We report 31 new compounds designed, synthesized and evaluated on Bcr-Abl, BTK and FLT3-ITD as part of our program to develop 2,6,9-trisubstituted purine derivatives as inhibitors of oncogenic kinases. The design was inspired by the chemical structures of well-known kinase inhibitors and our previously developed purine derivatives. The synthesis of these purines was simple and used a microwave reactor for the final step. Kinase assays showed three inhibitors with high selectivity for each protein that were identified: 4f (IC50 = 70 nM for Bcr-Abl), 5j (IC50 = 0.41 μM for BTK) and 5b (IC50 = 0.38 μM for FLT-ITD). The 3D-QSAR analysis and molecular docking studies suggested that two fragments are potent and selective inhibitors of these three kinases: a substitution at the 6-phenylamino ring and the length and volume of the alkyl group at N-9. The N-7 and the N-methyl-piperazine moiety linked to the aminophenyl ring at C-2 are also requirements for obtaining the activity. Furthermore, most of these purine derivatives were shown to have a significant inhibitory effect in vitro on the proliferation of leukaemia and lymphoma cells (HL60, MV4-11, CEM, K562 and Ramos) at low concentrations. Finally, we show that the selected purines (4i, 5b and 5j) inhibit the downstream signalling of the respective kinases in cell models. Thus, this study provides new evidence regarding how certain chemical modifications of purine ring substituents provide novel inhibitors of target kinases as potential anti-leukaemia drugs.

Departamento de Ciencias Preclínicas Facultad de Medicina Universidad de La Frontera Manuel Montt 112 Temuco 4780000 Chile

Departamento de Farmacia Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Avenida Vicuña Mackenna 4860 Santiago 7820436 Chile

Departamento de Química Orgánica Facultad de Química y de Farmacia Pontificia Universidad Católica de Chile Avenida Vicuña Mackenna 4860 Santiago 7820436 Chile

Department of Experimental Biology Palacký University Olomouc Šlechtitelů 27 783 71 Olomouc Czech Republic

Facultad de Farmacia Centro de Investigación Farmacopea Chilena Universidad de Valparaíso Avenida Gran Bretaña 1093 Valparaíso 2360102 Chile

Institute of Molecular and Translational Medicine Faculty of Medicine and Dentistry Palacký University Olomouc Hněvotínská 5 779 00 Olomouc Czech Republic

Instituto de Química y Bioquímica Facultad de Ciencias Universidad de Valparaíso Avenida Gran Bretaña 1111 Valparaíso 2360102 Chile

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