Effects of phenolic acid analogs on the structure, iron oxidation/iron release, and stability of phytoferritin

Ferritin is a universal macromolecule protein that stores iron and regulates iron oxidative deposition and release. The physicochemical properties of ferritin can be affected by coexisting bioactive substances. This study investigated the effects of two phenolic acid analogs (caffeic acid and tanshinol) on the physicochemical properties of soybean ferritin. The results indicated that Fe(III) interacted with caffeic acid or tanshinol to form phenolic acid-Fe(III) complexes, and interacted with ferritin to form a ferritin-phenolic acid-Fe(III) complex with hydrogen bonds, which affected the ferritin structure of the complexes to a different extent due to their different structures. Caffeic acid and tanshinol facilitated iron oxidative deposition and release by promoting the Fe(II)-oxidation reaction and increasing Fe(III)-release from ferritin, while caffeic acid exhibited a more pronounced effect. In addition, caffeic acid protected ferritin from degradation by free radicals during the release of iron. Caffeic acid displayed a higher Fe(II) chelating ability and a higher hydroxyl radical (•OH) scavenging ability owing to the conjugated structure compared to tanshinol. These findings elucidated the mechanism for the interaction among ferritin, iron, and polyphenols, and provide a theoretical basis for applying ferritin in protein-ligand interactions and iron supplementation of food.