Isolation and characterization of two positional isomers of novel heterogeneous branched cyclomaltohexaoses (α-cyclodextrins) having a D-galactobiosyl residue on the side chain Original Research Article

Transgalactosylated products, 2-O-α-D-galactobiosyl-cyclomaltohexaoses (α-cyclodextrins, αCDs), were synthesized by α-galactosidase from coffee bean using melibiose and αCD as a donor substrate and an acceptor, respectively. Two positional isomers of 2-O-α-galactobiosyl-αCDs were isolated and purified by HPLC, and their structures were elucidated by FABMS and NMR spectroscopies, as well as by an enzymatic degradation method. The chromatographic behavior of these novel galactosylated αCDs was compared on three HPLC columns with different separation modes.