Synthesis of acetyl ferulic 7‐hydroxyisoflavone ester and evaluating its antioxidant activity on improving fish oil thermal stability

Abstract

SummaryAcetyl ferulic 7‐hydroxyisoflavone ester (AHE) was synthesized and its antioxidant capacity in vitro was evaluated by free radical scavenging assay and thermo‐oxidative stability analysis of fish oil in this study. The formation of primary and secondary oxidation products can be effectively inhibited by AHE, tert‐butylhydroxyquinone (TBHQ), ferulic acid and 7‐hydroxyisoflavone. The intensity of UV‐Vis absorption spectra increased significantly, whereas the intensity of fluorescence spectra decreased obviously with the deepening of oxidation degree of fish oil. AHE significantly alleviated the degradation of unsaturated fatty acids in fish oil. The results demonstrated that AHE was more effective than TBHQ, ferulic acid and 7‐hydroxyisoflavone in retarding the oxidative degradation of fish oil during high temperature storage (80 °C). Moreover, the formation of oxidation products in fish oil followed a first‐order kinetic model, and AHE effectively reduced reaction rate constant and delayed secondary lipid oxidation process. As a result, AHE is an effective antioxidant that can stabilise fish oil.