The binding interactions of molybdenocene dichloride (Cp2MoCl2) and [Cp-2(L)(n)]Cl-2 (n = 1, L = 6-mercaptopurine, 6-mercaptopurineribose, 2-amine-6-mercaptopurine and 2-amine-6-mercaptopurineribose and n = 2, L = D-penicillamine) complexes with calfthymus DNA have been investigated by cyclic voltammetry. Cp2MoCl2 belongs to a group of metallocene antitumor agents and [Cp2Mo(L)(n)]Cl-2 complexes are structural modifications of molybdenocene dichloride that have also been shown to possess antitumor properties. From the mechanistic point, there is interest in discovering whether molybdenocene dichloride binds DNA or not. To investigate this issue in more detail, we carried out molybdenocene-DNA titrations monitored by cyclic voltammetry. The changes in oxidation potentials (E-pa) allowed us to determine the degree of Mo-DNA interaction. (Cp2MoCl2) and [Cp2Mo(L)(n)]Cl-2 (n = 1, L = 2-amine-6-mercaptopurine and 2-amine-6-mercaptopurineribose and n = 2, L = D-penicillamine) complexes showed weak DNA bindings (3.2-10.1%) while the complexes containing the ligands 6-mercaptopurine and 6-mercaptopurineribose showed negligible interactions. ICP-AES was used to corroborate the CV results. (C) 2004 Published by Elsevier B.V.