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 a-tocopherol and γ-tocotrienol on osteoblasts, the bone forming cells, against oxidative stress.
MATERIALS AND METHODS: Toxicity tests were carried out on hydrogen peroxide (H(2)O(2)), a-tocopherol and γ-tocotrienol and their inhibitory concentration 50 (IC(50)) on osteoblasts were determined if any. Osteoblast cultures were then pretreated with different concentrations of a-tocopherol or γ-tocotrienol for 24 hours before incubated with the IC50 of H(2)O(2) for 2 hours. Cell viability was determined by using MTS assay to compare the protective effects of both vitamin E on osteoblast exposed to H(2)O(2).
RESULTS: The IC(50) after 2 hours and 24 hours incubation time for H(2)O(2) were 490 µM and 280 µM respectively. γ-Tocotrienol was found to be toxic to osteoblasts with the IC(50) of 290 µM after 24 hours incubation time while a-tocopherol was not toxic to osteoblasts at any doses. However, γ-tocotrienol was able to protect osteoblasts from H(2)O(2) toxicity at low concentration (1 µM), whereras a-tocopherol was not able to offer protection against H2O2 toxicity.
CONCLUSIONS: γ-tocotrienol was found to be toxic to osteoblasts at high concentrations but at much lower concentration, it has better antioxidant activity than a-tocopherol to protect osteoblasts from oxidative stress.