Inclusion complexation of a family of Cyclosophoraoses with indomethacin

Abstract

Cyclosophoraoses are a class of unbranched cyclic-(1→2)-β-D-glucans found in the Rhizobium species. Their unique cyclic structures and high solubility make them potent for inclusion complexation as a host for an insoluble guest molecule. A family of neutral cyclosophoraoses (DP 17-27) isolated from Rhizobium meliloti 2011 was used as a host for inclusion complexation with an insoluble guest drug, indomethacin. A high performance liquid chromatographic analysis indicated that the inclusion complexation of cyclosophoraoses greatly enhanced the solubility of indomethacin compared with β-cyclodextrin. The estimated value of the association constant of the complex in water for β-cyclodextrin and cyclosophoraoses was 523 M -1 and 17,570 M -1 , respectively. NMR spectroscopy showed that the inclusion complex was characterized by the interaction of the indole ring moiety of indomethacin with the cavity of cyclosophoraoses.