Sanguiin H-6, a constituent of Rubus parvifolius L., inhibits receptor activator of nuclear factor-κB ligand-induced osteoclastogenesis and bone resorption in vitro and prevents tumor necrosis factor-α-induced osteoclast formation in vivo.
BACKGROUND
Osteoclasts are multinucleated bone-resorbing cells that differentiate in response to receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL). Enhanced osteoclastogenesis contributes to bone diseases, such as osteoporosis and rheumatoid arthritis. Rubus parvifolius L. is traditionally used as an herbal medicine for rheumatism; however, its detailed chemical composition and the molecular mechanisms responsible for its biological action have not been elucidated.


OBJECTIVE
To investigate the mechanisms by which R. parvifolius L. extract and its major constituent sanguiin H-6, inhibit osteoclastogenesis and bone resorption.


METHODS
Cell proliferation, cell differentiation, and bone resorption were detected in vitro. Inhibition of signaling pathways, marker protein expression, and protein nuclear translocation were evaluated by western blot analysis. Tumor necrosis factor-α (TNF-α)-mediated osteoclastogenesis was examined in vivo.


RESULTS
R. parvifolius L. extract inhibited the bone-resorption activity of osteoclasts. In addition, sanguiin H-6 markedly inhibited RANKL-induced osteoclast differentiation and bone resorption, reduced reactive oxygen species production, and inhibited the phosphorylation of inhibitor of NF-κB alpha (IκBα) and p38 mitogen-activated protein kinase. Sanguiin H-6 also decreased the protein levels of nuclear factor of activated T cells cytoplasmic-1 (NFATc1), cathepsin K, and c-Src. Moreover, sanguiin H-6 inhibited the nuclear translocation of NFATc1, c-Fos, and NF-κB in vitro, as well as TNF-α-mediated osteoclastogenesis in vivo.


CONCLUSIONS
Our data revealed that R. parvifolius L. has anti-bone resorption activity and suggest that its constituent, sanguiin H-6, can potentially be used for the prevention and treatment of bone diseases associated with excessive osteoclast formation and subsequent bone destruction.
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan. Electronic address: eiko-s@nagasaki-u.ac.jp.
Eiko
E
Sakai
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Yuri
Y
Aoki
Division of Orthodontics and Dentofacial Orthopedics, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Masako
M
Yoshimatsu
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Kazuhisa
K
Nishishita
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Mayumi
M
Iwatake
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Yutaka
Y
Fukuma
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Kuniaki
K
Okamoto
Division of Natural Product Chemistry, Department of Molecular Medicinal Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8131, Japan.
Takashi
T
Tanaka
Division of Dental Pharmacology, Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Takayuki
T
Tsukuba
D000818:Animals; D001862:Bone Resorption / Q000517:prevention & control*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D047348:Hydrolyzable Tannins / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects*; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D021381:Protein Transport / Q000187:drug effects; D053245:RANK Ligand / Q000187:drug effects; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D065856:Rubus / Q000737:chemistry*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D047348:Hydrolyzable Tannins; D010936:Plant Extracts; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505688:TNFSF11 protein, human; D014409:Tumor Necrosis Factor-alpha; C081844:sanguiin H 6
Nuclear factor of activated T cells cytoplasmic-1; Osteoclast; Receptor activator of nuclear factor-κb; Sanguiin H-6; c-Fos