Synthesis and in vitro Toxicity of <scp>d</scp>‐Glucose and <scp>d</scp>‐Fructose Conjugated Curcumin–Ruthenium Complexes

Abstract

A series of carbohydrate‐conjugated bis(demethoxy)curcumin (BDC) ligands were synthesized by using the Huisgen copper(I)‐catalyzed cycloaddition between azido‐functionalized d ‐glucose and d ‐fructose as well as propargyl‐modified BDC. The unprotected sugar ligands were treated with Ru(bpy) 2 Cl 2 to form curcumin‐conjugated Ru complexes of general formula Ru(bpy) 2 (L)Cl. The ligands as well as Ru complexes were analyzed by NMR, IR, UV/Vis, and fluorescence spectroscopy, mass spectrometry as well as by elemental analysis (EA). Incubation of L929, HepG2 and the breast cancer cell line MDA‐MB‐231 revealed lower cytotoxicity of all carbohydrate‐conjugated ligands compared with BDC. The Ru complexes exhibited higher cytotoxicity than the parent ligands, in particular against HepG2 cells, whereas the noncancerous L929 cell line remained unaffected. Unexpectedly, the d ‐fructose‐conjugated ligand and its corresponding Ru complex did not show any significant toxicity against MDA‐MB‐231 cells.