Amaranthus mangostanus Inhibits the Differentiation of Osteoclasts and Prevents Ovariectomy-Induced Bone Loss

Bone homeostasis is dynamically balanced between bone forming osteoblasts and bone resorbing osteoclasts. Osteoclasts play an important role in bone destruction and osteoporosis, and they are derived from monocyte/macrophages in response to macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor κB (NF-κB) ligand (RANKL). Amaranthus mangostanus L. (AM) is a plant with powerful antioxidant and other biological activities including anti-inflammatory, antidiabetic, and antihyperlipidemic effects. However, its effects on bone health are unknown. In this study, we explored whether AM could affect RANK-mediated osteoclastogenesis. AM significantly suppressed RANKL-induced osteoclast differentiation and expression of osteoclast-specific genes, TRAP, cathepsin K, NF-activated T-cells (NFATc1), and Dc-stamp in RAW 264.7 cells. Moreover, AM significantly inhibited extracellular signal-regulated kinase (ERK), Akt, and NF-κB signaling pathways in RAW 264.7 cells. In addition, AM preserved ovariectomy-induced bone loss in mice. Taken together, our results suggest that AM might be a potential candidate for the treatment of postmenopausal osteoporosis.