Distinct effects of dinuclear ruthenium(III) complexes on cell proliferation and on cell cycle regulation in human and murine tumor cell lines

Binuclear ruthenium complexes inhibit the fibril formation of human islet amyloid polypeptide

Binuclear ruthenium complexes reverse the aggregation of human islet amyloid polypeptide.

Antitumor and biological investigation of doubly cyclometalated ruthenium(ii) organometallics derived from benzimidazolyl derivatives

In this study, we report the synthesis, anticancer and biological properties of three doubly cyclometalated phenylbenzimidazole derived ruthenium(ii) organometallics (1–3) and their corresponding three organic ligands.

Antioxidant activity of new ruthenium compounds

Many biological properties have been attributed to ruthenium complexes including anti-tumor activity and the attenuation of reperfusion damage and infarct size. In this work, we characterize the antioxidant activity of trans-[RuCl2(nic)4] where nic is 3-pyridinecarboxylic acid and trans-[RuCl2(i-nic)4] where i-nic is 4-pyridinecarboxylic acid by (i) evaluation of total antioxidant potential (TRAP); (ii) prevention of DNA damage induced by hydrogen peroxide using the alkaline comet assay; and (iii) the prevention of lipid peroxidation and cell death induced by iron in liver slices. Our results suggest that nic has stronger antioxidant potential when compared to the i-nic. Higher doses (above 200 microM) of these compounds gave genotoxic effects, but the antioxidant potential could be obtained with the use lower doses (0.1-10 microM).

Transferring the concept of multinuclearity to ruthenium complexes for improvement of anticancer activity

Multinuclear platinum anticancer complexes are a proven option to overcome resistance of established anticancer compounds. Transferring this concept to ruthenium complexes led to the synthesis of dinuclear Ru(II)-arene compounds containing a bis(pyridinone)alkane ligand linker. A pronounced influence of the spacer length on the in vitro anticancer activity was found, which is correlated to the lipophilicity of the complexes. IC(50) values in the same dimension as for established platinum drugs were found in human tumor cell lines. No cross-resistance to oxoplatin, a cisplatin prodrug, was observed for the most active complex in three resistant cell lines; in fact, a 10-fold reversal of sensitivity in two of the oxoplatin-resistant lines was found. (Bio)analytical characterization of the representative examples showed that the ruthenium complexes hydrolyze rapidly, forming predominantly diaqua species that exhibit affinity toward transferrin and DNA, indicating that both proteins and nucleobases are potential targets.

Tuning heavy metal compounds for anti-tumor activity: is diversity the key to ruthenium’s success?

This review aims to bring the reader up to date with the more recent ruthenium compounds that have been synthesized and tested for their cytotoxicity. The chemistry of these transition metal complexes will be introduced and the basic principles that govern their common behavior outlined. The recent history of established compounds within this field will be presented alongside those that now represent the cutting-edge. The inherent variety within this class of compounds will lead the reader to appreciate their diversity and pose questions as to their similarities aside from the presence of a shared metal ion. This review aims to discuss and contextualize the state-of-the-art research within the context of the speculative advancement of this developing field. There is an evident need to specify the molecular and cellular targets of these drug molecules in order to ultimately elucidate their mode or modes of action. The evidence presented herein suggests that new avenues of research require novel analytical probes and methods for tracing the fate of ruthenium complexes in cells in order to understand their very promising cytotoxic activity.

Gold(III) compounds as anticancer agents: relevance of gold-protein interactions for their mechanism of action

Gold(III) compounds constitute an emerging class of biologically active substances, of special interest as potential anticancer agents. During the past decade a number of structurally diverse gold(III) complexes were reported to be acceptably stable under physiological-like conditions and to manifest very promising cytotoxic effects against selected human tumour cell lines, making them good candidates as anti-tumour drugs. Some representative examples will be described in detail. There is considerable interest in understanding the precise biochemical mechanisms of these novel cytotoxic agents. Based on experimental evidence collected so far we hypothesize that these metallodrugs, at variance with classical platinum(II) drugs, produce in most cases their growth inhibition effects through a variety of "DNA-independent" mechanisms. Notably, strong inhibition of the selenoenzyme thioredoxin reductase and associated disregulation of mitochondrial functions were clearly documented in some selected cases, thus providing a solid biochemical basis for the pronounced proapoptotic effects. These observations led us to investigate in detail the reactions of gold(III) compounds with a few model proteins in order to gain molecular-level information on the possible interaction modes with possible protein targets. Valuable insight on the formation and the nature of gold-protein adducts was gained through ESI MS (electrospray ionization mass spectrometry) and spectrophotometric studies of appropriate model systems as it is exemplified here by the reactions of two representative gold(III) compounds with cytochrome c and ubiquitin. The mechanistic relevance of gold(III)-induced oxidative protein damage and of direct gold coordination to protein sidechains is specifically assessed. Perspectives for the future of this topics are briefly outlined.

