Cathepsin inhibitor 1 (Compound 25) is a potent and selective inhibitor of Cathepsin , with pIC 50 s of 7.9, 6.7, 6.0, 5.5 and 5.2 for CatL , CatL2 , CatS , CatK , and CatB , respectively. Cathepsin inhibitor 1 is promising for research of osteoarthritis [1] .
