Cytoprotective effects of Morinda officinalis against hydrogen peroxide-induced oxidative stress in Leydig TM3 cells

Aim: To investigate the antioxidant effects of Morinda officinalis (Morindae radix, MR) on H2O2-induced oxidative stress in cultured mouse TM3 Leydig cells. Methods: We carried out 2,2-diphenyl-1-picrylhydrazyl free radical scavenging, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, lipid peroxidation, testosterone enzyme immunoassay, superoxide dismutase (SOD), and catalase (CAT) assays in Leydig TM3 cells. Results: MR showed a 47.8% 2,2-diphenyl-1-picrylhydrazyl radical scavenging effect in TM3 cells with no significant cytotoxicity. Oxidative stress was induced in TM3 cells with 100 mu mol H2O2, and treatment of the cells with 250 mu g/mL MR showed the most significant protective effect (64%, P < 0.001) in the cell viability assay with a decreased lipid peroxidation level (1.75 nmol/mg protein, P < 0.05), increased testosterone production (43.5 pg/mL), and improvements in SOD activity (7.49 units of SOD/mg protein, P < 0.001) and CAT activity (74.6 units of CAT/mg protein, P < 0.001). Conclusion: These findings indicate that MR, as an antioxidant, protects functions of cultured mouse TM3 Leydig cells from H2O2-induced oxidative stress.