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