Improved stability and anticancer activity of curcumin via pH-driven self-assembly with soy protein isolate

Curcumin exhibits promising anticancer properties, but its significant hydrophobic nature, instability, and low oral bioavailability pose challenges in utilizing it effectively in food and pharmaceutical fields. In this study the self-assembly of soy protein isolate (SPI) with curcumin (Cur) was driven by pH-driven method to realize the nanoencapsulation of curcumin by soy protein isolate. Characterization and stability analysis of soy protein isolate-curcumin nanoparticles (SPI-Cur) revealed that the SPI and Cur self-assembly altered the secondary structure of SPI, resulting in a significant reduction in the average particle size of SPI-Cur nanoparticles, and exhibited high aqueous dispersibility and stability. In addition, the self-assembly of SPI with Cur resulted in a significant reduction of the IC 50 value of curcumin from 29.33 μg/mL to 17.44 μg/mL in human hepatocellular carcinoma HepG2 cells treated for 24 h, which effectively improved the anticancer activity. The molecular mechanism underlying its potentiating effect is the ROS-induced mitochondria-mediated cascade of caspase apoptotic pathways that exacerbate SPI-Cur-induced cell death events. These findings provide a theoretical basis for utilizing curcumin delivery carriers based on soy protein isolate to exert anticancer effects and increase the possibility of plant protein-curcumin nanoparticles for medical and food healthcare applications.