Design, synthesis and biological evaluation of cobalt(II)-Schiff base complexes as ATP-noncompetitive MEK1 inhibitors.

In this report, we designed and synthesized a series of cobalt(II)-Schiff base complexes (CoSBC) with competent MEK1 (mitogen-activated protein kinase kinase−1) inhibitory activity. Based on our previous report, the CoSBC exhibited high binding affinity with MEK1 protein. To further explore metal complexes as MEK1 inhibitors, a series of transition metals and ligands were employed to build a library of various metal Schiff base complexes. The MEK inhibition assays revealed that only CoSBC exhibited obvious inhibitory activity, complex 2b showed the best inhibition both in BRaf (B-rapidly accelerated fibrosarcoma)/MEK1 and MEK1/ERK2 (extracellular signal-regulated kinases-2) cascading (IC50 is 1.988 ± 0.14 μM and 1.589 ± 0.054 μM respectively). In addition, homogeneous time-resolved fluorescence test method was used to prove that CoSBC as ATP-noncompetitive MEK1 inhibitor. MEK kinase selectivity assay indicated that CoSBC can selectively inhibit MEK1/2 kinases rather than other MAPKs (mitogen-activated protein kinases) family kinases. Moreover, the interaction mode of 2b with MEK1 protein has been demonstrated by computer aided drug design.