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Steven A Barker

Louisiana State University, Department of Comparative Biomedical Sciences, Baton Rouge, LA 70803, United States of America. Electronic address: sbarke1@lsu.edu.

6 papers in the library · 493 citations · publishing 2009-2019

Papers

A critical review of reports of endogenous psychedelic N, N-dimethyltryptamines in humans: 1955-2010.

Drug testing and analysis January 1, 2012 Steven A Barker, Ethan H Mcilhenny, Rick Strassman 143 citations

Three indole alkaloids with varying psychedelic activity—DMT, bufotenine, and 5-MeO-DMT—have been reported as naturally occurring in humans. A critical review of 69 studies from 1955 to 2010 examined their detection in blood, urine, and cerebrospinal fluid. The review evaluates the methods and criteria used, highlighting strengths and weaknesses of past approaches. It notes shortcomings in existing data given recent findings and suggests future directions for research on these endogenous psychedelics.

Biosynthesis and Extracellular Concentrations of N,N-dimethyltryptamine (DMT) in Mammalian Brain.

Scientific reports June 27, 2019 Jon G Dean, Tiecheng Liu, Sean Huff et al. 111 citations

The psychedelic compound N,N-dimethyltryptamine (DMT) is produced naturally in mammals, but whether it is made in the brain was unclear. This study found that the enzymes needed to synthesize DMT are present in the cerebral cortex, pineal gland, and choroid plexus of both rats and humans. In rat brain tissues, the two key enzymes were found together, unlike in peripheral tissues. DMT concentrations in the cerebral cortex of behaving rats were similar to those of neurotransmitters like serotonin. DMT levels in the visual cortex rose significantly after cardiac arrest, even without the pineal gland. These findings indicate the rat brain can synthesize and release DMT at neurotransmitter-like levels, suggesting human brains might do the same.

LC/MS/MS analysis of the endogenous dimethyltryptamine hallucinogens, their precursors, and major metabolites in rat pineal gland microdialysate.

Biomedical chromatography : BMC December 1, 2013 Steven A Barker, Jimo Borjigin, Izabela Lomnicka et al. 73 citations

A qualitative liquid chromatography-tandem mass spectrometry method was developed to simultaneously analyze three known N,N-dimethyltryptamine endogenous hallucinogens, their precursors and metabolites, as well as melatonin and its metabolic precursors. The method was characterized using artificial cerebrospinal fluid and applied to rat brain pineal gland microdialysate. It allows direct injection of 23 chemically diverse compounds plus a deuterated internal standard without dilution or extraction. The approach is simple, sensitive, specific, and uses stringent MS confirmatory criteria including exact mass measurements. For the first time, N,N-dimethyltryptamine was detected in pineal gland microdialysate from the rat.

Direct analysis of psychoactive tryptamine and harmala alkaloids in the Amazonian botanical medicine ayahuasca by liquid chromatography-electrospray ionization-tandem mass spectrometry.

Journal of chromatography. A December 18, 2009 Ethan H Mcilhenny, Kelly E Pipkin, Leanna J Standish et al. 58 citations

A new analytical method using direct injection and liquid chromatography-tandem mass spectrometry can simultaneously measure 11 psychoactive compounds in ayahuasca, a plant-based Amazonian beverage used in traditional medicine and religious ceremonies. The technique uses a deuterated internal standard for accurate quantitation and requires only simple dilution of samples up to 200-fold, avoiding complex extraction steps. It shows high specificity, low detection and quantitation limits, and appears to eliminate matrix effects. The method was tested on three different ayahuasca preparations and is expected to aid clinical, ethnobotanical, and forensic studies.

Methodology for determining major constituents of ayahuasca and their metabolites in blood.

Biomedical chromatography : BMC March 1, 2012 Ethan H Mcilhenny, Jordi Riba, Manel J Barbanoj et al. 57 citations

A new single analytical method can directly measure 14 major alkaloid components of ayahuasca, including known and potential metabolites of N,N-dimethyltryptamine and harmala alkaloids, in human blood plasma. The method uses 96-well plate protein precipitation and filtration followed by HPLC-ion trap-ion trap-mass spectrometry with heated electrospray ionization to reduce matrix effects. It provides adequate sensitivity, specificity, and reproducibility for clinical research, expanding the list of compounds that can be monitored after ayahuasca administration while simplifying the analysis compared to previous combined techniques.

Methodology for and the determination of the major constituents and metabolites of the Amazonian botanical medicine ayahuasca in human urine.

Biomedical chromatography : BMC September 1, 2011 Ethan H Mcilhenny, Jordi Riba, Manel J Barbanoj et al. 51 citations

The primary metabolite of N,N-dimethyltryptamine (DMT) in humans after ayahuasca ingestion is the corresponding N-oxide, the first time this metabolite has been described in in vivo human studies. Very little DMT was detected in urine, despite monoamine oxidase inhibition by harmala alkaloids. The major harmala alkaloid excreted was tetrahydroharmine. A rapid, sensitive method using HPLC-electrospray ionization-selected reaction monitoring-tandem mass spectrometry was developed and applied to urine samples from three individuals administered ayahuasca, identifying and quantifying major constituents and metabolites. The protocol is suitable for toxicological and clinical research on ayahuasca.