By
Dennis J. McKenna, PhD Director of Ethnopharmacology, Heffter Research
Institute
Editor’s note: A previous version of this
article was published as the first chapter of the new book Ethnopharmacologic Search for Psychoactive Drugs (Synergetic Press, 2018),1 a volume of essays based on presentations made at the Ethnopharmacologic
Search for Psychoactive Drugs symposium in Buckinghamshire, England, in June
2017. This symposium was the 50th anniversary commemoration of the first Ethnopharmacologic
Search for Psychoactive Drugs symposium held in 1967 in San Francisco under the
sponsorship of the US National Institute of Mental Health. Present at the initial
conference were some of the leading pioneering researchers who initiated much
of the modern chemical, ethnopharmacological, and ethnobotanical investigations
of various plants and non-botanical materials with known psychoactive uses in
native cultures.
The First Ethnopharmacologic Search
for Psychoactive Drugs Symposium (San Francisco, 1967)
In
1967, a landmark symposium in the history of psychedelics was held in San
Francisco, California, under the sponsorship of the US National Institute of Mental
Health (NIMH), which was part of the US Department of Health, Education, and
Welfare (now called the US Department of Health and Human Services [HHS]). The
title of the invitational symposium was “Ethnopharmacologic Search for
Psychoactive Drugs” (ESPD), and a volume of the proceedings was published under
the same name later that year and sold through the US Government Printing
Office (now called the US Government Publishing Office [GPO]). The volume, now
out of print, has become a classic reference in the ethnobotanical literature.
This
was probably the first time that an interdisciplinary group of specialists,
ranging from ethnobotanists to neuroscientists, gathered in one place to share
their findings on a topic of widespread interest at the time: the use of
psychoactive plants in the context of indigenous and non-Western societies. In
1967, the word “psychedelic” had not yet become stigmatized. (According to the
National Institute of Drug Abuse, a psychedelic is a substance that “distorts
perception, thought, and feeling.” A psychoactive substance is defined more
generally as a substance that has a “specific effect on the brain.”2)
There were still expectations in the psychiatric and neuroscientific
communities that these little-known and curious agents, used for centuries in
the ethnomedicine and rituals of traditional cultures, might yield new healing substances
that could be used in our own troubled society, and serve as important tools for
exploring the human mind.
The
roster of attendees at the 1967 symposium reads like a Who’s Who of
ethnopharmacology: John Daly, PhD; Daniel Efron, MD, PhD; Daniel X. Freedman,
MD; Bo Holmstedt, MD, PhD; Nathan Kline, MD; Richard Schultes, PhD; Alexander Shulgin, PhD; Stephen Szára, MD; R. Gordon Wasson; Andrew Weil, PhD; and many others. Only a few of the
researchers who attended the original symposium are still alive, and, of those,
even fewer remain active in the field. Their work contributed to making the
first ESPD symposium one of the most unusual and interdisciplinary scientific
convocations ever organized.
Originally,
follow-up symposia were planned to be held about every 10 years. That time frame,
it was thought, was sufficient to accommodate the stately progress of
scientific research, yet frequent enough to enable researchers in various
specialties to come together in a collegial environment to share research
results in a timely fashion.
After
the summer of 1967, the political winds shifted, and psychedelic substances
soon became demonized, feared, and banned. The federal government did not want to
sponsor any similar symposia. In fact, its sponsorship of the original
symposium, as valuable as it was for the dissemination of research findings,
became an embarrassment, and, as a result, no follow-up symposia were held. The
symposium proceedings were available for a time from the GPO (US Public Health
Service Publication #1645) but eventually went out of print, closing that
particular chapter in the history of psycho-ethnopharmacology.
