There are no proven health benefits to supplementing with Vitamin E, so why do we require it for healthy living? The whole notion that vitamin E is an in-vivo antioxidant is now being seriously questioned. We believe the debate in literature is due to much of the existing data being collected using techniques which require the presences of non-biological and invasive probes, and often in the wrong model systems. Using neutron diffraction, supported by solid state 2H NMR, we have correlated vitamin E's location in model membranes with its antioxidant activity. Experiments were conducted using phosphatidylcholine (PC) bilayers whose fatty acid chains varied in their degree of unsaturation. PC bilayers made up of mixed acyl chains (i.e., saturated and unsaturated) and different headgroup moieties were also studied. UV/Vis spectroscopy studies were conducted to examine vitamin E's oxidation at its various locations within the different model membranes. Both water soluble and lipid soluble initiators were used to start the oxidation process.We observe vitamin E up-right in all lipids examined, with its overall height in the bilayer lipid dependant. Interestingly we observe vitamin E's hydroxyl in the headgroup region of the bilayer for both the fully saturated and poly unsaturated lipids. Vitamin E was most effective at intercepting water borne oxidants than radical initiated within the bilayer core. However for lipids where vitamin E resides slightly lower(glycerol backbone) we observe comparable antioxidant activity against both water borne and hydrocarbon borne oxidants. Thus showing lipid species can modulate the location of vitamin E's activity.
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