Design and synthesis of an anthranyl bridged optically active dinuclear iron(II)-ligand and evaluation of DNA-cleaving activity

Structural Characterization of Zinc(II)/Cobalt(II) Complexes of Chiral N-(Anthracen-9-yl)methyl-N,N-bis(2-picolyl)amine and Evaluation of DNA Photocleavage Activity

We designed and synthesized a chiral ligand N-(anthracen-9-ylmethyl)-1-(pyridin-2-yl)-N-(pyridin-2-ylmethyl)ethanamine (APPE) DNA photocleavage agent to investigate the effects of chirality of bis(2-picolyl)amine on the DNA photocleavage activity of metal complexes. The structures of Zn^II and Co^II complexes in APPE were analyzed via X-ray crystallography and fluorometric titration. APPE formed metal complexes with a 1 : 1 stoichiometry in both the crystalline and solution states. Fluorometric titration was used to show that the Zn^II and Co^II association constants of these complexes (log K_as) were 4.95 and 5.39, respectively. The synthesized complexes were found to cleave pUC19 plasmid DNA when irradiated at 370 nm. The DNA photocleavage activity of the Zn^II complex was higher than that of the Co^II complex. The absolute configuration of the methyl-attached carbon did not affect DNA cleavage activity and, unfortunately, an achiral APPE derivative without the methyl group (ABPM) was found to perform DNA photocleavage more effectively than APPE. One reason for this may be that the methyl group suppressed the structural flexibility of the photosensitizer. These results will be useful for the design of new photoreactive reagents.

DNA-cleavage activity of the iron(II) complex with optically active ligands, meta- and para-xylyl-linked N',N'-dipyridylmethyl-cyclohexane-1,2-diamine

DNA-cleavage agents such as bleomycin have potential anticancer applications. The development of a DNA-cleavage reagent that recognizes specific sequences allows the development of cancer therapy with reduced side effects. In this study, to develop novel compounds with specific DNA-cleavage activities, we synthesized optically active binuclear ligands, (1R,1'R,2R,2'R)-N¹,N^1'-(meta/para-phenylenebis(methylene))bis(N²,N²-bis(pyridin-2-ylmethyl)cyclohexane-1,2-diamine) and their enantiomers. The DNA-cleavage activities of these compounds were investigated in the presence of Fe(II)SO₄ and sodium ascorbate. The obtained results indicated that the Fe(II) complexes of those compounds efficiently cleave DNA and that their cleavage was subtle sequence-selective. Therefore, we succeeded in developing compounds that can be used as small-molecule drugs for cancer chemotherapy.