Nikolaos Klouras

A proposed mechanism for the inhibitory effect of the anticancer agent titanocene dichloride on tumour gelatinases and other proteolytic enzymes

Titanocene dichloride, the most studied metallocene, exhibits antiproliferative activity in a wide spectrum of murine and human tumours. In this article it is demonstrated that titanocene dichloride inhibits tumour gelatinases in a dose-dependent manner. Substrate saturation experiments and the fact that the IC50 values were increased in correlation with collagen substrate concentrations indicate that the titanocene dichloride induced inhibition is of a competitive type. Titanocene dichloride also specifically inhibits clostridium collagenase and trypsin, particularly when collagens are used as substrates. Binding experiments demonstrate that cyclopentadiene–Ti(IV) moieties, resulting from titanocene dichloride at physiological pH, are bound mainly to different types of collagens and to a lesser extent to casein or bovine serum albumin, forming soluble and stable adducts. These results indicate that titanocene dichloride behaves as a competitive inhibitor against various proteolytic enzymes by binding to the substrate rather than to the enzyme active site. This property may be responsible for the antiangiogenic effect of titanocene dichloride and additionally contributes to its anticancer action.

Dinuclear Lanthanide(III) Complexes by Metal-Ion-Assisted Hydration of Di-2-pyridyl Ketone Azine

The initial employment of di-2-pyridyl ketone azine in 4f metal chemistry has led to a unique ligand transformation; the resulting anionic ligand is able to bridge two Ln(III) ions, affording neutral and cationic dinuclear complexes with interesting properties.

The crystal and molecular structure of bis(η5-trimethylsilylcyclopentadienyl)titanium(IV) dichloride, Ti(η5-C5H4SiMe3)2Cl2

SummaryThe crystal and molecular structure of the titanocene complex Ti(η5-C5H4SiMe3)2Cl2 has been determined by X-ray diffraction studies. The compound crystallizes in the triclinic crystal system [a=6.747(8),b=12.815(2),c=12.928(4) Å and α=67.16(2), β=82.29(5), γ=74.83(4)°] in the space group

Unexpected formation, X-ray structure, and characterization of the triangular [Ti3Ο(OMe)6(η5-C5H5)3](I3) complex from hydrolysis and methanolysis of [Ti(η5-C5H5)2I2]

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Reaction of titanocene dihalides with Na2H2EDTA. Crystal structure of [Ti(EDTA)(H2O)]

with 2 formula units in the unit cell. The coordination about the titanium atom formed by the two chlorine atoms and the centroids of the cyclopentadienyl rings is that of a distorted tetrahedron. The Cl-Ti-Cl angle is 91.63° while the (centroid)-Ti-(centroid) angle is 131.02°.ZusammenfassungDie Kristall- und Molekülstruktur des Titanocen-Komplexes Ti(η5-C5H4SiMe3)2Cl2 wurde durch eine Röntgenstrukturanalyse bestimmt. Die Verbindung kristallisiert im triklinen Kristallsystem [a=6.747(8),b=12.815(2),c=12.928(4) Å und α=67.16(2), β=82.29(5), γ=74.83(4)°] in der Raumgruppe

SYNTHESE VON RINGSUBSTITUIERTEN TITANOCEN-SULFIDOTETRASELENID-CHELATEN

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