In the 50 years that have passed since the first symposium, numerous federal
administrations have come and gone. Our recent past and current administrations,
along with most of their affiliated institutions, remain as far from developing
a viable, realistic drug policy today as they were then. A new generation of
researchers, many inspired by the giants at the first conference, has continued
to investigate the outer limits of psycho-ethnopharmacology. Some outstanding
discoveries have been made, and the work continues. At the same time, there has
been a change in public and medical perception of psychedelics. There is now a
renaissance in research around the world, and the therapeutic potential of some
of these agents is being reinvestigated. While psychedelic substances have
become less stigmatized than in the past, they remain controversial. Much work
in this field remains unfinished, and the most significant discoveries may
still lie in the future.
How ESPD Changed
my Life — Summer 1968
When
the first ESPD symposium was held in 1967, I was 16 years old, a bored teenager
living in a small town in western Colorado. More than anything, I longed to
escape my dreary life and travel to San Francisco, the Mecca for the
counterculture and the epicenter of the psychedelic revolution. My late brother,
Terence, a lifelong friend and mentor, had escaped our soft prison a few years
earlier and was a student at Berkeley at the time. We were both just beginning
to discover the wondrous world of psychedelics, and we agreed that they were
the most fascinating things that we had encountered in our young lives. The
fascination we felt continued to guide our interests and even careers for the
rest of our lives.
In
1967, while we were fascinated by psychedelics and wanted to immerse ourselves
in the counterculture, neither of us had much of a clue about them. Terence was
living in Berkeley, and I managed to get away from my small town and visit him
during the height of the Summer of Love. Neither of us was aware of the obscure
private symposium that had taken place in San Francisco just a few months
earlier.
Like
most of our like-minded contemporaries, we had no context in which to
understand the emergence of these compounds into mass consciousness in the
1960s. Timothy Leary, PhD, had transformed from a mild-mannered Harvard
researcher to the Messiah of LSD, and although much of his message resonated
with us, we were slow to plunge full tilt into the hippie movement. This was
partly because we identified as intellectuals and, to some degree, were put off
by the distinctly anti-intellectual trappings of hippie culture. We thought
there had to be more to psychedelics than their superficial depictions in the
mass media, but we had no idea where to find a more in-depth and balanced perspective.
Sometime
in 1968, while we were busy trying to sort all this out, two books surfaced in
our world. These works provided deep background context in which psychedelics
made sense to us. One of these books was The
Teachings of Don Juan: A Yaqui Way of Knowledge (University of California
Press, 1968), which was Carlos Castaneda’s first of many
books and described his apprenticeship with a Yaqui shaman.3
Although subsequent events have shown that much of Castaneda’s work is highly
fictionalized if not completely fabricated, we did not know that at the time.
For
me, at least, that book was influential because it provided a cultural context
for psychedelics based on traditions older and richer than anything I had
encountered in mass media sources. It made clear that there was nothing new
about psychedelics. In fact, these sacred plants and fungi had been used in
indigenous shamanic practices for hundreds, if not thousands, of years. While
Castaneda’s book was not scientific, or even accurate, it gave me insights into
shamanism, a set of practical methodologies and beliefs involving the use of
these materials for healing and the exploration of consciousness. Terence gave
me a copy of the first edition of The
Teachings of Don Juan for my 18th
birthday in 1968; it was a very special gift. I still have it, and I still
cherish it.
The proceedings of
the first ESPD symposium were published some months after the symposium under
the sponsorship of the Pharmacology Section, Psychopharmacology Research Branch
of the NIMH.4
A
rather worn copy came into my possession in the summer of 1968. I dropped
whatever I was reading and devoured the book from cover to cover. This book
provided the perfect balance to The Teachings of Don Juan. While that work
had made me aware of the cultural contexts related to the indigenous uses of
psychedelics, the Ethnopharmacologic
Search for Psychoactive Drugs was even more influential, because through it
I became aware that this discipline — ethnopharmacology, or more specifically
psycho-ethnopharmacology — was a real field of scientific investigation.
Moreover, it was my first introduction to people like Schultes, Holmstedt,
Shulgin, Wasson, and others, who became iconic figures in my personal pantheon,
and in some cases, as with Schultes and Shulgin, mentors and friends.