Effect of ruthenium complexes on the activities of succinate dehydrogenase and cytochrome oxidase

In this article, we report the effects of acute administration of ruthenium complexes, trans-[RuCl(2)(nic)(4)] (nic=3-pyridinecarboxylic acid) 180.7 micromol/kg (complex I), trans-[RuCl(2)(i-nic)(4)] (i-nic=4-pyridinecarboxylic acid) 13.6 micromol/kg (complex II), trans-[RuCl(2)(dinic)(4)] (dinic=3,5-pyridinedicarboxylic acid) 180.7 micromol/kg (complex III) and trans-[RuCl(2)(i-dinic)(4)]Cl (i-dinic=3,4-pyridinedicarboxylic acid) 180.7 micromol/kg (complex IV) on succinate dehydrogenase (SDH) and cytochrome oxidase (COX) activities in brain (hippocampus, striatum and cerebral cortex), heart, skeletal muscle, liver and kidney of rats. Our results showed that complex I inhibited SDH activity in hippocampus, cerebral cortex, heart and liver; and inhibited COX in heart and kidney. Complex II inhibited SDH in heart and hippocampus; COX was inhibited in hippocampus, heart, liver and kidney. SDH activity was inhibited by complex III in heart, muscle, liver and kidney. However, COX activity was increased in hippocampus, striatum, cerebral cortex and kidney. Complex IV inhibited SDH activity in muscle and liver; COX activity was inhibited in kidney and increased in hippocampus, striatum and cerebral cortex. In a general manner, the complexes tested in this work decrease the activities of SDH and COX in heart, skeletal muscle, liver and kidney. In brain, complexes I and II were shown to be inhibitors and complexes III and IV activators of these enzymes. In vitro studies showed that the ruthenium complexes III and IV did not alter COX activity in kidney, but activated the enzyme in hippocampus, striatum and cerebral cortex, suggesting that these complexes present a direct action on COX in brain.

Modulation of creatine kinase activity by ruthenium complexes

Creatine kinase is a crucial enzyme for brain, heart and skeletal muscle energy homeostasis, and a decrease of its activity has been associated with cell death. Many biological properties have been attributed to ruthenium complexes. In this context, this work was performed in order to evaluate creatine kinase activity from rat brain, heart and skeletal muscle (quadriceps) after administration of ruthenium complexes, trans-[RuCl(2)(nic)(4)] (nic=3-pyridinecarboxylic acid) 180.7 micromol/kg (complex I), trans-[RuCl(2)(i-nic)(4)] (i-nic=4-pyridinecarboxylic acid) 13.6 micromol/kg (complex II), trans-[RuCl(2)(dinic)(4)] (dinic=3,5-pyridinedicarboxylic acid) 180.7 micromol/kg (complex III) and trans-[RuCl(2)(i-dinic)(4)] (i-dinic=3,4-pyridinedicarboxylic acid) 180.7 micromol/kg (complex IV). Our results showed that complex I caused inhibition of creatine kinase activity in hippocampus, striatum, cerebral cortex, heart and skeletal muscle. Besides, complex II did not affect the enzyme activity. complexes III and IV increased creatine kinase activity in hippocampus, striatum, cerebral cortex and heart, but not in skeletal muscle. Besides, none of the complexes in vitro altered creatine kinase activity, suggesting that enzymatic activity is indirectly affected by complexes I, III and IV. It is believed that diminution of creatine kinase in brain of rats caused by complex I may be related to results from other study reporting memory impairment caused by the same complex. Further research is necessary in order to elucidate the effects of ruthenium complexes in other important metabolic enzymes.