Therapeutic properties of Oak Bark (Quercus Pro Parte) as an Anti-osteoporosis Induced Experimentally by Methylprednisolone in Female Rabbits

Osteoporosis is a progressive skeletal disorder characterized by decreased bone mass and microarchitectural deterioration, leading to increased fracture risk. Glucocorticoid-induced osteoporosis represents a major secondary form of the disease, necessitating the exploration of safer and more effective therapeutic alternatives. Natural products rich in polyphenols, such as oak bark (Quercus pro parte), have demonstrated promising biological activities that may support bone health. This study aimed to evaluate the anti-osteoporotic effects of ethanolic extract of oak bark in methylprednisolone-induced osteoporosis in female rabbits. Fifty-six female rabbits were used, including six for acute toxicity testing (LD₅₀) and forty divided into five experimental groups: negative control, positive control (methylprednisolone-induced osteoporosis), oak bark-treated, alendronate-treated, and combination therapy (oak bark + alendronate). Osteoporosis was induced using methylprednisolone and tamoxifen. Oak bark extract (200 mg/kg/day) and alendronate (3.6 mg/kg/week) were administered for 30 days. Bone mineral density (BMD) was assessed using DEXA scanning. Serum biochemical markers, including calcium, phosphorus, vitamin D, parathyroid hormone (PTH), malondialdehyde (MDA), and superoxide dismutase (SOD), were evaluated. The phytochemical composition was analyzed by GC–MS. The LD₅₀ of oak bark extract was determined to be 1850.7 mg/kg, indicating moderate toxicity. GC–MS analysis identified bioactive compounds, including gallic acid, Linalool, and caffeic acid, with known antioxidant and anti-inflammatory properties. Osteoporotic rabbits showed significant reductions in BMD and serum calcium, phosphorus, and vitamin D levels, along with increased PTH and oxidative stress markers. Treatment with oak bark extract significantly improved these parameters (P ≤ 0.05), while combination therapy with alendronate demonstrated the most pronounced effects, restoring BMD and biochemical markers close to normal levels. Oxidative stress was markedly reduced, as evidenced by decreased MDA and increased SOD activity. Oak bark ethanolic extract exhibits significant anti-osteoporotic effects, likely mediated through its antioxidant, anti-inflammatory, and osteoprotective phytoconstituents. The combination of oak bark with alendronate showed synergistic efficacy in improving bone density and biochemical parameters. These findings suggest that oak bark may serve as a potential natural adjunct therapy for glucocorticoid-induced osteoporosis.