Simultaneous analysis of tropane alkaloids in teas and herbal teas by liquid chromatography coupled to high-resolution mass spectrometry (Orbitrap)

Reports of tropane alkaloid poisonings and analytical techniques for their determination in food crops and products from 2013 to 2023

Food safety is crucial to attaining food security and sustainability. Unsafe foods for human and animal consumption lead to product recalls and rejection, negatively impacting the global economy and trade. Similarly, climate change can adversely affect the availability of safe and nutritious food at the table. The changing climatic conditions and global food trade and transport can make the movement of toxic plants possible, resulting in food crops being increasingly invaded by some species of plants that produce toxic secondary metabolites, such as tropane alkaloids (TAs). Datura stramonium from the Solanaceae plant family is an invasive and virulent plant that produces high amounts of two TAs, atropine and scopolamine. Various food poisoning events following accidental or deliberate ingestion of foods contaminated by atropine and scopolamine from seeds of D. stramonium have been recorded in different locations globally. Due to these incidents, regulatory agencies require the development of plant toxin detection methods that can be used in the food chain as early as possible. This systematic review thus focuses on the TA determination techniques in food and feeds published between 2013 and 2023. A particular focus was given to the sample preparation methods, the improvements of each technique claimed, and data to support the performance of each method, especially the ability to measure at or below the maximum level. The review concludes with other technological advancements, including rapid spectroscopy, electrophoresis, and colorimetric methods, as well as the possibility of coupling with smartphones for use in on-farm detection and the challenges in applying them.

A comprehensive study on the digestion, absorption, and metabolization of tropane alkaloids in human cell models

Tropane alkaloids (TAs) are toxic compounds with potent anticholinergic effects. Herbal infusions are among the most contaminated food commodities; however, the fate of TAs after ingestion remains poorly understood. This study presents a comprehensive investigation into the absorption, and metabolism of five TAs (atropine, scopolamine, tropine, homatropine, and apoatropine) following the digestion of contaminated tea. In vitro human cell models were employed, including gastric (NCI-N87), intestinal (Caco-2:HT29-MTX), and hepatic (HEP-G2) cells. TAs were found to be highly absorbed in the intestinal epithelium, while gastric cells exhibited poor absorption. Metabolism was studied using a custom-made database, revealing that it occurs predominantly in intestinal cells, involving hydroxylation and methylation reactions. Cell metabolomics was conducted using annotation, fragment simulation, and statistical software platforms. Significant statistical differences were observed for 40 tentatively identified compounds. MetaboAnalyst 5.0 was employed to discern the most disturbed metabolic pathways, with amoniacids biosynthesis pathways and TCA cycles being the most affected. These pathways are involved in responses to cellular metabolic stress, neurotransmitter production, cellular energy generation, and the regulation of oxidative stress response. The findings of this study enhance our understanding of the fate of TAs after ingestion, their metabolization and their effects at the cellular level.

The screening method for 39 phytotoxins and mycotoxins in blood and urine with liquid chromatography-high resolution mass spectrometry

BACKGROUND

Poisonings caused by plant toxins and mycotoxins occur frequently, which do great harm to human health and social public health safety. When a poisoning incident occurs, biological samples are commonly be used to conduct the detection of toxic substances and their metabolites for targeted clinical treatment and incident analysis.

OBJECTIVE

To establish an efficient and accurate analysis method of 39 phytotoxins and mycotoxins in blood and urine by high performance liquid chromatography quadrupole tandem orbitrap mass spectrometry (HPLC-Orbitrap MS).

METHOD

After 3 mL of methanol being added to 1 mL blood and urine respectively for extraction and protein precipitation, the supernatant was injected into HPLC-Orbitrap MS for analysis. The phytotoxins and mycotoxins were separated by Hypersil GOLD PFP column with gradient elution using methanol-5 mmol/L ammonium acetate as mobile phase. The data were collected in ESI positive ion mode using Full MS/dd-MS2 for mass spectrometry detection.

