DNA-binding studies of two dioxomolybdenum(VI) complexes of salicylaldehyde benzoylhydrazone ligands

The reaction of [MoO2(acac)2] with salicylaldehyde benzoylhydrazone (H2L1) and with one of its derivatives (H2L2) resulted in the production of two neutral mononuclear dioxomolybdenum complexes; MoO2L1(MeOH) 1 and MoO2L2(MeOH) 2, respectively. (H2L1) was derived from the reaction of benzhydrazide and 2-hydroxybenzaldehyde (salicylaldehyde) and (H2L2) was derived from the reaction of benzhydrazide and 2-hyroxy-3-methoxybenzaldehyde. Interactions of the complexes were investigated with calf thymus DNA by UV–Vis, fluorescence and circular dichroism spectroscopies to determine their biological effects. Results evaluated the binding affinity of complexes 1 and 2 to CT-DNA by UV and presented binding constants (Kb) of (3.52 ± 0.1) × 103 M−1 and (4.49 ± 0.1) × 103 M−1, respectively. Evaluations of fluorescence approved the binding of the fluorescent complex 2, to DNA. Competitive studies with ethidium bromide (EB) showed that none of the complexes displaced the DNA–EB binding efficiency effectively while they changed the polarity of the environment by occupying the previous place of water molecules around the helix. CD spectral studies revealed that as a result of interaction with both complexes, calf thymus B-DNA turned into A-like structure.According to our results both complexes bind to DNA via a non-intercalative mode, presumably through groove binding.

Biological interactions of two dioxomolybdenum complexes with calf thymus DNA identified by UV-Vis, UV–Vis, fluorescence and circular dichroism spectroscopies and defined by their binding affinities. Their competitive studies with EB showed their effects on polarity leading to effective binding. The interaction caused changes of B-DNA structure into A-like structure. The interactions of both complexes were carried out via a non-intercalative mode, through groove binding.Figure optionsDownload as PowerPoint slideHighlights
► The interaction of two Mo(VI) complexes of salicylaldehyde benzoylhydrazone with DNA was examined.
► UV and fluorescence spectroscopies indicate that the complexes bind to DNA via a groove binding mode.
► CD studies reveal that as a result of interaction with complexes, B-DNA turns into A form.
► The Mo complexes may aggregate DNA molecules and can probably be considered as inhibitors in gene expression.