Synthesis and Evaluation of Radioiodinated Acyloxymethyl Ketones as Activity-Based Probes for Cathepsin B

Dipeptidyl (acyloxy)methyl ketones (AOMKs) were functionalized with different iodine-containing prosthetic groups to generate a library of candidate cathepsin B probes. Compound 23a, (S)-20-[(S)-2-{[(benzyloxy)carbonyl]amino}-3-phenylpropanamido]-1-(4-iodophenyl)-1,14,21-trioxo-5,8,11-trioxa-2,15-diazadocosan-22-yl 2,4,6-trimethylbenzoate, was identified as a potential lead through in vitro screening, having a Ki = 181 ± 9 nM and demonstrating …