OPEN Foundation

D. McKenna

The Therapeutic Potential of Ayahuasca

Abstract

Ayahuasca is a plant-based psychoactive decoction traditionally utilized by cultural groups throughout parts of Brazil, Peru, Colombia, Bolivia, Venezuela, and Ecuador during rites of passage, divination, warfare, magico-religious practices, and for healing in ethnomedical contexts. Over the last 150 years, ayahuasca has entered the global sphere and become a focus of scientific inquiry due to its reported use as an effective medicine to diagnose and treat illness. As a result, the use of ayahuasca within a healing context has become widespread and prompted researchers to investigate its putative therapeutic potential. In this chapter, the authors discuss current therapeutic applications of ayahuasca to treat addiction, depression, and anxiety. In this context, we highlight several studies to help facilitate a greater understanding of the therapeutic potential of ayahuasca.

Coe, M. A., & McKenna, D. J. (2017). The Therapeutic Potential of Ayahuasca. In Evidence-Based Herbal and Nutritional Treatments for Anxiety in Psychiatric Disorders (pp. 123-137). Springer International Publishing. 10.1007/978-3-319-42307-4_7

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New World Tryptamine Hallucinogens and the Neuroscience of Ayahuasca

Abstract

New World indigenous peoples are noted for their sophisticated use of psychedelic plants in shamanic and ethnomedical practices. The use of psychedelic plant preparations among New World tribes is far more prevalent than in the Old World. Yet, although these preparations are botanically diverse, almost all are chemically similar in that their active principles are tryptamine derivatives, either DMT or related constituents. Part 1 of this paper provides an ethnopharmacological overview of the major tryptamine-containing New World hallucinogens.

McKenna, D., & Riba, J. (2015). New World Tryptamine Hallucinogens and the Neuroscience of Ayahuasca. Current Topics in Behavioral Neuroscience. https://dx.doi.org/10.1007/7854_2015_368

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A possibly sigma-1 receptor mediated role of dimethyltryptamine in tissue protection, regeneration, and immunity

Abstract

N,N-dimethyltryptamine (DMT) is classified as a naturally occurring serotonergic hallucinogen of plant origin. It has also been found in animal tissues and regarded as an endogenous trace amine transmitter. The vast majority of research on DMT has targeted its psychotropic/psychedelic properties with less focus on its effects beyond the nervous system. The recent discovery that DMT is an endogenous ligand of the sigma-1 receptor may shed light on yet undiscovered physiological mechanisms of DMT activity and reveal some of its putative biological functions. A three-step active uptake process of DMT from peripheral sources to neurons underscores a presumed physiological significance of this endogenous hallucinogen. In this paper, we overview the literature on the effects of sigma-1 receptor ligands on cellular bioenergetics, the role of serotonin, and serotoninergic analogues in immunoregulation and the data regarding gene expression of the DMT synthesizing enzyme indolethylamine-N-methyltransferase in carcinogenesis. We conclude that the function of DMT may extend central nervous activity and involve a more universal role in cellular protective mechanisms. Suggestions are offered for future directions of indole alkaloid research in the general medical field. We provide converging evidence that while DMT is a substance which produces powerful psychedelic experiences, it is better understood not as a hallucinogenic drug of abuse, but rather an agent of significant adaptive mechanisms that can also serve as a promising tool in the development of future medical therapies.

Frecska, E., Szabo, A., Winkelman, M. J., Luna, L. E., & McKenna, D. J. (2013). A possibly sigma-1 receptor mediated role of dimethyltryptamine in tissue protection, regeneration, and immunity. Journal of Neural Transmission, 120(9), 1295-1303. http://dx.doi.org/10.1007/s00702-013-1024-y
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Pharmacokinetics of Hoasca alkaloids in healthy humans

Abstract

N,N-Dimethyltryptamine (DMT), harmine, harmaline and tetrahydroharmine (THH) are the characteristic alkaloids found in Amazonian sacraments known as hoasca, ayahuasca, and yajè. Such beverages are characterized by the presence of these three harmala alkaloids, where harmine and harmaline reversibly inhibit monoamine oxidase A (MAO-A) while tetrahydroharmine weakly inhibits the uptake of serotonin. Together, both actions increase central and peripheral serotonergic activity while facilitating the psychoactivity of DMT. Though the use of such ‘teas’ has be known to western science for over 100 years, little is known of their pharmacokinetics. In this study, hoasca was prepared and administered in a ceremonial context. All four alkaloids were measured in the tea and in the plasma of 15 volunteers, subsequent to the ingestion of 2 ml hoasca/kg body weight, using gas (GC) and high pressure liquid chromatographic (HPLC) methods. Pharmacokinetic parameters were calculated and peak times of psychoactivity coincided with high alkaloid concentrations, particularly DMT which had an average Tmax of 107.5±32.5 min. While DMT parameters correlated with those of harmine, THH showed a pharmacokinetic profile relatively independent of harmine’s.

Callaway, J. C., McKenna, D. J., Grob, C. S., Brito, G. S., Raymon, L. P., Poland, R. E., … & Mash, D. C. (1999). Pharmacokinetics of Hoasca alkaloids in healthy humans. Journal of ethnopharmacology, 65(3), 243-256. 10.1016/S0378-8741(98)00168-8
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Monoamine oxidase inhibitors in South American hallucinogenic plants: tryptamine and beta-carboline constituents of ayahuasca

Abstract

Ayahuasca is a hallucinogenic beverage derived by boiling the bark of the Malpighiaceous liana Banisteriopsis caapi together with the leaves of various admixture plants, viz. Psychotria viridis, Psychotria carthagenensis, or Diplopterys cabrerana. B. caapi contains harmine, harmaline, and tetrahydroharmine while the admixtures contain N,N-dimethyltryptamine (DMT). DMT, a potent hallucinogen, is inactive orally due to degradation by visceral monoamine oxidase (MAO). The β-carbolines, however, are highly active reversible inhibitors of MAO and may protect the DMT from deamination by MAO and render it orally active. This mechanism has been proposed to underlie the oral activity of ayahuasca but has not been experimentally confirmed. In the present study the constituents of the admixture plants and the alkaloids of eight ayahuasca samples from Peru were qualitatively and quantitatively analyzed using two-dimensional thin-layer chromatography (TLC), high pressure liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS).

Several B. caapi cultivars were quantitatively compared for variations in alkaloid content. Three admixture plants used rarely in the manufacture of ayahuasca were also screened for alkaloids. A selected sample of β-carbolines were screened for activity as MAO inhibitors using an in vitro assay system, and structure/activity relationships were compared. Inhibition observed with single compounds was compared with the activity of selected samples of ayahuasca which were screened in the system and also with the activity of mixtures of β-carbolines. The levels of DMT and β-carbolines found in the ayahuasca samples examined in the present study were an order of magnitude greater than the levels reported in a previous study. Ayahuasca was found to be an extremely effective inhibitor of MAO in vitro and the degree of inhibition was directly correlated with the concentration of MAO-inhibiting β-carbolines. Inhibition experiments using mixtures of β-carbolines indicated that their effects in combination are additive, rather than synergistic or antagonistic. Implications of the results in understanding the pharmacology of ayahuasca are discussed.

McKenna, D. J., Towers, G. N., & Abbott, F. (1984). Monoamine oxidase inhibitors in South American hallucinogenic plants: tryptamine and β-carboline constituents of ayahuasca. Journal of ethnopharmacology, 10(2), 195-223. 10.1016/0378-8741(84)90003-5
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