Effects of Low-Dose versus High-Dose γ-Tocotrienol on the Bone Cells Exposed to the Hydrogen Peroxide-Induced Oxidative Stress and Apoptosis

Oxidative stress and apoptosis can disrupt the bone formation activity of osteoblasts which can lead to osteoporosis. This study was conducted to investigate the effects of gamma-tocotrienol on lipid peroxidation, antioxidant enzymes activities, and apoptosis of osteoblast exposed to hydrogen peroxide (H2O2). Osteoblasts were treated with 1, 10, and 100 mu M of beta-tocotrienol for 24 hours before being exposed to 490 mu M(IC50) H2O2 for 2 hours. Results showed that gamma-tocotrienol prevented the malondialdehyde (MDA) elevation induced by H2O2 in a dose-dependent manner. As for the antioxidant enzymes assays, all doses of gamma-tocotrienol were able to prevent the reduction in SOD and CAT activities, but only the dose of 1 mu M of GTT was able to prevent the reduction in GPx. As for the apoptosis assays, gamma-tocotrienol was able to reduce apoptosis at the dose of 1 and 10 mu M. However, the dose of 100 mu M of gamma-tocotrienol induced an even higher apoptosis than H2O2. In conclusion, low doses of gamma-tocotrienol offered protection for osteoblasts against H2O2 toxicity, but itself caused toxicity at the high doses.