Quantification of 24 circulating endocannabinoids, endocannabinoid-related compounds, and their phospholipid precursors in human plasma by UHPLC-MS/MS

Effects of fermentation and alkalisation on the formation of endocannabinoid-like compounds in olives

The increasing interest in endocannabinoid-like compounds (ECL) in food stems from their important physiological roles, including energy metabolism and satiety. In this study, the effect of fermentation or alkalisation on the formation of ECL compounds in table olives was investigated. N-acylethanolamines, monoacylglycerols, N-acylamino acids, and N-acylneurotransmitters were monitored. Results revealed that alkaline treatment led to a significant increase in the concentrations of N-oleoylethanolamide (80%), N-palmitoylethanolamide (93%), N-linoleoylethanolamide (51%), and 1-oleoylglycerol (679%) compared to control. While N-oleoylethanolamide, N-palmitoylethanolamide, N-linoleoylethanolamide, 1- and 2-oleoylglycerol, 1- and 2-linoleoylglycerol, and oleoylphenylalanine were initially absent or present in trace amounts, their levels significantly rose during fermentation. The formation rate of these compounds was higher in olives fermented in water than those in brine. The study provides detailed information on how specific ECL compounds respond to different processing methods, offering valuable information for optimising table olive production to enhance its nutritional benefits.

Advances in targeted liquid chromatography-tandem mass spectrometry methods for endocannabinoid and N-acylethanolamine quantification in biological matrices: A systematic review

Liquid chromatography paired with tandem mass spectrometry (LC-MS/MS) is the gold standard in measurement of endocannabinoid concentrations in biomatrices. We conducted a systematic review of literature to identify advances in targeted LC-MS/MS methods in the period 2017-2024. We found that LC-MS/MS methods for endocannabinoid quantification are relatively consistent both across time and across biomatrices. Recent advances have primarily been in three areas: (1) sample preparation techniques, specific to the chosen biomatrix; (2) the range of biomatrices tested, recently favoring blood matrices; and (3) the breadth of endocannabinoid and endocannabinoid-like analytes incorporated into assays. This review provides a summary of the recent literature and a guide for researchers looking to establish the best methods for quantifying endocannabinoids in a range of biomatrices.

Microbiome metabolite quantification methods enabling insights into human health and disease

Many of the health-associated impacts of the microbiome are mediated by its chemical activity, producing and modifying small molecules (metabolites). Thus, microbiome metabolite quantification has a central role in efforts to elucidate and measure microbiome function. In this review, we cover general considerations when designing experiments to quantify microbiome metabolites, including sample preparation, data acquisition and data processing, since these are critical to downstream data quality. We then discuss data analysis and experimental steps to demonstrate that a given metabolite feature is of microbial origin. We further discuss techniques used to quantify common microbial metabolites, including short-chain fatty acids (SCFA), secondary bile acids (BAs), tryptophan derivatives, N-acyl amides and trimethylamine N-oxide (TMAO). Lastly, we conclude with challenges and future directions for the field.

Metabolomic profile of acute myeloid leukaemia parallels of prognosis and response to therapy

The heterogeneity of acute myeloid leukemia (AML), a complex hematological malignancy, is caused by mutations in myeloid cells affecting their differentiation and proliferation. Thus, various cytogenetic alterations in AML cells may be characterized by a unique metabolome and require different treatment approaches. In this study, we performed untargeted metabolomics to assess metabolomics differences between AML patients and healthy controls, AML patients with different treatment outcomes, AML patients in different risk groups based on the 2017 European LeukemiaNet (ELN) recommendations for the diagnosis and management of AML, AML patients with and without FLT3-ITD mutation, and a comparison between patients with FLT3-ITD, CBF-AML (Core binding factor acute myelogenous leukemia), and MLL AML (mixed-lineage leukemia gene) in comparison to control subjects. Analyses were performed in serum samples using liquid chromatography coupled with mass spectrometry (LC-MS). The obtained metabolomics profiles exhibited many alterations in glycerophospholipid and sphingolipid metabolism and allowed us to propose biomarkers based on each of the above assessments as an aid for diagnosis and eventual classification, allowing physicians to choose the best-suited treatment approach. These results highlight the application of LC-MS-based metabolomics of serum samples as an aid in diagnostics and a potential minimally invasive prognostic tool for identifying various cytogenetic and treatment outcomes of AML.

