Bone-protecting effect of Rubus coreanus by dual regulation of osteoblasts and osteoclasts

Bone loss occurs with increasing age and/or as a secondary occurrence to chronic metabolic disease. Certain nutritional and pharmacological, as well as nonpharmacologic interventions such as weight-bearing exercise and muscle strengthening help prevent bone loss. We examined the effect of the methanol extract from the fruit of Rubus coreanus (RCM) on postmenopausal osteoporosis.

Ovariectomized rats were assigned to sham (negative control), vehicle control, positive control, safflower seed 200 mg/kg, RCM 100 mg/kg (RCM 100), RCM 200 mg/kg (RCM 200), and RCM 400 mg/kg (RCM 400) groups for 10 weeks after the operation. Serum biochemistry, histochemistry, immunohistochemistry, and other related biomarkers of bone metabolism were investigated.

We observed that RCM could prevent bone loss by increasing the femur trabecular bone area in a dose-dependent manner in ovariectomized rats. The mineral composition of RCM contains many more valuable elements, especially potassium, magnesium, and vitamins D and B2, than safflower seed. The effect of RCM increased not only osteoblast differentiation but also osteoclast apoptosis. In addition, the extract of RCM contained in quercetin suggests that the extract of RCM resulted in improved aging-related bone loss through an antioxidant effect.

The present data provide the first direct in vivo evidence that RCM has a bone-protecting effect caused by estrogen deficiency, without undesirable side effects on the uterus and other solid organs. The beneficial effect of RCM may be mediated, at least in part, by dual regulation of the enhancement of osteoblast function and induction of osteoclast apoptosis.