44E-6 |
Induction of Phase II enzyme activity in murine hepatoma (Hepa 1c1c7) cells by selected vegetable extracts |
M. WETTASINGHE, H. Xiao, B. Bolling, and K. Parkin. Dept. of Food Science, Univ. of Wisconsin, Madison, 1605 Linden Dr., Madison, WI 53706 Consumption of vegetables is known to confer health benefits, such as the reduced risk of developing vitamin deficiencies, heart diseases and cancer. Vegetables contain phenolic antioxidants, which protect against cancer mediated by free radical mechanisms, and also induce antioxidant, protective enzyme activities (Phase II enzymes) in bodily tissues. These enzymes have multiple functions, including detoxification, neutralization of the effects of free radicals and recycling of antioxidants. The hypothesis behind this study was that common vegetable tissues contain agents that induce Phase II enzyme activity. The objective of this study was to evaluate the effects of corn, kale, green bean and table beet extracts on Phase II enzyme induction in hepatoma cell cultures. Aqueous (100oC) and aqueous ethanol (5:95, v/v; 65oC) extracts of vegetables were prepared and dried. Hepatoma cells were cultured on microtiter plates and treated with vegetable extracts (0-0.312 mM sinapinic acid equivalents) or reference inducer compound (b-naphthoflavone at 0.3 mM). Induction of quinone reductase (QR, a Phase II enzyme) specific activity was measured using the kinetics of tetrazolium dye reduction, and total protein was assayed (crystal violet staining) relative to controls absent in inducing agents. Hepatoma cell cultures treated with aqueous extracts of corn, kale, green bean and table beets at a concentration of 0.312 mM, resulted in a ratio QR specific activity (treated/non-treated) of about 13, 3, 5 and 1.5, respectively. The aqueous ethanol extracts, at the same concentration, resulted in QR induction levels of about 1, 3, 2 and 2 for corn, kale, green bean and table beets, respectively. QR induction by b-naphthoflavone was about 4-fold. Aqueous and aqueous ethanol extracts of vegetables possess endogenous Phase II enzyme inducing agents. Regular consumption of vegetables may provide for sustained chemopreventative capacity in bodily tissues.
Session 44E, Nutraceuticals & Functional Foods
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