LAUSR

Abstract Two isomeric ruthenium(II) complexes, [Ru- m -OH] 2+ and [Ru- o -OH] 2+ with two hydroxyl substituents at different positions of ligands, had been designed and synthesized. We found that the cellular uptake efficiency of Ru- o -OH] 2+ was much better than Ru- m -OH] 2+ , and it exhibited higher toxicity toward cancer cell (BEL-7402) than its isomeric compound, [Ru- m -OH] 2+ . Importantly, [Ru- o -OH] 2+ showed great selectivity between cancer cells and human normal cell (HBMEC). Confocal microscopy and inductively coupled plasma mass spectrometry (ICP-MS) indicated that [Ru- o -OH] 2+ mainly accumulated in mitochondria. It could up-grade the expression of Bax and down-grade the level of Bcl-2, which trigger in mitochondrial apoptotic pathway. This study suggests that isomeric metal complexes might make differences in the field of medicine for anti-cancer.