Metabolism guided optimization of peptidomimetics as non-covalent proteasome inhibitors for cancer treatment.

A series of novel non-covalent peptidomimetic proteasome inhibitors possessing bulky group at the C-terminus and N -alkylation at the N -terminus were designed with the aim to increase metabolic stabilities in vivo. All the target compounds were screened for their inhibitory activities against human 20S proteasome, and most analogs exhibited notable potency compared with the positive control bortezomib with IC 50 values lower than 10 nM, which also displayed potent cytotoxic activities against multiple myeloma (MM) cell lines and human acute myeloid leukemia (AML) cells. Furthermore, whole blood stability and in vivo proteasome inhibitory activity experiments of selected compounds were conducted for further evaluation, and the representative compound 43 (IC 50 = 8.39 ± 2.32 nM, RPMI-8226: IC 50 = 15.290 ± 2.281 nM, MM-1S: IC 50 = 9.067 ± 3.103 nM, MV-4-11: IC 50 = 2.464 ± 0.713 nM) revealed a half-life extension of greater than 9-fold (329.21 min VS 36.79 min) and potent proteasome inhibitory activity in vivo. The positive results confirmed the reliability of the metabolism guided optimization strategy, and the analogs discovered are potential leads for exploring new anti -MM drugs. [Display omitted] • A series of non-covalent proteasome inhibitors with bulky group and N -alkylation were synthesized and evaluated. • Compounds 43 and 53 exhibited excellent proteasome inhibitory activities. • Compounds 43 and 53 displayed potent antiproliferative activities against RPMI-8226, MM-1S and MV-4-11 cell lines. • Compound 43 showed high metabolic stability in vitro. [ABSTRACT FROM AUTHOR]