Cytotoxic hydrogen bridged ruthenium quinaldamide complexes showing induced cancer cell death by apoptosis

Rianne M. Lord, Simon J. Allison, Karen Rafferty, Laura Ghandhi, Christopher M. Pask, Patrick C. McGowan

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13 Citations (Scopus)


This report presents the first known p-cymene ruthenium quinaldamide complexes which are stabilised by a hydrogen-bridging atom, [{(p-cym)RuIIX(N,N)}{H+}{(N,N)XRuII(p-cym)}][PF6] (N,N = functionalised quinaldamide and X = Cl or Br). These complexes are formed by a reaction of [p-cymRu(μ-X)2]2 with a functionalised quinaldamide ligand. When filtered over NH4PF6, and under aerobic conditions the equilibrium of NH4PF6 ⇔ NH3 + HPF6 enables incorporation of HPF6 and the stabilisation of two monomeric ruthenium complexes by a bridging H+, which are counter-balanced by a PF6 counterion. X-ray crystallographic analysis is presented for six new structures with O⋯O distances of 2.420(4)–2.448(15) Å, which is significant for strong hydrogen bonds. Chemosensitivity studies against HCT116, A2780 and cisplatin-resistant A2780cis human cancer cells showed the ruthenium complexes with a bromide ancillary ligand to be more potent than those with a chloride ligand. The 4′-fluoro compounds show a reduction in potency for both chloride and bromide complexes against all cell lines, but an increase in selectivity towards cancer cells compared to non-cancer ARPE-19 cells, with a selectivity index >1. Mechanistic studies showed a clear correlation between IC50 values and induction of cell death by apoptosis.
Original languageEnglish
Pages (from-to)13196-13203
Number of pages8
JournalDalton Transactions
Issue number33
Publication statusPublished - 4 Jul 2016

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