Cis-enone resorcylic acid lactones (RALs) as irreversible protein kinase inhibitors.

Resorcylic acid lactones (RALs) constitute a group of polyketide natural products with a large macrocyclic ring fused to resorcylic acid. Despite distinct core scaffold from all marketed kinase inhibitors, RALs bearing a cis-enone moiety have recently shown irreversible yet selective inhibition on a subset of kinases along the MAPK signaling pathway such as MEK, ERK and TAK1. The biochemical and structural studies have demonstrated that the cis-enone RALs can inhibit kinase activity by forming a covalent Michael adduct with an adequately positioned cysteine residue in the ATP binding pocket. This review discusses the mechanism of action, synthetic strategies, and structure-activity relationships (SARs) of cis-enone RALs. It is anticipated that design, synthesis and evaluation of cis-enone RALs analogs will diversify the chemical space of kinase inhibitors and facilitate the development of new leads for the treatment of various diseases such as cancer and inflammatory disorders.