Novel Guanidine-Containing Molecular Transporters Based on Lactose Scaffolds: Lipophilicity Effect on the Intracellular Organellar Selectivity

We have synthesized two lactose‐based molecular transporters, each containing seven guanidine residues attached to the lactose scaffold through ω‐aminocarboxylate linker chains of two different lengths, and have examined their cellular uptakes and intracellular and organellar localizations in HeLa cells, as well as their tissue distributions in mice. Both molecular transporters showed higher cellular uptake efficiencies than Arg8, and wide tissue distributions including the brain. Mitochondrial localization is of special interest because of its potential relevance to “mitochondrial diseases”. Interestingly, it has been found that the intracellular localization sites of the G7 molecular transporters—namely either mitochondria or lysosomes and endocytic vesicles—are largely determined by the linker chain lengths, or their associated lipophilicities. Drug‐delivery vehicles: Two lactose‐based G7 molecular transporters with different linker chain lengths were synthesized (see scheme, FITC=fluorescein isothiocyanate). They showed good cellular uptake and preferential localization either in mitochondria or in lysosomes and endocytic vesicles, depending on their chain lengths.