Dietary linoleic acid lowering alone does not lower arachidonic acid or endocannabinoids among women with overweight and obesity: A randomized, controlled trial

The linoleic acid (LA)-arachidonic acid (ARA)-inflammatory axis suggests dietary LA lowering benefits health because it lowers ARA and ARA-derived endocannabinoids (ECB). Dietary LA reduction increases concentrations of omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and DHA derived ECB. The aim of this study was to examine targeted reduction of dietary LA, with and without EPA and DHA, on plasma EPA and DHA and ECB (2-arachidonoyl glycerol [2-AG], anandamide [AEA], and docosahexaenoyl ethanolamide [DHA-EA]). Healthy, pre-menopausal women (n = 62, BMI 30 ± 3 kg/m2 , age 35 ± 7 years; mean ± SD) were randomized to three 12-week controlled diets: (1) high LA, low omega-3 EPA and DHA (H6L3); (2) low LA, low omega-3 EPA and DHA (L6L3); or (3) low LA, high omega-3 EPA and DHA (L6H3). Baseline plasma fatty acids and ECB were similar between diets. Starting at 4 weeks, L6L3 and L6H3 lowered plasma LA compared to H6L3 (p < 0.001). While plasma ARA changed from baseline by 8% in L6L3 and -8% in L6H3, there were no group differences. After 4 weeks, plasma EPA and DHA increased from baseline in women on the L6H3 diet (ps < 0.001) and were different than the H6L3 and L6L3 diets. No differences were found between diets for AEA or 2-AG, however, in L6L3 and L6H3, AEA increased by 14% (ps < 0.02). L6H3 resulted in 35% higher DHA-EA (p = 0.013) whereas no changes were seen with the other diets. Lowering dietary LA did not result in the expected changes in fatty acids associated with the LA-ARA inflammatory axis in women with overweight and obesity.

Set up and validation of a sensitive method to quantify prostaglandins, prostaglandin-glycerol esters and prostaglandin-ethanolamides, as well as their respective precursors

Arachidonic acid-derived prostaglandins are widely studied for their role in inflammation. However, besides arachidonic acid, other arachidonic moiety-containing lipids can be metabolized by COX-2. Indeed, the endocannabinoids 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide, AEA) can follow the same biochemical pathways than arachidonic acid leading to the formation of prostaglandin-glycerol esters (PG-G) and prostaglandin-ethanolamides (or prostamides, PG-EA), respectively. The data reported so far support the interest of these bioactive lipids in inflammatory conditions. However, there is only a handful of methods described for their quantification in biological matrices. Moreover, given the shared biochemical pathways for arachidonic acid, 2-AG and AEA, a method allowing for the quantification of these precursors and the corresponding prostaglandin derivatives appears as largely needed. Thus, we report here the development and validation of a single run UPLC-MS/MS quantification method allowing the quantification of these endocannabinoids-derived mediators together with the classical prostaglandin. Moreover, we applied the method to the quantification of these lipids in vitro (using lipopolysaccharides-activated J774 macrophage cells) and in vivo in several tissues from DSS-induced colitis mice. This femtomole-range method should improve the understanding of the interaction between these lipid mediators and inflammation.

PE, or not PE, that is the question: The case of overlooked lyso-N-acylphosphatidylethanolamines

RATIONALE

Lyso derivatives of N-acyl-1,2-diacylglycero-3-phosphoethanolamines (L-NAPEs) are a lipid class mostly expressed in vegetables during stress and tissue damage that is involved in the synthesis of the lipid mediator N-acylethanolamines. L-NAPEs can be challenging to distinguish from isomeric phosphatidylethanolamines (PEs), especially in extracted complex samples where they could be confused with abundant PEs.

