DNA binding properties and cell viabilities of metal complexes derived from (E)-2-hydroxy-N’-((thiophen-2-yl)methylene)benzohydrazone and (E)-N’-((thiophen-2-yl)methylene)isonicotinylhydrazone

Y.-C. Liu, J. Luo, S.-Y. Wang, Z.-X. Liang, X. Zhang, B.-D. Wang, Y.-Y. Li, R.-X. Lei, J.-Y. Wang, G.-P. Zhao, C.-X. Bai, H. Chen

College of Chemistry and Chemical Engineering, FLUOBON Pilot Base of Chemical Engineering, Longdong University, Qingyang, China. ychliu001@163.com

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• Molecular Biology

OBJECTIVE: This study aims to investigate the CT-DNA (Calf thymus DNA) binding properties and HeLa cell viabilities of metal complexes derived from (E)-2-hydroxy-N’-((thiophen-2-yl)methylene)benzohydrazone (H2L1) and (E)-N’-((thiophen-2-yl)methylene)isonicotinylhydrazone (HL2).

MATERIALS AND METHODS: A series of metal complexes derived from (E)-2-hydroxy-N’-((thiophen-2-yl)methylene)benzohydrazone (H2L1) and (E)-N’-((thiophen-2-yl)methylene)isonicotinylhydrazonewere (HL2) were synthesized, and their structures were characterized through FT-IR, ESI-MS, elemental analysis, molar conductivities and X-ray diffraction. DNA binding properties between CT-DNA and metal complexes were investigated by UV-Vis spectrophotometry and viscosity titration. The toxicological properties of compounds on HeLa cell were measured in vitro.

RESULTS: Ligand H2L1 or HL2 exhibits a tridentate and anion ligand and uses oxygen anion, nitrogen atom and sulfur atom to coordinate with metal ions. When coordinated with metal ions, the unit O=C–NH– of each ligand has been enolized and deprotonated into –O–C=N–. The suggested chemical formulas of metal complexes are: [Co(HL1)2], [Ni(HL1)2], [Cu(HL1)2], [Co(L2)2], [Cu(L2)2], [Zn(L2)2], [ScL2(NO3)2(H2O)2], [Pr(L2)2(NO3)] and [Dy(L2)2(NO3)]. Both ligands and their metal complexes can bind strongly to CT-DNA through hydrogen bond and intercalation with Kb of 104~105 L mol−1 compared to ethidium bromide [classical DNA intercalator, Kb(EB–DNA) = 3.068 × 104 L mol–1]; however, the groove pattern cannot be excluded. The coexistence of multiple binding modes may be a common form of drug binding to DNA. HeLa cell shows lower viabilities in the presence of [Ni(HL1)2] and [Cu(HL1)2] (*p < 0.05) compared to the other compounds, with the LC50 of 2.6 μmol L–1 and 2.2 μmol L–1, respectively.

CONCLUSIONS: These compounds, especially [Ni(HL1)2] and [Cu(HL1)2], will be promising for anti-tumor drugs, which should be further studied.

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