title: Tocotrienol Rich Palm Oil Extract Is More Effective Than Pure Tocotrienols at Improving Endothelium-Dependent Relaxation in the Presence of Oxidative Stress.
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.
authors.affiliation: School of Medical Sciences, Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia.
authors.forename: Saher F
authors.initials: SF
authors.lastname: Ali
authors.affiliation: School of Medical Sciences, Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia.
authors.forename: Owen L
authors.initials: OL
authors.lastname: Woodman
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D000073878:Palm Oil; D010936:Plant Extracts / Q000494:pharmacology*; D010938:Plant Oils / Q000494:pharmacology*; D011748:Pyrogallol / Q000494:pharmacology; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism; D024508:Tocotrienols / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*; D014969:Xanthine Oxidase / Q000378:metabolism; D024502:alpha-Tocopherol / Q000494:pharmacology
chemical_list: D016166:Free Radical Scavengers; D010936:Plant Extracts; D010938:Plant Oils; C570135:Tocomin; D024508:Tocotrienols; D011748:Pyrogallol; D013481:Superoxides; D009599:Nitroprusside; D000073878:Palm Oil; D014969:Xanthine Oxidase; D024502:alpha-Tocopherol; D000109:Acetylcholine