Issue 33, 2016

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

Abstract

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.

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

Supplementary files

Article information

Article type
Paper
Submitted
15 Apr 2016
Accepted
01 Jul 2016
First published
04 Jul 2016

Dalton Trans., 2016,45, 13196-13203

Author version available

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

R. M. Lord, S. J. Allison, K. Rafferty, L. Ghandhi, C. M. Pask and P. C. McGowan, Dalton Trans., 2016, 45, 13196 DOI: 10.1039/C6DT01464J

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