Oxidative stress is caused by imbalance between the productions of reactive oxygen species (ROS) and antioxidant defense mechanisms. Palm oil antioxidants such as tocotrienol rich fraction (TRF) is known to have neuroprotective effects on neurones by acting against free radical induced neuronal cell death. This study was undertaken to elucidate the effect of TRF on oxidative DNA damage and cognitive functions in experimental rats.
Accumulating evidence suggests that altered arginine metabolism is involved in the aging and neurodegenerative processes. This study sought to determine the effects of age and vitamin E supplementation in the form of tocotrienol-rich fraction (TRF) on brain arginine metabolism. Male Wistar rats at ages of 3 and 21 months were supplemented with TRF orally for 3 months prior to the dissection of tissue from five brain regions. The tissue concentrations of L-arginine and its nine downstream metabolites were quantified using high-performance liquid chromatography and liquid chromatography tandem mass spectrometry. We found age-related alterations in L-arginine metabolites in the chemical- and region-specific manners. Moreover, TRF supplementation reversed age-associated changes in arginine metabolites in the entorhinal cortex and cerebellum. Multiple regression analysis revealed a number of significant neurochemical-behavioral correlations, indicating the beneficial effects of TRF supplementation on memory and motor function.