A water extract of Malva verticillata seeds suppresses osteoclastogenesis and bone resorption stimulated by RANK ligand

Malva verticillata Linné seeds are used as a therapeutic medicine to treat kidney dysfunction in traditional Chinese medicine (TCM) [1]. TCM has suggested that herbal medicine tonifying kidney function may have beneficial effect on bone metabolism [2, 3]. Osteoclastogenesis was examined in bone marrow macrophages by measuring tartrate-resistant acid phosphatase (TRAP) activity and counting the number of TRAP-stained multinuclear cells. The activation of receptor activator of nuclear factor-κB (RANK) ligand (RANKL) signaling, and the expression of c-Fos and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) were investigated by western blot analysis. Transcription factor and bone resorption marker mRNA levels were evaluated using real-time quantitative polymerase chain reaction. The bone resorption activity of mature osteoclast was examined in osteoclasts cultured on a hydroxyapatite-coated culture plate. A water extract of M. verticillata seeds (WEMV) inhibited osteoclastogenesis stimulated by RANKL. WEMV also strongly inhibited phosphorylation of c-Jun N-terminal kinase, p38, I-κBα, and phospholipase γ2, as well as expression of c-Fos and NFATc1. Furthermore, WEMV significantly attenuated osteoclast resorption activity and downregulated expression of resorption markers. These results demonstrate that WEMV inhibits osteoclastogenesis and bone resorption by suppressing the RANKL signaling pathway and suggest that M. verticillata seed may be used as a therapeutic agent in complementary alternative medicine to treat pathological bone diseases.

Acknowledgements: This work was supported by a grant (Grant No. K15280) awarded to the Korean Institute of Oriental Medicine by the Ministry of Education, Science and Technology (MEST), Korea.

Keywords: Malvaceae, Malva verticillata seed, receptor activator of nuclear factor-κB ligand, osteoclasts, nuclear factor of activated T-cells, cytoplasmic 1.

References:

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