The
realization that real science was being pursued in this field was a revelation
to me, partly because it opened the possibility that one day I, too, might be
able to achieve a place in this exclusive fellowship. At first, I thought I
would be able to prove to my parents that I was serious about psychedelics and
not just a confused hippie in search of cheap thrills, but they were not very
reassured. However, over the years, they came to recognize the merits of my
chosen career.
Two Decades Later
The
shabby volume of that first edition resides on my shelf to this day. While I
don’t remember exactly how it came into my hands, I remember very well how my
second copy came to me in 1986. I had completed my PhD at the University of
British Columbia in 1984 under the supervision of Neil Towers, PhD, another
lifelong mentor and friend. My thesis was an ethnopharmacological investigation
of the ethnobotany, chemistry, and pharmacology of ayahuasca (Banisteriopsis caapi, Malpighiaceae) and
another hallucinogen, a relatively more obscure preparation known as oo’koey, derived from Virola (Myristicaceae) species. Though
derived from entirely different botanical sources, both ayahuasca and oo’koey were orally active
tryptamine hallucinogens, and my thesis was a comparative study of their active
constituents and pharmacology.
After
the completion of my thesis in early 1984, I moved to San Diego, California,
and began the first of three post-doctoral research projects. About a year
after I moved, my thesis publications came out, and one attracted the attention
of Juan Saavedra, MD, a researcher at NIMH. When Saavedra requested a reprint
of my publication on ayahuasca in the Journal
of Ethnopharmacology,5 I was surprised. I recognized his name
from an early paper he had published with Julius Axelrod on the endogenous
synthesis of the psychoactive compound DMT (dimethyltryptamine) in rat and
human brains.6 (Axelrod later won the Nobel Prize for his work on
mechanisms of neurotransmission.)
Figuring
it was a long shot, I enclosed a letter with my signed reprint, timidly
enquiring if there might be a chance I could come to NIMH and work with him on
endogenous tryptamines. A few weeks passed, and one day I received a kind
reply. He thanked me for my reprint and mentioned that he had been in the
Amazon in 1979 with Schultes and Towers, my mentor, along with a dozen other
researchers on the research vessel (RV) Alpha-Helix,
operated by the Scripps Institution of Oceanography. He informed me that there
was a fellowship program at National Institute of General Medical Sciences
called the Pharmacology Research Associate Training (PRAT) that was targeted to
young investigators who wanted to expand their scientific training outside
their field of specialization. He said it was a perfect fit for me and
encouraged me to apply. I did, was accepted into the program, and began my
second post-doc in the fall of 1986, in the hallowed environs of the Laboratory
of Clinical Pharmacology at NIMH.
I
had been in the lab for less than two weeks when Saavedra pointed to an upper
shelf in a cabinet in the lab. He said there was a box up there containing some
research chemicals that he and Axelrod had used in their research on endogenous
tryptamines. He suggested that I go through it and see if there was anything
useful, and to send the rest to the hazardous waste disposal center on the National
Institutes of Health campus. I didn’t waste any time; I stayed late one
afternoon until most of my fellow workers had called it a day, then got up on
the bench and retrieved the box. Inside, I found a mint-condition copy of the Ethnopharmacologic Search for Psychoactive
Drugs! How many years it had languished on the shelf next to that box of chemicals
I had no idea, but it had clearly never been opened.
Here
I was, just beginning my post-doctoral studies in the heart of NIMH, the very
institution where the original ESPD symposium had originated, and suddenly, the
book that had so enthralled me as a curious teenager magically reappeared. How
cool was that? I took it as a very good omen. It quietly disappeared into my
library, where it sits beside my first copy from 1968. Some of those research
chemicals turned out to be interesting as well. Along with a couple of vials of
DMT and 5-methoxy-DMT, there was an interesting assortment of other
derivatives, such as 5,7-dihydroxy-DMT, 6-methoxy-DMT, and so on. I kept those
for many years, but never found the courage to personally bioassay them.
