Characterization of Curcumin/Cyclodextrin Polymer Inclusion Complex and Investigation on Its Antioxidant and Antiproliferative Activities

The aims of this study were to characterize the curcumin/cyclodextrin polymer inclusion complex using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and UV–vis spectroscopy, and to determine the antioxidant activity of this complex by methods of scavenging 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals assays and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals assays. The inhibitory effect of inclusion complex on A375 cells was also investigated by CCK-8 assay, Annexin-V/PI staining assay, and caspase activity assay. The results showed that the complex exhibited different physicochemical characteristics from that of free curcumin. Moreover, the inclusion complex exhibited novel antioxidant activity by scavenging the ABTS and DPPH free radicals and displayed higher antiproliferative activity on A375 cells. Further investigation revealed that inclusion complex could induce A375 cell apoptosis. These findings suggest that inclusion complex could be developed as a novel natural antioxidant with potential applications in cancer chemoprevention.