Scientific validation of traditionally used omija (Schisandra chinensis) extract mixture for postprandial glucose regulation

Abstract According to Dongeuibogam (東醫寶鑑), a UNESCO Memory of the World-registered medical text, Omigalsu (五味喝水) was a traditional Korean beverage formulated from Schisandra chinensis (Turcz.) Baill. (Omija, Schisandra) extract and soybean. It was historically prescribed for treating “sogal” (消渴), a condition characterized by symptoms analogous to diabetes mellitus, including polydipsia, polyphagia, and polyuria. This study aimed to scientifically validate its historical use through modern experimental analysis. To increase ligan contents from the traditional formulation, we developed Omija extract and soybean mixture (OSM) by combining 50% ethanol extract of Omija with cooked soybean powder (5:1, w/w). In vitro α-glucosidase inhibition assays demonstrated that OSM exhibited concentration-dependent inhibitory activity, reaching 39.8 ± 3.4% inhibition at 10,000 μg/mL. In Sprague–Dawley rats, oral sucrose tolerance testing (OSTT) was conducted using 2 g sucrose/kg body weight (BW) after OSM administration. The OSM group maintained significantly lower blood glucose levels compared to the control group, suggesting significantly inhibiting post-prandial blood glucose elevation. Area under the curve (AUC) analysis further confirmed OSM’s glucose-regulating efficacy, with the OSM group exhibiting significantly lower AUC values than controls. These findings provide scientific validation for the traditional use of Omigalsu such as OSM in post-prandial blood glucose regulation, as documented in classical Korean medical texts. Furthermore, they suggest that OSM has the potential of a functional food ingredient for diabetes prevention and management.