No abstract

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.

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.

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.

No abstract

Wurzenberger, M.; Gorsch, W. Enzymic oxidation of linolenic acid to l,Z-5-octadien-3-ol, Z-2-Z-5-octadien-l-ol and 10-oxo-E-8decenoic acid by a protein fraction from mushroom. (Psalliota bis pora). Lipids 1986, 21, 261-266.

An assay of lipoxygenase activity was developed that depends on measurements of the time needed for the bleaching of methylene blue to begin. This time was inversely related to the level of lipoxygenase activity (y = 114.5132 - 0.0132x; r= -0.99); it was not affected by the concentration of methylene blue, linoleic acid, or hydroperoxide. Lipoxygenase activity can be calculated from the time needed for the bleaching of methylene blue to begin.

Oxidative stability of original silky fowl's eggs was investigated. The silky fowl's whole eggs indicated significant oxidative stability compared to hen's eggs in storage for 14 days. The hen eggs showed an increased amount of hydroperoxides on 6 days of storage at room temperature. In contrast, the silky fowl eggs showed restricted generation of hydroperoxides until 8 days and then a gradual increase. Though pigment extracted with chloroform/methanol (2:1) solvent from hen's whole egg turned brown for 14 days, the pigment extracted from silky fowl's whole egg slowly turned brown. Unsaturated fatty acids in silky fowl eggs were 62.5% among total fatty acids, while the unsaturated fatty acids of hen's eggs were 53.9%. It is speculated that the silky fowl eggs show oxidative stability owing to the higher ratio of unsaturated fatty acids in the silky fowl eggs compared with that of hen eggs.