Synthesis and Biological Evaluation of Urea Derivatives as Highly Potent and Selective Rho Kinase Inhibitors

RhoA and its downstream effector ROCK mediate stress fiber formation and cell contraction through their effects on the phosphorylation of myosin light chain (MLC). Inhibition of the RhoA/ROCK pathway has proven to be a promising strategy for several indications such as cardiovascular disease, glaucoma, and inflammatory disease. In 2010, our group reported urea-based ROCK inhibitors as potential antiglaucoma agents. These compounds showed potent IC50 values in enzymatic and cell-based assays and significant intraocular pressure (IOP)-lowering effects in rats (∼7 mmHg). (22) To develop more advanced ROCK inhibitors targeting various potential applications (such as myocardial infarction, erectile dysfunction, multiple sclerosis, etc.) in addition to glaucoma, a thorough SAR for this urea-based scaffold was studied. The detailed optimization process, counter-screening, and in vitro and in vivo DMPK studies are discussed. Potent and selective ROCK inhibitors with various in vivo pharmacokinetic properties were discovered.