Methanol (MeOH) extract of the aerial parts of Dendropanax morbifera (Araliaceae) has demonstrated a significant dose-dependent inhibitory effect on the RANKL-induced differentiation of bone marrow-derived macrophages to osteoclasts. Bioassay-guided fractionation of the extract resulted in the isolation of a novel diacetylene carboxylic acid (1), together with a known diacetylenic compounds (2) as phytochemicals to strongly inhibit the osteoclast differentiation. The chemical structure of 1 was determined by spectroscopic analyses as (9Z,16S)-16-O-acetyl-9,17-octadecadiene-12,14-diynoic acid, that is acetyl derivative of 2. Two diacetylenic components of D. morbifera, 1 and 2 exhibited a dose-dependent inhibitory effect on the RANKL-induced formation of tartrate-resistant acid phosphatase-positive multinucleated cells with IC50 values of 2.4 and 3.1 μM, respectively. Seven other known components (3-9) were also isolated from the extract: dendropanoxide (3), friedelin (4), epifriedelanol (5), α-amyrin (6), β-amyrin (7), β-sitosterol (8), and stigmasterol (9). The significant anti-osteoclastogenic activities of 3, 4, 5, and 7 were first reported in this study.
Keywords: Araliaceae; Dendropanax morbifera; Diacetylene; Osteoclast differentiation.