α-Tocopheryl acetate (alpha-tocopherol acetate), also known as vitamin E acetate, is a form of vitamin E with D-Alpha Tocpheryl Acetate as the natural form and DL-Alpha Tocopheryl Acetate as the synthetic form. DL-indicates the synthetic form where as D- indicates the natural form. It is the esterofacetic acid and α-tocopherol.[2]
α-Tocopheryl acetate is often used in dermatologicalproducts such as skin creams. It is not oxidized and can penetrate through the skin to the living cells, where about 5% is converted to free tocopherol. Claims are made for beneficial antioxidant effects.[7] α-Tocopheryl acetate is used as an alternative to tocopherol itself because the phenolichydroxyl group is blocked, providing a less acidic product with a longer shelf life. It is believed that the acetate is slowly hydrolyzed after it is absorbed into the skin, regenerating tocopherol and providing protection against the sun's ultraviolet rays.[8] Tocopheryl acetate was first synthesized in 1963 by workers at Hoffmann-La Roche.[9]
Although there is widespread use of tocopheryl acetate as a topical medication, with claims for improved wound healing and reduced scar tissue,[10] reviews have repeatedly concluded that there is insufficient evidence to support these claims.[11][12] There are reports of vitamin E-induced allergic contact dermatitis from use of vitamin E derivatives such as tocopheryl linoleate and tocopherol acetate in skin care products. Incidence is low despite widespread use.[13]
On September 5, 2019, the United States Food and Drug Administration (US FDA) announced that 10 out of 18, or 56% of the samples of vape liquids sent in by states, linked to the recent vaping-related lung disease outbreak in the United States, tested positive for vitamin E acetate[14] which had been used as a thickening agent by illicit THC vape cartridge manufacturers.[15] On November 8, 2019, the Centers for Disease Control and Prevention (CDC) identified vitamin E acetate as a very strong culprit of concern in the vaping-related illnesses, but has not ruled out other chemicals or toxicants as possible causes.[3] The CDC's findings were based on fluid samples from the lungs of 29 patients with vaping-associated pulmonary injury, which provided direct evidence of vitamin E acetate at the primary site of injury in all the 29 lung fluid samples tested.[3] Research suggests when vitamin E acetate is inhaled, it may interfere with normal lung functioning.[5] A 2020 study found that vaporizing vitamin E acetate produced carcinogenic alkenes and benzene, but also exceptionally toxic ketene gas, which may be a contributing factor to the pulmonary injuries.[6]
At room temperature, α-tocopheryl acetate is a fat-soluble liquid. It has 3 chiral centers and thus 8 stereoisomers. It is made by esterifyingα-tocopherol with acetic acid. 2R,4R,8R-isomer, also known as RRR-α-tocopheryl acetate, is the most common isomer used for various purposes. This is because α-tocopherol occurs in nature primarily as RRR-α-tocopherol.[2]
^Beijersbergen van Henegouwen G, Junginger H, de Vries H (1995). "Hydrolysis of RRR-alpha-tocopheryl acetate (vitamin E acetate) in the skin and its UV protecting activity (an in vivo study with the rat)". J Photochem Photobiol B. 29 (1): 45–51. doi:10.1016/1011-1344(95)90251-1. PMID7472802.
^Mayer H, Schudel P, Rüegg R, Isler O (1963). "Über die Chemie des Vitamins E. 3. Mitteilung. Die Totalsynthese von (2R, 4′R, 8′R)- und (2S, 4′R, 8′R)-α-Tocopherol". Helvetica Chimica Acta. 46 (2): 650–671. doi:10.1002/hlca.19630460225. ISSN0018-019X.
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