Evaluation of a ginkgo biloba extract (EGb 761) in functional tests for monoamine oxidase inhibition

A standardized extract of ginkgo biloba (EGb 761) was evaluated in function al tests for monoamine oxidase (MAO) inhibition in mice: 1-dihydroxyphenyla lanine (CAS 59-92-7,1-DOPA) potentiation, tryptamine (CAS 61-54-1) potentia tion, 5-hydroxytryptophan (CAS 4350-07-6,5-HTP) potentiation and phenylethy lamine (CAS 64-04-0) potentiation. The doses investigated (25, 50 and 100 m g/kg p.o once daily for 5 days) were those known to possess antistress prop erties in other animal models. In contrast to the reference substances inve stigated (nialamide (CAS 51-12-7), clorgyline (CAS 17780-75-5) and 1-depren yl (CAS 14611-52-01), EGb 761 did not exhibit any activity indicative of MA O inhibition. It was concluded that MAO inhibition was not the mechanism pr imarily responsible for EGb 761's antistress activity.