ESPD Returns: 50 Years Later
So,
that is the story of my personal history with this book. It has haunted most of
my professional career. It opened my eyes to the science of ethnopharmacology,
and later, I was fortunate to meet and befriend some of the people who
presented at that 1967 symposium. Though its contents are dated now, that book
influenced my life and career in profound ways, and I am sure that my career in
ethnopharmacology, such as it has been, would never have happened had I not
encountered that obscure tome in the summer of 1968.
I
have wanted to organize a follow-up symposium for many years. In fact, I first
drafted a proposal about it in 1995, hoping to stage it in 1997, the 30th
anniversary of the San Francisco symposium. It never happened for various
reasons, mostly due to lack of funds, time, and an appropriate venue. In 2017,
the 50th anniversary of the ESPD, all of those necessary elements came together
almost miraculously.
I
hope that the commemorative symposium and the publication of both symposium
volumes, 1967 and 2017, will attract the attention of younger investigators
working in the field of ethnopharmacology and inspire them to continue this
valuable work. There is still more — much more — to be discovered. I hope that
the quest represented in the book’s title — The Ethnopharmacologic Search for Psychoactive Drugs — will be carried
on by a new generation, who one day will report their discoveries to the world
at a future ESPD symposium. I also hope that it will not take another 50 years!
Significant Discoveries of the Last 50
Years
Psycho-ethnopharmacology
has not stood still over the last 50 years. Significant discoveries have been
made and are still being made. The ESPD50 anniversary conference in June 2017
included presentations on some of the most interesting discoveries of those
decades but must necessarily omit many others that are just as worthy. Though
it’s not my intention to discuss them in any detail, a few are worth mentioning
in brief.
- Ayahuasca
Admixtures
— The importance of the many ayahuasca admixtures had not received much
attention in 1967. Some of Schultes’ students were reporting on the use of the
DMT-containing admixtures that give ayahuasca its psychedelic properties, but
most of this work was not published until 1968 or later.7
Interestingly, the word “Psychotria” occurs only once in the entire 1967
edition. This genus includes Psychotria viridis (Rubiaceae), the most
widely used ingredient in ayahuasca admixtures. In the 1980s, Luis Eduardo Luna,PhD,
and I also published on the many other species that are occasionally used in
these admixtures.8,9* Many of these remain poorly investigated, both
in terms of their chemistry and pharmacology. For a later publication,10
I screened many of these species using neuroreceptor-binding assays as part of
a broad sampling of reported plants with potential anti-dementia and
anti-schizophrenic activities. I have contributed a condensed version of that
paper in the final section of the 2017 symposium volume.
- Salvia divinorum and Salvinorin A — Although ethnographic reports of
the use of this member of the mint (Lamiaceae) family in Mazatec shamanism date
back to at least the 1930s,11,12 it was not discussed during the 1967
symposium. The primary active constituent, the diterpene salvinorin A, was
isolated and characterized in the 1990s,13 and its potent activity
as a highly selective kappa-opioid receptor agonist was described in 2002.14
This initial discovery has led to a flurry of research on the chemistry and
pharmacology of salvinorin A and its analogs. More than 30 papers on salvinorin
A have been published since (for a review, see Cunningham et al., 201115).
Ethnopharmacologist Michael Heinrich, PhD, and his student, Ivan Casselman, contribute
a retrospective on this interesting plant in the 2017 volume.1
- Kava (Piper
methysticum) — The term “kava” refers to both the
plant in the pepper (Piperaceae) family and the mildly psychoactive beverage
prepared from its roots. Kava was reported on during the first ESPD symposium
in 1967 (see Session II, ESPD 1967), but much additional work has been done on
this plant in subsequent decades. It is now widely available as a dietary
supplement, and its anxiolytic, muscle-relaxant, and sedative properties have
made it a popular alternative to pharmaceuticals such as benzodiazepines (for a
review, see LaPorte et al., 201116).
