18E-22 |
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A. Y. KANG, Dept. of Food Science and Technology, School of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National Univ., San 56-1 Shillim-dong, Kwanak-gu, Seoul, Korea, Seoul, 151-742, South Korea, L. G. Yoo, Dept. of Food Science and Technology,School of Agricultural Biotechnology, Seoul National Univ., San 56-1, Shillim-dong, Kwanak-gu, Seoul, 151-742, South Korea, and T. W. Moon, Center for Agricultural Bio-Materials, Seoul National Univ., National Research Laboratory for Functional Food Carbohydrate, San 56-1 Sillim Dong Kwan-ak Gu, Seoul, 151-742, South Korea. Soy isoflavones have hypocholesterolemic effects. The effects of flavonoids on inhibition of cholesterol biosynthesis have been known. Recently, biotechnological production of highly soluble isoflavone glycosides was reported. However, the hypocholesterolemic effects of isoflavone glycoside and saponins, naturally occurring surface-active glycosides with several biological effects have not been studied yet. In this study, inhibitory effects of soyasaponins and isoflavone glycosides on hydroxy-3-methylglutaryl-CoA reductase(HMGR), which is the rate-limiting enzyme in the biosynthesis of cholesterol in animals, were investigated and the kinetics of HMGR were determined. The kinetic value was determined with respect to HMG-CoA. The kinetic experiments with Syrian hamster HMGR suggest that genistein-7-O-triglucoside is competitive and soyasapogenol A and B are noncompetitive with respect to HMG-CoA. At 100 mmol, soyasapogenol A and B inhibited 9.8% and 13.6% of HMGR activity, respectively. Genistein-7-O-triglucoside inhibited 5.6% of HMGR activity, whereas daidzein-7-O-triglucoside had no inhibitory effect. From these results, genistein-7-O-triglucoside, soyasapogenol A and B are judged to be inhibitors of HMGR. The mechanism of inhibition by genistein-7-O-triglucoside is postulated that the hypocholesterolemic effect is in part through the direct regulation of HMGR. However, the inhibitory mechanism of soyasapogenols remain unclear.
Session 18E, Nutraceutical & Functional Foods: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |