Dehydropyrrolizidine Alkaloid Toxicity, Cytotoxicity, and Carcinogenicity

UHPLC-Q-TOF analysis of pyrrolizidine alkaloids in North-Macedonian honey

Honey contaminated with pyrrolizidine alkaloids (PAs) could pose a risk for human consumption, being a widely consumed food product. A fast and simple LC/MS method for the analysis of pyrrolizidine alkaloids in honey was optimised to collect occurrence data. The extraction efficiency was evaluated by a systematic study of multiple solvent mixtures and clean-up procedures. The best results for PA extraction were obtained using a formic acid/methanol mixture with subsequent clean-up by the QuEChERS method, resulting in a mean recovery range of 91.8-102%. The method validation showed satisfactory intra-day (RSD < 5.1%) and inter-day precision (RSD < 9.1%). The proposed method was applied to 14 samples. A total of six PAs and two N-oxides were detected, with levels between 89 and 8188 µg/kg. This assessment highlights the potential risk of intoxication and the need for further investigations regarding an effective quality system for manufacturers to control PAs in honey.

Pyrrolizidine alkaloid contamination of food in Africa: A review of current trends and implications

Pyrrolizidine alkaloids (PAs) contamination of foodstuffs has become a topical issue in recent years on account of its potential hepatotoxicity to consumers. This review therefore highlights human exposure to PAs across Africa, focusing on their occurrence, current trends of food contamination, and their associated health implications. A comprehensive search of peer-scientific literature and relevant databases, PubMed, Google Scholar, Science Direct, Web of Science and Scopus, was conducted from 2001 to 2023 focusing mainly on foodstuffs, including grains, herbs, teas, honey, and livestock products. The findings revealed that PA contamination is a prevalent issue in several African countries, with the primary sources of contamination attributed to the consumption of honey and the use of PA plants as herbs in food preparations. Additionally, poor farming practices have been found to influence the presence and levels of PAs in foodstuffs. To mitigate PA contamination in food and safeguarding public health across the continent, several strategies are proposed, including the implementation of stringent regulatory and quality control measures, adoption of Good Agricultural Practices, and public awareness campaigns to educate producers, consumers and beekeepers about the risks associated with PA-contaminated food products.

Analysis of Pyrrolizidine Alkaloids in Stingless Bee Honey and Identification of a Botanical Source as Ageratum conyzoides

Stingless bee honeys (SBHs) from Australian and Malaysian species were analysed using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the presence of pyrrolizidine alkaloids (PAs) and the corresponding N-oxides (PANOs) due to the potential for such hepatotoxic alkaloids to contaminate honey as a result of bees foraging on plants containing these alkaloids. Low levels of alkaloids were found in these SBHs when assessed against certified PA standards in targeted analysis. However, certain isomers were identified using untargeted analysis in a subset of honeys of Heterotrigona itama which resulted in the identification of a PA weed species (Ageratum conyzoides) near the hives. The evaluation of this weed provided a PA profile matching that of the SBH of H. itama produced nearby, and included supinine, supinine N-oxide (or isomers) and acetylated derivatives. These PAs lacking a hydroxyl group at C7 are thought to be less hepatoxic. However, high levels were also observed in SBH (and in A. conyzoides) of a potentially more toxic diester PA corresponding to an echimidine isomer. Intermedine, the C7 hydroxy equivalent of supinine, was also observed. Species differences in nectar collection were evident as the same alkaloids were not identified in SBH of G. thoracica from the same location. This study highlights that not all PAs and PANOs are identified using available standards in targeted analyses and confirms the need for producers of all types of honey to be aware of nearby potential PA sources, particularly weeds.

