Inhibitory effects of extractives from leaves of Morus alba on human and rat small intestinal disaccharidase activity

Tsuneyuki Oku, Mai Yamada, Mariko Nakamura, Naoki Sadamori, Sadako Nakamura
2006 British Journal of Nutrition  
The inhibitory effect on human and rat intestinal disaccharidase by the extractive from the leaves of Morus alba (ELM) containing 0·24 % 1-deoxynojirimycin equivalent and its inhibitory activities were investigated by the modified Dahlqvist method. In the presence of 1000-fold diluted ELM solution, the sucrase activity of four human samples was inhibited by 96 % and that of maltase and isomaltase by 95 and 99 %, respectively. The activities of trehalase and lactase were inhibited by 44 and 38
more » ... ited by 44 and 38 %, respectively. The human disaccharidase activities varied from sample to sample because the samples were obtained from different resected regions after surgery. However, the ratio of the inhibitory effect for sucrase, maltase, isomaltase, trehalase and lactase was very similar among the four samples, and also that of resembled rat intestinal disaccharides. The inhibitory constant of the 1-deoxynojirimycin equivalent for sucrase, maltase and isomaltase was 2·1 £ 10 24 , 2·5 £ 10 24 and 4·5 £ 10 24 mM, respectively, and these inhibitory activities were shown, using rat brush border membrane vesicles, to be competitive. These results demonstrate that digestion is inhibited when an appropriate amount of ELM is orally ingested with sucrose or polysaccharide in man. When ELM was orally administered in a sucrose solution to fasted rats, the elevation in blood glucose was significantly suppressed, depending on the concentration of ELM given. These results suggest that ELM could be used as an ingredient in health foods and in foods that help to prevent diabetes. Inhibitory effects: Human disaccharidase: Morus alba extractive * Corresponding author: Dr Tsuneyki Oku, fax þ81 95 813 5211, email okutsune@sun.ac.jp Abbreviations: AUC, area under the curve; BBMV, brush border membrane vesicles; DNJ, 1-deoxynojirimycin; ELM, extractive from the leaves of Morus alba; K i , inhibitory constant; V max , maximum velocity.
doi:10.1079/bjn20061746 pmid:16611383 fatcat:d5ttx3jqwjey7pqzkysojtpkw4