(A) The structure of embelin. (B) RAW264.7 cells (10×103/ml) were incubated with either medium or RANKL (5 nmol/L) or RANKL and embelin (15 μmol/L) for 3, 4, and 5 days and then stained for TRAP expression. TRAP-positive cells were photographed. Original magnification, ×100. (C) RAW 264.7cells (10×103/ml) were incubated with either medium or RANKL (5 nmol/L) along with 5, 10, 15 μM of embelin for 3, 4, or 5 days and then stained for TRAP expression. Multinucleated osteoclasts (i.e., those containing three nuclei) were counted. Cells exposed to medium alone are control (C). (D) RAW264.7 cells (2×103/0.1ml) were incubated with either medium (Ctrl) or with 5, 10, 15 μM of embelin for 1, 3, and 5 days and then cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method.