Synthesis of branched cyclomaltooligosaccharide carboxylic acids (cyclodextrin carboxylic acids) by microbial oxidation.

Novel branched cyclomaltooligosaccharide carboxylic acid (cyclodextrin carboxylic acid) derivatives were synthesized by microbial oxidation using Pseudogluconobacter saccharoketogenes to oxidize five types of branched cyclodextrins, including maltosyl β-cyclodextrin (maltosyl-β-CyD). For each novel cyclodextrin carboxylic acid derivative synthesized, the hydroxymethyl group of the terminal glucose residue in the branched part of the molecule was regiospecifically oxidized to a carboxyl group to give the corresponding uronic acid. In addition, the physicochemical properties of cyclomaltoheptaosyl-(6→1)-α-d-glucopyranosyl-(4→1)-α-d-glucopyranosiduronic acid (GUG-β-CyD) (1) and its sodium salt were studied more extensively, as these compounds are most likely to have a practical application.