Improved synthesis of lysine- and arginine-derived Amadori and Heyns products and in vitro measurement of their angiotensin I-converting enzyme inhibitory activity.

The L-lysine- and L-arginine-derived Amadori and Heyns products consisting of N-(1-deoxy-d-fructos-1-yl)amino acid and N-(2-deoxy-d-glucos-2-yl)amino acid were prepared by reaction of d-fructose and d-glucose with l-lysine hydrochloride and l-arginine hydrochloride using commercial zinc powder as deprotonating reagent and also as catalyst precursor in a simple synthetic route in high yield. These compounds were screened for angiotensin I-converting enzyme (ACE) inhibitory activity using a high-throughput colorimetric assay (utilizing porcine kidney ACE). The IC(50) values fall in the range of 1030-1175 μM, with N(α)-(1-deoxy-d-fructos-1-yl)arginine showing the best IC(50) value (1030 ± 38 μM). This study demonstrates an improved synthetic method for simple Amadori and Heyns products and their moderate ACE inhibitor activity.