RESULT

The mass database of 39 phytotoxins and mycotoxins was developed, and accurate qualitative analysis can be obtained by matching with the database using the proposed identification criteria. Limit of detections (LODs) were 1.34 × 10-4 ∼ 1.92 ng/mL and 1.92 × 10-4 ∼ 9.80 ng/mL for blood and urine samples, respectively. Limits of quantification (LOQ) of toxins in blood and urine ranged from 4.47 × 10-4 ∼ 6.32 ng/mL and 6.39 × 10-4 ∼ 32.67 ng/mL, respectively. Intra-day relative standard deviations (RSDs) were 0.79 % ∼ 10.90 %, and inter-day RSDs were 1.08 % ∼ 18.93 %. The recoveries can reach 90 % ∼ 110 % with matrix matching calibration curves.

CONCLUSION

The established method is simple and rapid to operate, which can complete the sample analysis within 30 min, providing technical support for clinical poisoning treatment and public health poisoning analysis.

Development and validation of an analytical method based on QuEChERS followed by UHPLC-ToF-MS for the determination of tropane alkaloids in buckwheat (Fagopyrum esculentum L.) and buckwheat products

A method was developed for the determination of tropane alkaloids (TAs), including atropine, scopolamine, anisodamine and homatropine in buckwheat and related products. This work presents an optimised methodology based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction procedure followed by ultra-high performance liquid chromatography combined with time-of-flight mass spectrometry for the determination of TAs (atropine, scopolamine, anisodamine and homatropine) in buckwheat samples. The analytical methodology was successfully validated, demonstrating good linearity, low limit of quantification, repeatability (RSDr < 15%), inter-day precision (RSDR < 19%) and recovery (74-113%). Finally, 13 commercial samples of buckwheat were analysed and the results demonstrated that they were in compliance with the current European regulations regarding TAs.

An insight into recent updates on analytical techniques for bioactive alkaloids

INTRODUCTION

Alkaloids represent a wide class of naturally existing nitrogen-containing organic compounds having diverse biological activities. They are primary bioactive substances extracted from diverse plant parts. Due to their diverse biological activities, they are frequently used as medicines. The alkaloids have diverse pharmacological impacts on the human body; alkaloids are used for prevention, treatment, and reduction of discomfort associated with chronic illnesses. As most alkaloids exist in plants in complex form, combined with numerous other natural plant components, it is essential to recognize and characterize these molecules using different analytical techniques.

OBJECTIVES

We aimed to review the literature on the methods and protocols for the analysis of naturally occurring alkaloids.

METHODS

We carried out a literature survey using the PubMed, Scopus, and Google Scholar databases and other relevant published materials. The keywords used in the searches were "alkaloids," "analytical methods," "HPLC method," "GC method," "electrochemical methods," and "bioanalytical methods," in various combinations.

RESULTS

In this article, several classes of alkaloids are presented, along with their biological activities. Moreover, it includes a thorough explanation of chromatographic techniques, hyphenated techniques, electrochemical techniques, and current trending analytical methods utilized for the isolation, identification, and comprehensive characterization of alkaloids.

CONCLUSIONS

The various analytical techniques play an important role in the identification as well as the characterization of various alkaloids from plants, plasma samples, and urine samples. The hyphenation of various chromatographic techniques with mass spectrometry and NMR spectroscopy plays a crucial role in the characterization of unknown compounds.

Generation of broad-spectrum recombinant antibody and construction of colorimetric immunoassay for tropane alkaloids: Recognition mechanism and application

Tropane alkaloids (TAs) have emerged as plant toxins, related to poisoning events. The development of stable antibodies is crucial to ensure the effectiveness of immunological methods in quickly and accurately monitoring these alkaloids. In this study, based on hybridoma, the variable region gene of monoclonal antibody (mAb) was amplified, and the recombinant antibody (rAb) gene sequence (VH-Linker-VL) was successfully constructed and expressed in HEK293F. The obtained rAb has kept the same performance as mAb, and the IC50 of 29 TAs ranged from 0.12 to 2642.78 ng/mL. In the recognition mechanism, the docking and dynamics model identified hydrophobic interaction as the most critical force. Substituent will impact recognition by influencing the spatial structure and hydrophobic properties. Then, a colorimetric immunoassay based on rAb was established, five types of water and thirty-nine nectars of honey were tested. The results demonstrated the absence of TAs in environmental water, whereas atropine was detected in more than 13.47% of honey samples at concentrations exceeding 1 μg/kg. The results show a good correlation with UHPLC-MS/MS, suggesting that the immunoassay has excellent screening ability. The data on TAs in honey and water could serve as a foundation for developing relevant policies.

Alkaloids in food: a review of toxicity, analytical methods, occurrence and risk assessments

Alkaloids have been utilized by humans for years. They have diverse applications in pharmaceuticals. They have been proven to be effective in treating a number of diseases. They also form an important part of regular human diets, as they are present in food items, food supplements, diet ingredients and food contaminants. Despite their obvious importance, these alkaloids are toxic to humans. Their toxicity is dependent on a range of factors, such as specific dosage, exposure time and individual properties. Mild toxic effects include nausea, itching and vomiting while chronic effects include paralysis, teratogenicity and death. This review summarizes the published studies on the toxicity, analytical methods, occurrence and risk assessments of six major alkaloid groups that are present in food, namely, ergot, glycoalkaloids, purine, pyrrolizidine, quinolizidine and tropane alkaloids.

Evaluation of Tropane Alkaloids in Teas and Herbal Infusions: Effect of Brewing Time and Temperature on Atropine and Scopolamine Content

Atropine and scopolamine belong to the tropane alkaloid (TA) family of natural toxins. They can contaminate teas and herbal teas and appear in infusions. Therefore, this study focused on analyzing atropine and scopolamine in 33 samples of tea and herbal tea infusions purchased in Spain and Portugal to determine the presence of these compounds in infusions brewed at 97 °C for 5 min. A rapid microextraction technique (µSPEed^®) followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze the selected TAs. The results showed that 64% of the analyzed samples were contaminated by one or both toxins. White and green teas were generally more contaminated than black and other herbal teas. Of the 21 contaminated samples, 15 had concentrations above the maximum limit for liquid herbal infusions (0.2 ng/mL) set by Commission Regulation (EU) 2021/1408. In addition, the effects of heating conditions (time and temperature) on atropine and scopolamine standards and naturally contaminated samples of white, green, and black teas were evaluated. The results showed that at the concentrations studied (0.2 and 4 ng/mL), there was no degradation in the standard solutions. Brewing with boiling water (decoction) for 5 and 10 min allowed for higher extraction of TAs from dry tea to infusion water.

Gastrointestinal bioaccessibility and fiber mitigation of tropane alkaloids assessed on tea and cookies by in vitro digestion

BACKGROUND

Tropane alkaloids (TAs) are toxic compounds with a high anticholinergic effect. They have been widely analyzed in food samples, but their fate in the gastrointestinal tract has not been evaluated yet.

RESULTS

In this study, static in vitro digestion was performed to assess gastrointestinal bioaccessibility of the most common TAs on tea and home-made cookies. Cookies enriched with dietary fiber (pectin, arabinogalactan, and κ-carrageenan) were also tested to evaluate their influence on TA bioaccessibility. Two extraction methods and a liquid chromatography-mass spectrometry method were optimized and validated. Bioaccessibility for tea (60-105%) was higher than for cookies (39-93%) (P = 0.001-0.002), which indicates TAs could be more easily absorbed when they are contaminating tea. Digestion of cookies enriched with 50 g kg^-1 of different fibers showed that, although no significant changes were observed in the gastric phase (P = 0.084-0.920), duodenal bioaccessibility was significantly reduced (P = 0.008-0.039). Pectin was the fiber with a better mitigation effect for all the compounds.

CONCLUSION

TAs bioaccessibility was determined after in vitro digestion of contaminated tea and cookies. Dietary fiber seems to be a promising mitigation strategy, significantly reducing TA bioaccessibility percentages. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Bright and Dark Sides of Herbal Infusions: Assessment of Antioxidant Capacity and Determination of Tropane Alkaloids

Herbal infusions are highly popular beverages consumed daily due to their health benefits and antioxidant properties. However, the presence of plant toxins, such as tropane alkaloids, constitutes a recent health concern for herbal infusions. This work presents an optimized and validated methodology based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction procedure followed by Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC-ToF-MS) for the determination of tropane alkaloids (atropine, scopolamine, anisodamine, and homatropine) in herbal infusions, in accordance with criteria established by Commission Recommendation EU No. 2015/976. One of the seventeen samples was contaminated with atropine, exceeding the current European regulation regarding tropane alkaloids. In addition, this study evaluated the antioxidant capacity of common herbal infusions available on Portuguese markets, indicating the high antioxidant capacity of yerba mate (Ilex paraguariensis), lemon balm (Melissa officinalis), and peppermint (Mentha x piperita).

Emerging Issues on Tropane Alkaloid Contamination of Food in Europe

The occurrence of tropane alkaloids (TAs), toxic plant metabolites, in food in Europe was studied to identify those TAs in food most relevant for human health. Information was extracted from the literature and the 2016 study from the European Food Safety Authority. Calystegines were identified as being inherent TAs in foods common in Europe, such as Solanum tuberosum (potato), S. melongena (eggplant, aubergine), Capsicum annuum (bell pepper) and Brassica oleracea (broccoli, Brussels sprouts). In addition, some low-molecular-weight tropanes and Convolvulaceae-type TAs were found inherent to bell pepper. On the other hand, atropine, scopolamine, convolvine, pseudotropine and tropine were identified as emerging TAs resulting from the presence of associated weeds in food. The most relevant food products in this respect are unprocessed and processed cereal-based foods for infants, young children or adults, dry (herbal) teas and canned or frozen vegetables. Overall, the occurrence data on both inherent as well as on associated TAs in foods are still scarce, highlighting the need for monitoring data. It also indicates the urge for food safety authorities to work with farmers, plant breeders and food business operators to prevent the spreading of invasive weeds and to increase awareness.

Evaluation of Thermal Degradation of Tropane and Opium Alkaloids in Gluten-Free Corn Breadsticks Samples Contaminated with Stramonium Seeds and Baked with Poppy Seeds under Different Conditions

In this work, the thermal degradation of tropane and opium alkaloids was studied in samples of breadsticks prepared with corn flour, contaminated with seeds of Datura stramonium, and containing seeds of Papaver somniferum L. A total of seven different samples were prepared and eight alkaloids were studied, three tropane (atropine, scopolamine, and anisodamine) and five opium (morphine, codeine, thebaine, papaverine, and noscapine) alkaloids. For this purpose, a fast, easy and efficient method based on solid-liquid extraction (SLE) prior to the analysis by high-performance liquid chromatography with a diode array detector (HPLC-DAD) was developed and validated. Thermal degradation studies showed a decrease in the TAs and OAs content under baking (180 °C for 20 min) that was between 7–65% for atropine, depending on the preparation conditions used, between 35–49% for scopolamine and anisodamine, up to 100% for morphine and codeine and between 14–58% for thebaine, papaverine, and noscapine. Results also evidenced that degradation of morphine and codeine was higher when the seeds were added as topping to the breadsticks.

Green extraction approach based on μSPEed® followed by HPLC-MS/MS for the determination of atropine and scopolamine in tea and herbal tea infusions

A high throught methododology based on a green extraction technique, µSPEed®, followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been proposed for the analysis of atropine and scopolamine in tea and herbal tea infusions. For this, a digiVOL® Digital Syringe was used with different sorbents and working conditions to obtain a fast and efficient µSPEed® extraction. The best performance was achieved with a PS/DVB sorbent phase, sample loading of 5 × 500 µL and elution with 2 × 100 µL aliquots of methanol. The strategy based on µSPEed® followed by HPLC-MS/MS was validated, attaining quantitation limits lower than 0.15 ng mL^-1 and recoveries between 94 and 106% for both analytes and applied to seventeen tea and herbal tea infusions. Fourteen infusions showed contamination with one or both analytes above the maximum content legislated (sum of atropine and scopolamine < 0.2 ng mL^-1).

Mesostructured Silicas as Cation-Exchange Sorbents in Packed or Dispersive Solid Phase Extraction for the Determination of Tropane Alkaloids in Culinary Aromatics Herbs by HPLC-MS/MS

In this work, Hexagonal Mesoporous Silica (HMS) and Santa Barbara Amorphous-15 (SBA-15) mesostructured silicas were synthesized and functionalized with sulfonic acid groups. The materials (HMS-SO3− and SBA-15-SO3−) were evaluated as strong cation exchange sorbents for sample extract clean-up, by solid phase extraction (SPE) and dispersive solid phase extraction, to determine atropine (At) and scopolamine (Sc) in commercial culinary aromatic herbs. Under optimized conditions, 0.25 g of sample was subject to solid−liquid extraction with acidified water (pH 1.0), and good recovery percentages were achieved for At and Sc using 75 mg of HMS-SO3− in SPE as the clean-up stage, prior to their determination by HPLC-MS/MS. The proposed method was validated in a thyme sample showing recoveries in the range of 70−92%, good linearity (R2 > 0.999), adequate precision (RSD ≤ 14%) and low limits (MDL 0.8−2.2 µg/kg and MQL 2.6−7.2 µg/kg for both analytes). Sixteen aromatic herbs samples (dried thyme, basil and coriander leaves) were analysed and At was found in fourteen samples over an interval of <5−42 μg/kg, whereas Sc was found in three of the sixteen samples studied (between <5−34 μg/kg). The amount of At and Sc found in some analysed samples confirms the importance of setting maximum levels of At and Sc in culinary aromatic herbs.

Occurrence and Chemistry of Tropane Alkaloids in Foods, with a Focus on Sample Analysis Methods: A Review on Recent Trends and Technological Advances

Tropane alkaloids (TAs) are natural toxins produced by different plants, mainly from the Solanaceae family. The interest in TAs analysis is due to the serious cases of poisoning that are produced due to the presence of TA-producing plants in a variety of foods. For this reason, in recent years, different analytical methods have been reported for their control. However, the complexity of the matrices makes the sample preparation a critical step for this task. Therefore, this review has focused on (a) collecting the available data in relation to the occurrence of TAs in foods for human consumption and (b) providing the state of the art in food sample preparation (from 2015 to today). Regarding the different food categories, cereals and related products and teas and herbal teas have been the most analyzed. Solid-liquid extraction is still the technique most widely used for sample preparation, although other extraction and purification techniques such as solid-phase extraction or QuEChERS procedure, based on the use of sorbents for extract or clean-up step, are being applied since they allow cleaner extracts. On the other hand, new materials (molecularly imprinted polymers, mesostructured silica-based materials, metal-organic frameworks) are emerging as sorbents to develop effective extraction and purification methods that allow lower limits and matrix effects, being a future trend for the analysis of TAs.

Suitability of High-Resolution Mass Spectrometry for Routine Analysis of Small Molecules in Food, Feed and Water for Safety and Authenticity Purposes: A Review

