Serine protease inhibitors from Amazon leguminosae seeds: purification and preliminary characterization of two chymotrypsin inhibitors from Inga umbratica

Nine species of Leguminosae seeds from Amazon forest have been screened for trypsin and chymotrypsin inhibitory activity. The species involved were Cassia basselari, Cassia grandis, Cassia occidentalis, Dialium guianense, Inga fagifolia, Inga rubiginosa, Inga umbratica, Inga velutina and Mimosa guillandinae. Extracts from all the species, except I. umbratica, contained significant activity against trypsin, chymotrypsin and blood human clotting factors Xa. Two new chymotrypsin inhibitors (IuCI-1 and IuCI-2) have been purified to homogeneity from I. umbratica with molecular masses of 20,088.6 and 20,271.2, respectively.