New 8---Hydroxylbenzylflavonol Glycosides from Pumpkin ( Duch.) Tendril and Their Osteoclast Differentiation Inhibitory Activities.

Six new 8---hydroxybenzylflavonol glycosides were isolated from a hot water extract of pumpkin ( Duch.) tendril and elucidated as 8---hydroxybenzylquercetin 3--rutinoside, 8---hydroxybenzoylquercetin 3--β-D-glucopyranoside, 8---hydroxybenzylkaempferol 3--(α-L-rhamnopyranosyl(1→6)-β-D-galactopyranoside, 8---hydroxybenzoylkaempferol 3--rutinoside, 8---hydroxybenzylisorhamnetin 3--rutinoside, and 8---hydroxybenzylisorhamnetin 3--(α-L-rhamnopyranosyl(1→6)-β-D-galactopyranoside. Their chemical structures were determined using nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometer (ESIMS) analyses. The 8---hydroxybenzylflavonol glycosides were found to inhibit the receptor activator of nuclear factor-κB (RANKL)-induced osteoclast differentiation of bone marrow derived macrophage (BMDM), an osteoclast progenitor. Additionally, 8---hydroxybenzylflavonol glycosides effectively reduced the expression of osteoclast-related genes, such as tartrate-resistant acid phosphatase, cathepsin K, nuclear factor activated T-cell cytoplasmic 1, and dendritic cell specific transmembrane protein in RANKL-treated BMDMs. These results indicate that the 8---hydroxybenzylflavonol glycosides may be the main components responsible for the osteoclast differentiation inhibitory effect of pumpkin tendril.