Synthesis and characterization of copper(II) complexes of 4-alkyl/aryl-1,2-naphthoquinones thiosemicarbazones derivatives as potent DNA cleaving agents

Copper (II) complexes of some alkyl/aryl-1,2 naphthoquinones thiosemicarbazone have been prepared and characterized. The crystal structure determined for one of the free ligands viz. 4-Pyrrolidine-1-yl-[1, 2] naphthaquinone thiosemicarbazone (5) indicates it to crystallize in the “E’ conformation which is supported by the NMR data. The ligands and copper complexes were evaluated for their DNA cleaving activities in case of circular double stranded plasmid DNA pBR322 under aerobic conditions. Amongst the ligands, compound 8 shows almost quantitative conversion to the linearized DNA in presence of H2O2 oxidant. All copper conjugates show more pronounced interaction with DNA while compounds 3 and 7 are able to yield linearized DNA in presence of the oxidant.

Graphical abstract1,2 naphthoquinone thiosemicarbazones bearing alkyl/aryl substituents at C-4 position are reported; upon metal conjugation structural changes occur consistent with ‘Z’ configuration for the ligands; metal conjugates are capable of facile quantitative conversion of circular double stranded plasmid DNA pBR322 to the linearized form in the presence of oxidant.Figure optionsDownload full-size imageDownload as PowerPoint slide