4,5-Diazafluorene N-glycopyranosyl hydrazones as scaffolds for potential bioactive metallo-organic compounds: Synthesis, structural study and cytotoxic activity

A series of novel N¹-(4,5-diazafluoren-9-yliden)-N²-glycopyranosyl hydrazines was prepared in synthetically useful yields by treatment of 9H-4,5-diazafluoren-9-hydrazone with different unprotected monosaccharides. The reactions with the monosaccharides tested afforded stereoselectively, and exclusively, cyclic derivatives, whose structures correspond to N-β-glycopyranosyl hydrazones except for the d-arabinose derivative that agrees with the α-anomer. Several copper(II) complexes having a 2:1 ligand to metal mole ratio were also prepared. The metal complexes can bind DNA sequences and preferentially stabilize G-quadruplex DNA structures over dsDNA. The fucose, rhamnose and deoxyglucose copper(II) complexes exhibited a cytotoxic activity against cultured HeLa and PC3 tumor cells comparable to other metal complexes normally used for chemotherapeutic purposes, such as cisplatin.