Screening of protease inhibitory activity in extracts of five Ascidian species from Cuban coasts

one of the most promising strategies to counteract malaria is by controlling the infectivity of plasmodium parasites with drugs aimed against their main targets. the participation of proteases (belonging to different classes) has been demonstrated in its infection mechanism, hence these proteins have become promising targets in treating this illness. this study involved the screening of crude and clarified extracts of five cuban ascidian species for inhibitory activity of proteases belonging to different mechanistic classes. ascidians are invertebrates that present many bioactive molecules, but, as yet, only a few protease inhibitors had been isolated from them. in this research we reported for the first time the presence of inhibitory activity of bovine pancreatic carboxypeptidase a and b, aminopeptidase n from porcine kidney and subtilisin a from bacillus licheniformis in some ascidian extracts tested. the most promising extracts were selected in terms of percentage of inhibition and they were characterized in terms of the behaviour of the extract concentration against residual enzymatic activity; the determination of ic50 values and specific inhibitory activity (sia), and the evaluation of their proteolytic activity through zymographic assays.