[Synthesis of beta-maltosides, derivatives of p-nitrophenol, 2-chloro-4-nitrophenol, and 4-methylumbelliferone, and their use as substrates for determining alpha-glucosidase activity].

Synthesis of beta-maltosides, p-nitrophenyl-beta-D-maltoside and 4-methylumbelliferyl-beta-D-maltoside, based on interaction of hepta-acetate-beta-D-maltosyl fluoride with the corresponding trimethylsilyl ethers of p-nitrophenol and 4-methylumbelliferone is described. 2-Chloro-4-nitrophenyl-beta-D-maltoside was synthesized by interaction of hepta-acetate-alpha-D-maltosyl bromide with 2-chloro-4-nitrophenol in two phase system using phase transfer catalyst. The method of assay of neutral alpha-glucosidase from human kidney and urine using synthesized beta-maltosides (p-nitrophenyl-beta-D-maltoside, 2-chloro-4-nitrophenyl-beta-D-maltoside and 4-methylumbelliferyl-beta-D-maltoside) as substrates and beta-glucosidase as an auxiliary enzyme is proposed. The method is simple, convenient and 10-fold more sensitive than the commonly used alpha-glucosidase assay procedure with the corresponding synthetic alpha-glucosides, p-nitrophenyl-alpha-D-glucoside and 4-methylumbelliferyl-alpha-D-glucoside. A modification of the method, with p-nitrophenyl-beta-D-maltoside as substrate, was applied to the semi-automatic assay of urinary alpha-glucosidase in 96-well microtitre plates.