Enhanced Antioxidant Activity and Sustained-Release Property of Curcumin Encapsulated in Glycated Soy β-Conglycinin Nanoparticles

Soy β-conglycinin (7S)-dextran conjugates prepared under dry-heating conditions were used to encapsulate curcumin, and the antioxidant activity and sustained-release property of encapsulated curcumin were investigated. Results showed that the grafting degree and browning index of 7S-dextran conjugates increased with increasing reaction time (0, 24, 48 and 72 h), reaching the highest values of 15.02% and 0.24 at 72 h, respectively. 7S-curcumin and 7S-dextran-curcumin nanocomplexes were fabricated by pH-shifting method. The highest curcumin loading of 129.61 μg/mg was observed in 7S-dextran conjugate obtained at 72 h of reaction time (7S-dextran-72 h), which was significantly higher than that in 7S (69.06 μg/mg). Fluorescence spectroscopy indicated that curcumin combined with 7S or 7S-dextran-72 h mainly through hydrophobic interactions. It was observed by transmission electron microscopy (TEM) that 7S-curcumin and 7S-dextran-72 h-curcumin nanocomplexes were spherical. The antioxidant activity of 7S-dextran-72 h-curcumin, which had stable sustained-release property, was approximately 2.36 times higher than that of free curcumin at 100 μg/mL. The bioavailability of curcumin encapsulated in 7S-dextran-72 h was 66.83%, while the bioavailability of curcumin encapsulated in 7S and free curcumin were 48.93% and 33.06%, respectively. 7S-dextran-72 h could be used as an outstanding nanocarrier for curcumin to enhance its antioxidant activity and sustained-release property.