METHODS

In this study, hydrophilic interaction liquid chromatography with electrospray ionization hyphenated with (tandem) mass spectrometry (MS) was proposed to distinguish L-NAPEs and PEs as deprotonated molecules, [M - H]^─ , using both high-resolution/accuracy Fourier transform MS and low-resolution linear ion trap (LIT) mass analyzers. MS³ experiments of [M - H - KE]^─ as precursor ions (KE, ketene loss) using the LIT instrument allowed us to distinguish between isomeric L-NAPE and PE species.

RESULTS

Regiochemical rules were proposed working on enzymatically synthesized L-NAPEs. A few key differences in MS/MS spectra, including abnormal intensity of acyl chain losses as fatty acids, the presence of N-acylphosphoethanolamine ions, and diagnostic ions of the polar head, were disclosed. Additionally, MS³ spectra of [M - H - KE]^─ as precursor ions allowed us to confirm the identification of L-NAPE species. The proposed rules were applied to samples extracted from tomato by-products including stems and leaves.

CONCLUSIONS

Overall, our methodology is demonstrated as a robust approach to recognizing L-NAPEs in complex samples. L-NAPEs 18:2-N-18:2, 18:2-N-18:3, 18:3-N-18:2, and 18:2-N-18:1 were the prevailing compounds in the analyzed tomato samples, accounting for more than 90%. In summary, a reliable method for identifying L-NAPEs in complex samples is described. The proposed method could prevent overlooking L-NAPEs and overestimating isomeric PE species in future lipid analyses.

Determination of endocannabinoids in fermented foods of animal and plant origin by liquid chromatography tandem mass spectrometry

An analytical method was developed for the determination of endocannabinoids and endocannabinoid-like compounds using ultra high performance liquid chromatography tandem mass spectrometry in fermented food products. Extraction optimization and method validation were carried out to detect 36 endocannabinoids and endocannabinoid-like compounds including N-acylethanolamines, N-acylamino acids, N-acylneurotransmitters, monoacylglycerols and primary fatty acid amides using 7 isotope labelled internal standards in foods. The method was able to detect precisely these compounds with good linearity (R2 > 0.982), reproducibility (0.1-14.4%), repeatability (0.3-18.4%), recovery (>67%) and high sensitivity. The limit of detection ranged between 0.01 and 4.30 ng/mL, and of quantitation between 0.02 and 14.2 ng/mL. Fermented sausage and cheese as animal-origin fermented foods and cocoa powder as plant-origin fermented foods were found to be rich in endocannabinoids and endocannabinoid-like compounds. N-Acylamino acids and N-acylneurotransmitters detected for the first time in fermented foods will provide important preliminary information for future studies.

Determination of endocannabinoids and their conjugated congeners in the brain by means of μSPE combined with UHPLC-MS/MS

The present study encompasses the development of a fast and reliable analytical method to quantify the main endocannabinoids and some of their conjugated congeners, particularly N-arachidonoyl amino acids, in brain tissue. Samples were homogenized and a micro solid phase extraction (μSPE) procedure was developed for brain homogenate clean-up. Miniaturized SPE was selected as it allowed to work with reduced sample amounts, while maintaining high sensitivity; this last feature was mandatory due to the low concentration of endocannabinoids in biological matrices that makes their determination a challenging analytical task. UHPLC-MS/MS was used for the analysis as it provided a great sensitivity, especially for conjugated forms that were detected by negative ionization. Polarity switching was applied during the run; low limits of quantification were between 0.003 ng g^-1 and 0.5 ng g^-1. This method provided also low matrix effect (lower than 30%) and good extraction recoveries in the brain. To the best of our knowledge, this is the first time that μSPE is applied on this matrix for this class of compounds. The method was validated according to international guidelines, and then tested on real cerebellum samples from mice, which were sub-chronically treated with URB597, a well-known inhibitor of the fatty acid amide hydrolase.

