Abstract
The toxicity caused by high concentrations of manganese (Mn) could be due to a production of free radicals. Minocycline is an effective antioxidant with a high potential to capture free radicals. We investigated the effect of minocycline in the activities of superoxide dismutase (SOD) and catalase, and in the concentrations of nitric oxide (NO), hydrogen peroxide (H2O2) and mitochondrial malondialdehyde (MDA) in manganese-treated Drosophila melanogaster. Five groups of flies were used: (1) control: not treated; (2) continuously treated with minocycline (0.05 mM); (3) treated with 30 mM Mn for 6 days and then no additional treatment; (4) continuously treated with Mn; (5) treated only with Mn for 6 days and then treated with minocycline; (6) simultaneously treated with Mn and minocycline. On the 6th day, Mn treatment caused 50 % mortality; in the surviving flies increased levels of MDA (67.93 %), NO (11.04 %), H2O2 (14.62 %) and SOD and catalase activity (165.34 and 71.43 %, respectively) were detected. All the flies continuously treated with Mn died by the 21st day. On day 40, MDA levels were decreased in groups two, three and five (43.04, 29.67, and 34.72 % respectively), as well as NO in group two (29.21 %) and H2O2 in groups two and five (53.94 % and 78.69 %, respectively), while in group three the concentration of H2O2 was increased (408.25 %). In conclusion, Mn exerted a pro-oxidant effect on the 6th day as shown by the increased levels of oxidative markers. Minocycline extended the lifespan, increased the activity of SOD and reduced the levels of NO, H2O2 and mitochondrial MDA.
