Synthesis and Biological Evaluation of Bolaamphiphilic Sophorolipids

Abstract

New synthetic pathways are proposed for the synthesis of a new set of bolaamphiphilic derivatives starting from microbiologically produced sophorolipids. A total set of 43 new derivatives was synthesized via reductive amination of a previously synthesized sophorolipid aldehyde with diamines and primary amines. The new derivatives were evaluated for their antimicrobial activity against Gram-negative and Gram-positive bacteria. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined for the active compounds. Transfection efficiencies were also evaluated for some of the deprotected derivatives via the assessment of their capacity to transfect three different eukaryotic cell lines in vitro. Finally, the self-assembly properties were evaluated for the deprotected derivatives. Antimicrobial activities were mostly observed for the peracetylated mono- or dicationic bolaamphiphiles, and only the deprotected monocationic bolaamphiphile with an octadecyl chain on the nitrogen atom was eligible for the evaluation of its transfection properties. Evaluation of the self-assembly properties indicated that the presence of an octadecyl chain was necessary for micelle formation. Both micelle formation and the net charge of the compounds seem to have an influence on the antimicrobial activity and transfection efficiency. These results are promising for use of bolaamphiphilic sophorolipids in medical and self-assembly applications.