title: HPLC Separation of Vitamin E and Its Oxidation Products and Effects of Oxidized Tocotrienols on the Viability of MCF-7 Breast Cancer Cells in Vitro.
abstract: Tocotrienols, a vitamin E subgroup, exert potent anticancer effects, but easily degrade due to oxidation. Eight vitamin E reference compounds, α-, β-, γ-, or δ-tocopherols or -tocotrienols, were thermally oxidized in n-hexane. The corresponding predominantly dimeric oxidation products were separated from the parent compounds by diol-modified normal-phase HPLC-UV and characterized by mass spectroscopy. The composition of test compounds, that is, α-tocotrienol, γ-tocotrienol, or palm tocotrienol-rich fraction (TRF), before and after thermal oxidation was determined by HPLC-DAD, and MCF-7 cells were treated with both nonoxidized and oxidized test compounds for 72 h. Whereas all nonoxidized test compounds (0-100 μM) led to dose-dependent decreases in cell viability, equimolar oxidized α-tocotrienol had a weaker effect, and oxidized TRF had no such effect. However, the IC50 value of oxidized γ-tocotrienol was lower (85 μM) than that of nonoxidized γ-tocotrienol (134 μM), thereby suggesting that γ-tocotrienol oxidation products are able to reduce tumor cell viability in vitro.
authors.affiliation: Department of Analytical Chemistry and ‡Department of Food Toxicology, Center for Food Sciences, Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover Foundation , Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Astrid M
authors.initials: AM
authors.lastname: Drotleff
authors.affiliation: Department of Analytical Chemistry and ‡Department of Food Toxicology, Center for Food Sciences, Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover Foundation , Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Büsing
authors.affiliation: Department of Analytical Chemistry and ‡Department of Food Toxicology, Center for Food Sciences, Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover Foundation , Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Willenberg
authors.affiliation: Department of Analytical Chemistry and ‡Department of Food Toxicology, Center for Food Sciences, Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover Foundation , Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Empl
authors.affiliation: Department of Analytical Chemistry and ‡Department of Food Toxicology, Center for Food Sciences, Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover Foundation , Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Pablo
authors.initials: P
authors.lastname: Steinberg
authors.affiliation: Department of Analytical Chemistry and ‡Department of Food Toxicology, Center for Food Sciences, Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover Foundation , Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Waldemar
authors.initials: W
authors.lastname: Ternes
mesh_terms: D001943:Breast Neoplasms / Q000503:physiopathology; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D010084:Oxidation-Reduction; D024508:Tocotrienols / Q000737:chemistry* / Q000494:pharmacology; D014810:Vitamin E / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D024508:Tocotrienols; D014810:Vitamin E
keywords: HPLC-DAD; alamarBlue assay; dimeric oxidation products; human MCF-7 breast cancer cells; tocopherols; tocotrienols; viability; vitamin E