Anti-osteoporosis agent-8 (Compound 4aa) is an inhibitor for RANKL , which inhibits RANKL-induced osteoclastogenesis and osteoclast differentiation ( IC 50 is 2.41 μM) in cells RAW264.7. Anti-osteoporosis agent-8 ameliorates bone loss in an ovariectomized (OVX) mice model.