Background: Eurycoma longifolia (EL) is a well-known aphrodisiac herb for men. Recently, the crude extract of EL was reported to possess anti-osteoporotic activities.
Objective: This study aims to determine the bone protective effects of the standardized quassinoid-rich EL extract in testosterone-deficient rat model.
Methods: Ninety-six intact male Sprague-Dawley rats were randomized into baseline, sham, orchidectomized, and chemically castrated groups. Chemical castration was performed via subcutaneous injection of degarelix at 2 mg/kg. The orchidectomized and degarelix-induced rats were administered with vehicle, intramuscularly injected with testosterone once a week, or orally supplemented with EL extract at doses of 25 mg/kg, 50 mg/kg or 100 mg/kg daily for 10 weeks. Bone mass, microarchitecture and strength were analyzed by dual-energy x-ray absorptiometry (DEXA), micro-CT and three-point bending test.
Results: Whole body bone mineral density and femoral bone mineral content significantly increased in testosterone groups (p < 0.05). Micro-CT analysis revealed that trabecular bone volume, number, separation and connectivity density were significantly improved by testosterone administration. However, the structural model index was only improved in degarelix group supplemented with 100 mg/kg EL extract (P < 0.05). The improvement of cortical thickness by EL extract was similar to that of testosterone groups (p < 0.05). Biomechanically, EL extract supplementation was able to improve stiffness, strain and modulus of elasticity in degarelix-induced groups, while stress parameter was significantly improved in orchidectomized groups (p < 0.05).
Conclusion: Quassinoid-rich EL extract enables to protect against bone loss due to testosterone deficiency. The protective effect on cortical thickness and biomechanical parameters is comparable to testosterone group.
Keywords: Bone mineral; Tongkat Ali; bone loss; bone strength; micro-CT.