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BioMed Research International
Volume 2018 (2018), Article ID 4810394, 10 pages
Research Article

Monoamine Oxidase-A Inhibition and Associated Antioxidant Activity in Plant Extracts with Potential Antidepressant Actions

Instituto de Ciencia y Tecnología de Alimentos y Nutrición (ICTAN), Spanish National Research Council (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain

Correspondence should be addressed to Tomás Herraiz

Received 3 August 2017; Accepted 12 December 2017; Published 15 January 2018

Academic Editor: Pierluigi Di Ciccio

Copyright © 2018 Tomás Herraiz and Hugo Guillén. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Monoamine oxidase (MAO) catalyzes the oxidative deamination of amines and neurotransmitters and is involved in mood disorders, depression, oxidative stress, and adverse pharmacological reactions. This work studies the inhibition of human MAO-A by Hypericum perforatum, Peganum harmala, and Lepidium meyenii, which are reported to improve and affect mood and mental conditions. Subsequently, the antioxidant activity associated with the inhibition of MAO is determined in plant extracts for the first time. H. perforatum inhibited human MAO-A, and extracts from flowers gave the highest inhibition (IC50 of 63.6 μg/mL). Plant extracts were analyzed by HPLC-DAD-MS and contained pseudohypericin, hypericin, hyperforin, adhyperforin, hyperfirin, and flavonoids. Hyperforin did not inhibit human MAO-A and hypericin was a poor inhibitor of this isoenzyme. Quercetin and flavonoids significantly contributed to MAO-A inhibition. P. harmala seed extracts highly inhibited MAO-A (IC50 of 49.9 μg/L), being a thousand times more potent than H. perforatum extracts owing to its content of β-carboline alkaloids (harmaline and harmine). L. meyenii root (maca) extracts did not inhibit MAO-A. These plants may exert protective actions related to antioxidant effects. Results in this work show that P. harmala and H. perforatum extracts exhibit antioxidant activity associated with the inhibition of MAO (i.e., lower production of H2O2).