OBJECTIVE: This review is aimed to discuss the literature reporting the effects of tocotrienols on osteoclasts, the cells specialized for resorbing bone.
RESULTS: Out of the total 22 studies from the literature search, only 11 of them were identified as relevant, which comprised of eight animal studies, two in vitro studies and only one combination of both. The in vivo studies indicated that tocotrienols improve the bone health and reduce bone loss via inhibition of osteoclast formation and resorption activity, which could be through regulation of RANKL and OPG expression as seen from their levels in the sera. This is well supported by data from the in vitro studies demonstrating the suppression of osteoclast formation and resorption activity following treatment with tocotrienol isomers.
CONCLUSION: Thus, tocotrienols are suggested to be potential antioxidants for prevention and treatment of bone-related diseases characterized by increased bone loss.
Methods: Human skeletal muscle myoblast (HSMM) cells were cultured and serial passaging was carried out to obtain young and senescent cells. The cells were then treated with C. vulgaris followed by differentiation induction. The expression of Pax7, MyoD1, Myf5, MEF2C, IGF1R, MYOG, TNNT1, PTEN, and MYH2 genes and miR-133b, miR-206, and miR-486 was determined in untreated and C. vulgaris-treated myoblasts on Days 0, 1, 3, 5, and 7 of differentiation.
Results: The expression of Pax7, MyoD1, Myf5, MEF2C, IGF1R, MYOG, TNNT1, and PTEN in control senescent myoblasts was significantly decreased on Day 0 of differentiation (p<0.05). Treatment with C. vulgaris upregulated Pax7, Myf5, MEF2C, IGF1R, MYOG, and PTEN in senescent myoblasts (p<0.05) and upregulated Pax7 and MYOG in young myoblasts (p<0.05). The expression of MyoD1 and Myf5 in young myoblasts however was significantly decreased on Day 0 of differentiation (p<0.05). During differentiation, the expression of these genes was increased with C. vulgaris treatment. Further analysis on myomiRs expression showed that miR-133b, miR-206, and miR-486 were significantly downregulated in senescent myoblasts on Day 0 of differentiation which was upregulated by C. vulgaris treatment (p<0.05). During differentiation, the expression of miR-133b and miR-206 was significantly increased with C. vulgaris treatment in both young and senescent myoblasts (p<0.05). However, no significant change was observed on the expression of miR-486 with C. vulgaris treatment.
Conclusions: C. vulgaris demonstrated the modulatory effects on the expression of MRFs and myomiRs during proliferation and differentiation of myoblasts in culture. These findings may indicate the beneficial effect of C. vulgaris in muscle regeneration during ageing thus may prevent sarcopenia in the elderly.
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.