Prevention by Ginkgo biloba extract (EGb 761) and trolox C of the decrease in synaptosomal dopamine or serotonin uptake following incubation

Biochem Pharmacol. 1992 Dec 15;44(12):2395-401. doi: 10.1016/0006-2952(92)90685-c.


Prolonged incubation of synaptosomes in Krebs-Ringer oxygenated medium in the presence of ascorbic acid (10(-4) M) led, after 20 min, to a decrease in [3H]dopamine (DA) (synaptosomes prepared from the striatum) and [3H]serotonin (5HT) (synaptosomes prepared from the cortex) uptake. The decrease was progressive and uptake was virtually abolished after a 60 min incubation period. A concentration-dependent (from 5 x 10(-6) M) role of ascorbic acid in the decrease of [3H]DA or [3H]5HT uptake was demonstrated. This decrease was potentiated by Fe2+ ions and prevented by the ferrous chelating agent desferrioxamine. Thus, the progressive decrease in synaptosomal uptake of either [3H]DA or [3H]5HT could depend on the generation of free radicals by the association of ascorbic acid with Fe2+ ions. The decrease in synaptosomal uptake was prevented, in a concentration-dependent manner, by the Ginkgo biloba extract EGb 761 (4-16 micrograms/mL) and the vitamin E analog trolox C (10(-4) M). The terpenic fraction of EGb 761, Bn 52063 (up to 0.5 microgram/mL), did not prevent the reduction of [3H]amine uptake. In contrast, the flavonoidic fraction, Cp 202, was effective (from 1 microgram/mL) and its efficacy was shared by the flavonoid quercetin (from 0.1 microgram/mL). The prolongation of the ability of synaptosomes to take up [3H]amine elicited by EGb 761, in particular its flavonoidic fraction, as well as by trolox C could be due to their free radical scavenger properties.

MeSH terms

  • Animals
  • Ascorbic Acid / pharmacology
  • Chromans / pharmacology*
  • Corpus Striatum / drug effects
  • Deferoxamine / pharmacology
  • Dopamine / metabolism*
  • Drug Interactions
  • Ginkgo biloba
  • In Vitro Techniques
  • Male
  • Mice
  • Plant Extracts / pharmacology*
  • Quercetin / pharmacology
  • Serotonin / metabolism*
  • Synaptosomes / drug effects*
  • Synaptosomes / metabolism
  • Tritium


  • Chromans
  • Plant Extracts
  • Tritium
  • Ginkgo biloba extract
  • Serotonin
  • Quercetin
  • Deferoxamine
  • Ascorbic Acid
  • 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid
  • Dopamine