From fundamentals in calibration to modern methodologies: A tutorial for small molecules quantification in liquid chromatography-mass spectrometry bioanalysis

Over the last two decades, liquid chromatography coupled to mass-spectrometry (LC‒MS) has become the gold standard to perform qualitative and quantitative analyses of small molecules. When quantitative analysis is developed, an analyst usually refers to international guidelines for analytical method validation. In this context, the design of calibration curves plays a key role in providing accurate results. During recent years and along with instrumental advances, strategies to build calibration curves have dramatically evolved, introducing innovative approaches to improve quantitative precision and throughput. For example, when a labeled standard is available to be spiked directly into the study sample, the concentration of the unlabeled analog can be easily determined using the isotopic pattern deconvolution or the internal calibration approach, eliminating the need for multipoint calibration curves. This tutorial aims to synthetize the advances in LC‒MS quantitative analysis for small molecules in complex matrices, going from fundamental aspects in calibration to modern methodologies and applications. Different work schemes for calibration depending on the sample characteristics (analyte and matrix nature) are distinguished and discussed. Finally, this tutorial outlines the importance of having international guidelines for analytical method validation that agree with the advances in calibration strategies and analytical instrumentation.

Cannabinoids as Prospective Anti-Cancer Drugs: Mechanism of Action in Healthy and Cancer Cells

Endogenous and exogenous cannabinoids modulate many physiological and pathological processes by binding classical cannabinoid receptors 1 (CB1) or 2 (CB2) or non-cannabinoid receptors. Cannabinoids are known to exert antiproliferative, apoptotic, anti-migratory and anti-invasive effect on cancer cells by inducing or inhibiting various signaling cascades. In this chapter, we specifically emphasize the latest research works about the alterations in endocannabinoid system (ECS) components in malignancies and cancer cell proliferation, migration, invasion, angiogenesis, autophagy, and death by cannabinoid administration, emphasizing their mechanism of action, and give a future perspective for clinical use.

Quantification of Endocannabinoids in Human Plasma

The determination of the concentration of endocannabinoids and related compounds in human plasma has become a matter of interest due to their implication in physiological processes and, thus, their possible relation with physiological conditions or illnesses. The analysis of these compounds though has to be carefully designed as they are found in very low concentrations, and some of them degrade easily once blood is collected. In this chapter, a simple method based on a liquid-liquid extraction and analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) is described to determine the concentration of eight of the most relevant endocannabinoids in plasma.

Plasma Oxylipins and Their Precursors Are Strongly Associated with COVID-19 Severity and with Immune Response Markers

COVID-19 is characterised by a dysregulated immune response, that involves signalling lipids acting as mediators of the inflammatory process along the innate and adaptive phases. To promote understanding of the disease biochemistry and provide targets for intervention, we applied a range of LC-MS platforms to analyse over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). The second publication in a series reports the results of quantitative LC-MS/MS profiling of 63 small lipids including oxylipins, free fatty acids, and endocannabinoids. Compared to samples taken from ward patients, intensive care unit (ICU) patients had 2−4-fold lower levels of arachidonic acid (AA) and its cyclooxygenase-derived prostanoids, as well as lipoxygenase derivatives, exhibiting negative correlations with inflammation markers. The same derivatives showed 2−5-fold increases in recovering ward patients, in paired comparison to early hospitalisation. In contrast, ICU patients showed elevated levels of oxylipins derived from poly-unsaturated fatty acids (PUFA) by non-enzymatic peroxidation or activity of soluble epoxide hydrolase (sEH), and these oxylipins positively correlated with markers of macrophage activation. The deficiency in AA enzymatic products and the lack of elevated intermediates of pro-resolving mediating lipids may result from the preference of alternative metabolic conversions rather than diminished stores of PUFA precursors. Supporting this, ICU patients showed 2-to-11-fold higher levels of linoleic acid (LA) and the corresponding fatty acyl glycerols of AA and LA, all strongly correlated with multiple markers of excessive immune response. Our results suggest that the altered oxylipin metabolism disrupts the expected shift from innate immune response to resolution of inflammation.

