Comparative interaction study of soy protein isolate and three flavonoids (Chrysin, Apigenin and Luteolin) and their potential as natural preservatives

In this work, the potential of soy protein isolate (SPI)-luteolin (Lut)/apigenin (Ap)/chrysin (Chr) complexes as natural preservatives for food and cosmetics was evaluated by comparing their interactional and functional properties with structure-activity relationship. The results of spectrometry and molecular docking indicated that the B-ring hydroxylation of flavonoids affected their binding constants with SPI, which were determined as Lut (1.45 x 106 L/mol) > Ap (2.04 x 105 L/mol) > Chr (3.81 x 104 L/mol) at 298.15 K. It demonstrated that the hydrogen bonding force played an important role in binding flavonoids to SPI. Moreover, the anti-oxidation ability, antimicrobial effect, and foaming properties were positively correlated with increase in number of hy-droxyl groups on the B-ring, but the amount and type of the preservative should be adjusted aimed at the nutrition components. This study provides a theoretical basis for the use of flavonoids and SPI-flavonoid com-plexes as natural preservatives for food and cosmetics.