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B. W. BOLLING and K. L. Parkin. Dept. of Food Science, Univ. of Wisconsin, Madison, 1605 Linden Dr., A-115-A Babcock Hall, Madison, WI 53706-1519 The use of soyfoods is now thought to afford a reduced risk of cancer, based on epidemiological and physiochemical evidence. Soy consumption is known to induce chemopreventive phase II enzymes in vivo. Phytoestrogens, phytic acid, protease inhibitors, and sterols present in soybean have not been shown to possess this property. Therefore, we hypothesize that other agents from soybeans might contribute to this mode of cancer chemoprevention. The objectives of this research were to screen for cancer chemopreventative agents in soybean isolates, 2) purify the active agents(s), 3) determine the dose-dependent nature of the identified purified components. A murine hepatoma (hepa1c1c7) cellular bioassay was used to direct the purification of components from soybean, in which active agents increase the level of the detoxification enzyme quinone reductase. Soybean isolates were prepared with sequential soxhlet solvent extraction of soyflour, phospholipid extraction, solvent partitioning, and FLASH C-18 silica column chromatography. Fractions were purified with conventional chromatographic approaches and identified using NMR and mass spectroscopy. An ethanolic extract doubled quinone reductase specific activity (CD, concentration required to double) at 460 ėg/ml. Solvent partitioning and phospholipid extraction enriched the fraction to 80 ėg/ml CD. Column chromatography produced 13 distinct fractions. Fractions 2, 8, and 10 held 47% of the recovered mass and were the least active, with CD values of 62, 194, and 328 ėg/ml respectively. Genistein and daidzein glycosides were identified in these fractions. Fractions 11, 12, and 13 were the most potent with CD values of 10, 6, and 7 ėg/ml and contained volatile savory compounds that remain to be identified. The profiles of ethanolic soyflour extract isolates indicate that multiple known and unknown components from soy can induce quinone reductase in vitro. Further, isolated sensory compounds may be quinone reductase inducers or markers for inducing agents in soy.
Session 83, Food Chemistry: Antioxidant and bioactive agents
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |