Assembly of perilla seed protein isolate-pectin nanocomplex to deliver curcumin: Properties, characterization, molecular interactions and antioxidant activity

In the present study, nanocomplexes composed of perilla seed protein isolate (PSPI) and pectin (PEC) were assembled for the delivery of curcumin (Cur) based on the pH-driven self-assembly method. The encapsulation efficiency of Cur was 87.77%, and the PSPI-Cur-PEC exhibited controlled release of Cur during the in vitro digestion. Moreover, the PSPI-Cur-PEC possessed efficient antioxidant activity and provided greater defense for Cur against thermal treatment and ultraviolet irradiation. Fourier transform infrared spectroscopy, fluorescence spectroscopy and X-ray diffraction results indicated that entrapped Cur was existed in the form of amorphous state in PSPI-PEC, and the process was driven by hydrophobic effects, hydrogen bonding and electrostatic interactions. Scanning electron microscopy images revealed substantial morphological changes of the nanocomplexes throughout the process, while transmission electron microscopy images observed the core-shell structure of PSPI-Cur-PEC nanocomplexes. Furthermore, PSPI-PEC exhibited excellent biocompatibility by the in vitro cytotoxicity assay on Caco-2 cells, and the intermolecular interactions and possible formation mechanism of PSPI-Cur-PEC were further determined by molecular docking. This work elucidated that PSPI-PEC nanocomplexes assembled by a green and energy-efficient pH-driven method was feasible to protect sensitive hydrophobic bioactive components and provided a possible utilization of perilla seed protein in delivery system for nutraceuticals.