Covalent docking modelling-based discovery of tripeptidyl epoxyketone proteasome inhibitors composed of aliphatic-heterocycles

The potential of specific proteasome inhibitors to act as anti-cancer agents has attracted intensive investigations. The proteasome can be covalently inhibited by epoxyketone derivatives via a two-step reaction. Several computational approaches have been developed to mimic the covalent binding event. Compound 1 composed of a six-membered heterocyclic ring was designed by using covalent docking. With a possible different binding mode from the clinical compound Carfilzomib, it occupied the S5 pocket of 20S proteasome and showed favorable inhibitory activity. Subsequently optimization and evaluation were taken place. Among these compounds, 11h demonstrated extraordinary in vitro inhibitory activity and selectivity, and good in vivo proteasome inhibitory activity, a favorable pharmacokinetic profile and xenograft tumor inhibition. The possible binding pattern of compound 11h against proteasome was further fully explored via calculations, providing a theoretical basis for finding potent proteasome inhibitors.