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 (0.2 mg/kg), glabridin (5 mg/kg) or glycyrrhizic acid (15 mg/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. (C) 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Sp. z o.o. All rights reserved.