- Synthesis, radiolabelling and initial biological characterisation of 18F-labelled xanthine derivatives for PET imaging of Eph receptors
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Eph receptor tyrosine kinases, particularly EphA2 and EphB4, represent promising candidates for molecular imaging due to their essential role in cancer progression and therapy resistance. Xanthine derivatives were identified to be potent Eph receptor inhibitors with IC50 values in the low nanomolar range (1-40 nm). These compounds occupy the hydrophobic pocket of the ATP-binding site in the kinase domain. Based on lead compound 1, we designed two fluorine-18-labelled receptor tyrosine kinase inhibitors ([18F]2/3) as potential tracers for positron emission tomography (PET). Docking into the ATP-binding site allowed us to find the best position for radiolabelling. The replacement of the methyl group at the uracil residue ([18F]3) rather than the methyl group of the phenoxy moiety ([18F]2) by a fluoropropyl group was predicted to preserve the affinity of the lead compound 1. Herein, we point out a synthesis route to [18F]2 and [18F]3 and the respective tosylate precursors as well as a labelling procedure to insert fluorine-18. After radiolabelling, both radiotracers were obtained in approximately 5% radiochemical yield with high radiochemical purity (>98%) and a molar activity of >10 GBq μmol-1. In line with the docking studies, first cell experiments revealed specific, time-dependent binding and uptake of [18F]3 to EphA2 and EphB4-overexpressing A375 human melanoma cells, whereas [18F]2 did not accumulate at these cells. Since both tracers [18F]3 and [18F]2 are stable in rat blood, the novel radiotracers might be suitable for in vivo molecular imaging of Eph receptors with PET.
- Belter, Birgit,Caflisch, Amedeo,K?ckerling, Martin,Kinski, Elisa,Mamat, Constantin,Neuber, Christin,Pietzsch, Jens,Pretze, Marc,Steinbach, J?rg
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p. 3104 - 3116
(2020/05/08)
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- NEW ANTI-ANGIOGENIC COMPOUNDS
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The invention relates to compounds of formula (I), tautomers and salts thereof wherein R1 is methyl or ethyl, R2 is n-butyl or o-methoxyphenyl, R3 is hydrogen or hydroxy; and R4 is hydrogen or methyl. These comp
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Page/Page column 12; 15
(2011/02/24)
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- Structure-based optimization of potent and selective inhibitors of the tyrosine kinase erythropoietin producing human hepatocellular carcinoma receptor B4 (EphB4)
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The tyrosine kinase EphB4 is an attractive target for drug design because of its recognized role in cancer-related angiogenesis. Recently, a series of commercially available xanthine derivatives were identified as micromolar inhibitors of EphB4 by high-throughput fragment-based docking into the ATP-binding site of the kinase domain. Here, we have exploited the binding mode obtained by automatic docking for the optimization of these EphB4 inhibitors by chemical synthesis. Addition of only two heavy atoms, methyl and hydroxyl groups, to compound 4 has yielded the single-digit nanomolar inhibitor 66, with a remarkable improvement of the ligand efficiency from 0.26 to 0.37 kcal/(mol per non-hydrogen atom). Compound 66 shows very high affinity for a few other tyrosine kinases with threonine as gatekeeper residue (Abl, Lck, and Src). On the other hand, it is selective against kinases with a larger gatekeeper. A 45 ns molecular dynamics (MD) simulation of the complex of EphB4 and compound 66 provides further validation of the binding mode obtained by fragment-based docking. 2009 American Chemical Society.
- Lafleur, Karine,Huang, Danzhi,Zhou, Ting,Caflisch, Amedeo,Nevado, Cristina
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experimental part
p. 6433 - 6446
(2010/03/31)
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