Abstract

Background Osteoporosis is a common metabolic bone disease characterized by an imbalance in bone remodeling, which leads to elevated bone resorption due to enhanced osteoclastic activity. Current anti-resorptive therapies are limited by adverse effects and suboptimal efficacy. Coixol, a natural compound derived from the traditional edible plant Coix lacryma-jobi L., exhibits anti-inflammatory properties. However, its role in osteoporosis remains unclear. Methods The effects of coixol on osteoclast formation and function during receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis were examined in bone marrow-derived macrophages. Differentiation was evaluated using tartrate-resistant acid phosphatase staining and F-actin ring formation assays, whereas bone resorption activity was quantified using pit formation assays. The expression levels of osteoclast-associated markers (NFATc1, CTSK, and MMP9) and hypoxia-inducible factor 1-alpha (HIF-1α) were assessed using reverse transcription quantitative real-time polymerase chain reaction and Western blot assays. In vivo efficacy in an ovariectomized mouse model was determined using micro-computed tomography and histomorphometric analyses. Results Coixol dose-dependently inhibited osteoclast differentiation, disrupted F-actin ring formation, and decreased bone resorption activity, and these activities were accompanied by the downregulation of key osteoclastogenic genes and proteins. Under normoxic conditions, coixol increased HIF-1α protein levels. In ovariectomized mice, coixol significantly attenuated bone loss, improved trabecular bone microstructure, and suppressed osteoclast activity. Conclusion Coixol likely inhibits osteoclast formation and bone resorption in vitro and in vivo by activating HIF-1α and suppressing nuclear factor-kappa B pathway signaling. These findings suggest th