(±)-α-Tocopherol is the compound demonstrating the highest vitamin E activity, which is available both in its natural form as RRR-alpha-tocopherol isolated from plant sources[1]. The alpha-tocopherol transfer protein (TTP) is a critical regulator of vitamin E status that stimulates the movement of vitamin E between membrane vesicles in vitro and facilitates the secretion of tocopherol from hepatocytes[2]. α-Tocopherol serves as a peroxyl radical scavenger that protects polyunsaturated fatty acids in membranes and lipoproteins. The biological activity of vitamin E is highly dependent upon regulatory mechanisms that serve to retain α-tocopherol and excrete the non-α-tocopherol forms. This preference is dependent upon the combination of the function of α-tocopherol transfer protein (α-TTP) to enrich the plasma with α-tocopherol and the metabolism of non-α-tocopherols[3]. In patients with Abetalipoproteinemia, tocofersolan and α-tocopherol acetate bioavailabilities were extremely low (2.8% and 3.1%, respectively) [4].
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