Anthony Deally

The Antiangiogenic and Antitumoral Activity of Titanocene Y* In Vivo

The 4-diethylaminomethylbenzyl-substituted titanocene dichloride (Titanocene Y*), which is completely water- soluble and showed nanomolar activity against the human renal cancer cells CAKI-1, was tested in vitro in an antiangiogenesis assay against human umbilical vein endothelial cells, HUVEC, delivering an IC50 value of 23 +/- 17 {Mu}M. Titanocene Y* was then given at 25, 50 and 75 mg/kg/d, on five consecutive days per week for up to three weeks to one cohort of six CAKI-1 tumor-bearing female NMRI:nu/nu mice, while a further cohort was treated with solvent only. At the two higher dosages Titanocene Y* showed high toxicity leading to mortality, while the titanocene-treated mouse cohort treated with the lowest dosage showed a moderate but statistically significant tumor growth reduction with respect to the solvent-treated control group, with an optimal T/C value of 76% at the end of the experiment. Immunohistological analysis revealed that the expression of the proliferation marker Ki-67 was reduced by 21%. Furthermore, anti-angiogenic activity was identified by CD31 staining; the number of micro vessels in a defined tumor area decreased by 23% due to Titanocene Y* treatment. The substance caused dose-dependent body weight loss but did not reduce the number of white blood cells at doses of 25 and 50 mg/kg/d.

Novel Nonsymmetrically p-Benzyl-Substituted (Benz)imidazole N-Heterocyclic Carbene-Silver(I) Acetate Complexes: Synthesis and Biological Evaluation

Nonsymmetrically substituted N-heterocyclic carbene (NHC) precursors 1a–d and 3a–d were synthesised by first reacting 1H-(benz)imidazole with p-cyanobenzyl bromide to give 4-(1H-imidazole-1-ylmethyl)benzonitrile (1) and 4-(1H-benzimidazole-1-ylmethyl)benzonitrile (3) and afterwards introducing benzyl bromide, 1-(bromomethyl)-4-methylbenzene, 1-(bromomethyl)-4-methoxybenzene, and methyl 4-(bromomethyl)benzoate. The NHC-silver(I) acetate complexes (1-benzyl-3-(4-cyanobenzyl)-2,3-dihydro-1H-imidazole-2-ylidene) silver(I) acetate (2a), (1-(4-cyanobenzyl)-3-(4-methylbenzyl)-2,3-dihydro-1H-imidazole-2-ylidene) silver(I) acetate (2b), (1-(4-cyanobenzyl)-3-[4-(methoxycarbonyl)benzyl]-2,3-dihydro-1H-imidazole-2-ylidene) silver(I) acetate (2c), (1-benzyl-3-(4-cyanobenzyl)-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4a), (1-(4-cyanobenzyl)-3-(4-methylbenzyl)-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4b), (1-(4-cyanobenzyl)-3-(4-methoxybenzyl)-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4c), and (1-(4-cyanobenzyl)-3-[4-(methoxycarbonyl)benzyl]-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4d) were yielded by reacting these NHC precursors with silver(I) acetate. The silver(I) acetate complex 4b was characterised by single crystal X-ray diffraction. Preliminary in vitro antibacterial studies against the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli, using the Kirby-Bauer disc diffusion method, were carried out on the seven NHC-silver(I) acetate complexes 2a–c and 4a–d. Also the IC50 values of these seven complexes were determined by an MTT-based assay against the human renal cancer cell line Caki-1. The complexes 2a–c and 4a–c revealed the following IC50 values, respectively, 25 (±1), 15 (±2), 5.4 (±0.8), 16 (±2), 7.1 (±1), 20 (±4), and 14 (±1) μM.

