In vitro antioxidant actions of sulfur-containing amino acids

Sulfur-containing amino acids such as methionine, cysteine, and taurine are present in animals and plants with biological functions. The aim of this study was to determine the antioxidant activities of representative sulfur-containing amino acids using various in vitro antioxidant assays including radical scavenger activities against DPPH, ABTS, and superoxide radicals, ferric reducing antioxidant power, hydrogen peroxide scavenging activity, and metal chelating activities. Of the three sulfur-containing amino acids, cysteine had the highest DPPH, ABTS, and O2− radical and H2O2 scavenging activities, FRAP, and metal chelating activities except for Fe2+ chelating. However, methionine and taurine failed to show DPPH or ABTS radical scavenging activity. Based on the results of the present study, sulfur-containing amino acids with excellent antioxidant abilities might be useful for the food processing industry as antioxidant additives to extend shelf-life of food or food products and offer beneficial pharmacological effect against cell damage caused by oxidative stress.