Determination of N,N-dimethyltryptamine and β-carboline alkaloids in human plasma following oral administration of Ayahuasca

A method to measure the four main alkaloids in ayahuasca (DMT, harmine, harmaline, and tetrahydroharmine) plus two major metabolites (harmol and harmalol) in human plasma is described. DMT is extracted with n-pentane and quantified by gas chromatography with nitrogen-phosphorus detection, achieving 74% recovery, precision and accuracy better than 9.9%, and a limit of quantification of 1.6 ng/ml. The beta-carbolines and metabolites are measured by high-performance liquid chromatography with fluorescence detection after solid-phase extraction, with recoveries above 87%, accuracy and precision better than 13.4%, and limits of quantification from 0.3 to 1.0 ng/ml. The methods allow adequate characterization of the pharmacokinetics of these compounds, including two major metabolites not previously described.

Study at a glance

Abstract

Ayahuasca is a South American psychotropic beverage prepared from plants native to the Amazon River Basin. It combines the hallucinogenic agent and 5-HT(2A/2C) agonist N,N-dimethyltryptamine (DMT) with beta-carboline alkaloids showing monoamine oxidase-inhibiting properties. In the present paper, an analytical methodology for the plasma quantification of the four main alkaloids present in ayahuasca plus two major metabolites is described. DMT was extracted by liquid-liquid extraction with n-pentane and quantified by gas chromatography with nitrogen-phosphorus detection. Recovery was 74%, and precision and accuracy were better than 9.9%. The limit of quantification (LOQ) was 1.6 ng/ml. Harmine, harmaline, and tetrahydroharmine (THH), the three main beta-carbolines present in ayahuasca, and harmol and harmalol (O-demethylation metabolites of harmine and harmaline, respectively) were measured in plasma by means of high-performance liquid chromatography (HPLC) with fluorescence detection. Sample preparation was accomplished by solid-phase extraction, which facilitated the automation of the process. All five beta-carbolines were measured using a single detector by switching wavelengths. Separation of harmol and harmalol required only slight changes in the chromatographic conditions. Method validation demonstrated good recoveries, above 87%, and accuracy and precision better than 13.4%. The LOQ was 0.5 ng/ml for harmine, 0.3 ng/ml for harmaline, 1.0 ng/ml for THH, and 0.3 ng/ml for harmol and harmalol. Good linearity was observed in the concentration ranges evaluated for DMT (2.5-50 ng/ml) and the beta-carbolines (0.3-100 ng/ml). The gas chromatography and HPLC methods described allowed adequate characterization of the pharmacokinetics of the four main alkaloids present in ayahuasca, and also of two major beta-carboline metabolites not previously described in the literature.