Synthesis of porphyrin-carbohydrate conjugates using "click" chemistry and their preliminary evaluation in human HEp2 cells

Using a Cu(I)-catalyzed carbohydrate azide-alkynylphenylporphyrin cycloaddition (the so-called "click" chemistry), we have synthesized in high yields, a series of four new porphyrin-carbohydrate conjugates containing either one or four galactose or lactose moieties linked via triazole units to a meso-phenyl group of a TPP or tetrabenzoporphyrin (TBP) macrocycle. The time-dependent uptake and subcellular distribution of this series of porphyrin-carbohydrate conjugates were evaluated in human carcinoma HEp2 cells. While the three TPP conjugates accumulated to a similar extent within cells and localized mainly in the ER and endosomes, the TBP-galactose conju gate was the one most efficiently taken up by the HEp2 cells, accumulating approximately 5 times more than the TPP conjugates, and localized preferentially within the cell lysosomes.