Synthesis of Selenium‐Enriched Cassava Starch with Immediate Antioxidant Activity and Its Antioxidant Catalytic Mechanism

Abstract

AbstractThe development of selenium‐enriched food is one of the most effective ways to acheive selenium supplementation. However, the selenium content in selenium‐enriched food is unstable, and the selenium in the food needs to be incorporated into glutathione peroxidase (GPx) by the human body before it can exert its antioxidant activity. Herein, a selenium‐enriched cassava starch (Se‐ca‐starch80) with immediate antioxidant activity is synthesized by the successive esterification and selenation of cassava starch. The characterizations such as proton nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscope (SEM), and X‐ray diffraction (XRD) indicate that the reactions mainly occur on the surface of starch and do not destroy the starch skeleton significantly. Such Se‐ca‐starch80 with selenium content of 9.44 µg g–1 reveals a remarkable antioxidant activity (the initial rate of the catalytic reaction, v0 > 10 µmol L–1 min–1) due to the cooperation of catalytic centers, substrate recognition sites, and hydrophobic microenvironments. Similar to the natural GPx, the Se‐ca‐starch80 is non‐cytotoxic and shows a saturation kinetic catalytic behavior. This work may open the door to design modified starch for functional foods and antioxidant drugs.