Molecular Alterations of the Endocannabinoid System in Psychiatric Disorders

The therapeutic benefits of the current medications for patients with psychiatric disorders contrast with a great variety of adverse effects. The endocannabinoid system (ECS) components have gained high interest as potential new targets for treating psychiatry diseases because of their neuromodulator role, which is essential to understanding the regulation of many brain functions. This article reviewed the molecular alterations in ECS occurring in different psychiatric conditions. The methods used to identify alterations in the ECS were also described. We used a translational approach. The animal models reproducing some behavioral and/or neurochemical aspects of psychiatric disorders and the molecular alterations in clinical studies in post-mortem brain tissue or peripheral tissues were analyzed. This article reviewed the most relevant ECS changes in prevalent psychiatric diseases such as mood disorders, schizophrenia, autism, attentional deficit, eating disorders (ED), and addiction. The review concludes that clinical research studies are urgently needed for two different purposes: (1) To identify alterations of the ECS components potentially useful as new biomarkers relating to a specific disease or condition, and (2) to design new therapeutic targets based on the specific alterations found to improve the pharmacological treatment in psychiatry.

Pre-analytical challenges for the quantification of endocannabinoids in human serum

Endocannabinoids (ECs) are potent lipid mediators with high physiological relevance. They are involved in a wide variety of diseases like depression or multiple sclerosis and are closely connected to metabolic parameters in humans. Therefore, their suitability as a biomarker in different (patho-)physiological conditions is discussed intensively and predominantly investigated by analyzing systemic concentrations in easily accessible matrices like blood. Carefully designed pre-analytical sample handling is of major importance for high-quality data, but harmonization is not achieved yet. Whole blood is either processed to serum or plasma before the onset of analytical workflows and while knowledge about pre-analytical challenges in plasma handling is thorough they were not systematically investigated for serum. Therefore, the ECs AEA and 2-AG, and closely related EC-like substances 1-AG, DHEA, and PEA were examined by LC-MS/MS in serum samples of nine healthy volunteers employing different pre-analytical sample handling protocols, including prolonged coagulation, and storage after centrifugation at room temperature (RT) or on ice. Furthermore, all analytes were also assessed in plasma samples obtained from the same individuals at the same time points to investigate the comparability between those two blood-based matrices regarding obtained concentrations and their 2-AG/1-AG ratio. This study shows that ECs and EC-like substances in serum samples were significantly higher than in plasma and are especially prone to ex vivo changes during initial and prolonged storage for coagulation at RT. Storage on ice after centrifugation is less critical. However, storage at RT further increases 1-AG and 2-AG concentrations, while also lowering the already reduced 2-AG/1-AG ratio due to isomerization. Thus, avoidance of prolonged processing at RT can increase data quality if serum as the matrix of choice is unavoidable. However, serum preparation in itself is expected to initiate changes of physiological concentrations as standard precautionary measures like fast and cooled processing can only be utilized by using plasma, which should be the preferred matrix for analyses of ECs and EC-like substances.

Endocannabinoids as potential biomarkers: It's all about pre-analytics

Introduction

Arachidonoyl ethanolamide (AEA) and 2-arachidonoyl glycerol (2-AG) are central lipid mediators of the endocannabinoid system. They are highly relevant due to their involvement in a wide variety of inflammatory, metabolic or malign diseases. Further elucidation of their modes of action and use as biomarkers in an easily accessible matrix, like blood, is restricted by their susceptibility to deviations during blood sampling and physiological co-dependences, which results in high variability of reported concentrations in low ng/mL ranges.

Objectives

The objective of this review is the identification of critical parameters during the pre-analytical phase and proposal of minimum requirements for reliable determination of endocannabinoids (ECs) in blood samples.

