Preparation and characterization of branched beta-cyclodextrins having alpha-L-fucopyranose and a study of their functions

Three positional isomers of 6 1 ,6 n -di-O-(α-L-fucopyranosyl)-β-cyclodextrin [6 1 ,6 n -di-O-(α-L-Fuc)-βCD, n=2-4] were chemically synthesized by using the corresponding authentic compounds, 6 1 ,6 n -di-O-(tert-butyldimethylsilyl)-βCD (n=2-4) as fucosyl acceptors and 2,3,4-tri-O-benzyl-L-fucopyranosyl trichloroacetimidate as a fucosyl donor. Their structures were analyzed by HPLC, MS and NMR spectroscopy. The hemolytic activities of the α-L-Fuc-βCDs were lower than that of βCD, while the water solubility of these branched βCDs was much higher than that of βCD. The molecular interaction between these compounds and the fucose-binding lectin, Aleuria aurantia lectin (AAL), was investigated by using an optical biosensor based on the surface plasmon resonance (SPR) technique. The order of binding affinity, as a function of the fucose-binding position, was 6 1 ,6 4 - > 6 1 ,6 3 - > 6 1 ,6 2 -di-O-(α-L-Fuc)-βCD > 6-O-(α-L-Fuc)-βCD.