Cathepsin L inhibitor (Z-FY-CHO) is a potent and selective inhibitor of Cathepsin L. In the pit formation assay with unfractionated rat bone cells, 1.5 nM of Z-FY-CHO markedly inhibited parathyroid hormone-stimulated osteoclastic bone resorption. In ovariectomized mice, it suppressed at 2.5-10 mg/kg/day ip for four weeks bone weight loss dose-dependently.
