Gamma-tocopherol is less effective than alpha-tocopherol in preventing oxidant-induced sister chromatid exchanges in Chinese hamster V79 cells.
Although alpha-tocopherol (alpha-TOC) is the most biologically active form of vitamin E and is found at high levels in plasma, gamma-tocopherol (gamma-TOC) has also been found to be a powerful antioxidant in vitro and constitutes up to 70% of the dietary intake of TOC. Low plasma levels of gamma-TOC and a high alpha-TOC:gamma-TOC ratio may be associated with coronary heart disease, suggesting that there may be a positive protective role for the gamma-form of TOC. In this study the ability of different forms of vitamin E to protect against sister chromatid exchanges (SCE) induced by either hydrogen peroxide or menadione was investigated. Chinese hamster V79 cells were pre-treated with 10 microM TOC for 24 h, and then challenged with a genotoxin. After a 24 h pre-treatment, there was a greater incorporation of gamma-TOC (319.8 +/- 66.2 ng/10(6) cells) into V79 cells compared to alpha-TOC (66.9 +/- 6.4 ng/10(6) cells). Gamma-TOC did not protect the cells against SCE induced by either hydrogen peroxide or menadione, alpha-TOC acetate was partially protective against both genotoxins, whereas alpha-TOC completely abolished the oxidant induced SCE. These results demonstrate that, despite a greater incorporation of gamma-TOC into V79 cells, alpha-TOC but not gamma-TOC was more effective at inhibiting oxidatively-induced SCE in V79 cells.
O'Leary
K A
KA
Department of Food Science, Food Technology and Nutrition, University College Cork, Republic of Ireland.
Woods
J A
JA
O'Brien
N M
NM
D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D008940:Mitotic Index; D016877:Oxidants / Q000494:pharmacology*; D012854:Sister Chromatid Exchange / Q000187:drug effects*; D024502:alpha-Tocopherol / Q000494:pharmacology*; D024504:gamma-Tocopherol / Q000494:pharmacology*
D016877:Oxidants; D024504:gamma-Tocopherol; D024502:alpha-Tocopherol