Preparation and characterization of dextran-zein-curcumin nanoconjugate for enhancement of curcumin bioactivity

Curcumin is one of the most important polyphenolic nutrients in pharmaceutical industries. Unfortunately, its poor solubility and bioavailability have hampered its clinical application. To improve curcumin solubility and bioavailability, a natural nanocarrier made from protein-polysaccharide conjugate has been developed. Following antisolvent precipitation method, zein (Z) nanoparticles coated with dextran sulphate (DS) have been fabricated as curcumin (C) nanocarrier (DSZCNPs). The physicochemical properties of the nanoconjugate were measured using different techniques. Morphologically, DSZCNPs appeared spherical and monodispersed in scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Curcumin encapsulation efficiency was ≈ 96%. DSZCNPs size was 180 nm and the polydispersity index value (PDI) 0.28. Zeta potential for DSZCNPs was -28.5 mV. DSZCNPs showed stability either for shelf storage (100 days) or at different pHs. Furthermore, DSZCNPs protected zein nanoparticles degradation in gastric environment and achieved controlled curcumin release in intestinal environment. DSZCNPs greatly enhanced the antioxidant activity of curcumin as demonstrated by DPPH assay. DSZCNPs had significant results in the reduction of colony forming unit (CFU%) against the tested microbes when compared with free curcumin. Also, the anticancer activity of DSZCNPs and free curcumin against hepatocellular carcinoma cells (HepG2) were assessed by MTT assay. IC₅₀ for DSZCNPs was 13 µg/ml compared to 50 µg/ml for free curcumin indicating the therapeutic impact of DSZCNPs over free curcumin.Based on the above results, the developed zein-dextran nanocomplex exhibited high stability and improved the efficacy and bioactivity of curcumin suggesting its potential utility as nanovehicle for the hydrophobic drug curcumin.