Recent Advances in the Detection of Food Toxins Using Mass Spectrometry

Edibles are the only source of nutrients and energy for humans. However, ingredients of edibles have undergone many physicochemical changes during preparation and storage. Aging, hydrolysis, oxidation, and rancidity are some of the major changes that not only change the native flavor, texture, and taste of food but also destroy the nutritive value and jeopardize public health. The major reasons for the production of harmful metabolites, chemicals, and toxins are poor processing, inappropriate storage, and microbial spoilage, which are lethal to consumers. In addition, the emergence of new pollutants has intensified the need for advanced and rapid food analysis techniques to detect such toxins. The issue with the detection of toxins in food samples is the nonvolatile nature and absence of detectable chromophores; hence, normal conventional techniques need additional derivatization. Mass spectrometry (MS) offers high sensitivity, selectivity, and capability to handle complex mixtures, making it an ideal analytical technique for the identification and quantification of food toxins. Recent technological advancements, such as high-resolution MS and tandem mass spectrometry (MS/MS), have significantly improved sensitivity, enabling the detection of food toxins at ultralow levels. Moreover, the emergence of ambient ionization techniques has facilitated rapid in situ analysis of samples with lower time and resources. Despite numerous advantages, the widespread adoption of MS in routine food safety monitoring faces certain challenges such as instrument cost, complexity, data analysis, and standardization of methods. Nevertheless, the continuous advancements in MS-technology and its integration with complementary techniques hold promising prospects for revolutionizing food safety monitoring. This review discusses the application of MS in detecting various food toxins including mycotoxins, marine biotoxins, and plant-derived toxins. It also explores the implementation of untargeted approaches, such as metabolomics and proteomics, for the discovery of novel and emerging food toxins, enhancing our understanding of potential hazards in the food supply chain.

Traditional medicine consumption in postpartum for HBV-infected women enrolled in the ANRS 12345 TA PROHM study in Cambodia

In Cambodia, traditional medicine was commonly described as being used by pregnant women at two time points: one month before birth and during early postpartum. The present study aims to describe traditional medicine consumption during postpartum phase for women enrolled in the TA PROHM study and to investigate the possible association between traditional medicine consumption and acute liver toxicity. An ethnobotanical survey was conducted in 2 groups of HBV-infected pregnant women (with and without postpartum hepatocellular injury) enrolled in the study. Hepatocellular injury was defined by having Alanine Aminotransferase (ALT) > 2.5 times the Upper Limit of Normal (ULN = 40 U/L) at the 6th week postpartum visit. Interviews were done using a standardized questionnaire. Plant samples were collected and later identified by two traditional healers. Chi-square test was used to find the association between hepatocellular injury and traditional medicine consumption or a specific plant species. In total, 75 women were enrolled and 52 (69.3%) used at least one traditional remedy composed of 123 different plants and 12 alcoholic macerations of porcupine stomach. Orally consuming at least one remedy with alcohol was significantly associated with hepatocellular injury (33% vs 13%, p = 0.034). Among the 123 plants species identified, four were found to be associated with hepatocellular injury, namely Amphineurion marginatum (Roxb.) D.J.Middleton [Apocynaceae] (p = 0.022), Selaginella tamariscina (P.Beauv.) Spring [Selaginellaceae] (p = 0.048), Mitragyna speciosa Korth. [Rubiaceae] (p = 0.099) and Tetracera indica (Christm. & Panz.) Merr. [Dilleniaceae] (p = 0.079). Consumption of traditional medicine in postpartum is a common practice for women enrolled in the TA PROHM study. Alcohol-based remedies may exacerbate the risk of acute hepatocellular injury in HBV-infected women already exposed to immune restoration. The complex mixtures of herbs need to be further evaluated by in vitro and in vivo studies.

Evolution of the Secondary Metabolites in Invasive Plant Species Chromolaena odorata for the Defense and Allelopathic Functions

