Imidazole-4-N-acetamide Derivatives as a Novel Scaffold for Selective Targeting of Cyclin Dependent Kinases

SIMPLE SUMMARY: General toxicity for the organism is a major drawback of anticancer drugs. Development of new generation chemotherapeutics requires the knowledge about macromolecules critical for tumor cell viability. Among these species (called therapeutic targets), the protein kinases are the established enzymes. However, the parts of protein kinases that are supposed to be targeted by drugs can be structurally similar. Therefore, it is difficult to design the compounds that selectively bind and inactivate individual kinases, especially if the proteins comprise the evolutionarily conserved families. In the present study, a set of advanced approaches of computational chemistry and biochemistry was used for the structure-based design of new compounds to inhibit cyclin-dependent protein kinases (CDK), the enzymes mechanistically implicated in tumor biology. We demonstrated the advantages of the non-equilibrium (NEQ) thermodynamics method for a time-efficacious, accurate, and informative prediction of CDK inhibitory properties of new compounds. Importantly, NEQ-based predictions correlated with experimental testing. ABSTRACT: The rational design of cyclin-dependent protein kinase (CDK) inhibitors presumes the development of approaches for accurate prediction of selectivity and the activity of small molecular weight anticancer drug candidates. Aiming at attenuation of general toxicity of low selectivity compounds, we herein explored the new chemotype of imidazole-4-N-acetamide substituted derivatives of the pan-CDK inhibitor PHA-793887. Newly synthesized compounds 1–4 containing an aliphatic methyl group or aromatic radicals at the periphery of the scaffold were analyzed for the prediction of relative free energies of binding to CDK1, -2, -5, and -9 using a protocol based on non-equilibrium (NEQ) thermodynamics. This methodology allows for the demonstration of a good correlation between the calculated parameters of interaction of 1–4 with individual targets and the values of inhibitory potencies in in vitro kinase assays. We provide evidence in support of NEQ thermodynamics as a time sparing, precise, and productive approach for generating chemical inhibitors of clinically relevant anticancer targets.