Glabridin and glycyrrhizic acid show no beneficial effect on the chemical composition and mechanical properties of bones in ovariectomized rats, when administered in moderate dose.

BACKGROUND: One of the major causes of osteoporosis and bone fracture in postmenopausal women is estrogen deficiency. To prevent the fractures, and avoid the side effects of hormone replacement therapy, phytoestrogens including the isoflavonoids are used. In the presented study two constituents occurring in the licorice root-the isoflavane glabridin and triterpenoid saponin glycyrrhizic acid were examined on the skeletal system of ovariectomized rats. METHODS: The female Wistar rats were divided into five groups: control group, ovariectomized group as well as three ovariectomized groups treated with estradiol (0.2mg/kg), glabridin (5mg/kg) or glycyrrhizic acid (15mg/kg). All substances were administered orally for 4 weeks. The estradiol served as a positive control. The mechanical properties of femoral diaphysis, tibial metaphysis and femoral neck were assessed using bending and compression tests. Moreover the chemical composition of the femur, tibia and L-4 vertebra - content of water, organic substances and minerals - was determined. RESULTS: Ovariectomy induced unfavorable changes in the skeletal system of the rats. Administration of glabridin and glycyrrhizic acid to the ovariectomized rats did not improve analyzed parameters of the bones. CONCLUSION: Obtained results indicate, that the tested substances revealed no beneficial effect on the mechanical properties and chemical composition of the tested bones, thus they cannot be used as the osteoporosis protective agents.

EFFECT OF GLABRIDIN AND GLYCYRRHIZIC ACID ON HISTOMORPHOMETRIC PARAMETERS OF BONES IN OVARIECTOMIZED RATS.

Licorice is a medicinal plant showing many therapeutic activities. Its roots contain numerous pharmacologically active compounds such as a triterpenoid saponin--glycyrrhizic acid and an isoflavan--glabridin. There are reports indicating that glabridin exhibits estrogen-like activity, therefore it can be classified into phytoestrogens, which may soothe menopause symptoms including postmenopausal osteoporosis. Due to this fact, the aim of the presented study was to evaluate the effect of glabridin and glycyrrhizic acid on histomorphometric parameters of bones in rats with ovariectomy-induced osteoporosis. The animals were divided into 6 group: (C)--control rats, (OVX)--ovariectomized rats, (OVX + E)--ovariectomized rats receiving estradiol at a dose of 0.1 mg/kg p.o., (OVX + G)--ovariectomized rats receiving genistein at a dose of 5 mg/kg p.o., (OVX + GL --ovariectomized rats treated with glabridin at a dose of 5 mg/kg p.o. and (OVX + GA)--ovariectomized rat administered with glycyrrhizic acid at a dose of 15 mg/kg p.o. Estradiol and genistein served as the positive controls in the study. Several macrometric and histomorphometric parameters were analyzed in the bones of tested rats. Obtained results indicate that glabridin shows slightly positive effect on osteoporotically changed bone tissue, and glycyrrhizic acid reveals meager influence on skeletal system with no preventive significance.