Synthesis and biological evaluation of vioprolide B and its dehydrobutyrine-glycine analogue

Herein, we describe the total synthesis of the depsipeptide vioprolide B and of an analogue, in which the ( E )-dehydrobutyrine amino acid was replaced by glycine. The compounds were studied in biological assays which revealed cytotoxicity solely for vioprolide B presumably by covalent binding to cysteine residues of elongation factor eEF1A1 and of chromatin assembly factor CHAF1A. Vioprolide B and an analogue, in which the ( E )-dehydrobutyrine was replaced by glycine, were synthesized and studied in biological assays which revealed cytotoxicity solely for vioprolide B, presumably by covalent binding to the target protein.