The aim of this study was to design a mixture consisting of plant-derived preparations containing inhibitors of carbohydrate digestion and/or glucose absorption that could lower postprandial glycemia and attenuate dietary-induced disorders. The following standardized preparations were tested: white mulberry leaf extract, green coffee bean extract, white kidney bean extract, pomelo fruit extract, bitter melon fruit extract, and purified l-arabinose. The study design was composed of oral sucrose and starch tolerance tests in Wistar rats preceded by a single ingestion of the preparations or their mixtures. Then, a 20 week-long experiment was conducted on rats that were fed a high-fat diet and supplemented with the most effective mixture. Based on the results of the oral sucrose and starch tolerance tests, the mulberry leaf extract, l-arabinose, kidney bean extract, and coffee bean extract were selected for composing three mixtures. The most effective inhibition of postprandial glycemia in the oral tolerance tests was observed after the ingestion of a mixture of mulberry leaf, kidney bean, and coffee bean extract. The glucose-lowering effect of the mixture and its effective dosage was confirmed in the feeding experiment.
Keywords: carbohydrate digestion; glucose absorption; impaired glucose tolerance; plant extracts; α-glucosidase inhibitors.