Antioxidant action and potential antidiabetic properties of an isoflavonoid-containing soyabean phytochemical extract (SPE)

The potential role of oestrogenic agents, antioxidants and intestinal gluco se-uptake inhibitors in the treatment of diabetes is briefly reviewed. Repo rts in the literature suggest that oestrogen replacement therapy may favour ably modulate glucose homeostasis, A soya phytochemical extract (SPE) conta ining the isoflavone phytoestrogens genistein and daidzein (mostly in their glycone forms as genistin and daidzin) was investigated as an antioxidant and modulator of intestinal glucose-transport. Lr the present study, SPE wa s found to protect against glucose-induced oxidation of human low density l ipoproteins (LDL) in vitro. Equol (a gut bacterial metabolite of daidzein) was a more effective antioxidant than daidzein or genistein in this system and was of similar antioxidant potency to the dietary flavonols quercetin a nd kaempferol and to the endogenous antioxidant 17 beta-oestradiol, SEE was found to be an inhibitor of glucose uptake into rabbit intestinal brush bo rder membrane vesicles in vitro, though of weaker potency than the classica l sodium dependent glucose transporter (SGLT) inhibitor, phlorizin. Thus SP E displays a range of properties which may be of benefit in diabetes, namel y as an oestrogenic agent, an inhibitor of intestinal glucose-uptake and a preventive agent for glucose-induced lipid peroxidation, Copyright (C) 1999 John Whey & Sons, Ltd.