Methods

Reported physiological processes influencing the EC concentrations were put into context with published pre-analytical research and stability data from bioanalytical method validation.

Results

The cause for variability in EC concentrations is versatile. In part, they are caused by inter-individual factors like sex, metabolic status and/or diurnal changes. Nevertheless, enzymatic activity in freshly drawn blood samples is the main reason for changing concentrations of AEA and 2-AG, besides additional non-enzymatic isomerization of the latter.

Conclusion

Blood samples for EC analyses require immediate processing at low temperatures (>0 °C) to maintain sample integrity. Standardization of the respective blood tube or anti-coagulant, sampling time point, applied centrifugal force and complete processing time can further decrease variability caused by sample handling. Nevertheless, extensive characterization of study participants is needed to reduce distortion of clinical data caused by co-variables and facilitate research on the endocannabinoid system.

The Role of Cannabinoids in Bone Metabolism: A New Perspective for Bone Disorders

Novel interest has arisen in recent years regarding bone, which is a very complex and dynamic tissue deputed to several functions ranging from mechanical and protective support to hematopoiesis and calcium homeostasis maintenance. In order to address these tasks, a very refined, continuous remodeling process needs to occur involving the coordinated action of different types of bone cells: osteoblasts (OBs), which have the capacity to produce newly formed bone, and osteoclasts (OCs), which can remove old bone. Bone remodeling is a highly regulated process that requires many hormones and messenger molecules, both at the systemic and the local level. The whole picture is still not fully understood, and the role of novel actors, such as the components of the endocannabinoids system (ECS), including endogenous cannabinoid ligands (ECs), cannabinoid receptors (CBRs), and the enzymes responsible for endogenous ligand synthesis and breakdown, is extremely intriguing. This article reviews the connection between the ECS and skeletal health, supporting the potential use of cannabinoid receptor ligands for the treatment of bone diseases associated with accelerated osteoclastic bone resorption, including osteoporosis and bone metastasis.

Quantitative profiling of inflammatory and pro-resolving lipid mediators in human adolescents and mouse plasma using UHPLC-MS/MS

OBJECTIVES

Lipid mediators are bioactive lipids which help regulate inflammation. We aimed to develop an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to quantify 58 pro-inflammatory and pro-resolving lipid mediators in plasma, determine preliminary reference ranges for adolescents, and investigate how total parenteral nutrition (TPN) containing omega-3 polyunsaturated fatty acid (n-3 PUFA) or n-6 PUFA based lipid emulsions influence lipid mediator concentrations in plasma.

METHODS

Lipid mediators were extracted from plasma using SPE and measured using UHPLC-MS/MS. EDTA plasma was collected from healthy adolescents between 13 and 17 years of age to determine preliminary reference ranges and from mice given intravenous TPN for seven days containing either an n-3 PUFA or n-6 PUFA based lipid emulsion.

RESULTS

We successfully quantified 43 lipid mediators in human plasma with good precision and recovery including several leukotrienes, prostaglandins, resolvins, protectins, maresins, and lipoxins. We found that the addition of methanol to human plasma after blood separation reduces post blood draw increases in 12-hydroxyeicosatetraenoic acid (12-HETE), 12-hydroxyeicosapentaenoic acid (12-HEPE), 12S-hydroxyeicosatrienoic acid (12S-HETrE), 14-hydroxydocosahexaenoic acid (14-HDHA) and thromboxane B2 (TXB2). Compared to the n-6 PUFA based TPN, the n-3 PUFA based TPN increased specialized pro-resolving mediators such as maresin 1 (MaR1), MaR2, protectin D1 (PD1), PDX, and resolvin D5 (RvD5), and decreased inflammatory lipid mediators such as leukotriene B4 (LTB4) and prostaglandin D2 (PGD2).

CONCLUSIONS

Our method provides an accurate and sensitive quantification of 58 lipid mediators from plasma samples, which we used to establish a preliminary reference range for lipid mediators in plasma samples of adolescents; and to show that n-3 PUFA, compared to n-6 PUFA rich TPN, leads to a less inflammatory lipid mediator profile in mice.

