Background and Aim: Both virgin coconut oil (VCO) and tocotrienol-rich fraction (TRF) are rich in antioxidants and may protect the bone against bone loss induced by ovariectomy and high-fat diet. The study aimed to determine the protective effects of combined therapy of VCO and TRF on osteoporosis in ovariectomized (OVX) rat fed with high-fat diet. Materials and Methods: Thirty-six female Sprague-Dawley rats were divided into six groups: Sham-operated (SHAM), OVX control, OVX and given Premarin at 64.5 μg/kg (OVX+E2), OVX and given VCO at 4.29 ml/kg (OVX+V), OVX and given TRF at 30 mg/kg (OVX+T), and OVX and given a combination of VCO at 4.29 ml/kg and TRF at 30 mg/kg (OVX+VT). Following 24 weeks of treatments, blood and femora samples were taken for analyses. Results: There were no significant differences in serum osteocalcin levels between the groups (p>0.05), while serum C-terminal telopeptide of Type I collagen levels of the OVX+VT group were significantly lower than the other groups (p<0.05). The dynamic bone histomorphometry analysis of the femur showed that the double-labeled surface/bone surface (dLS/BS), mineral apposition rate, and bone formation rate/BS of the OVX+E2, OVX+T, and OVX+VT groups were significantly higher than the rest of the groups (p<0.05). Conclusion: A combination of VCO and TRF has the potential as a therapeutic agent to restore bone loss induced by ovariectomy and high-fat diet.

Osteoporosis, the most common bone disease, is associated with compromised bone strength and increased risk of fracture. Previous studies have shown that oxidative stress contributes to the progression of osteoporosis. Specifically, for postmenopausal osteoporosis, the reduction in estrogen levels leads to increased oxidative stress in bone remodeling. Tocotrienol, a member of vitamin E that exhibits antioxidant activities, has shown potential as an agent for the treatment of osteoporosis. Most studies on the osteoprotective effects of tocotrienols had used the oral form of tocotrienols, despite their low bioavailability due the lack of transfer proteins and high metabolism in the liver. Several bone studies have utilized tocotrienol combined with a nanocarrier to produce a controlled release of tocotrienol particles into the system. However, the potential of delivering tocotrienol–nanocarrier combination through the intraosseous route has never been explored. In this study, tocotrienol was combined with a nanocarrier, poly lactic-co-glycolic acid (PLGA), and injected intraosseously into the bones of ovariectomized rats to produce targeted and controlled delivery of tocotrienol into the bone microenvironment. This new form of tocotrienol delivery was compared with the conventional oral delivery in terms of their effects on bone parameters. Forty Sprague–Dawley rats were divided into five groups. The first group was sham operated, while other groups were ovariectomized (OVX). Following 2 months, the right tibiae of all the rats were drilled at the metaphysis region to provide access for intraosseous injection. The estrogen group (OVX + ESTO) and tocotrienol group (OVX + TTO) were given daily oral gavages of Premarin (64.5 mg/kg) and annatto-tocotrienol (60 mg/kg), respectively. The locally administered tocotrienol group (OVX + TTL) was given a single intraosseous injection of tocotrienol–PLGA combination. After 8 weeks of treatment, both OVX + TTO and OVX + TTL groups have significantly lower bone markers and higher bone mineral content than the OVX group. In terms of bone microarchitecture, both groups demonstrated significantly higher trabecular separation and connectivity density than the OVX group (p &lt; 0.05). Both groups also showed improvement in bone strength by the significantly higher stress, strain, stiffness, and Young’s modulus parameters. In conclusion, daily oral tocotrienol and one-time intraosseous injection of tocotrienol–PLGA combination were equally effective in offering protection against ovariectomy-induced bone changes.