Epoxyravsyrederivater

Epoxysuccinic acid derivatives having general formula (I) (wherein R represents hydrogen, alkyl, aryl or aralkyl; R and R independently represent each aryl, aralkyl or alkyl; and X represents -O-or NR - wherein R represents hydrogen, alkyl or aralkyl) which is useful in the prevention or treatment of bone diseases such as osteoporosis, malignant hypercalcemia, and bone Behcet's disease, in the treatment of osteoarthritis and rheumatoid arthritis in association with the abnormal hyperergasia of cathepsin L activity, and as a remedy for diseases in which cathepsins L and B participate such as muscular dystrophy and amyotrophy.