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MAO inhibitors: Plant enzymes for mood, libido and psychedelic experiences

Written by Matthew Clark

Monoamine oxidases

Monoamine oxidases (MAOs) are a family of enzymes[i] found in the brain, gut, liver and other tissues; they catalyse the oxidation and inactivation of monoamine neurotransmitters, including serotonin, noradrenaline and dopamine, which are important in the regulation of mood.

There are two kinds of MAO: MAO-A and MAO-B. MAO-A is found primarily in the intestine and in the regions of the brain that have serotonin, norepinephrine, dopamine and tyramine substrates; MAO-B is found primarily in platelets and in the regions of the brain that are rich in dopaminergic neurons.

The function of MAO inhibition was discovered in 1958 (22). Drugs that suppress MAO-A in the brain have been used as anti-depressants since then. These drugs remain far longer in the system than plant-based sources. MAO inhibitors (MAOIs) inhibit the MAO enzyme, thereby allowing serotonin, norepinephrine and dopamine to accumulate in the synapse (5). Mood changes induced by MAOIs can also be aphrodisiac, and the plants considered below are sometimes used for that purpose in various cultures around the world.


[i] Oxidases are enzymes that utilize molecular oxygen as acceptor, and convert phenolic substances to quinones.

Since 2004, Dr. Matthew Clark has been a Research Associate at the School of Oriental and African Studies (SOAS, University of London), where he taught courses on Hinduism between 1999 and 2004. He has spent many years in India, which he first visited in 1977, visiting nearly all important (several hundred) pilgrimage sites and trekking around 2,000 miles in the Himalayas. He first engaged with yoga in the mid-1970s and began regularly practising Ashtanga Yoga in 1990. Since 2006, Matthew has been lecturing world-wide on yoga, philosophy and psychedelics. He is currently the managing editor of the Journal of Yoga Studies and is one of the administrators of the SOAS Centre of Yoga Studies.

His publications include The Daśanāmī-Saṃnyāsīs: The Integration of Ascetic Lineages into an Order (2006), which is a study of a sect of sādhus; The Tawny One: Soma, Haoma and Ayahuasca (2017), which is an exploration of the use of psychedelic plant concoctions in ancient Asia and Greece; and a short book on yoga, The Origins and Practices of Yoga: A Weeny Introduction (revised edition) (2018). In June 2021, he published another short book, Therapeutic Experiences and Psychedelics: Soma/Haoma and Complex Plant Formulas in Asia. Matthew also writes songs, plays guitar and records as Mahabongo.

Matthew Clark

Since 2004, Dr. Matthew Clark has been a Research Associate at the School of Oriental and African Studies (SOAS, University of London), where he taught courses on Hinduism between 1999 and 2004. He has spent many years in India, which he first visited in 1977, visiting nearly all important (several hundred) pilgrimage sites and trekking around 2,000 miles in the Himalayas. He first engaged with yoga in the mid-1970s and began regularly practising Ashtanga Yoga in 1990. Since 2006, Matthew has been lecturing world-wide on yoga, philosophy and psychedelics. He is currently the managing editor of the Journal of Yoga Studies and is one of the administrators of the SOAS Centre of Yoga Studies.

His publications include The Daśanāmī-Saṃnyāsīs: The Integration of Ascetic Lineages into an Order (2006), which is a study of a sect of sādhus; The Tawny One: Soma, Haoma and Ayahuasca (2017), which is an exploration of the use of psychedelic plant concoctions in ancient Asia and Greece; and a short book on yoga, The Origins and Practices of Yoga: A Weeny Introduction (revised edition) (2018). In June 2021, he published another short book, Therapeutic Experiences and Psychedelics: Soma/Haoma and Complex Plant Formulas in Asia. Matthew also writes songs, plays guitar and records as Mahabongo.

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