Recent development of cyclic amide (pyridone/lactam) moiety containing heterocycles as protein kinase inhibitors.

Staurosporine, pyridone 6 and hydroxyfasudil are cyclic amide (pyridone/lactam) moiety containing heterocycles that are discovered/developed as potent protein kinase inhibitors targeting on the ATP (Adenosine-5'-triphosphate) binding pocket. Despite different molecular shapes (pentacycle, tetracycle and bicycle, respectively), they all bind to the residues of the hinge region at ATP binding pocket of protein kinases in a very similar manner: the cyclic amide moiety occupies the adenine region of ATP binding pocket and forms at least two hydrogen bonding interaction with the hinge region via its hydrogen bond acceptor/donor pair. Using a few examples of cyclic amide (pyridone/lactam) moiety containing heterocyclic protein kinase inhibitors, this review discusses their therapeutic application, structural basis of kinase inhibition, as well as their associated syntheses. It is anticipated that the design, synthesis and profiling of the kinase inhibitor-biased library based upon the cyclic amide (pyridone/lactam) moiety containing core scaffolds may significantly enhance the efficiency of high-throughput screenings (HTS), accelerate hit-to-lead process and improve the success rate in the development of protein kinase inhibitors for the treatment of various diseases especially cancer.