Evaluation of enzymatic and non-enzymatic antioxidant status and biomarkers of oxidative stress in saliva of patients with oral squamous cell carcinoma and oral leukoplakia: a pilot study.

The study aimed to evaluate total antioxidant capacity as well as levels of various enzymatic and non-enzymatic antioxidants, and oxidative stress markers in saliva of patients with oral squamous cell carcinoma (OSCC) and oral leukoplakia (OL). Twenty patients with OSCC, 20 patients with OL and 20 healthy subjects were enrolled into this prospective study. Total Antioxidant Capacity (TAC), activity of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) as well as levels of total glutathione (tGSH), reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG ratio, uric acid (UA), 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) were estimated in saliva using appropriate biochemical methods. The activity of SOD was significantly higher in OSCC group in comparison with OL and control groups. The levels of GSH were markedly lower in OSCC and OL patients as compared to the control group. Likewise, we found that GSH/GSSG ratio was markedly lower in the OSCC and OL groups. Levels of some biomarkers were influenced by clinical staging of OSCC and OL as well as by sociodemographic factors. The results of this pilot study suggest that salivary activity of SOD is higher in OSCC patients, whereas levels of GSH and GSH/GSSG ratio are lower in saliva of patients with OSCC and OL. Clinical staging of OSCC and OL, as well as some sociodemographic factors may also influence salivary antioxidant status.