Effects of emulsified and non-emulsified palm tocotrienol on bone and joint health in ovariectomised rats with monosodium iodoacetate-induced osteoarthritis

Abstract

Postmenopausal women are susceptible to osteoporosis and osteoarthritis. Tocotrienol, a bone-protective nutraceutical, is reported to prevent osteoarthritis in male rats. However, its efficacy on joint health in oestrogen deficiency has not been validated. Besides, data on the use of emulsification systems in enhancing bioavailability and protective effects of tocotrienol are limited. Ovariectomised adult female Sprague-Dawley rats (3 months old) were treated with refined olive oil, emulsified (EPT, 100 mg/kg/day with 25% vitamin E content), non-emulsified palm tocotrienol (NEPT, 100 mg/kg/day with 50% vitamin E content) and calcium carbonate (1% w/v in drinking water) plus glucosamine sulphate (250 mg/kg/day) for 10 weeks. Osteoarthritis was induced with monosodium iodoacetate four weeks after ovariectomy. Baseline control was sacrificed upon receipt, while the sham group was not ovariectomised and treated with refined olive oil. EPT and NEPT prevented femoral metaphyseal and subchondral bone volume decline caused by ovariectomy. EPT decreased subchondral trabecular separation compared to the negative control. EPT preserved stiffness and Young’s Modulus at the femoral mid-shaft of the rats. Circulating RANKL was reduced post-treatment in the EPT group. Joint width was reduced in all the treatment groups vs the negative control. The EPT group’s grip strength was significantly improved over the negative control and NEPT group. EPT also preserved cartilage histology based on several Mankin’s subscores. EPT performed as effectively as NEPT in preventing osteoporosis and osteoarthritis in ovariectomised rats despite containing less vitamin E content. This study justifies clinical trials for the use of EPT in postmenopausal women with both conditions.