- Kratom (Mitragyna speciosa) — The leaf of this
Southeast Asian tree in the madder (Rubiaceae) family is the source of
mitragynine and related alkaloids that are mu-opioid receptor agonists. The
plant can cause mild addiction like any source of opioids, but in traditional
contexts it is often used as an alternative to opium, and as a way to gradually
end dependence on opium and heroin. The kratom alkaloids do not seem to cause
respiratory depression, unlike heroin and other opioids, and hence show promise
as a less toxic, and less addictive, analgesic. Kratom was not illegal in the United
States when I first wrote this chapter in 2017, but has been identified as a “drug
of concern” by the US Drug Enforcement Administration, and may be scheduled
under the Controlled Substances Act in the near future. At the same time, some
investigators, such as Christopher McCurdy, PhD, have urged that it not be
prohibited because it may enable many opioid addicts to overcome their habits.17,18
McCurdy has reported on his research and the current “state of the art” with
respect to kratom in the second section of the 2017 symposium volume.1
- Iboga (Tabernanthe
iboga) and Ibogaine — Iboga, sometimes
spelled eboga, is a West African plant in the Apocynaceae family, used in
traditional initiation rites in the spiritual discipline of Bwiti in Gabon. In
those rites, young men and women, coming of age as adults, undergo an
initiation in which they consume large — sometimes nearly lethal — amounts of iboga
root. They experience a deep trance, sometimes lasting up to 36 hours, during
which they often claim to experience visits from their ancestors and are
initiated and given ancestral wisdom. Ibogaine, the major alkaloid, has
received recognition and notoriety, because it is effective for the treatment
of opioid and other addictions.19 Although a Schedule I controlled
substance in the United States, it is unregulated in many countries and is used
in treatment centers in various parts of the world, especially Mexico.20
Kenneth Alper, MD, a leading authority on the chemistry and pharmacology of ibogaine,
contributes “The Iboga Project: Urban Ethnomedicine For Opioid Use Disorder” in
the second section of the 2017 symposium volume.1
- Kougoed (Sceletium
tortuosum) — Kougoed, also
called channa or kanna, is a South African succulent in the Aizoaceae family
whose roots contain a spectrum of alkaloids with central nervous system activities.
Some, such as mesembrenone, mesembrine, and mesembrenol, are potent 5HT-reuptake
inhibitors and phosphodiesterase 4 inhibitors. These are only three of more
than 30 alkaloids that have been isolated from the plant; the pharmacological
properties of most have not been thoroughly characterized.21 In section
two of the 2017 symposium volume, Nigel Gericke, MD, reports on his research
with S. tortuosum that has led to the
commercial development of Zembrin (HG&H Pharmaceuticals; Johannesburg,
South Africa), a natural herbal anxiolytic and antidepressant sold as a dietary
supplement.1
- Jurema (Mimosa
hostilis syn. Mimosa tenuiflora) and yuremamine — This Brazilian tree in
the legume (Fabaceae) family has long been known as the source of Vinho de Jurema, a psychoactive beverage
that contains DMT as its main active constituent. However, it has been an
ethnopharmacological enigma because DMT is not orally active unless potentiated
by a monoamine oxidase inhibitor (MAOI). Yet, no plants with MAOI activity have
been reported to be added to the mixture in traditional shamanism. Recently, a
novel compound, yuremamine, was isolated from the roots of M. hostilis at about the same concentration as DMT.22
This compound has an interesting structure, in that the structure of DMT is “caged”
within the larger molecule, and it may be a prodrug that is converted to DMT in
vivo. The initially proposed structure has been challenged, and total synthesis
has so far been elusive.23 It may also be an MAOI itself, and thus
could potentiate the DMT. So far, there have been no human bioassays of this
compound, so its pharmacological properties in a pure form are unknown.
