Harmalacidine, also known as 7-methoxy-2,3,4,9-tetrahydro-1H-β-carbolin-1-one or as 1-keto-7-methoxytryptoline, is a harmala alkaloid and β-carboline found in Peganum harmala (Syrian rue) and Banisteriopsis caapi. It is a reversible inhibitor of monoamine oxidase A (RIMA), with similar potency as harmine ( = 457nM and 506nM, respectively). The alkaloid was isolated from Banisteriopsis caapi in 1976 and from Peganum harmala in 1988. The amounts of harmalacidine in Peganum harmala seeds vary widely, ranging from milligram to gram quantities.
See also Substituted β-carboline Harmala alkaloid
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