Evaluation of synthetic acridones and 4-quinolinones as potent inhibitors of cathepsins L and V

► Synthesis of quinolinone and acridone alkaloids. ► Evaluation of inhibitory activities on enzymes cathepsin L and V. ► Quinolinone and acridone alkaloids displayed IC50 in the low micromolar. ► Acridones showed to be reversible competitive inhibitors. ► Quinolinone showed to be noncompetitive inhibitors for both enzymes.