Total synthesis of a novel host-[3]rotaxane as intracellular transport agent

ORGN 449

Xiaofeng Bao, xbao76@yahoo.com and David B Smithrud. Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221
A novel host-[3]rotaxane (Cy3R) and host-[2] Rotaxane (Cy2R) were designed and synthesized to improve the affinity, selectivity, and delivery of guests into the cells. The binding properties of the Cy3R with a series of amino acids, peptides, fluoresceinated guests were studied and compared to Cy2R. The second wheel of Cy3R can form additional salt-bridges, cation-g interactions with appropriately functionalized guests. Flow cytometry experiments demonstrated that a high percentage of the cells, in the presence of Cy3R (10 ėM) and a Fl-peptide (10 ėM), contained Fl-AVWAL (76%) and a moderate level of cells contained Fl-QEAVD (26%). The level of delivery is concentration dependent and largely temperature and ATP independent, suggesting that the Cy3R·peptide complexes pass through the cellular membrane without requiring active cell-mediated processes. Novel Cy2R, on the other hand, does not deliver materials into cells at the same or higher concentrations of components that were used for Cy3R and other Cy2R.