Fast and long acting neoflavonoids dalbergin isolated from Dalbergia sissoo heartwood is osteoprotective in ovariectomized model of osteoporosis: Osteoprotective effect of Dalbergin.

ABSTRACT

OBJECTIVE: This study aims to evaluate the skeletal effects of dalbergin (DBN), isolated from Dalbergia sissoo heartwood, in ovariectomized (OVx) BALB/c mice, a postmenopausal osteoporosis model of bone loss. METHODS: Adult BALB/c mice were used and randomly assigned in to six groups with 6 animals (n=6) in each group sham (surgery operated without ovariectomy) with vehicle, ovariectomy with vehicle, ovariectomy (OVx) with estradiol (E2 5.0µgkg-1day-1), or ovariectomy with dalbergin at three different doses of DBN (1.0, 5.0 and10mgkg-1day-1). Daily oral administration of the vehicle, estradiol, or DBN was started 8 weeks post-surgery and continued for 8 weeks. At the end of experiment, mice were sacrificed and assessed for trabecular bone structure of tibia, lumbar vertebra (L5) and alterations in biochemical and uterine parameters, pharmacokinetic profile and gene expression were monitored for each group. RESULTS: Treatment with DBN prevented trabecular bone loss in cancellous bone in the tibial metaphysis and lumbar vertebra region of the ovariectomized mice. Micro-CT data showed that mice treated with DBN at 1.0mgkg-1day-1 exhibited improved bone micro-architecture that was sustained with decreased expression of bone resorption markers like TRAP and RANK and caused an increase in osteogenic markers like RUNX2, BMP2 and OPG/RANKL ratio compared with OVx+vehicle treated mice. Moreover, DBN treatment induced no uterine estrogenicity and significantly lowered the osteocalcin amount in serum when compared with OVx+V group. DBN reached its maximum concentration (Cmax) 238.49±21.37ngml-1 in serum as early as 1h of administration. Overall, DBN (1.0mgkg-1day-1) treatment exhibited similar bone conserving effect against bone-loss as estradiol treatment. CONCLUSION: Daily oral administration of DBN for 8 weeks showed significant anabolic effects on bone micro-architectural parameters along with down regulation of bone resorptive markers without compromising safety at uterine level. Therefore, our study provides basis for DBN as a therapeutic candidate against postmenopausal osteoporosis.