Codonopsis pilosula extract protects against osteoporosis by reducing oxidative stress and inflammation

Osteoporosis (OP) is characterized by oxidative stress, inflammasome activation, and disordered bone remodeling. Codonopsis pilosula extract (CPE) possesses antioxidative and immunomodulatory activities, but its role in OP remains unclear. This study evaluated the protective effects of CPE in ovariectomy (OVX)-induced OP and oxidative stress-challenged osteoblasts.An OVX model was established in Sprague-Dawley rats and divided into control, sham, OVX, and CPE groups. CPE was administered by gavage (200 mg/kg/day) for 28 days. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA). Moreover, biomechanical parameters (Fmax, Fmax dL, Emod) were evaluated via three-point bending; and trabecular morphology was assessed through histological staining (H&E for structure, TRAP for osteoclasts, Masson for collagen, and TUNEL for apoptosis). Western blotting quantified osteogenic, pyroptotic, and Wnt/β-catenin proteins. In parallel, MC3T3-E1 osteoblast precursors were subjected to H₂O₂-induced oxidative stress with or without CPE (100 µg/mL; selected from a dose-response, IC₅₀≈107 µg/mL). Cell proliferation (CCK-8, EdU), apoptosis (flow cytometry, TUNEL), ROS accumulation (DCFH-DA), inflammatory cytokines and antioxidant enzyme activity (ELISA), and related signaling proteins were evaluated.OVX rats exhibited reduced BMD and biomechanical strength, trabecular deterioration, increased osteoclasts, apoptosis, and elevated inflammatory cytokines (IL-1β, IL-6). CPE restored BMD, improved bone strength, and reduced levels of key inflammatory cytokines (e.g., IL-1β and IL-6, P < 0.05). CPE suppressed NLRP3, GSDMD-N, cleaved Caspase-1/3, Bax, and necroptotic proteins (p-RIPK1/3, p-MLKL), and restored Bcl-2 and osteoblast markers (Runx2, ALP). Wnt3a, β-catenin, and p-GSK3β which were suppressed in OP rats were normalized by CPE. In vitro, CPE reduced ROS and MDA, restored SOD and GSH-Px, decreased inflammatory protein expression, and enhanced osteoblast proliferation under oxidative stress.In conclusion, CPE mitigates OP progression by reducing oxidative stress and inflammation, thereby protecting bone structure and function. These findings support CPE as a multifunctional natural agent with therapeutic potential for OP.