New antioxidant protein in seaweed (Porphyra yezoensis Ueda).

Gel filtration was used to partially purify the antioxidizing component of a crude extracted solution of seaweed (Porphyra yezoensis Ueda), and its properties were studied. The antioxidizing effect did not decrease after dialysis or heating. The finding of no change after dialysis suggested that the compound was of high molecular weight, estimated at 52.2 kDa by gel filtration chromatography. The antioxidizing effect decreased with irradiation, accompanied by a parallel decrease in the riboflavin content. The antioxidizing component of this 52.2-kDa fraction may be a protein-bound riboflavin. The structural of protein-bound riboflavin in seaweed was analyzed with hydrogen-1 nuclear magnetic resonance, and the results suggested that the 52.2-kDa fraction was riboflavin. We found an antioxidizing component in seaweed (P. yezoensis Ueda). This antioxidizing component is estimated at 52.2 kDa and may be a protein-bound riboflavin.