Present trends in vitamin E research.
Nearly after one century of research and thousands of publications, the physiological function(s) of vitamin E remain unclear. Available evidence suggests a role in cell homeostasis that occurs through the modulation of specific signaling pathways and genes involved in proliferative, metabolic, inflammatory, and antioxidant pathways. Vitamin E presence in the human body is under close metabolic control so that only alpha-tocopherol and, to a lower extent, gamma-tocopherol are retained and delivered to tissues. Other vitamin E forms that are not retained in the body in significant amounts, exhibit responses in vitro that are different form those of alpha-tocopherol and may include tumor cell specific toxicity and apoptosis. These responses provide a therapeutic potential for these minor forms, either as such or metabolically modified, to produce bioactive metabolites. These cellular effects go beyond the properties of lipophilic antioxidant attributed to alpha-tocopherol particularly investigated for its alleged protective role in atherosclerosis or other oxidative stress conditions. Understanding signaling and gene expression effects of vitamin E could help assign a physiological role to this vitamin, which will be discussed in this review. Besides vitamin E signaling, attention will be given to tocotrienols as one of the emerging topics in vitamin E research and a critical re-examination of the most recent clinical trials will be provided together with the potential use of vitamin E in disease prevention and therapy.
Galli
Francesco
F
Department of Internal Medicine, Laboratory of Clinical Biochemistry and Nutrition, University of Perugia, Perugia, Italy.
Azzi
Angelo
A
D002318:Cardiovascular Diseases / Q000517:prevention & control; D002839:Chromans / Q000378:metabolism; D006801:Humans; D007109:Immunity / Q000187:drug effects; D009369:Neoplasms / Q000517:prevention & control; D010766:Phosphorylation; D011422:Propionates / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D024508:Tocotrienols / Q000378:metabolism; D014810:Vitamin E / Q000502:physiology* / Q000627:therapeutic use / Q000633:toxicity
D002839:Chromans; D011422:Propionates; D024508:Tocotrienols; D014810:Vitamin E; C107690:2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman; C084852:2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman