Inhibition of ascorbate autoxidation by the dialyzed soluble fraction of mammalian nervous tissues.
The effect of the soluble fraction of mammalian nervous tissue was tested on the autoxidation of ascorbic acid in a physiological salt solution. Ascorbic acid was determined spectrophotometrically at 265 nm. Tissues tested were from humans and guinea pigs (ascorbate-dependent species); cats, rats and mice (ascorbate-synthesizing species). Samples representing the major anatomical areas of the CNS and adrenal glands were homogenized in phosphate buffer (10% w/v), centrifuged at 100,000 g for 60 min and the supernatant was dialyzed in 25,000 mol.wt. cut-off tubing. The preparations produced basically uniform inhibitory activity: extracts at 10(4)-fold dilution reduced the rate of autoxidation by approximately 90%. The effect was marginal at 5 X 10(4)-fold dilution. Serum samples displayed similar activity. The results indicate that mammalian nervous tissue and serum contain a substance of relatively large molecular weight that stabilizes reduced ascorbic acid against oxidative breakdown.
D000368:Aged; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002415:Cats; D002540:Cerebral Cortex / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D006168:Guinea Pigs; D006801:Humans; D007700:Kinetics; D051379:Mice; D009928:Organ Specificity; D010084:Oxidation-Reduction; D051381:Rats; D013045:Species Specificity; D013116:Spinal Cord / Q000378:metabolism*
D001205:Ascorbic Acid