Interaction of a copper (II) complex containing an artificial sweetener (aspartame) with calf thymus DNA

• Copper is an essential trace element in plants and animals which binds to aspartame and makes stable complex.
• Aspartam rapidly picks up toxic metals and carries into the body.
• All the results showed that Cu(APM)2Cl2⋅2H2O complex was a DNA groove binder.

A copper (II) complex containing aspartame (APM) as ligand, Cu(APM)2Cl2⋅2H2O, was synthesized and characterized. In vitro binding interaction of this complex with native calf thymus DNA (CT-DNA) was studied at physiological pH. The interaction was studied using different methods: spectrophotometric, spectrofluorometric, competition experiment, circular dichroism (CD) and viscosimetric techniques. Hyperchromicity was observed in UV absorption band of Cu(APM)2Cl2⋅2H2O. A strong fluorescence quenching reaction of DNA to Cu(APM)2Cl2⋅2H2O was observed and the binding constants (Kf) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated to be +89.3 kJ mol−1 and +379.3 J mol−1 K−1 according to Van’t Hoff equation which indicated that reaction is predominantly entropically driven. Experimental results from spectroscopic methods were comparable and further supported by viscosity measurements. We suggest that Cu(APM)2Cl2⋅2H2O interacts with calf thymus DNA via a groove interaction mode with an intrinsic binding constant of 8 × 10+4 M−1. Binding of this copper complex to DNA was found to be stronger compared to aspartame which was studied recently.

A copper (II) complex containing aspartame (APM) as ligand, Cu(APM)2Cl2⋅2H2O, was synthesize and characterized. In vitro binding interaction of this complex with native calf thymus DNA (CT-DNA) was studied at physiological pH.Figure optionsDownload as PowerPoint slide