AN INDENONE DERIVATIVE OF FORMULA (I) IS EFFECTIVE IN ENHANCING THE ACTIVITY OF OSTEOBLASTIC CELLS AND INHIBITING BONE RESORPTION BY OSTEOCLASTIC CELLS, AND A PHARMACEUTICAL COMPOSITION COMPRISING THE INDENONE DERIVATIVE OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF IS USEFUL FOR PREVENTING OR TREATING BONE DISEASES SUCH AS OSTEOPOROSIS. FIGURE 2