- Acacia spp. and tryptamines — The large genus Acacia (Fabaceae) has proven to be an
unusually rich source of DMT and other psychoactive tryptamines. At the time of
the first ESPD conference in 1967, the tryptaminic Acacia species were unknown to science. The earliest reference in
PubMed is Wahba and Elkheir (1975).24 Since then, tryptamines have
been detected in more than 60 species of Acacia,
as documented in the review paper “Australian Psychoactive Acacia Species and
their Alkaloids” by Snu Voogelbreinder in section two of the
2017 symposium volume.1 Many more Acacia species contain unidentified alkaloids, and
phenylethylamines, ß-carbolines, tetrahydroisoquinolines, pyridines, and other
structural classes have been reported. Interestingly, much of what science
knows about the chemistry of psychoactive Acacia
species is due to investigations by amateur scientists who have conducted
research outside conventional academic channels, and, as a result, much of it
does not appear in the peer-reviewed literature.
- Frog and Toad Medicines — Although
obviously neither botanical nor fungal, psychoactive and psychedelic amphibians
— frogs and toads — have attracted attention recently as potentially
therapeutic. Among these are the so-called sapo medicine, more properly termed
kambô, from Phyllomedusa bicolor (the giant leaf frog), a frog
containing a variety of neuroactive peptides in its skin secretions. This
species is used by the Matsés (Mayoruna) tribe as hunting magic, and taking “sapo”
is becoming a popular pastime among tourists in Peru. So far, the peptides
identified include phyllocaerulein (hypotensive), phyllomedusin (tachykinin,
potent vasodilator, and secretagogue), phyllokinin (a potent arterial smooth
muscle dilator), and several delta-opioid-selective peptides, the deltorphins, as
well as mu-opioid-active peptides, the dermorphins. Many of these compounds may
have therapeutic potential, and the neuroactive peptides are only a part of
this rich peptide cocktail. For reviews and more information see Erspamer et
al.,25 Daly et al.,26 and den Brave et al.27
In
addition to the Phyllomedusa
peptides, the poison of Bufo species
contains psychedelic tryptamine derivatives, either bufotenine or 5-methoxy-DMT,
and its use has gained popularity in various neo-shamanic practices. Although
the subjective effects of Bufo poison
were first reported by Weil and Davis (1994),28 there is little
evidence that these species were ever utilized as psychedelic medicines in any
ethnomedical or shamanic tradition. A comprehensive review of the use of Bufo species as sources for psychedelics,
and a discussion of some of the controversies surrounding this practice, can be
found in Lyttle et al. (1996).29
- Old Yet New:
Harmine and Related ß-carbolines — Harmine is the major ß-carboline and MAOI
in the ayahuasca vine. Harmine is an “old” alkaloid, meaning that it has been known
for many years, having first been identified in the seeds of Syrian rue (Peganum
harmala, Nitrariaceae) by chemist J. Fritsch in 1847, more than ten years
before ayahuasca came to the attention of science as a result of explorer Richard
Spruce’s discovery in 1858. However, recent investigations have shown that even
old alkaloids can still harbor secrets. New research has shown that harmine and
some of its derivatives can display a diverse array of biological activities.
It has been shown to have antimicrobial, antidiabetic, antidepressant, antitumor,
neuroprotective, and other effects. It interacts with a number of
neuroreceptors, including 5-HT2A, 5-HT2C, imidazoline,
and dopamine transporter (DAT) receptors. Significantly, it recently has been
shown to be a potent inhibitor of DYRK1A, a kinase involved in a variety of
intracellular signaling functions related to cell proliferation and
neurogenesis, and has been shown to potently stimulate proliferation of neural
cell progenitors, an effect linked to its inhibition of DYRK1A.30
For recent reviews on the pharmacology of harmine and other ß-carbolines, see
Cao et al.,31 Patel et al.,32 and the paper by Dale
Millard (2017)1 in section one of the 2017 symposium volume.
