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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

Drotleff, Astrid M., Busing, Anne, Willenberg, Ina, Empl, Michael T., Steinberg, Pablo, Ternes, Waldemar
Journal of agricultural and food chemistry 2015 v.63 no.40 pp. 8930-8939
alpha-tocotrienol, antineoplastic activity, breast neoplasms, cell viability, dose response, gamma-tocotrienol, hexane, high performance liquid chromatography, inhibitory concentration 50, mass spectrometry, neoplasm cells, oxidation
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.