Potent, specific, chemically stable and non-peptide/small-molecular inhibitors of puromycin- sensitive aminopeptidase, such as 3-(2, 6-diethylphenyl)-2, 4 (1H, 3H)-quinazolinedione (PAQ-22, 5), were prepared by the structural development of a potent PSA inhibitor, 2-(2, 6- diethylphenyl)-1, 2, 3, 4-tetrahydroisoquinoline-1, 3-dione (PIQ-22, 4). The design was carried out partly by applying electrostatic potential field information obtained from PIQ-22 ...