The present invention relates to a novel class of compounds mainly, leucinamide-amino-carboxylate derivatives of formula (I) wherein Y is CR<1>R<2>, O, S, -SO2, C=0 or NR<9>; Z is CR<1>R<2>, O, S, -SO2, C=O or NR<9> and each G is independently a CR<1>CR<2>. Said compounds are cathepsin cysteine protease inhibitors, including but not limited to, inhibitors of cathepsin K, L, S and B and to pharmaceutical compositions thereof. These compounds are useful for treating and preventing cathepsin dependent conditions in which inhibition of bone resorption is indicated, such as osteoporosis. |