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J Korean Med Rehabil 2019 Apr; 29(2): 135-147  
Effects of Pyrola japonica Extracts on Osteoclast Differentiation and Bone Resorption
Published online April 30, 2019
Copyright © 2019 The Society of Korean Medicine Rehabilitation.

Jung-Sik Park, K.M.D., Hyung-Ho Lim, K.M.D.

College of Korean Medicine, Gachon University
Correspondence to: Hyung-Ho Lim, College of Korean Medicine, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam 13120, Korea
TEL +82-31-750-8599
FAX +82-31-750-5416
Received: March 28, 2019; Revised: April 8, 2019; Accepted: April 12, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Objectives This study was performed to evaluate the effect of Pyrola japonica extract (NJ) and its principal constituent, homoarbutin (HA) on osteoclast differentiation and gene expression and bone resorption. The osteoclastogenesis and gene expression were determined in receptor activator of nuclear factor kappa B ligand (RANKL)-stimulated RAW264.7 cell.

Methods In order to evaluate the effect of HA extracted from NJ on bone resorption, osteoclasts were used to be differentiated and formed by stimulating RAW264.7 cells with RANKL. Tartarate-resistant acid phosphatase (TRAP) (+) polynuclear osteoclast formation ability was evaluated, and differentiation control genes including cathepsin K, matrix metalloproteinases- 9 (MMP-9), and TRAP in osteoclast differentiation were analyzed by real-time polymerase chain reaction (PCR). Immunoblotting was performed to measure the effect of mitogen-activated protein kinase (MAPK) factors on bone resorption, and the effect of osteoclasts on osteoclast differentiation was measured.

Results Both NJ and high concentration of HA blocked RANKL-stimulated differentiation from RAW264.7 cell to TRAP-positive multinucleated cells. NJ reduced RANKL-induced expression of TRAP, cathepsin K. Both NJ and high concentration of HA inhibited RANKLmediated expression of MMP-9, nuclear factor of activated T-cells, cytoplasmic 1, and cellular Jun-fos. NJ suppressed RANKL-stimulated expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase, tumor necrosis factor-alpha, and levels of interleukins. Both NJ and HA decreased bone resorption in osteoclast-induced bone pit formation model.

Conclusions These results suggest that NJ and HA blocked bone resorption by decreasing RANKL-mediated osteoclastogenesis through down-regulation of genes for osteoclast differentiation.

Keywords : Osteoclast, Poncirin, Receptor activator of nuclear factor kappa B ligand (RANKL), Tartarate-resistant acid phosphatase (TRAP), Japonica extract, Homoarbutin

April 2019, 29 (2)

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