During the last decade, food, feed and environmental analysis using high-resolution mass spectrometry became increasingly popular. Recent accessibility and technological improvements of this system make it a potential tool for routine laboratory work. However, this kind of instrument is still often considered a research tool. The wide range of potential contaminants and residues that must be monitored, including pesticides, veterinary drugs and natural toxins, is steadily increasing. Thanks to full-scan analysis and the theoretically unlimited number of compounds that can be screened in a single analysis, high-resolution mass spectrometry is particularly well-suited for food, feed and water analysis. This review aims, through a series of relevant selected studies and developed methods dedicated to the different classes of contaminants and residues, to demonstrate that high-resolution mass spectrometry can reach detection levels in compliance with current legislation and is a versatile and appropriate tool for routine testing.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Comprehensive tropane alkaloids analysis and retrospective screening of contaminants in honey samples using liquid chromatography-high resolution mass spectrometry (Orbitrap)

A wide-scope analytical method was developed and validated for the determination of tropane alkaloids (TAs) in honey samples. A simple and fast extraction procedure, using a mixture of methanol/water/formic acid (75/25/0.4, v/v/v) as extraction solvent, followed by a clean-up with graphitized black carbon (GBC) and magnesium sulphate was optimized, and compounds were analysed by liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS-Orbitrap). Validation of the proposed method provided adequate linearity (R² > 0.99), trueness (recoveries 71-120%) and precision (relative standard deviation, RSD ≤ 20.1%), with limits of quantitation (LOQs) at 20 µg/kg (except anisodamine and scopolamine at 40 µg/kg) and a significant matrix effect (≤-50%). Nineteen honey samples were analysed, but only one was positive, containing 27 µg/kg of scopolamine. Additionally, a post-targeted screening was performed, and 47% of samples were contaminated with different herbicides, insecticides and veterinary drugs. Therefore, the proposed analytical method is a powerful tool for both targeted TAs and post-targeted contaminant analyses.

Determination of Calystegines in Several Tomato Varieties Based on GC-Q-Orbitrap Analysis and Their Classification by ANOVA

In this study, several calystegines (A₃, A₅, B₁, B₂, B₃, B₄, and C₁) were determined in tomato. A simple extraction followed by a derivatization step with silylating agents was performed prior to their analysis by gas chromatography coupled to high resolution mass spectrometry (GC-HRMS-Q-Orbitrap), which allowed the monitoring of several ions at accurate mass. The validation of the method has provided suitable values of linearity, trueness (73.7-120.0%), and precision (≤20.0%, except for calystegines B₃ and B₄ at 0.5 mg/kg). The limit of quantitation was set at 0.5 mg/kg for all analytes. The validated method was successfully applied to the analysis of nine different tomato varieties, and calystegines A₃, A₅, B₂, and C₁ were found at concentrations ranging between 0.65 mg/kg (C₁) and 12.47 mg/kg (B₂). Tomato varieties were classified according to their calystegines content by applying an analysis of variance (ANOVA).

A modified QuEChERS method coupled with liquid chromatography-tandem mass spectrometry for the simultaneous detection and quantification of scopolamine, L-hyoscyamine, and sparteine residues in animal-derived food products

We developed a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (CEN QuEChERS) extraction method coupled with liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI⁺/MS-MS) to identify and quantify residues of three botanical alkaloids, namely, scopolamine, L-hyoscyamine, and sparteine, in animal-derived foods, including porcine muscle, egg, and milk. A combination of ethylenediaminetetraacetic acid disodium buffer and acetonitrile acidified with 0.5% trifluoroacetic acid was used as an extraction solvent, whereas QuEChERS (CEN, 15662) kits and sorbents were applied for cleanup procedures. The proposed method was validated by determining the limits of quantification (LOQs), with values of 1-5 µg/kg achieved for the target analytes in various matrices. Linearity was estimated from matrix-matched calibration curves constructed using six concentration levels ranging from 1- to 6-fold increases in the LOQs of each analyte, and the correlation coefficients (R² ) were ≥0.9869. Recoveries (at three concentration levels of 1-, 2-, and 3-fold increases in the LOQ) of 73-104% were achieved with relative standard deviations (RSDs) ≤7.7% (intra-day and inter-day precision). Ten types of each matrix procured from large markets were evaluated, and all tested samples showed negative results. The current protocol is simple and versatile and can be used for routine detection of plant alkaloids in animal food products.