Chromolaena odorata (L.) R.M. King & H. Robinson is native to tropical America, and has naturalized in many other countries in tropical Asia, Austria, and West Africa. The species often forms dense thickets and reduces the native species diversity and population in the invasive ranges. The species is also considered as a noxious weed in agriculture fields, and listed in the 100 of the world's worst invasive alien species. The characteristics of its life-history such as the seed production rate, growth pattern, and adaptative ability to the environmental conditions may contribute to the invasiveness of the species. Possible evidence of the defense capacity against the natural enemy, and the allelopathic potential against the competitive plant species for C. odorata has been accumulated in the literature over three decades. The extracts, residues, and/or rhizosphere soil of C. odorata increased the mortality of various insects and parasitic nematodes, and decreased their population. The extracts, residues, and/or rhizosphere soil of C. odorata also inhibited the germination and growth of several plant species including the indigenous plant species in the invasive ranges of C. odorata. Toxic substances, pyrrolizidine alkaloids were found in the leaves and flowers of C. odorata. These pyrrolizidine alkaloids may work as the defense agents against the natural enemies. Several potential allelochemicals such as flavonoids, phenolic acids, and terpenoids were also found in the plant extracts of C. odorata. Some of these compounds may work as allelopathic agents of C. odorata and inhibit the germination and growth of the competitive plant species. These characteristics of C. odorata for the defense function against their natural enemies such as insects and parasitic nematodes, and allelopathic potential against the competitive native plant species may contribute to the invasiveness and naturalization of C. odorata in the new habitats as invasive plant species. However, it is necessary to determine the concentration of these allelochemicals in the neighboring environment of C. odorata such as the rhizosphere soil since allelochemicals are able to work only when they are released into the neighboring environment. It is the first review article focusing on the defense function and allelopathy of C. odorata.

Biomarkers and their potential for detecting livestock plant poisonings in Western North America

The United States National Cancer Institute defines a biomarker as: "A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease." In Veterinary Medicine, biomarkers associated with plant poisonings of livestock have great utility. Since grazing livestock poisoned by toxic plants are often found dead, biomarkers of plant poisoning allow for a more rapid postmortem diagnosis and response to prevent further deaths. The presence and concentration of toxins in poisonous plants are biomarkers of risk for livestock poisoning that can be measured by the chemical analysis of plant material. More difficult is, the detection of plant toxins or biomarkers in biological samples from intoxicated or deceased animals. The purpose of this article is to review potential biomarkers of plant poisoning in grazing livestock in the Western North America including recently investigated non-invasive sampling techniques. Plants discussed include larkspur, lupine, water hemlock, swainsonine-containing plants, selenium-containing plants, and pyrrolizidine alkaloid containing plants. Other factors such as animal age and sex that affect plant biomarker concentrations in vivo are also discussed.

A seasonal idiopathic hepatitis syndrome in horses presented to a Midwestern veterinary teaching hospital

OBJECTIVE

To report history, clinical examination findings, clinicopathologic findings, diagnostic test results, treatment, and outcome in horses with a novel idiopathic hepatitis syndrome.

ANIMALS

13 client-owned horses.

PROCEDURES

Medical records of horses that were presented with fever and increased blood liver enzyme activity over a 16-month period were reviewed (December 1, 2020, to April 1, 2022). Collected data included signalment, history, clinical and clinicopathologic findings, diagnostic test results, treatment, clinical progression, and short-term outcome.

RESULTS

Affected horses were presented between December and April of each of the 2 seasons investigated. The majority of horses developed cyclic fevers over the course of 3 weeks, during which time histologic evidence of hepatitis was observed. Histologic lesions included hepatic necrosis, neutrophilic to lymphohistiocytic inflammation, biliary epithelial injury, and portal fibrosis. Systemic inflammation was evidenced by increased serum amyloid A concentration and leukon changes. No horse developed signs of hepatic insufficiency, and all horses clinically recovered. Return of serum activity of GGT to within the reference range occurred within 16 weeks in most horses. Histologic lesions remained evident up to 27 weeks after initial presentation in 1 horse.

CLINICAL RELEVANCE

Although an etiologic agent has not been identified, an apparently seasonal equine hepatitis syndrome was characterized by fever, systemic inflammation, increased liver enzyme activity, and histologic evidence of hepatitis. An infectious cause is suspected on the basis of histology and outcome.

