Gel filtration was used to partially purify the antioxidizing component of a centrifuged serum of raw cow milk, 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 38,000 by gel filtration. The antioxidizing effect decreased with irradiation, accompanied by a parallel decrease in the riboflavin content. The antioxidizing component of this serum fraction may be a protein-bound riboflavin.
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.
The antioxidant effect of beta-carotene was investigated in an emulsified linoleic acid model system with or without exposure to light. The effect of tocopherol on the antioxidant action of beta-carotene was also investigated. The antioxidant effect of beta-carotene was significant, and synergistically increased by the addition of rac alpha-tocopherol, in the dark but not in the light. It was#10; confirmed that superoxide anions (O(2)(-)) and hydrogen peroxide (H(2)O(2)) were formed during the light exposure, and that their formation could be significantly inhibited by the addition of tryptophan or mannitol, scavenger of hydroxyl radicals. These results strongly suggest direct participation of hydroxyl radicals, formed via the Haber-Weiss reaction, in the emulsified linoleic acid model system, with beta-carotene inhibition in the dark but an increase in the light. Regarding the mechanism of the antioxidant effect of beta-carotene, when beta-carotene is oxidized, the hydroperoxide in the acts as an electron acceptor and the hydroperoxide itself then decomposes.
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