Ayahuasca is a Quechua name used to describe a pan-Amazonian botanical hallucinogenic beverage produced by boiling the stems of the liana Banisteriospsis caapi with the leaves of the shrub Psychotria viridis.¹,²B. caapi is rich in β-carbolines such as harmine, tetrahydroharmine (THH), and harmaline, while P. viridis contains considerable amounts of the hallucinogenic tryptamine N,N-dimethyl-tryptamine (DMT), a 5-HT_1A/2A/2C agonist.^{1 2 3 4}–⁵ Pure DMT is not psychoactive after oral administration,⁶ but liver and gastrointestinal monoamine oxidase A (MAO-A) inhibition by the β-carbolines in ayahuasca – especially by harmine – allows DMT to reach the systemic circulation and the brain, where it activates 5-HT_1A/2A/2C receptors in frontal and paralimbic areas.⁵,⁷,⁸

Ayahuasca has been traditionally used by indigenous and mestizo populations of Amazonian countries such as Brazil, Colombia, Peru, and Ecuador for magical-religious and therapeutic purposes.¹,² However, in the last 25 years, ritual and therapeutic use of ayahuasca has spread from small cities in the Amazonian jungle to the urban centers of South America, United Sates, Europe, Asia, and Africa.⁹

Anecdotal evidence, studies conducted among ayahuasca consumers, and preliminary studies in patients suggest that ayahuasca has broad therapeutic potential, especially for the treatment of substance dependence and anxiety and mood disorders.^{10 11 12 13 14 15 16 17}–¹⁸ Moreover, pharmacological studies of acute ayahuasca administration to healthy volunteers and mental health assessments of long-term ayahuasca consumers suggest that this compound is relatively safe.⁴,⁵,⁷,¹⁰–¹⁵,^{19 20}–²¹

Thus, this study aimed to conduct a systematic literature review of animal and human studies that investigated anxiolytic and antidepressive effects of ayahuasca or of some of its isolated alkaloids (dimethyltryptamine, harmine, THH, and harmaline).

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