Nanocomplexation between curcumin and proteins by charge-switch method for improved physicochemical and biological properties of curcumin

Curcumin, a natural polyphenol, has various biological functions including antioxidant and antimicrobial properties, but the functions are limited by its low aqueous solubility. To address this, two proteins, bovine serum albumin (BSA) and gelatin were used to form curcumin-protein nanocomplexes using a charge-switch method, by mixing oppositely charged curcumin and proteins. Complexation with BSA and gelatin increased the curcumin solubility to 391.77 (±15.70) μg mL^-1 and 143.64 (±2.29) μg mL^-1 respectively, and the loading amount (LA) of curcumin to 21.36% and 15.57%, respectively. Moreover, enhanced bioaccessibility, and antioxidant and antimicrobial properties were observed after complexation. After complexation, the minimum inhibitory concentration (MIC) of curcumin decreased by eightfold against <i>Vibrio parahaemolyticus</i>, more than eightfold against <i>Vibrio harveyi</i>, and twofold against <i>Bacillus cereus</i> and <i>Streptococcus iniae</i>, which are food and aquaculture related pathogens. The curcumin-protein nanocomplexes presented in this work could serve as non-antibiotic additives for preventing and managing microbial diseases in agri-food applications.