A Comprehensive Database for DNA Adductomics

The exposure of human DNA to genotoxic compounds induces the formation of covalent DNA adducts, which may contribute to the initiation of carcinogenesis. Liquid chromatography (LC) coupled with high-resolution mass spectrometry (HRMS) is a powerful tool for DNA adductomics, a new research field aiming at screening known and unknown DNA adducts in biological samples. The lack of databases and bioinformatics tool in this field limits the applicability of DNA adductomics. Establishing a comprehensive database will make the identification process faster and more efficient and will provide new insight into the occurrence of DNA modification from a wide range of genotoxicants. In this paper, we present a four-step approach used to compile and curate a database for the annotation of DNA adducts in biological samples. The first step included a literature search, selecting only DNA adducts that were unequivocally identified by either comparison with reference standards or with nuclear magnetic resonance (NMR), and tentatively identified by tandem HRMS/MS. The second step consisted in harmonizing structures, molecular formulas, and names, for building a systematic database of 279 DNA adducts. The source, the study design and the technique used for DNA adduct identification were reported. The third step consisted in implementing the database with 303 new potential DNA adducts coming from different combinations of genotoxicants with nucleobases, and reporting monoisotopic masses, chemical formulas, .cdxml files, .mol files, SMILES, InChI, InChIKey and IUPAC nomenclature. In the fourth step, a preliminary spectral library was built by acquiring experimental MS/MS spectra of 15 reference standards, generating in silico MS/MS fragments for all the adducts, and reporting both experimental and predicted fragments into interactive web datatables. The database, including 582 entries, is publicly available (https://gitlab.com/nexs-metabolomics/projects/dna_adductomics_database). This database is a powerful tool for the annotation of DNA adducts measured in (HR)MS. The inclusion of metadata indicating the source of DNA adducts, the study design and technique used, allows for prioritization of the DNA adducts of interests and/or to enhance the annotation confidence. DNA adducts identification can be further improved by integrating the present database with the generation of authentic MS/MS spectra, and with user-friendly bioinformatics tools.

Regulatory Perspectives of Pyrrolizidine Alkaloid Contamination in Herbal Medicinal Products

The toxicity of plants containing certain pyrrolizidine alkaloids has long been recognized in grazing animals and humans. Genotoxicity and carcinogenicity data from in vitro and in vivo (animal) studies were published over the last few decades for some of the 1,2-unsaturated pyrrolizidine alkaloids, leading to regulatory action on herbal medicinal products with pyrrolizidine alkaloid-containing plants more than 30 years ago. In recent years, it has become evident that in addition to herbal medicinal products containing pyrrolizidine alkaloid-containing plants, these products may also contain pyrrolizidine alkaloids without actually including pyrrolizidine alkaloid-containing plants. This is explained by contamination by accessory herbs (weeds). The national competent authorities of the European member states and the European Medicines Agency, in this case, the Committee on Herbal Medicinal Products, reacted to these findings by setting limits for all herbal medicinal products. This review article will briefly discuss the data leading to the establishment of thresholds and the regulatory developments and consequences, as well as the current discussions and research in this area.

Hematological and Serum Biochemical Changes and Their Prognostic Value in Horses Spontaneously Poisoned by Crotalaria spectabilis

Determining the prognosis of poisoning by plants containing pyrrolizidine alkaloids is usually challenging. This study aimed to identify important prognostic parameters that can determine the severity of spontaneous poisoning by Crotalaria spectabilis in horses. Blood samples from 42 horses spontaneously poisoned by oats contaminated with C. spectabilis seeds were evaluated. Complete blood counts (CBC) and serum biochemical tests [urea, creatinine, total protein, albumin, total and direct bilirubin concentrations, aspartate aminotransferase (AST), γ-glutamyl transferase (GGT), and creatine kinase (CK) activities] were performed. Horses were followed up for 12 months to determine the long-term survival rate; after 12 months, they were divided into two groups: survivors (n = 30) and non-survivors (n = 12). Horses spontaneously poisoned with C. spectabilis had higher levels of urea, globulin, bilirubin (total, direct, and indirect), AST, GGT, and CK than the reference values. Non-survivor horses showed significantly higher (p < 0.05) values of hemoglobin, GGT, and direct bilirubin than the survivor horses. Horses with serum GGT activity higher than 95 U/l had 14.0 times the risk of death compared to animals showing activities equal to or lower than this value, whereas horses with serum direct bilirubin concentration higher than 0.6 mg/dl (10.26 μmol/L) had 5.78 times the risk of death compared to the others. In summary, serum GGT activity and direct bilirubin concentration may be useful prognostic indicators for assessing the severity of C. spectabilis-poisoned horses.

