Acyloxybenzyl halides, inhibitors of elastases.

3-Benzyl-6-chloromethyl-3,4-dihydrocoumarin inhibits human leucocyte elastase (HLE) and porcine pancreatic elastase (PPE) through a mechanism-based process characterized by the following apparent enzyme-inhibitor dissociation constants, Ki, and limiting inactivation rate constants k2: 200 microM (HLE), 69 microM (PPE) and 5.10(-2) s-1 (HLE), 17.7.10(-2) s-1 (PPE) at pH 8.0, 37 degrees C. Bis(4-acyloxyphenyl)methane derivatives with a benzylic halogen as potential leaving group have also been synthesized and studied. They transiently inactivate PPE and HLE through the formation of an acyl-enzyme.