Structural determinants for ERK5 (MAPK7) and leucine rich repeat kinase 2 activities of benzo[e]pyrimido-[5,4-b]diazepine-6(11H)-ones

The benzo[e]pyrimido-[5,4-b]diazepine-6(11H)-one core was discovered as a novel ERK5 (also known as MAPK7 and BMK1) inhibitor scaffold, previously. Further structure-activity relationship studies of this scaffold led to the discovery of ERK5-IN-1 (26) as the most selective and potent ERK5 inhibitor reported to date. 26 potently inhibits ERK5 biochemically with an IC50 of 0.162 +/- 0.006 mu M and in cells with a cellular EC50 for inhibiting epidermal growth factor induced ERK5 autophosphorylation of 0.09 +/- 0.03 W. Furthermore, 26 displays excellent selectivity over other kinases with a KINOMEscan selectivity score (S-10) of 0.007, and exhibits exceptional bioavailability (F%) of 90% in mice. 26 will serve as a valuable tool compound to investigate the ERK5 signaling pathway and as a starting point for developing an ERK5 directed therapeutic agent. (C) 2013 Elsevier Masson SAS. All rights reserved.