Natural products: potential treatments for cisplatin-induced nephrotoxicity

Cisplatin is a clinically advanced and highly effective anticancer drug used in the treatment of a wide variety of malignancies, such as head and neck, lung, testis, ovary, breast cancer, etc. However, it has only a limited use in clinical practice due to its severe adverse effects, particularly nephrotoxicity; 20%–35% of patients develop acute kidney injury (AKI) after cisplatin administration. The nephrotoxic effect of cisplatin is cumulative and dose dependent and often necessitates dose reduction or withdrawal. Recurrent episodes of AKI result in impaired renal tubular function and acute renal failure, chronic kidney disease, uremia, and hypertensive nephropathy. The pathophysiology of cisplatin-induced AKI involves proximal tubular injury, apoptosis, oxidative stress, inflammation, and vascular injury in the kidneys. At present, there are no effective drugs or methods for cisplatin-induced kidney injury. Recent in vitro and in vivo studies show that numerous natural products (flavonoids, saponins, alkaloids, polysaccharide, phenylpropanoids, etc.) have specific antioxidant, anti-inflammatory, and anti-apoptotic properties that regulate the pathways associated with cisplatin-induced kidney damage. In this review we describe the molecular mechanisms of cisplatin-induced nephrotoxicity and summarize recent findings in the field of natural products that undermine these mechanisms to protect against cisplatin-induced kidney damage and provide potential strategies for AKI treatment.

Hepatotoxicity of Pyrrolizidine Alkaloid Compound Intermedine: Comparison with Other Pyrrolizidine Alkaloids and Its Toxicological Mechanism

Pyrrolizidine alkaloids (PAs) are common secondary plant compounds with hepatotoxicity. The consumption of herbal medicines and herbal teas containing PAs is one of the main causes of hepatic sinusoidal obstruction syndrome (HSOS), a potentially life-threatening condition. The present study aimed to reveal the mechanism underlying the cytotoxicity of intermedine (Im), the main PA in Comfrey. We evaluated the toxicity of the retronecine-type PAs with different structures to cell lines derived from mammalian tissues, including primary mouse hepatocytes, human hepatocytes (HepD), mouse hepatoma-22 (H₂₂) and human hepatocellular carcinoma (HepG2) cells. The cytotoxicity of Im to hepatocyte was evaluated by using cell counting kit-8 assay, colony formation experiment, wound healing assay and dead/live fluorescence imaging. In vitro characterization showed that these PAs were cytotoxic and induced cell apoptosis in a dose-dependent manner. We also demonstrated that Im induced cell apoptosis by generating excessive reactive oxygen species (ROS), changing the mitochondrial membrane potential and releasing cytochrome c (Cyt c) before activating the caspase-3 pathway. Importantly, we directly observed the destruction of the cell mitochondrial structure after Im treatment through transmission electron microscopy (TEM). This study provided the first direct evidence of Im inducing hepatotoxicity through mitochondria-mediated apoptosis. These results supplemented the basic toxicity data of PAs and facilitated the comprehensive and systematic evaluation of the toxicity caused by PA compounds.

CHOP Regulates Endoplasmic Reticulum Stress-Mediated Hepatoxicity Induced by Monocrotaline

Monocrotaline (MCT), a pyrrolizidine alkaloid, is the major toxin in Crotalaria, which causes cell apoptosis in humans and animals. It has been reported that the liver is a vulnerable target of MCT. However, the exact molecular mechanism of the interaction between endoplasmic reticulum (ER) stress and liver injury induced by MCT is still unclear. In this study, the cytotoxicity of MCT on primary rat hepatocytes was analyzed by a CCK-8 assay and Annexin V-FITC/PI assay. Protein expression was detected by western blotting and immunofluorescence staining. As a result, MCT significantly decreased the cell viability and mediated the apoptosis of primary rat hepatocytes. Meanwhile, MCT could also induce ER stress in hepatocytes, indicated by the expression of ER stress-related proteins, including GRP78, p-IRE1α, ATF6, p-eIF2α, ATF4, and CHOP. Pretreatment with 4-PBA, an inhibitor of ER stress, or knockdown of CHOP by siRNA could partly enhance cell viability and relieve the apoptosis. Our findings indicate that ER stress is involved in the hepatotoxicity induced by MCT, and CHOP plays an important role in this process.

