Synthesis and antibacterial properties of carbohydrate-templated lysine surfactants.

The synthesis of four dicationic glucose-templated D-lysine-derived surfactants and their two unmodified D-lysine-analogs is described. Replacement of D-lysine by D-glucose-templated-D-lysine provides a general tool to introduce chemical diversity into the side chain of lysine. The presence of the polyfunctional D-gluco-configured polyol scaffold provides rich opportunities to study structure-activity relationships in lysine-lipid conjugates. All cationic lipids were tested for inhibition of bacterial growth using a panel of clinically relevant Gram-positive and Gram-negative strains. Our results show that substitution of D-lysine by D-glucose-templated D-lysine surfactants retains, but does not improve, the antibacterial activity. Similarly, conversion of the D-gluco-based polyol scaffold into a hydrophobically enhanced tri-O-phenylcarbamate scaffold does not further enhance the antibacterial activity of the cationic lipid. However, improvements in the antibacterial activity were observed by guanidinylation of the two lysine-based amino groups.