Conclusion
This article comprises a brief
summary of some of the most significant discoveries in psycho-ethnopharmacology
in the five decades since the first ESPD symposium in 1967. These findings are
only a small sampling of the discoveries that have been made in the last 50
years. The 2017 ESPD50 Symposium — and the publication of the proceedings as a
two-volume set that includes a reprinting of the 1967 symposium proceedings — demonstrates
that the field of psycho-ethnopharmacology is far from a dead or dying
discipline. It is potentially more vibrant than ever. There are still exciting
discoveries to be made in years to come. In today’s world, no science can
thrive without financial support and academic legitimacy. It is my hope that
the publication of this symposium volume will bring a measure of both to this
field, and will inspire and excite the next generation of
psycho-ethnopharmacologists.
Acknowledgements
The
author expresses his profound thanks to those who have made contributions to the
50th anniversary ESPD symposium volume, and the website and e-book that go with
it, as well as to the many individuals who saw and shared his vision, and
stepped up in so many ways to help make it happen.
* This
paper was originally published in Spanish in the journal America Indigena in 1986.8 An English translation was
published as a chapter in an anthology, Ethnobotany:
Evolution of a Discipline.9
References
- Prance GT, McKenna DJ, de Leonen B,
Davis W, eds. Ethnopharmacologic Search
for Psychoactive Drugs: 50th Anniversary Symposium Volume. Santa Fe, NM:
Synergetic Press; 2018.
- Commonly used terms in addiction
science. National Institute of Drug Abuse website. Available at: www.drugabuse.gov/publications/media-guide/glossary.
Accessed September 19, 2018.
- Castaneda C. 1968. The Teachings of Don Juan: a Yaqui Way of
Knowledge. Berkeley, CA: University of California Press; 1968.
- Efron DH, Holmstedt B, Kline NS,
eds. Ethnopharmacologic Search for Psychoactive Drugs – 1967. Workshop Series
of Pharmacology Section, NIMH No. 2. Sponsored by Pharmacology Section,
Psychopharmacology Research Branch, National Institute of Mental Health. Public
Health Service, U.S. Department of Health, Education, and Welfare. Public
Health Service Publication No. 1645, U.S. Government Printing Office; 1967.
- McKenna DJ, Towers GHN, Abbott FS. Monoamine
oxidase inhibitors in South American hallucinogenic plants: Tryptamine and
ß-carboline constituents of Ayahuasca. Journal
of Ethnopharmacology. 1984;10:195-223.
- Saavedra JM, Axelrod J.
Psychotomimetic N-methylated tryptamines: formation in brain in vivo and in
vitro. Science. 1972;175(4028):1365-1366.
- Pinkley HV. Plant admixtures to Ayahuasca, the South
American hallucinogenic drink. Lloydia.
1969;32:305-314.
- McKenna DJ, Luna
LE, Towers GHN. Ingredientes biodinamicos en las plantas que se meszclan al
ayahausca. Una farmacopea tradicional no investigada. America Indigena. 1986;46:73-101 (Spanish with English abstract).
- McKenna DJ, Luna
LE, Towers GHN. Biodynamic constituents in Ayahuasca admixture plants: an
uninvestigated folk pharmacopoeia. In: von Reis S, Schultes RE, eds. Ethnobotany: Evolution of a Discipline. Portland,
OR: Dioscorides Press; 1995.
- McKenna DJ, Ruiz JM, Hoye TR, Roth
BR, Shoemaker AP. Receptor screening technologies in the evaluation of
Amazonian ethnomedicines with potential applications to cognitive deficits. Journal of Ethnopharmacology. 2011;134,
475-492.
- Johnson JB.
Some notes on the Mazatec. Revista
Mexicana de Estudios Antropologicoa. 1939;3:142-156.
- Johnson JB. The
elements of Mazatec witchcraft. Etnologiska
Studier. 1939;9:128-150.
- Valdés LJ. Salvia divinorum
and the unique diterpene hallucinogen, Salvinorin (divinorin) A. Journal of Psychoactive Drugs. 1994;26:277-83.