Crotalaria spectabilis poisoning in horses fed contaminating oats

The present report describes the clinical and pathological changes induced by the consumption of oats contaminated with Crotalaria spectabilis seeds by horses. Eighty horses were exposed to oats containing 10 g/kg of C. spectabilis seeds with 0.46% pyrrolizidine alkaloids, and 21 horses died within a 6-month period. Clinical signs included jaundice, apathy, a hypotonic tongue, ataxia, hyporexia, weight loss, aimless wandering, violent behavior, and proprioceptive deficits. Pathological findings were predominant in the liver and included periportal bridging fibrosis, megalocytosis, centrilobular necrosis, and bile stasis. Other findings were Alzheimer's type II astrocytes in the cortex, midbrain, basal nuclei, brainstem and pons; multifocal edema and hemorrhage in the lungs; and degeneration and necrosis of the tubular epithelium of kidneys. Horses are highly sensitive to pyrrolizidine alkaloid-containing plants, and the observed clinical and pathological findings are typical of this poisoning. The seeds were planted, and botanical identification of the adult plants confirmed the diagnosis of C. spectabilis poisoning.

CYP2C and CYP2B Mediated Metabolic Activation of Retrorsine in Cyp3a Knockout Mice

Background:

Retrorsine is one of the hepatotoxic pyrrolizidine alkaloids, which could be converted into a highly reactive metabolite, dehydroretrorsine, by CYP3A, and to a lesser extent by CYP2C and CYP2B.

Objective:

We employed Cyp3a knockout (3AKO) mice to investigate whether the absence of CYP3A could attenuate dehydroretrorsine formation and the role of CYP2C and CYP2B in the formation.

Methods:

Blood and liver samples were collected after intragastrical administration of 35 mg/kg retrorsine or saline for seven days in wild-type (WT) and 3AKO mice. Blood pyrrole-protein adducts were semi quantified by high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. The formations of glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (GSH-DHP) and the activities of CYP3A, CYP2B and CYP2C were evaluated in the liver microsomes of WT and 3AKO mice before and after treatment. The metabolic phenotype of retrorsine was determined in human liver microsomes. The gene and protein expression of retrorsine metabolism-related CYP450s in the liver was measured by quantitative real-time PCR method and western blotting method. The serum cytokine level was detected by the ELISA method to reveal the potential mechanism of Cyp3a, Cyp2b and Cyp2c downregulation.

Results:

After an oral administration of 35 mg/kg retrorsine for seven days, the blood exposures of DHP adducts between WT and 3AKO mice were similar, consistent with the comparable formation of GSH-DHP in their liver microsomes. The chemical inhibitor experiment in liver microsomes indicated the predominant role of CYP3A and CYP2C in GSH-DHP formation in WT and 3AKO mice, respectively. Real-time qPCR analysis showed that the expressions of Cyp2b10 and Cyp2cs increased 2.3-161-fold in 3AKO mice, which was consistent with protein changes. The increased CYP2B activity in 3AKO mice supported the potential role of CYP2B in GSH-DHP formation. After a seven-day treatment of retrorsine, the yields of GSH-DHP were lower than the untreated ones in both alleles, accompanied by the decreased mRNA of Cyp3a, Cyp2b and Cyp2c. The increased serum IL6 might mediate the retrorsine-induced downregulation of Cyp450s.

Conclusion:

These data demonstrated the increased transcription of Cyp2c and Cyp2b caused by Cyp3a ablation, which played a vital role in the metabolic activation of retrorsine, and long-term exposure of retrorsine can reduce the CYP450 activities.

