Synthesis and Structure-Activity Study of Protease Inhibitors. I. (Guanidinophenyl) propionate and Guanidinocinnamate Derivatives

Abstract

Guanidino-ester derivatives were synthesized and evaluated for inhibitory activities against trypsin, plasmin, kallikrein, thrombin and Cl esterase, as well as on in vitro complement-mediated hemolysis. Among the compounds synthesized, phenyl α-ethyl-p-guanidinocinnamate (IVg) and phenyl α-propyl-p-guanidinocinnamate (IVh) exhibited potent and selective Cl esterase inhibition (IC₅₀ : 7×10^-6 and 6×10^-6 M, respectively) and 6-methyl-3-pyridyl α-ethyl-p-guanidinocinnamate (IVi) markedly suppressed complement-mediated hemolysis (86% inhibition at 1×10^-3M).