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 %, 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

SummaryThe influence of the chronic intake of a newly developed sweetener named "Neosugar" (fructooligosaccharide) on body weight gain, organ weight, serum lipids, fecal excretion and intestinal function was investigated in rats. The following results were obtained. 1) Body weight gain was diminished more severely in rats fed on 20% Neosugar diet than in rats fed on 10% Neosugar diet. 2) The wet weights of cecum and colon were greatly increased by Neosugar feeding. 3) Fecal wet weight was significantly increased and gastrointestinal transit time was shortened by Neosugar feeding compared with those of the control group. 4) Serum triacylglycerol levels were significantly lower in rats fed Neosugar, whereas serum cholesterol levels were similar to those of the control group. 5) Fecal excretions of neutral sterol and volatile fatty acids were significantly increased by Neosugar feeding. These results were quite similar, with the exception of diarrhea to those obtained using a dietary fi ber such as glucomannan. Therefore, Neosugar with a pleasant-tasting sweetness appears to be an unavailable oligosaccharide with a dietary fi ber-like action. Key Words Neosugar, fructooligosaccharide, dietary fiber, chronic in take, sweetener, undigestibility, gastrointestinal A dietary preference for sweet foods accompanied by an excessive intake of energy leads inevitably to obesity in people who continue to consume more energy than they burn. In this sense, pleasant-tasting, non-energy sweetener that is entirely safe would make it possible to enjoy sweetened food and at the same time, to avoid both obesity and its complications such as diabetes mellitus. The newly developed 111

The digestion of Neosugar, a mixture of 1F-(1-beta-fructofuranosyl)n-1 sucrose [n = 2, 1-kestose (GF2); n = 3, nystose (GF3); n = 4, 1F-beta-fructofuranosyl nystose (GF4)] was investigated in vitro and in vivo by using the rat. The results obtained were as follows. GF2 and GF3 were not hydrolyzed by a pancreatic homogenate. The GF2- and GF3-hydrolyzing activities of the enzymes in the intestinal mucosa homogenate were negligible compared with the activities of maltase and sucrase. GF2 and GF3 added to the incubation mixture did not affect the activities of sucrase and maltase in the intestinal mucosa. Long-term ingestion of Neosugar did not cause induction or suppression of GF2- and GF3-hydrolyzing enzymes in the small intestine. [U-14C]Neosugar injected intravenously was rapidly excreted in the urine without having undergone any degradation. These results indicate that Neosugar, which consists of GF2, GF3 and GF4, is scarcely hydrolyzed by the digestive enzymes of the gastrointestinal tract and internal organs, and that suggests to us that Neosugar is not utilized as an energy source in the body.

Many kinds of oligosaccharides and sugar alcohols have been newly developed as bulking sugar substitutes that have beneficial health effects. A sugar substitute that is not digested and absorbed in the small intestine reaches the large intestine, where it is completely fermented by intestinal bacteria and produces short-chain fatty acids, which are converted to energy. The available energy of a nondigestible sugar substitute, which is completely fermented by intestinal microbes, is estimated as approximately 2 kcal/g. On the other hand, a sufficiently high ingestion of nondigestible sugar substitutes regularly causes overt diarrhea in human and animals. However, the diarrhea disappears within a few days because intestinal microbes, which readily utilize these saccharides, increase during ingestion. The maximum permissible dose, by which transitory diarrhea is not caused by the ingestion of nondigestible sugar substitutes, is estimated as approximately 0.3 g per kg body weight in single ingestion for Japanese adults. The value is varied by some factors, such as separate ingestion, repeat ingestion, test substance, and body condition, etc.

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