Low dose of tocotrienols protects osteoblasts against oxidative stress

Aims. Vitamin E is an antioxidant that may protect bone against oxidative stress-induced osteoporosis. This in vitro study was conducted to determine the protective effects of alpha-tocopherol and gamma-tocotrienol on osteoblasts, the bone forming cells, against oxidative stress. Materials and Methods. Toxicity tests were carried out on hydrogen peroxide (H2O2), alpha-tocopherol and gamma-tocotrienol and their inhibitory concentration 50 (IC50) on osteoblasts were determined if any. Osteoblast cultures were then pretreated with different concentrations of alpha-tocopherol or gamma-tocotrienol for 24 hours before incubated with the IC50 of H2O2 for 2 hours. Cell viability was determined by using MTS assay to compare the protective effects of both vitamin E on osteoblast exposed to H2O2. Results. The IC50 hours and 24 hours incubation time for H2O2 were 490 mu M and 280 mu M respectively. gamma-Tocotrienol was found to be toxic to osteoblasts with the IC50 of 290 mu M after 24 hours incubation time while alpha-tocopherol was not toxic to osteoblasts at any doses. However, gamma-tocotrienol was able to protect osteoblasts from H2O2 toxicity at low concentration (1 mu M), whereras alpha-tocopherol was not able to offer protection against H2O2 toxicity. Conclusions. gamma-tocotrienol was found to be toxic to osteoblasts at high concentrations but at much lower concentration, it has better antioxidant activity than alpha-tocopherol to protect osteoblasts from oxidative stress. Clin Ter 2011; 162(6):533-538