Analysis of 14 endocannabinoids and endocannabinoid congeners in human plasma using column switching high-performance atmospheric pressure chemical ionization liquid chromatography-mass spectrometry

The endocannabinoid system (ECS) is a complex cell-signaling system. To address the growing need of analytics capturing endocannabinoid levels to investigate the ECS, we developed and validated an assay for the quantitative analysis of 14 endocannabinoids and congeners. A simple extraction using protein precipitation with acetonitrile followed by online-trapping high-performance liquid chromatography-tandem mass spectrometry (LC/LC-MS/MS) was used to monitor the levels of 14 endocannabinoids in plasma. The assay was validated and intra-run and inter-run accuracies and imprecisions as well as matrix effects, recoveries, and sample stabilities were determined. As a proof of concept, a subset of study samples after naturalistic administration of Cannabis flower and concentrate was analyzed. With the exception of N-oleoyl dopamine and oleamide, all endocannabinoids fulfilled the predefined acceptance criteria. Reproducible recoveries and no significant matrix effects were observed. Sample stability was an issue. Analysis of the proof-of-concept study samples revealed a significantly (p = 0.006) higher concentration of docosatetraenoyl ethanolamide in concentrate users (300 ± 13 pg/mL) compared to flower users (252 ± 11 pg/mL). A robust, sensitive high-throughput assay for the quantitation of 14 endocannabinoids and congeners was successfully validated. Our study showed that it is mandatory to (A) appropriately stabilize samples and (B) separate and separately quantify 1-AG and 2-AG; otherwise, study results are unreliable. The analysis of study samples from Cannabis flower users versus Cannabis concentrate users revealed higher levels of docosatetraenoyl ethanolamide and anandamide (n.s.) in high THC concentrate users in accordance with the existing literature, supporting the validity of the assay measurements. Graphical abstract.

Endocannabinoids, endocannabinoid-like molecules and their precursors in human small intestinal lumen and plasma: does diet affect them?

PURPOSE

To determine the small intestinal concentration of endocannabinoids (ECs), N-acylethanolamines (NAEs) and their precursors N-acylphosphatidylethanolamines (NAPEs) in humans. To identify relationships between those concentrations and habitual diet composition as well as individual inflammatory status.

METHODS

An observational study was performed involving 35 participants with an ileostomy (18W/17M, aged 18-70 years, BMI 17-40 kg/m²). Overnight fasting samples of ileal fluid and plasma were collected and ECs, NAEs and NAPEs concentrations were determined by LC-HRMS. Dietary data were estimated from self-reported 4-day food diaries.

RESULTS

Regarding ECs, N-arachidonoylethanolamide (AEA) was not detected in ileal fluids while 2-arachidonoylglycerol (2-AG) was identified in samples from two participants with a maximum concentration of 129.3 µg/mL. In contrast, mean plasma concentration of AEA was 2.1 ± 0.06 ng/mL and 2-AG was 4.9 ± 1.05 ng/mL. NAEs concentrations were in the range 0.72-17.6 µg/mL in ileal fluids and 0.014-0.039 µg/mL in plasma. NAPEs concentrations were in the range 0.3-71.5 µg/mL in ileal fluids and 0.19-1.24 µg/mL in plasma being more abundant in participants with obesity than normal weight and overweight. Significant correlations between the concentrations of AEA, OEA and LEA in biological fluids with habitual energy or fat intakes were identified. Plasma PEA positively correlated with serum C-reactive protein.

CONCLUSION

We quantified ECs, NAEs and NAPEs in the intestinal lumen. Fat and energy intake may influence plasma and intestinal concentrations of these compounds. The luminal concentrations reported would allow modulation of the homeostatic control of food intake via activation of GPR119 receptors located on the gastro-intestinal mucosa.

CLINICAL TRIAL REGISTRY NUMBER AND WEBSITE

NCT04143139; www.clinicaltrials.gov .