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Oxidative Medicine and Cellular Longevity
Volume 2015, Article ID 150829, 10 pages
http://dx.doi.org/10.1155/2015/150829
Research Article

Tocotrienol Rich Palm Oil Extract Is More Effective Than Pure Tocotrienols at Improving Endothelium-Dependent Relaxation in the Presence of Oxidative Stress

School of Medical Sciences, Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia

Received 5 January 2015; Revised 24 April 2015; Accepted 24 April 2015

Academic Editor: Giuseppe Cirillo

Copyright © 2015 Saher F. Ali and Owen L. Woodman. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Oxidative endothelial dysfunction is a critical initiator of vascular disease. Vitamin E is an effective antioxidant but attempts to use it to treat vascular disorders have been disappointing. This study investigated whether tocotrienols, the less abundant components of vitamin E compared to tocopherols, might be more effective at preserving endothelial function. Superoxide generated by hypoxanthine/xanthine oxidase or rat aorta was measured using lucigenin-enhanced chemiluminescence. The effect of α-tocopherol, α-, δ-, and γ-tocotrienols and a tocotrienol rich palm oil extract (tocomin) on levels of superoxide was assessed. Endothelial function in rat aorta was assessed in the presence of the auto-oxidant pyrogallol. Whilst all of the compounds displayed antioxidant activity, the tocotrienols were more effective when superoxide was produced by hypoxanthine/xanthine oxidase whereas tocomin and α-tocopherol were more effective in the isolated aorta. Tocomin and α-tocopherol restored endothelial function in the presence of oxidant stress but α-, δ-, and γ-tocotrienols were ineffective. The protective effect of tocomin was replicated when the tocotrienols were present with, but not without, α-tocopherol. Tocotrienol rich tocomin is more effective than α-tocopherol at reducing oxidative stress and restoring endothelium-dependent relaxation in rat aortae and although α-, δ-, and γ-tocotrienols effectively scavenged superoxide, they did not improve endothelial function.