Identification\nand Benchmarking of Myokinasib-II as\na Selective and Potent Chemical Probe for Exploring MLCK1 Inhibition

Deciphering the functional relevance of every protein\nis crucial\nto developing a better (patho)physiological understanding of human\nbiology. The discovery and use of quality chemical probes propel exciting\ndevelopments for developing drugs in therapeutic areas with unmet\nclinical needs. Myosin light-chain kinase (MLCK) serves as a possible\ntherapeutic target in a plethora of diseases, including inflammatory\ndiseases, cancer, etc. Recent years have seen a substantial increase\nin interest in exploring MLCK biology. However, there is only one\nwidely used MLCK modulator, namely, ML-7, that too with a narrow working\nconcentration window and high toxicity profile leading to limited\ninsights. Herein, we report the identification of a potent and highly\nselective chemical probe, Myokinasib-II, from the synthesis and structure–activity\nrelationship studies of a focused indotropane-based compound collection.\nNotably, it is structurally distinct from ML-7 and hence meets the\nneed for an alternative inhibitor to study MLCK biology as per the\nrecommended best practices. Moreover, our extensive benchmarking studies\ndemonstrate that Myokinasib-II displays better potency, better selectivity\nprofile, and no nonspecific interference in relevant assays as compared\nto other known MLCK inhibitors.