Anticancer and Antibacterial Activity of Transition Metal Complexes

Herein, we report 30 new β-diketonate titanium compounds of the type [Ti(O,O)2X2], whereby O,O=asymmetric or symmetric β-diketonate ligand and X=Cl, Br, OEt or OiPr. Thirteen new crystal structures are discussed and show that these octahedral species all adopt cis geometries in the solid state. These compounds have been tested for their cytotoxicity using SRB and MTT assays, showing several of the compounds are as potent as cisplatin against a range of tumor cell lines. Results also show the [Ti(O,O)2Br2] complexes are more potent than [Ti(O,O)2Cl2], [Ti(O,O)2(OEt)2] and [Ti(O,O)2(OiPr)2]. Using a simple symmetrical heptane-3,5-dione (O,O) ligand bound to titanium, we observed more than a 50-fold increase in potency with the [Ti(O,O)2Br2] (28) when compared to [Ti(O,O)2Cl2] (27). One of the more potent compounds (6) has been added to three different sixmers of DNA, in order to analyse the potential DNA binding of the compound. NMR studies have been carried out on the compounds, in order to understand the structural properties and the species formed in solution during the in vitro cell assays.

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β‐Diketonate Titanium Compounds Exhibiting High In Vitro Activity and Specific DNA Base Binding

Novel enantiopure cyclopentadienyl Ti(IV) oximato compounds as potential anticancer agents

The interaction of the potential anti-tumor agent vanadocene dichloride ([Cp2VCl2] or VDC) with some relevant bioligands of the cytosol such as proteins (Hb), amino acids (glycine and histidine), NADH derivatives (NADH, NADPH, NAD+ and NADP+), reductants (GSH and ascorbic acid), phosphates (HPO42−, P2O74−, cAMP, AMP, ADP and ATP) and carboxylate derivatives (lactate) and its uptake by red blood cells were studied. The results indicated that [Cp2VCl2] transforms at physiological pH into [Cp2V(OH)2] and that only HPO42−, P2O74−, lactate, ATP and ADP form mixed species with the [Cp2V]2+ moiety replacing the two hydroxide ions. EPR and electronic absorption spectroscopy, agarose gel electrophoresis and spin trapping measurements allow excluding any direct interaction and/or intercalation with DNA and the formation of reactive oxygen species (ROS) in Fenton-like reactions. Uptake experiments by erythrocytes suggested that VDC crosses the membrane and enters inside the cells, whereas ‘bare’ VIV transforms into VIVO species with loss of the two cyclopentadienyl rings. This transformation in the cellular environment could be related to the mechanism of action of VDC.

Dennis Alex

Papers

Titanocene Y and Vanadocene Y: Platinum Resistance-Breaking Cytotoxic and DNA-Targeting Anticancer Drug Candidates