- The first iron(III) complexes with cyclin-dependent kinase inhibitors: Magnetic, spectroscopic (IR, ES+ MS, NMR, 57Fe M?ssbauer), theoretical, and biological activity studies
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The first FeIII complexes 1-6 with cyclin-dependent kinase (CDK) inhibitors of the type [Fe(Ln)Cl3]·nH2O (n=0 for 1, 1 for 2, 2 for 3-6; L1-L6=C2- and phenyl-substituted CDK inhibitors derived from 6-benzylamino-9-isopropylpurine), have been synthesized and characterized by elemental analysis, IR, 57Fe Mo?ssbauer, 1H and 13C NMR, and ES+ mass spectroscopies, conductivity and magnetic susceptibility measurements, and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The study revealed that the compounds are mononuclear, tetrahedral high-spin (S=5/2) FeIII complexes with an admixture of an S=3/2 spin state originating probably from five-coordinated FeIII ions either connecting with a bidentate coordination mode of the CDK inhibitor ligand or relating to the possibility that one crystal water molecule enters the coordination sphere of the central atom in a portion of molecules of the appropriate complex. Nearly spin-only value of the effective magnetic moment (5.82μeff/μB) was determined for compound 1 due to absence of crystal water molecule(s) in the structure of the complex. Based on NMR data and DFT calculations, we assume that the appropriate organic ligand is coordinated to the FeIII ion through the N7 atom of a purine moiety. The cytotoxicity of the complexes was tested in vitro against selected human cancer cell lines (G-361, HOS, K-562 and MCF-7) along with the ability to inhibit the CDK2/cyclinE kinase. The best cytotoxicity (IC50: 4-23μM) and inhibition activity (IC50: 0.02-0.09μM) results have been achieved in the case of complexes 2-4, and complexes 3, 4 and 6, respectively. In addition, the X-ray structure of 2-chloro-6-benzylamino-9-isopropylpurine, i.e. a precursor for the preparation of L1, L4 and L5, is also described.
- Trávní?ek, Zdeněk,Popa, Igor,?ajan, Michal,Zbo?il, Radek,Kry?tof, Vladimír,Mikulík, Ji?í
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p. 405 - 417
(2011/12/22)
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- Cytokinin-derived cyclin-dependent kinase inhibitors: Synthesis and cdc2 inhibitory activity of olomoucine and related compounds
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Cyclin-dependent kinases (cdk) have recently raised considerable interest in view of their essential role in the regulation of the cell division cycle. The structure-activity relationships of edk inhibition showed that the 1, 3, and 7 positions of the purine ring must remain free, probably for a direct interaction, in which it behaves as a hydrogen bond acceptor. Olomoucine (6-(benzylamino)-2-[(2-hydroxyethyl)amino]-9-methylpurine, OC), roscovitine (6-(benzylamino)2(R)-[[1-(hydroxymethyl)propyl]amino]-9- isopropylpurine), and other N6,2,9-trisubstituted adenines were found to exert a strong inhibitory effect on the p34(cdc2)/cyclin B kinase. Removal or change of the side chain at position 2 or the hydrophobic group at position 9 dramatically decreased the inhibitory activity of olomoucine or roscovitine. Inhibition of cdk with OC and related compounds clearly arrests cell proliferation of many tumor cell lines at G1/S and G2/M transitions and also triggers apoptosis in the target tumor cells in vitro and in vivo. Thus, from a pharmacological point of view, OC may represent a model compound for a new class of antimitotic and antitumor drugs.
- Havlí?ek, Libor,Hanu?, Jan,Vesely, Jaroslav,Leclerc, Sophie,Meijer, Laurent,Shaw, Gordon,Strnad, Miroslav
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p. 408 - 412
(2007/10/03)
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