Quinoxaline derivative of oleanolic acid inhibits osteoclastic bone resorption and prevents ovariectomy-induced bone loss

• DOI: 10.1097/gme.0b013e3181fd7f4b
• Publication Date: 2011-01-12T10:05:07Z
• Authors: Yu Zhao; Yue Huai; Jie Jin; Mei Geng; Jian-Xin Li
• Keywords: 0301 basic medicine; Quinuclidines; Osteoblasts; Dose-Response Relationship, Drug; Ovariectomy; Osteoclasts; Cell Differentiation; Mice; 03 medical and health sciences; Animals; Female; Bone Resorption; Cells, Cultured

Through bioassay-guided natural product research, it has been discovered that oleanolic acid and its glycosides possess an antibone resorption activity. Quinoxaline derivative of oleanolic acid (QOA-8a), a novel compound, is sourced from a structural modification of oleanolic acid. The aim of the present study was to evaluate the activities of QOA-8a on bone resorption in vitro and its osteoprotective effect in vivo.Osteoclast precursors and mature osteoclasts were used to assay antibone resorption activities in vitro. RAW264.7 cells cultured for 2 days in the presence of the receptor activator for nuclear factor κB ligand were used as osteoclast precursors. Mature osteoclasts were generated from either primary cultures of mouse bone marrow-derived macrophages or RAW264.7 cells. Eight-week-old female mice that underwent either ovariectomy or sham surgical operation were used for the evaluation of the osteoprotective effect of QOA-8a at doses of 0.1, 1, and 10 mg kg(-1) day(-1).QOA-8a significantly inhibited the differentiation, formation, and bone resorptive activity of mature osteoclasts without cytotoxicity. QOA-8a selectively induced apoptosis at an early stage of mature osteoclasts at least via increasing the caspase-3 activity, but not osteoclast precursors. Furthermore, QOA-8a significantly prevented bone loss in ovariectomized mice without any hormone-like adverse effects, whereas the mice treated with 1 mg kg(-1) day(-1) kept the same bone mineral density level as that of the sham mice.QOA-8a inhibits bone resorption without cytotoxicity and prevents bone loss without any hormone-like adverse effects. Although further investigations are necessary to elucidate the detailed molecular mechanisms, QOA-8a demonstrates great potential as a novel agent for the treatment of osteoporosis.