Role of endothelial-microparticles and the tissue factor pathway in ginsenoside Rb1-mediated prevention of umbilical vein endothelial cell injury

Hepatic veno-occlusive disease (VOD) is a life-threatening complication of hematopoietic stem cell transplantation, which urgently requires effective prevention and treatment. Endothelial damage is recognized as the first event in patients with hepatic VOD. However, the mechanism by which endothelial injury induces thrombosis in hepatic VOD is still not clear. In the present study, monocrotaline (MCT) was used to induce endothelial cell injury in EA.hy926 cells to imitate in vitro hepatic VOD. MCT significantly increased apoptosis in EA.hy926 endothelial cells and the secretion of endothelial microparticles (EMPs) which can be used to reflect the level of endothelial injury. Additionally, MCT significantly enhanced the expression of soluble tissue factor (TF) and EMP-bound TF protein, suggesting that EMPs may participate in the development of hepatic VOD by regulating coagulation. Ginsenoside Rb1, a major constituent and effective ingredient of Panax ginseng, was found to significantly decrease MCT-induced endothelial injury and release of EMPs. Moreover, Ginsenoside Rb1 decreased soluble TF released by EA.hy926 cells and EMP-bound TF protein induced by MCT. These data suggest that ginsenoside Rb1 may serve as a potent prophylactic and/or as a treatment of hepatic VOD by protecting endothelial cells and preventing microthrombosis induced by endothelial injury.

Pyrrolizidine alkaloids and beehive products: A review

Pyrrolizidine alkaloids (PA) are secondary metabolites of plants, which are mostly found in the genus Senecio, Echium, Crotalaria, and Eupatorium. The presence of 1,2-unsaturated PA in foods is a concern to food regulators around the world because these compounds have been associated to acute and chronic toxicity, mainly in the liver. The intake foods with PA/PANO usually occur through accidental ingestion of plants and their derivatives, besides to products of vegetal-animal origin, such as honey. PA/PANO are transferred to honey by their presence in nectar, honeydew, and pollen, which are collected from the flora by bees. In addition to honey, other beekeeping products, such as pollen, royal jelly, propolis, and beeswax, are also vulnerable to PA contamination. In this context, this review provides information about chemical characteristics, regulation, and toxicity, as well as summarizes and critically discusses scientific publications that evaluated PA in honeys, pollens, royal jelly, and propolis.

Toxicological Risk Assessment of the Accidental Ingestion of a Honeybee (Apis mellifera L.) Present in Food

The aim of the present work was to evaluate the possible risk of toxic effects due to the ingestion of a honeybee (Apis mellifera L.) accidentally present in food. The methodology used in this study was a bibliographic survey of studies on the toxic effects related to honeybees, with a critical analysis of the possible risks of accidental ingestion of these insects. The amount of venom present in a bee is considered insufficient to induce detectable toxic effects in a person who ingests it by accident, and various components of the venom are destroyed by gastric secretions. However, despite the rare frequency, there is a risk of the ingestion of a bee, causing an allergic reaction to some components of the venom in sensitized individuals. In addition, pollen carried by a bee may cause an allergic reaction in a sensitive individual. Thus, the accidental ingestion of a bee present in a food does not pose the risk of toxic effects for the majority of the population but may promote allergic reactions in susceptible individuals.

In vitro biotransformation of pyrrolizidine alkaloids in different species: part II-identification and quantitative assessment of the metabolite profile of six structurally different pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PA) exert their toxic effects only after bioactivation. Although their toxicity has already been studied and metabolic pathways including important metabolites were described, the quantification of the latter revealed a large unknown portion of the metabolized PA. In this study, the qualitative and quantitative metabolite profiles of structurally different PAs in rat and human liver microsomes were investigated. Between five metabolites for europine and up to 48 metabolites for lasiocarpine were detected. Proposals for the chemical structure of each metabolite were derived based on fragmentation patterns using high-resolution mass spectrometry. The metabolite profiles of the diester PAs showed a relatively good agreement between both species. The metabolic reactions were summarized into three groups: dehydrogenation, oxygenation, and shortening of necic acid(s). While dehydrogenation of the necine base is considered as bioactivation, both other routes are considered as detoxification steps. The most abundant changes found for open chained diesters were dealkylations, while the major metabolic pathway for cyclic diesters was oxygenation especially at the nitrogen atom. In addition, all diester PAs formed several dehydrogenation products, via the insertion of a second double bond in the necine base, including the formation of glutathione conjugates. In rat liver microsomes, all investigated PAs formed dehydropyrrolizidine metabolites with the highest amount formed by lasiocarpine, whereas in human liver microsomes, these metabolites could only be detected for diesters. Our findings demonstrate that an extensive analysis of PA metabolism can provide the basis for a better understanding of PA toxicity and support future risk assessment.

