Molecular interactions between dimethoxycurcumin and Pamam dendrimer carriers.

Dimethoxycurcumin, a lipophilic analog of curcumin found as a major pigment in the Indian species turmeric (Curcuma longa Linn.), is known to possess significant activity against various cancer cell lines, but its use as an anticancer drug is hindered by its poor water solubility. The conjugation of dimethoxycurcumin to water-soluble PAMAM dendrimers (generations 3.5 and 4) is demonstrated. The maximum drug-dendrimer incorporation efficiency is 4.3 and 5.0 molar for G3.5 and G4, respectively. The FTIR-ATR investigation of the neat compounds and the drug-dendrimer systems indicate that dimethoxycurcumin is in the enolic form, while its interaction with the integer generation dendrimer involves the major conformational change of the terminal ethylene amine groups.