Effects of coenzyme Q10 on oxidative stress biomarkers in printing workers with low-level exposure to toluene and xylene: a randomized, double-blind, placebo-controlled crossover clinical trial.

Some evidence exists in supporting the beneficial impact of coenzyme Q10 as a protective agent against solvents-induced oxidative stress. This study aimed to assess coenzyme Q10 supplementation effect on selected oxidative stress biomarkers in printing workers (PWs) exposed to mixture low-levels of urinary biomarkers of toluene and xylene. Workers' urine samples were tested for Hippuric acid (HA), and the three isomers of methyl hippuric acids (ortho-, meta-, and para-MHA) through high-performance liquid chromatography to assess the internal exposure levels. In a 2-month randomized, double-blind, placebo-controlled crossover clinical trial, 42 PWs were randomly assigned to receive either 60 mg of coenzyme Q10 twice daily or placebo, with 21 participants in each group. Changes in serum levels of malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were evaluated at the baseline and after each intervention phases to assess primary outcomes during coenzyme Q10 administration compared to placebo. Based on estimated effect size (ES) and mean difference analysis, coenzyme Q10 administration decreased MDA levels (ESMD = - 1.63; 95% CI: - 2.00, - 1.25, P < 0.001) and CAT activity (ESMD = - 5.52; 95% CI: - 7.47, - 3.57, P < 0.001), while it increased TAC levels (ESMD = 0.15; 95% CI: 0.02, 0.29, P = 0.030) and GPx activity (ESMD = 19.84; 95% CI: 11.73, 27.95, P < 0.001). However, coenzyme Q10 supplementation had no significant effect on SOD activity (ESMD = 2.91; 95% CI: - 0.55, 6.38, P = 0.093). Our data suggested that coenzyme Q10 may play a role in reducing oxidative stress caused by exposure to low levels of toluene and xylene in PWs, as it improved all examined oxidative stress biomarkers except SOD.