The role of metalloelements in tissue maintenance, function and response to injury offer a new approach to decreasing and/or treating radiation injury. We investigated the roles of CuL₂SO₄, [MnL₂O]₂Cl₄(H₂O)₂ and [(VL₂O)(VL₂H₂O)]Cl₆ complexes (L=2-methylaminopyridine) of SOD-mimetic activities, in ameliorating the radiation-induced oxidative stress and alterations in some biochemical parameters in liver, kidney, spleen and brain in pretreated female rats exposed to γ-irradiation.

Both untreated-rats and rats treated with the above complexes were subjected to whole-body γ-irradiation (6 Gy). 5′-Nucleotidase (5′-NT), acetylcholinesterase (AChE), adenosne triphosphatase (ATPase), superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GSSG-R) were assessed as well as liver DNA and RNA contents and total protein concentration were estimated in tissue homogenates of the above organs. The same parameters were assessed in non-irradiated treated rats and normal control rats. Results were compared to irradiated non-treated and normal control rats.

Pretreatment of γ-irradiated rats with Mn(IV) or V(IV) complex produced a significant decrease in liver 5′-NT activity compared to the corresponding value of the untreated irradiated rats. In contrast, liver DNA and RNA contents and brain AChE and ATPase activities were significantly increased in irradiated rat group pre-treated with these metal complexes. Cu II, Mn IV or V IV complex inoculation prior to irradiation of normal rats exhibited a significant increase in SOD, CAT, GSSG-R activities and protein content of liver, kidney, spleen and brain homogenates compared with that of the untreated irradiated rats. The treatment of non-irradiated rats with these complexes produced a highly significant increase in mean activities of SOD and CAT, with no changes in other parameters vs. controls.

Cu(II), Mn(IV) and V(IV) 2-methylaminopyridine complexes offer a physiological approach to ameliorate the radiation-induced biochemical alterations. In addition, they provide sufficient protection against radiation injury of radiosensitive tissues.