Potent and irreversible cysteine protease inhibitor (IC50 values are 1.4, 2.5 and 4.1 nM for cathepsin K, L and S respectively. Also inhibits papain, calpain, cathepsin B and cathepsin H. Has no effect on serine proteases. Reduces HSC-3 tongue cancer cell invasion and induces oxidative stress and apoptosis in filarial parasites. Also inhibits autophagy-associated lysosomal degradation in vitro. Purity 98%. MW (observed): 357.41