Preventive effect of melatonin against DNA damage induced by cyanide, kainate, glutathione/Fe3+/O-2, or H2O2/Fe2+

We have investigated hydroxyl free radical ((OH)-O-.)-mediated damage to ca lf thymus DNA produced by potassium cyanide. kainate. H2O2/Fe2+, or glutath ione/Fe3+ by in vitro method. When calf thymus DNA was exposed to potassium cyanide (0.5, 0.75, 1.0, 1.5, or 2.0 mM) or kainate (0.25. 0.5, or 1.0 mM) for 90 min at 37 degreesC in homogenate or the 9000g supernatant of mice b rain, the quantity of DNA damage was observed to be concentration-dependent . Similarly, glutathione (1.0, 2.0, 4.0, 5.0, or 6.0 mM) inflicted damage o n calf thymus DNA in the presence of Fe3+ (3.0 muM). In addition. hydrogen peroxide (0.15, 0.30, 0.75, 1.50, or 3.0 mM) also caused damage to calf thy mus DNA in the presence of Fe2+ (3.0 muM) in the same manner. Furthermore, it was observed that the DNA damage induced by potassium cyanide (2.0 mM), kainate (0.5 mM), glutathione (4.0 mM)/Fe3+, and H2O2 (1.5 mM)/Fe2+ was pre vented by the treatment with melatonin (1.0 or 1.5 mM), a potent (OH)-O-. s cavenger. These results suggest that cyanide, kainate, glutathione/Fe3+, an d H2O2/Fe2+-mediated (OH)-O-. may play a cardinal role for DNA damage induc ed by these chemicals. Hence the conclusion of the present study is that me latonin protects against DNA damage induced by the (OH)-O-. produced by the se chemicals.