Cellular uptake of aminoglycosides, guanidinoglycosides, and poly-arginine

Aminoglycosides (including neomycin B and tobramycin) exhibit poor uptake by eukaryotic cell lines. When the amines of these natural products are converted into guanidine groups, their cellular uptake is dramatically enhanced. We have synthesized BODIPY-containing aminoglycosides and guanidinoglycosides to evaluate their cellular uptake properties. Fluorescence activated cell sorting (FACS) and fluorescence microscopy are used to compare the membrane translocation and the cellular localization of these compounds. Upon guanidinylation, the cellular uptake efficiencies of tobramycin and neomycin B are enhanced by 10-fold and 20-fold, respectively. Guanidino-neomycin B exhibits a highly efficient uptake, superior to a fluorescent poly-arginine peptide. Interestingly, the cellular uptake of this common transduction peptide is inhibited by guanidine-neomycin B, suggesting a similar uptake mechanism for both the arginine-rich peptides and the guanidinoglycosides.