The inhibition of glyoxalase I enzyme to increase cellular levels of methylglyoxal has been developed as a rationale for the production of anticancer agents. Synthesis of a peptidomimetic analog of the previously prepared potent glyoxalase inhibitor, S-(p-bromobenzyl)glutathione (PBBG), was accomplished by inserting a urea linkage, NH-CO-NH, to replace the gamma-glutamyl peptide bond. Thus, the target compound, gamma-(L-gamma-azaglutamyl)-S-(p-bromobenzyl)-L-cysteinylglycine 6, was a potent inhibitor of glyoxalase I with almost no loss of activity when compared to PBBG. However, unlike PBBG, 6 was completely resistant to enzymatic degradation by kidney homogenate or by purified gamma-glutamyltranspeptidase enzyme.