Pectin–curcumin composite: synthesis, molecular modeling and cytotoxicity

Pectin–curcumin composite was synthesized in a reaction mediated by dicyclohexylcarbodiimide and dimethylaminopyridine. The formation of pectin–curcumin composite was confirmed by FTIR and NMR spectral analyses. The results of differential scanning calorimetry, X-ray diffraction and scanning electron microscopy studies established that the composite is amorphous in nature. The curcumin contents in the composite were found to be 384.39 μg/g of the composite. The critical aggregation concentration determined by fluorescence spectroscopy and dynamic light scattering technique was found to be in the range of 140–180 μg/mL. The results of in silico molecular mechanistic simulations of the interaction between pectin and curcumin revealed the stability of pectin–curcumin composite, which favored its formation. In vitro release study showed 93% (pH 1.2) and 46% (pH 7.4) of curcumin getting released in 48 h. Further, the release of curcumin from the composite followed first-order (pH 1.2) and zero-order (pH 7.4) kinetics, with anomalous release mechanism. Further, the results of cytotoxicity studies showed a significantly higher inhibition of KYSE-30 cell lines by composite over curcumin. Thus, coupling of curcumin to pectin improves its therapeutic delivery and efficacy.