In vivo protective effect of rosemary ethanol extract on osteoporosis through regulation of osteoclast differentiation and bone resorption activity

Bone is dynamic tissue that is constantly destroyed or resorbed by osteoclasts and then replaced by osteoblasts in physiological process referred to as bone remodeling. In this study, the protective effect of rosemary ethanol extract (REE) on osteoporosis was investigated using RANKL‐induced osteoclasts and ovariectomized rats. In animal study, the total of sixty 8 week‐old female Spraque‐Dawley rats were randomly divided into sham‐operated group and four ovariectomized (OVA) groups: OVA, OVA + 17β‐estradiol (E 2 , 50 μg/kg/day) and OVA + REE (125 or 250 mg/kg/day). Daily oral administration of E 2 or REE began 3 weeks after surgery and lasted for 12 weeks. REE inhibited the decrease in total BMD and BMC of the femur induced by OVA, which was accompanied by a significant reduction in bone remodeling. The bone turnover markers such as BALP, PICP, OPG, RANKL, TRAP, and ICTP were regulated by REE treatment. In addition, TRAP and bone resorption activity were dose‐dependently by REE in RANKL‐induced osteoclast differentiation. In conclusion, the protective of REE on osteoporosis can be accomplished by attenuating RANKL‐induced osteoclast differentiation and bone resorption activity. These results indicate that REE may utilized as a therapeutic agent for the prevention of bone metabolism‐related diseases as osreoporosis