Inhibitory effect of validamine, valienamine and valiolamine on activities of carbohydrases in rat small intestinal brush border membranes.
Three pseudo-aminosugars, validamine, valienamine and valiolamine, produced by Streptomyces hygroscopicus subsp. limoneus showed potent inhibitory action on rat small intestinal carbohydrase activities such as sucrase, maltase, glucoamylase, isomaltase and trehalase activities, but negligible action on lactase activity and pancreatic alpha-amylase activity. Where inhibition was seen, kinetic analysis showed fully competitive inhibition of the carbohydrase activities by all three inhibitors. Valiolamine has more potent carbohydrase inhibitory activity than validamine or valienamine, and the apparent Ki values of valiolamine for sucrase, maltase, glucoamylase, isomaltase and trehalase activities were 3.2 x 10(-7), 2.9 x 10(-6), 1.2 x 10(-6), 9.1 x 10(-7) and 4.9 x 10(-5) M, respectively, which are 10(-5) to 10(-3) times smaller than the apparent Km values.
Takeuchi
M
M
Department of Biochemistry, School of Pharmacy, Hokuriku University, Ishikawa, Japan.
Takai
N
N
Asano
N
N
Kameda
Y
Y
Matsui
K
K
D000818:Animals; D053138:Cyclohexenes; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors*; D006595:Hexosamines / Q000494:pharmacology*; D066298:In Vitro Techniques; D007294:Inositol / Q000031:analogs & derivatives* / Q000494:pharmacology; D007421:Intestine, Small / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008871:Microvilli / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D050111:Imino Sugars
D053138:Cyclohexenes; D006026:Glycoside Hydrolases; D006595:Hexosamines; D007294:Inositol; C042908:validamine; C030791:valienamine; C043270:valiolamine; D050111:Imino Sugars; C019822:carbohydrase