Evaluation of the inhibitory effects of quercetin-related flavonoids and tea catechins on the monoamine oxidase-A reaction in mouse brain mitochondria

J Agric Food Chem. 2012 Oct 17;60(41):10270-7. doi: 10.1021/jf303055b. Epub 2012 Oct 8.


Quercetin, a typical dietary flavonoid, is thought to exert antidepressant effects by inhibiting the monoamine oxidase-A (MAO-A) reaction, which is responsible for regulation of the metabolism of the neurotransmitter 5-hydroxytryptamine (5-HT) in the brain. This study compared the MAO-A inhibitory activity of quercetin with those of O-methylated quercetin (isorhamnetin, tamarixetin), luteolin, and green tea catechins ((-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-epigallocatechin gallate) by measuring the formation of the oxidative deamination product of 5-HT, 5-hydroxyindole aldehyde (5-HIAL), in mouse brain mitochondria. Quercetin was inferior to luteolin in the inhibition of MAO-A activity, whereas isorhamnetin, tamarixetin, and tea catechins scarcely exerted inhibitory activity. Quercetin did not affect MAO-A activity in mouse intestinal mitochondria, indicating that it does not evoke side effects on the metabolism of dietary monoamines in the gut. These data suggest that quercetin is a weak (but safe) MAO-A inhibitor in the modulation of 5-HT levels in the brain.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / ultrastructure*
  • Catechin / pharmacology*
  • Flavonoids / pharmacology
  • Humans
  • Intestine, Small / ultrastructure
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mitochondria / enzymology*
  • Monoamine Oxidase / metabolism*
  • Monoamine Oxidase Inhibitors / pharmacology*
  • Quercetin / pharmacology*
  • Recombinant Proteins / antagonists & inhibitors
  • Tea / chemistry


  • Flavonoids
  • Monoamine Oxidase Inhibitors
  • Recombinant Proteins
  • Tea
  • Catechin
  • Quercetin
  • Monoamine Oxidase