Novel Achiral Aryl-Substituted Vanadocenes: Synthesis and Preliminary Cytotoxicity Studies

From the reaction of 6-(4-methoxymethyl-phenyl) fulvene (1a), 6-(N-methyl-pyrrole) fulvene (1b), and 6-(4-dimethylamino-phenyl) fulvene (1c) with LiBEt3H, the corresponding lithium cyclopentadienide intermediates (2a–c) were synthesized. These intermediates were then transmetallated to vanadium with VCl4 to yield the substituted vanadocene dichlorides bis-[(4-methoxymethyl-benzyl)cyclopentadienyl] vanadium(iv) dichloride (3a), bis-[(N-methylpyrrole)2-methylcyclopentadienyl] vanadium(iv) dichloride (3b), and bis-[(p-dimethylaminobenzyl)cyclopentadienyl] vanadium(iv) dichloride (3c). The vanadocene dichloride 3a was characterized by single crystal X-ray diffraction. All three vanadocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the human renal cell line Caki-1 in order to determine their IC50 values. Vanadocenes 3a–b were found to have IC50 values of 6.5 and 5.2 µM, respectively, while 3c displayed a superior value of 1.7 µM.

Pseudo-halide derivatives of titanocene: synthesis and cytotoxicity studies.

The well-known anticancer drug candidate bis-[(p-methoxybenzyl)cyclopentadienyl] titanium(IV) dichloride (Titanocene ) was reacted with sodium azide or potassium cyanate, thiocyanate or selenocyanate in order to give pseudo-halide analogues of Titanocene . and were characterised by single crystal X-ray diffraction, which confirmed the expected nitrogen binding of the cyanate and thiocyanate to the titanium centre. All four titanocenes had their cytotoxicity investigated through preliminary in vitro testing on the LLC-PK (pig kidney epithelial) cell line in an MTT based assay in order to determine their IC50 values. Titanocenes were found to have IC50 values of 24 (± 8) μM, 101 (± 14) μM, 54 (± 21) μM and 27 (± 4) μM respectively. All four titanocene derivatives show significant cytotoxicity improvement when compared to unsubstituted titanocene dichloride and and showed similiar cytotoxic behaviour to Titanocene in vitro.

The Activity of Titanocene T Against Xenografted Caki-1 Tumors

The indole-substituted titanocene dichloride derivative Titanocene T, which is completely water-soluble and shows micromolar activity against the human renal cancer cells Caki-1, was tested in vivo an against xenografted human renal cell tumors in mice. Titanocene T was then given at 25 and 50 mg/kg, seven times every four days during three weeks to two groups (n=6) of Caki-1 tumor-bearing female NMRI: nu/nu mice, while the control group was treated with solvent only. At both doses Titanocene T induced a moderate to good tumor growth reduction with respect to the solvent-treated control group, with an optimal T/C value of 51% and 32% and showed neither mortality nor toxicity. Immunohistochemical analysis revealed that the expression of the proliferation marker Ki-67 was reduced in the high-dosage group. Furthermore, anti-angiogenic activity was identified by CD31 staining; the number of micro vessels in a defined tumor area decreased by 27% and 29% due to Titanocene T treatment.

Synthesis and biological evaluation of achiral indole-substituted titanocene dichloride derivatives.

Six new titanocene compounds have been isolated and characterised. These compounds were synthesised from their fulvene precursors using Super Hydride (LiBEt3H) followed by transmetallation with titanium tetrachloride to yield the corresponding titanocene dichloride derivatives. These complexes are bis-[((1-methyl-3-diethylaminomethyl)indol-2-yl)methylcyclopentadienyl] titanium (IV) dichloride (5a), bis-[((5-methoxy-1-methyl,3-diethylaminomethyl)indol-2-yl)methylcyclopentadienyl] titanium (IV) dichloride (5b), bis-[((1-methyl,3-diethylaminomethyl)indol-4-yl)methylcyclopentadienyl] titanium (IV) dichloride (5c), bis-[((5-bromo-1-methyl)indol-3-yl)methylcyclopentadienyl] titanium (IV) dichloride (5d), bis-[((5-chloro-1-methyl)indol-3-yl)methylcyclopentadienyl] titanium (IV) dichloride (5e), and bis-[((5-fluoro-1-methyl)indol-3-yl)methylcyclopentadienyl] titanium (IV) dichloride (5f). All six titanocenes 5a–5f were tested for their cytotoxicity through MTT-based in vitro tests on CAKI-1 cell lines using DMSO and Soluphor P as solubilising agents in order to determine their IC50 values. Titanocenes 5a–5f were found to have IC50 values of 10 (±2), 21 (±3), 29 (±4), 140 (±6), and 450 (±10) μM when tested using DMSO.