdehyde [MDA], protein carbonyl, and 8-hydroxy-2'-deoxyguanosine) and antioxidant defense (total antioxidant capacity [TAC], superoxide dismutase, glutathione peroxidase, and catalase [CAT) were analyzed. Results. Salivary MDA level in the khat users group (45 +/- 9.2 nmol/mL) was significantly increased in comparison with controls (13 +/- 2.1 nmol/mL; P < .001), but there were no significant differences between the 2 groups regarding the levels of salivary protein carbonyl and oxidized guanine species. Salivary TAC was significantly reduced in khat users (0.25 +/- 0.028 mmol/L) in comparison with controls (0.34 +/- 0.037 mmol/L). Salivary CAT level was significantly reduced in khat users (6.0 +/- 0.47 U/mL) in comparison with controls (7.7 +/- 0.43 units/mL; P < .05), but no significant differences were observed between the 2 groups with regard to salivary superoxide dismutase or glutathione peroxidase levels. Conclusions. Chronic khat chewing is associated with increased levels of salivary MDA and reduced levels of TAC and CAT among a population of adult men in comparison with non-khat-chewing controls. These findings suggest that the pro-oxidative effect of khat chewing may be a contributing mechanism for various oral diseases associated with khat use, including cancer, periodontitis, and caries.