Fermented soybean-derived Touchi-extract with anti-diabetic effect via alpha-glucosidase inhibitory action in a long-term administration study with KKA(y) mice

A water-soluble Touchi-extract (TE) exerts a potent inhibitory activity aga inst rat intestinal alpha -glucosidase in foodstuffs, and elicited anti-gly cemic effects in rats and humans with single-bolus oral administration. In the present study, genetically modified diabetic model KKA(y) mice were use d to examine the long-term effects of TE. Eight-week-old male KKA(y) mice w ere fed with CE-2 chow containing 0.08 and 0.4% of TE for 60 days. In the l atter group, fasting blood glucose levels decreased (6.68 +/- 0.41 mmol/L) significantly (p<0.05) after a 60-day ingestion period compared with contro ls (8.75 +/- 0.54 mmol/L). Moreover, postprandial blood glucose levels were also significantly reduced (16.79 +/- 2.28 mmol/L; p<0.01) after ingesting TE for only 30 days compared with controls (28.49 +/- 0.59 mmol/L). On ora l TE treatment for 60 days, postprandial increases in the blood glucose lev el after oral loading of sucrose (2 g/kg) at 30 (p<0.05) and 60 (p<0.01) mi n were significantly depressed compared with controls. Indexes for serum li pids; viz., total cholesterol (p<0.05) and triglyceride (p<0.01) levels sig nificantly decreased after TE ingestion. Indexes for hepatic functions, suc h as glutamic-oxaloacetic transaminase (p<0.01), glutamic-pyruvic transamin ase and gama-glutamyl transpeptide levels, were similarly suppressed. Organ weights of the heart, kidney, jejunum, liver and spleen increased in contr ol KKA(y) mice due to hyperinsulinemia. Interestingly, the respective organ weights decreased (p<0.05, 0.01) and the jejunum length was reduced (p<0.0 5) significantly in the TE-treated groups. All in all, TE demonstrated an a nti-hyperglycemic effect and may have potential use in the management of no n-insulin-dependent diabetic mellitus. ((C) 2001 Elsevier Science Inc. All rights reserved.