Baicalein inhibits osteoclast differentiation and induces mature osteoclast apoptosis.
In bone remodeling, an imbalance caused by increased bone resorption over bone formation leads to adult skeletal diseases such as osteoporosis. Therefore, the development of anti-resorptive agents has still gained more interest. In this study, using cell-based assay systems in RAW264.7 murine macrophage cells, we found that baicalein significantly inhibited the receptor activator of NF-kappaB ligand (RANKL)-induced tartrate-resistance acid phosphatase (TRAP) activity and the formation of multinucleated osteoclasts in a dose-dependent manner. Interestingly, baicalein inhibited RANKL-induced activation of signaling molecules (Akt, ERK/MAP kinase and NF-kappaB) and mRNA expression of osteoclast-associated genes (TRAP, matrix metalloproteinase 9 and c-Src) and another transcription factors (c-Fos, Fra-2 and NFATc1). In addition, baicalein inhibited the bone resorptive activity of mature osteoclasts by inducing apoptosis. The inhibitory effects of baicalein on the formation of mouse bone marrow macrophage-derived osteoclasts and their bone resorptive activity were also observed. In conclusion, although further studies are needed to determine its biological efficacy and precise mechanism in bone, the present results demonstrated that baicalein has a potential to inhibit osteoclast differentiation and induce mature osteoclast apoptosis.
Kim
Myung Hee
MH
Laboratory of Chemical Genomics, Korea Research Institute of Chemical Technology, P.O. Box 107, Yuseong-gu, Daejeon 305-600, Republic of Korea.
Ryu
Shi Yong
SY
Bae
Myung Ae
MA
Choi
Joon-Sig
JS
Min
Yong Ki
YK
Kim
Seong Hwan
SH
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001862:Bone Resorption / Q000378:metabolism / Q000517:prevention & control*; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D044950:Flavanones / Q000494:pharmacology*; D008264:Macrophages; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010010:Osteoclasts / Q000187:drug effects* / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects; D053245:RANK Ligand / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D000975:Antioxidants; D044950:Flavanones; D016328:NF-kappa B; D053245:RANK Ligand; D014157:Transcription Factors; C006680:baicalein; D020928:Mitogen-Activated Protein Kinases; D000135:Acid Phosphatase