Peganum harmala L. is a multipurpose medicinal plant increasingly used
for psychoactive recreational purposes (Ayahuasca analog). Harmaline,
harmine, harmalol, harmol and tetrahydroharmine were identified and
quantified as the main beta-carboline alkaloids in P. harmala extracts.
Seeds and roots contained the highest levels of alkaloids with low
levels in stems and leaves, and absence in flowers. Harmine and
harmaline accumulated in dry seeds at 4.3% and 5.6% (w/w), respectively,
harmalol at 0.6%, and tetrahydroharmine at 0.1% (w/w). Roots contained
harmine and harmol with 2.0% and 1.4% (w/w), respectively.
beta carboline
Seed extracts were potent reversible and competitive inhibitors of
human monoamine oxidase (MAO-A) with an IC(50) of 27 microg/l whereas
root extracts strongly inhibited MAO-A with an IC(50) of 159 microg/l.
In contrast, they were poor inhibitors of MAO-B. Inhibition of MAO-A by
seed extracts was quantitatively attributed to harmaline and harmine
whereas inhibition by root extracts came from harmine with no additional
interferences. Stems and leaves extracts were poor inhibitors of MAO.
The potent inhibition of MAO-A by seed and root extracts of P. harmala
containing beta-carbolines should contribute to the
psychopharmacological and toxicological effects of this plant and could
be the basis for its purported antidepressant actions.
The Wall