DNA interaction with dipolar ruthenium(II) ammine complexes containing 4,4 '-bipyridinium as photochemotherapeutic agents

摘要

The interaction of DNA with dipolar ruthenium(II) ammine complexes containing 4,4'-bipyridinium cations L+, [Ru(L+)(NH3)(5)](3+), has been investigated by spectroscopic and electrochemical methods. These ruthenium(II) complexes undergo strong stacking interactions of L+ with the base-pairs of DNA duplex in addition to the electrostatic and hydrogen binding modes. The phbp(+) ([2](3+)) and pymbp(+) ([3](3+)) complexes bind to DNA more strongly than the mebp(+) ([1](3+)) complex, due to the presence of extended planar aromatic ligands. [3](3+) which exhibited the strongest interaction with DNA can bind to supercoiled plasmid pBR322 DNA following photoinduced loss of ligands pymbp(+) and NH3. The finding led to the photoc-leavage of supercoiled plasmid pBR322 DNA by [3](3+) with visible light under aerobic and unaerobic conditions. Since similar photolysis of [1](3+) and [2](3+) has been observed, all the dipolar ruthenium(II) ammine complexes bearing 4,4'-bipyridinium cations can function as O-2-independent photochemotherapeutic agents. (C) 2014 Elsevier B.V. All rights reserved.