- Roth BL, Baner K, Westkaemper R, et al. Salvinorin A: a
potent naturally occurring nonnitrogenous kappa opioid selective agonist. Proceeding of the National Academy of Sciences USA. 2002;18:11934-11939.
- Cunningham CW, Rothman RB, Prisinzano TE. Neuropharmacology
of the naturally occurring kappa-opioid hallucinogen salvinorin A. Pharmacological Reviews. 2011;63:316-347.
- LaPorte E, Sarris J, Stough C, Scholey A. Neurocognitive
effects of kava (Piper methysticum):
a systematic review. Human
Psychopharmacology. 2011;26:102-111.
- Ward J, Rosenbaum C, Hernon C, McCurdy CR, Boyer EW.
Herbal medicines for the management of opioid addiction: safe and effective
alternatives to conventional pharmacotherapy? CNS Drugs. 2011;25:999-1007.
- Babu KM, McCurdy CR, Boyer EW. Opioid receptors and legal
highs: Salvia divinorum and Kratom. Clinical Toxicology (Philadelphia).
2008;46:146-152.
- Alper KR. 2001.
Ibogaine: a review. The alkaloids. Chemistry
and Biology. 2001;56:1-38.
- Brown TK. Ibogaine
in the treatment of substance dependence. Current
Drug Abuse Reviews. 2013;6:3-16.
- Gericke N, Viljoen AM. Sceletium — a review update. Journal of Ethnopharmacology. 2008;119:653-663.
- Vepsäläinen JJ, Auriola S, Tukiainen M, Ropponen N,
Callaway JC. Isolation and characterization of yuremamine, a new phytoindole. Planta Medica. 2005;71:1053-1057.
- Calvert MB, Sperry J. Bioinspired total synthesis and
structural revision of yuremamine, an alkaloid from the entheogenic plant Mimosa tenuiflora. Chemical Communications (Cambridge). 2015;51:6202-6205.
- Wahba KSK,
Elkheir YM. Dimethyltryptamine from the leaves of certain Acacia species of northern Sudan. Lloydia. 1975;38:176-177.
- Erspamer V, Erspamer GF, Severini C, et al. Pharmacological
studies of 'sapo' from the frog Phyllomedusa bicolor skin: a drug used by the
Peruvian Matses Indians in shamanic hunting practices. Toxicon. 1993;31:1099-1111
- Daly JW, Caceres
J, Moni RW, et al. Frog secretions and hunting magic in the upper Amazon:
identification of a peptide that interacts with an adenosine receptor. Proceedings of the National Academy of Sciences USA.
1992;89:10960-10963.
- den Brave PS,
Bruins E, Bronkhorst MW. Phyllomedusa bicolor skin secretion and the Kambô ritual. The Journal
of Venomous Animals and Toxins Including Tropical Diseases. 2014;20:40.
- Weil AT, Davis W. Bufo
alvarius: a potent hallucinogen of animal origin. Journal of Ethnopharmacology. 1994;41:1-8.
- Lyttle T,
Goldstein D, Gartz J. Bufo toads and bufotenine: fact and
fiction surrounding an alleged psychedelic. Journal
of Psychoactive Drugs. 1996;28:267-290.
- Dakic V, Maciel
RM, Drummond H, Nascimento JM, Trindade P, Rehen SK. Harmine
stimulates proliferation of human neural progenitors. Peer J. 2016;4:e2727.
- Cao R, Peng W, Wang Z, Xu A. Beta-carboline
alkaloids: biochemical and pharmacological functions. Current Medicinal Chemistry. 2007;14:479-500.
- Patel K, Gadewar M, Tripathi R, Prasad SK,
Patel DK. A review on medicinal importance, pharmacological activity and
bioanalytical aspects of beta-carboline alkaloid “Harmine.” Asian Pacific Journal of Trop Biomedicine.
2012;2:660-664.
|