Figure 1

Schematic representations of curcumin, metallo-curcumin, and metallo-curcumin binding to DNA. (a) The molecular structure of curcumin, with functional groups containing two methoxy-phenolic moieties connected by a seven-carbon linker. (b) Structure of metallo-curcumin, showing the deprotonation of the hydroxyl group in the keto-enol tautomeric group which forms a bidentate di-ketone group where the ion binds. M²⁺ represents one of the divalent metal ions, namely Cu²⁺, Ni²⁺, and Zn²⁺. (c) Schematic representation of metallo-curcumin binding to the minor groove and the phosphate backbone of the DNA duplex. The orange dumbbell-shaped structures represent curcumin molecules and the red spheres in the curcumins represent M²⁺.