Pyrrolizidine alkaloids in borage (Borago officinalis): Comprehensive profiling and development of a validated LC-MS/MS method for quantification

High-throughput direct profiling of natural products in plant leaves using ambient ionization high-resolution mass spectrometry

Plant leaves contain natural products that may have nutritional and medicinal values. In this work, a modified ambient ion source of angled direct analysis in real time (aDART) and high-resolution mass spectrometry (HRMS) was used for direct surface analysis of different plant leaves. Untreated leaves, leaves with the wax layer removed, and leaf imprints were all successfully analyzed by aDART-HRMS in min, observing abundant natural product information including esters, amino acids, saccharides, flavonoids, alkaloids, alcohols, and ketones/aldehydes. Different plant samples have their unique features. Fresh leaves facilitate instant analysis without sample preparation, dewaxed leaves can help expose chemicals concealed by the epidermis, and the leaf imprints can better reveal substances inside the leaf tissues. Traditional leaf extracts were compared and analyzed using DART-HRMS, and it was shown that more compounds were discovered by surface analysis. aDART-HRMS is capable of obtaining samples' composition directly from plant leaves, without destroying leaf morphology and tedious sample preparation. This modified aDART-MS technology provides a simple and robust ambient ionization method for direct characterization of natural products contained in various plant samples.

Rapid on-site identification of pyrrolizidine alkaloids in herbal medicines using miniature mass spectrometry

Pyrrolizidine alkaloids (PAs) are naturally occurring plant toxins with significant multi-organ toxicity, especially hepatotoxicity. Accidental consumption of PAs-containing herbal medicines can lead to severe health consequences, emphasizing the need for rapid and effective detection methods to ensure medicinal safety. In this study, we developed a novel on-site rapid analytical method using paper capillary spray miniature mass spectrometry (PCS-mini MS), and created a database containing 34 different PAs with a detection limit ranging from 0.5 to 2 ng mL-1. This method is particularly suitable for identifying PAs in herbal medicines, the accuracy of PCS-mini MS was validated through high-performance liquid chromatography-mass spectrometry. Furthermore, the method's environmental impact was assessed using three green evaluation tools, demonstrating its compliance with green analytical chemistry principles, highlighting both efficiency and sustainability. This study provides a convenient and precise approach for regulating the herbal medicine market, enabling quick identification of toxic plants and reducing the risk of adverse health effects from herb misidentification. In the future, this method is expected to be widely adopted for clinical applications and market regulation of herbal products.

Quantitative Analysis of Pyrrolizidine Alkaloids in Food Matrices and Plant-Derived Samples Using UHPLC-MS/MS

Pyrrolizidine alkaloids (PAs) are a class of nitrogen-containing basic organic compounds that are frequently detected in foods and herbal medicines. Owing to their potential hepatotoxic, genotoxic, and carcinogenic properties, PAs have become a significant focus for monitoring global food safety. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the detection and analysis of three foods (tea, honey, and milk) susceptible to PA contamination. This optimized method effectively separated and detected three types of PAs, namely, three pairs of isomers and two pairs of chiral compounds. The limits of detection (LODs) and limits of quantification (LOQs) were determined to be 0.015-0.75 and 0.05-2.5 µg/kg, respectively, with the relative standard deviations (RSDs) of both the interday and intraday precisions remaining below 15%. The average PA recoveries from the honey, milk, and tea matrices fell within the ranges of 64.5-103.4, 65.2-112.2, and 67.6-107.6%, respectively. This method was also applied to 77 samples collected from 33 prefecture-level cities across 16 provinces and included 40 tea, 6 milk, 8 honey, 14 spice, and 9 herbal medicine samples. At least one PA was detected in twenty-three of the samples, with herbal medicines exhibiting the highest total PA content. The obtained results indicate that the developed method demonstrated good repeatability and stability in the detection and quantitative analyses of PAs in food- and plant-derived samples. This method is therefore expected to provide reliable technical support for food safety risk monitoring.

Pyrrolizidine Alkaloids in Foods, Herbal Drugs, and Food Supplements: Chemistry, Metabolism, Toxicological Significance, Analytical Methods, Occurrence, and Challenges for Future

Consumers are increasingly seeking natural alternatives to chemical compounds, including the use of dried aromatic plants as seasonings instead of salt. However, the presence of pyrrolizidine alkaloids (PAs) in food supplements and dried plants has become a concern because of their link to liver diseases and their classification as carcinogenic by the International Agency for Research on Cancer (IARC). Despite European Union (EU) Regulation (EU) 2023/915, non-compliance issues persist, as indicated by alerts on the Rapid Alert System for Food and Feed (RASFF) portal. Analyzing PAs poses a challenge because of their diverse chemical structures and low concentrations in these products, necessitating highly sensitive analytical methods. Despite these challenges, ongoing advancements in analytical techniques coupled with effective sampling and extraction strategies offer the potential to enhance safety measures. These developments aim to minimize consumer exposure to PAs and safeguard their health while addressing the growing demand for natural alternatives in the marketplace.

Chromatographic Methods for Detection and Quantification of Pyrrolizidine Alkaloids in Flora, Herbal Medicines, and Food: An Overview

Pyrrolizidine alkaloids (PAs) are natural toxins produced by some plants that gained special interest due to their potential hazardous effects in humans and animals. These substances have been found in wild flora, herbal medicines and food products raising health concerns. Recently, maximum concentration levels of PAs were established for some food products; however, maximum daily intake frequently surpasses the upper limit set by the competent authorities posing a health risk. Given the scarcity or absence of occurrence data on PAs in many products, there is an urgent need to measure their levels and establish safety intake levels. Analytical methods have been reported to detect and quantify PAs in different matrices. The commonly used chromatographic methodologies provides accurate and reliable results. Analytical methods include diverse steps as extraction and sample preparation procedures that are critical for sensitivity and selectivity of the analytical method. Great efforts have been directed toward optimization of extraction procedures, clean up and chromatographic conditions to improve recovery, reduce matrix effects, and achieve low limits of detection and quantification. Therefore, this paper aims to give a general overview about the occurrence of PAs in flora, herbal medicines, and foodstuff; and discuss the different chromatographic methodologies used for PAs analysis, namely extraction and sample preparation procedures and chromatographic conditions.