In vitro, a large number of coumarin derivatives display a remarkable inhibitory potency against several proteases including human leukocyte elastase, trypsin, human thrombin, as well as bovine - chymotrypsin. By gradual variation of the structures, specific inhibitors of human leucocyte elastase were obtained, acting as transient inactivators (stable acyl-enzymes).

This invention describes derivatives with an specific inhibitory action on human leukocyte elastase.