Noradrenaline Metabolite a Powerful Antioxidant

The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 5 No. 5 • October 2002


Noradrenaline Metabolite a Powerful Antioxidant

We read years ago that vitamin C is the most important antioxidant in the brain and that after vitamin C is depleted, noradrenaline becomes the most important antioxidant. A new paper1 suggests a possible mechanism to explain the importance of noradrenaline in antioxidative systems. The oxidatively deaminated noradrenaline metabolite 3,4-dihydroxymandelic acid (DHMA) is found in different mammalian tissues, and in especially large amounts in the heart. Researchers performed a number of tests to determine the antioxidative and radical-scavenging ability of DHMA.

In one test (the 2,2-diphenyl-1-picrylhydrazyl assay), DHMA had a 4-fold higher radical-scavenging activity compared to ascorbic acid, alpha-tocopherol, and butylated hydroxytoluene (BHT). DHMA was shown to be a powerful superoxide radical scavenger with a 5-fold smaller IC50 value (the amount required to inhibit a reaction by 50%) compared to ascorbic acid. DHMA at 0.001% and 0.0005% levels protected human primary fibroblasts against hydrogen peroxide-induced oxidative stress.

The authors concluded that DHMA in a concentration below 0.001% is not cytotoxic, supports intracellular antioxidative status, and therefore may be important for the defense system of cells against oxidative stress. D&S Note: Noradrenaline is converted to DHMA by the enzyme MAO (monoamine oxidase). People taking an MAO inhibitor antidepressant may, therefore, be at greater risk for free radical damage.

  1. Ley et al. 3,4-Dihydroxymandelic acid, a noradrenalin metabolite with powerful antioxidative potential. J Agri Food Chem 50:5897-902 (2002).

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