RESUMO
OBJECTIVE: Natural medicines derived from plants have aroused increasing interest in the prevention and treatment of osteoporosis. This is due to their unique characteristics as these are more suitable for long-term use compared with synthesized chemicals and have apparently fewer adverse effects. Curculigo orchioides (CO) has a long history in the treatment of postmenopausal osteoporosis in traditional Chinese medicine. The present study was designed to investigate the protective effects of ethanol extracts of CO on ovariectomy-induced bone loss. METHODS: Sixty female (4.5-month-old) Sprague-Dawley rats were assigned to sham and OVX groups. The OVX rats were further divided into five subgroups treated respectively, with vehicle, nylestriol (1 mg/kg, i.g.) and CO extract (0.5, 1.0, and 2.0 g/kg, i.g.) for 12 weeks. Bone mineral density (BMD) and bone mineral content (BMC) were measured by peripheral quantitative computerized tomography (pQCT) densitometry. Serum phosphorus, calcium, ACTH, corticosterone, deoxypyridinoline crosslinks to creatinine ratio (DPD/Cr), alkaline phosphate (ALP), tartrate-resistant acid phosphatase (TRAP), osteoprotegerin (OPG), IL-6, and TNF-alpha were also determined. RESULTS: Administration of CO extract prevented bone loss in the trabecular bone of the tibia in ovariectomized rats without affecting the weight of the body and the uterus, and increased serum phosphorus, calcium, and OPG levels, decreased serum DPD/Cr, TRAP, ACTH, and corticosterone levels, but did not alter serum TNF-alpha, IL-6, and ALP levels in ovariectomized rats. CONCLUSION: CO ethanol extract has a definite protective effect on bone loss in ovariectomized rats by inhibiting bone resorption and increasing serum phosphorus and calcium levels, without affecting bone formation. Therefore, CO can be considered a potential antiosteoporosis herbal plant, although more studies are needed to clarify its real potential chemical constituents and their mechanism of action.