Sadako Nakamura, Michiru Hashiguchi, Kenichi Tanabe and Tsuneyuki Oku
Department of Food and Nutritional Sciences, Institute of Food, Nutrition and Health, Jumonji University, Japan
Alginate is a co-polymer of alpha-L-guluronate and beta-D-mannuronate, and sodium alginate is a dietary fiber which is gelling polysaccharides found as a part of cell wall and intracellular material in the brown seaweeds. First, we prepared partially decomposed sodium alginate (Alg53) by the coculture of sodium alginate and Viblio alginolyticus SUN53, and partial purification. The average molecular weight of Alg53 was approximately 1,800. We hypothesized that Alg53 inhibits small intestinal disaccharidases and glucosyltransferase (GTase) based on the facts that several mono- and di-saccharides inhibit disaccharidase competitively.
GTase was purified from Streptococcus sobrinus. Rat and human small intestinal disaccharidase was prepared by modified Kesseler methods. Disaccharidase activity was measured by Oku method using glucose oxidase and GTase activity was evaluated based on the production of glucan using sucrose as a substrate. The study protocol using human intestine was approved by the ethical committee of University of Nagasaki.
The activities of rat and human disaccharidases were inhibited strongly by Alg53 and sucrase, maltase and lactase were competitively inhibited. The production of glucan by GTase was inhibited Alg53 and the acid production by S. sobrinus was clearly inhibited. We believe that these results may contribute to the prevention of diabetes and dental caries.
Keywords: Sodium Alginate, disaccharidase, glucosyltransferase.