P-nitroaniline is a chromogenic molecule that is used as a dyestuff intermediate in industrial applications. In biochemical research, enzyme assays utilize modified aminoacyl or peptidyl p-nitroanilines as substrates. The enzyme catalyzes the release of free p-nitroaniline, which is the basis of the colorimetric determination of the enzyme activity. Applications of the colorimetric properties of p-nitroanilide include the design of biopolymer drug delivery systems and of solid supports for enzyme immobilization. A kinetic analysis of the α-chymotrypsin catalyzed hydrolysis of aminoacyl and peptidyl p-nitroanilide substrates in vesicles has been reported. It has been shown to possess anti-leishmanial activity.