Antioxidant activities of curcumin and ascorbyl dipalmitate nanoparticles and their activities after incorporation into cellulose-based packaging films

Curcumin (Ccm) and ascorbyl dipalmitate (ADP) nanoparticles (NPs) with average sizes of ～50 and ～80 nm, respectively, were successfully produced by rapid expansion of subcritical solutions into liquid solvents (RESOLV). Pluronic F127 was employed as a stabilizer for both Ccm- and ADP-NPs in an aqueous receiving solution. Antioxidant activities of the Ccm-NPs and ADP-NPs were subsequently investigated using four assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ABTS radical cation decolorization, β-carotene bleaching, and ferric reducing antioxidant power. Ccm-NPs and ADP-NPs showed higher antioxidant activities than those of Ccm and ADP. Ccm-NPs yielded higher antioxidant activities than those of Ccm in ethanol and water (Ccm-EtOH and Ccm-H(2)O), respectively. ADP-NPs yielded lower antioxidant activities than that of ADP in ethanol (ADP-EtOH) but higher activities than that of ADP in water (ADP-H(2)O). Moreover, incorporation of Ccm-NPs and ADP-NPs into cellulose-based films indicated that Ccm-NPs and ADP-NPs significantly enhanced the antioxidant activities of Ccm and ADP (p < 0.05). Our results show that the environmentally benign supercritical CO(2) technique should be generally applicable to NP fabrication of other important bioactive ingredients, especially in liquid form. In addition, we suggest that Ccm-NPs and ADP-NPs can be used to reduce the dosage of Ccm and ADP and improve their bioavailability, and thus merit further investigation for antioxidant packaging film and coating applications.