Effects of physicochemical factors and <i>in vitro</i> gastrointestinal digestion on antioxidant activity of R‐phycoerythrin from red algae <i>Bangia fusco‐purpurea</i>

Abstract

Summary R ‐phycoerythrin ( R ‐ PE ) was purified from the red algae B angia fusco‐purpurea after 35–50% ammonium sulphate fractionation followed by ion‐exchange column chromatography on DEAE‐Sepharose, resulting in a purity (A 565 /A 280 ) ratio of 5.1. The circular dichroism spectroscopy results suggested that the structure of R‐PE is predominately helical. The antioxidant activity of R‐PE was studied and revealed changes in conformation and antioxidant activity at different temperatures and pH values. After in vitro ‐simulated gastrointestinal (GI) digestion of R‐PE, the scavenging activity of ABTS radical (EC 50 , 769.9 μg mL −1 ), DPPH radical (EC 50 , 421.9 μg mL −1 ), hydroxyl radical (EC 50 , 32.4 μg mL −1 ) and reducing power (A 700 = 0.5, 625.8 μg mL −1 ) were measured. Gel filtration chromatography analysis showed that the molecular weight distribution of the final GI digest that still contained high antioxidant activity was &lt;3 kD a. Our present results indicate that digestion‐resistant antioxidant peptides of R‐PE may be obtained by in vitro GI proteinases degradation.