Abstract
Three positional isomers of 61, 6n-di-O-α-D-glucosyl-cyclomaltoheptaose [1, n-(G)2-βCDs; n=2-4] which existed in the digests with glucoamylase of the products from cyclomaltoheptaose (β-cyclodextrin, βCD) and maltose with Klebsiella pneumoniae pullulanase, were purified by HPLC. The solubilities of two isomers of those doubly branced βCDs, 1, 2- and 1, 3-(G)2-βCDs, in water were much higher than those of parent non-branched βCD and mono-branched βCD, 6-O-α-D-glucosyl-βCD (G-βCD), while the solubility of another isomer, 1, 4-(G)2-βCD, was significantly lower than these two isomers, though it was higher than that of βCD. On the other hand, the solubilities of 1, 2- and 1, 3-isomers in 10, 30, and 50% (v/v) aqueous methanol at 25°C were independent of methanol concentrations and their solubilities were the same as those in water at 25°C. However, that of 1, 4-isomer increased with increasing methanol concentrations. The hemolytic activities of 1, n-(G)2-βCDs on human erythrocytes in isotonic solution were lower than those of G-βCD and βCD, and became weaker in the order of 1, 4->1, 2->1, 3-isomers. The complex-forming abilities of 1, n-(G)2-βCDs for digitoxin, digoxin, fluorometholone, flurbiprofen, hydrocortisone acetate, and norfloxacin were about the same as those of βCD and G-βCD, whereas reserpine was more difficult to include within 1, n-(G)2-βCDs than βCD and G-βCD. Nevertheless, the solubilities of those guest compounds were much more enhanced by 1, n-(G)2-βCDs and G-βCD than by βCD.
