Ethanol Extract of Piper longum L., a Culinary Spice, Suppresses Osteoclastogenesis and Protects Against...

Piper longum L., commonly consumed as a culinary spice and referred to as Piperis Fructus (PF) in traditional East Asian medicine, has been associated with various pharmacological activities; however, the anti-osteoporotic potential of its ethanol extract has not been fully elucidated. In this study, we prepared a PF extract (containing 25.3 mg/g piperine) and investigated its effects on osteoclastogenesis using RANKL-stimulated RAW 264.7 cells (12.5-50 µg/mL) and ovariectomized (OVX) rats orally administered PF (2.37 and 16.59 mg/kg for 8 weeks). In vitro, anti-osteoclastogenic effects were evaluated using TRAP, pit formation, F-actin ring formation, western blot analysis, and qPCR, while in vivo effects were assessed using micro-computed tomography and serum biomarker analysis. In vitro, PF significantly suppressed osteoclast formation (p < 0.05-0.01), TRAP activity (p < 0.01), resorption pit area (p < 0.01), and F-actin ring formation (p < 0.05-0.01), accompanied by reduced c-Fos (p < 0.01) and NFATc1 protein expression (p < 0.05-0.01), as well as the downregulation of osteoclast-related genes (p < 0.05-0.01). In OVX rats, PF-H significantly reduced serum ALP (p < 0.01) and showed a reduction in serum TRAP levels (p < 0.05) and improved trabecular microarchitecture with increased BV/TV (p < 0.05), Tb.Th (p < 0.01), Tb.N (p < 0.01), and decreased Tb.Sp (p < 0.05). Collectively, PF mitigates estrogen deficiency-induced bone loss by suppressing osteoclast differentiation and function, suggesting its potential relevance for bone health; however, further studies are required. PRACTICAL APPLICATIONS: Piper longum L. is widely consumed as a culinary spice and represents a dietary source of bioactive phytochemicals. The present findings suggest that the ethanol extract of Piper longum may help reduce bone loss by suppressing osteoclast activity. These results indicate its potential application as a functional food ingredient or nutraceutical for supporting bone health.