Some Properties and the Inclusion Behavior of Branched Cyclodextrins

Maltosyl (G2)- and maltotriosyl (G3)-cyclodextrins (CDs), synthesized from maltose or maltotriose and α-, β- or γ-CD with Pseudomonas isoamylase or Klebsiella aerogenes pullulanase were purified by high-performance liquid chromatography, and their solubilities in water and in various concentrations of methanol in water, specific rotations, and hemolytic activities were studied. G2-and G3-CDs, as well as glucosyl (G1)-CDs, were much more soluble than each parent CD in water and methanol aqueous solutions. The hemolytic activities of the branched CDs decreased with increasing side chain length; CD>G1-CD>G2-CD>G3-CD. The inclusion behavior of the branched CDs with slightly soluble or insoluble drugs in aqueous solution and in the solid state was examined by the solubility method and the differential scanning calorimetry. The complexation abilities of G1-, G2-, G3-CD and their parent CD in a series appeared to be almost the same and the stabilities of complexes in water practically unaffected by the length of the side chain. However, the enhancement of solubility of poorly water-soluble drugs by branched CDs was much more marked than that by the parent CD.