DNA cleavage activity of VIVO(acac)2 and derivatives

The DNA cleavage activity of several beta-diketonate vanadyl complexes is examined. Vanadyl acetylacetonate, (VO)-O-IV(acac)(2), 1, shows a remarkable activity in degrading plasmid DNA in the absence of any activating agents, air and photoirradiation. The cleaving activity of several related complexes (VO)-O-IV(lid) (2, HIM 3,-heptanedione). (VO)-O-VI(acac-NH2)(2) (3. Hacac-NH2, acetoacetamide) and (VO)-O-IV(acac-NMe2)(2) (4, Hacac-NMe2, = N,N-dimethylacetoacetamide) is also evaluated. It is shown that 2 exhibits ill activity similar to 1, while 3 and 4 are much less efficient cleaving agents. The different activity of the complexes is related to their stability towards hydrolysis it) aqueous solution, Which follows the order 1 similar to 2 >> 3 similar to 4 The nature of the pH buffer was also found to he determinant in the nuclease activity of 1 and 2. In a phosphate buffered medium DNA cleavage by these agents is much more efficient that) in tris, hepes, mes or inops buffers. The reaction seems to take place through a mixed mechanism, involving the formation of reactive oxygen species; (ROS), namely OH radicals, and possibly also direct cleavage at phosphodiester linkages induced by the vanadium complexes. (C) 2009 Elsevier Inc. All rights reserved.