Fermented soybean-derived water-soluble Touchi extract inhibits alpha-glucosidase and is antiglycemic in rats and humans after single oral treatments.

A water-soluble extract of Touchi, a traditional Chinese food, was found to exert a strong inhibitory activity against rat intestinal alpha-glucosidase. We orally administered sucrose (2 g/kg) with or without Touchi extract (TE) to normal rats at 100 and 500 mg/kg. Postprandial increases in blood glucose levels at 30 and 60 min after the administration of TE were significantly depressed compared with controls. In humans, eight borderline diabetic subjects were administered 0.1-10.0 g TE before sucrose loading (75 g). TE decreased the glycemic response dose dependently after sucrose loading. Compared with the area under the curve of the postprandial rise in blood glucose with various doses, TE elicited a significant antiglycemic effect at a minimum effective dose of 0.3 g. In addition, when four diabetics were administered 0.3 g TE before eating 200 g of cooked rice, the postprandial increases in blood glucose and mean insulin levels were significantly depressed at 60 and 120 min, respectively, after ingestion compared with levels when no TE was administered. TE, which exhibits alpha-glucosidase inhibitory activity, demonstrated an antihyperglycemic effect and may have potential use in the management of patients with non-insulin-dependent diabetic mellitus.