Figure 3.

Superoxide dismutase (SOD) activity of the human hepatocytes LO2 after 24 h of exposure to sulfide solutions. The values were determined by the xanthine and xanthine oxidase reaction using 2-(4-iodophenyl)-3-(4-nitrophenol)-5-phenyl tetrasodium chloride [34]. Data are given as means of three replicates ± SD. * p < 0.05, ** p < 0.01: significant differences from controls.