Structure-activity relationship studies of prostate-specific membrane antigen (PSMA) inhibitors derived from α-amino acid with (S)- or (R)-configuration at P1′ region

Prostate-specific membrane antigen (PSMA), a type II membrane glycoprotein, is considered an excellent target for the diagnosis or treatment of prostate cancer. We previously investigated the effect of β- and γ-amino acids with (S)- or (R)-configuration in the S1 pocket on the binding affinity for PSMA. However, comprehensive studies on the effect of α-amino acid with (R)-configuration in the S1′ pocket has not been reported yet. We selected ZJ-43 (1) and DCIBzL (5) as templates and synthesized their analogues with (S)- or (R)-configuration in the P1 and P1′ regions. The PSMA-inhibitory activities of compounds with altered chirality in the P1′ region were dropped dramatically, with their IC50 values changing from nM to μM ranges. The compounds with (S)-configuration at both P1 and P1′ regions were more potent than the others. The findings of this study may provide insights regarding the structural modification of PSMA inhibitor in the S1′ binding pocket.