Spread of Jacobaea vulgaris and Occurrence of Pyrrolizidine Alkaloids in Regionally Produced Honeys from Northern Germany: Inter- and Intra-Site Variations and Risk Assessment for Special Consumer Groups

Pyrrolizidine alkaloids (PA) and PA N-oxides (PANO) are secondary plant metabolites exhibiting genotoxic and carcinogenic properties. Apart from the roots and leaves, PA/PANO are particularly present in pollen and nectar. Therefore, the spread of Jacobaea vulgaris in certain regions of northern Germany has an impact on the safety of honey produced in that region. In this study, raw honey samples (n = 437) were collected from usually three individual beehives per site (n = 73) in the district of Ostholstein and analyzed for 25 PA/PANO. The results reveal mean levels of 8.4, 1.5, and 72.6 µg/kg and maximum levels of 111, 59.4, and 3313 µg/kg, depending on the season (summer 2015 and spring/summer 2016, respectively). As far as individual data are concerned, sites near areas with J. vulgaris growth did not necessarily result in high PA/PANO values. Furthermore, intra-site investigations revealed remarkable differences in PA/PANO levels of raw honey collected by different bee colonies at the same site. Consumption of these regionally produced honeys entails an increased exposure to PA/PANO, especially in children and high consumers. Margin of exposure values of <10,000 and an exceedance of the health-based guidance value highlight that regionally produced and marketed honey must be considered with care for a proper risk assessment and risk management.

Preincubation format for a sensitive immunochromatographic assay for monocrotaline, a toxic pyrrolizidine alkaloid

INTRODUCTION

Monocrotaline (MCT), which is classified as a 1,2-dehydropyrrolizidine alkaloid (DHPA), is a toxic compound that is mainly produced by Crotalaria spp. MCT contamination in cereals and herbs leads to hepatitis, gastroenteritis, pulmonary vasculitis and hypertension, and different types of cancer. The current analytical methods for MCT are complicated and expensive using liquid chromatography equipped with mass spectrometry detection.

OBJECTIVE

The aim of this study was to develop a simple and sensitive preincubation format for an immunochromatographic assay (PI-ICA) for MCT detection.

METHODOLOGY

We conducted the PI-ICA via incubation of an MCT-containing sample with an anti-MCT monoclonal antibody conjugated with colloidal gold before strip dipping. We compared the PI-ICA detection sensitivity with that of the conventional ICA (Conv-ICA) format.

RESULTS

The PI-ICA was sensitive with a limit of detection (LOD) of 0.61 ng/mL, which is a 16-fold improvement over the Conv-ICA format. These results indicated that the PI-ICA method exhibits high binding specificity for MCT and low cross-reactivity towards retronecine, retrorsine, senecionine and heliotrine. Sample solutions from plants containing MCT and related DHPAs produced positive results via PI-ICA analysis.

CONCLUSIONS

The proposed PI-ICA system provides a highly sensitive method compared to Conv-ICA. In addition, the developed PI-ICA method is simple and highly effective for detecting MCT contamination.

Simultaneous Determination and Risk Assessment of Pyrrolizidine Alkaloids in Artemisia capillaris Thunb. by UPLC-MS/MS Together with Chemometrics

Pyrrolizidine alkaloids (PAs) are natural toxins found in some genera of the family Asteraceae. However, it has not been reported whether PAs are present in the widely used Asteraceae plant Artemisia capillaris Thunb. (A. capillaris). The purpose of this study was to establish a sensitive and rapid UPLC-MS/MS method together with chemometrics analysis for simultaneous determination and risk assessment of PAs in A. capillaris. The developed UPLC-MS/MS method was validated and was confirmed to display desirable high selectivity, precision and accuracy. Risk assessment was conducted according to the European Medicines Agency (EMA) guideline. Chemometrics analysis was performed with hierarchical clustering analysis and principal component analysis to characterize the differences between PAs of A. capillaris. Finally, PAs were found in 29 out of 30 samples and at least two were detected in each sample, besides, more than half of the samples exceeded the EMA baseline. Nevertheless, the chemometrics results suggested that the PAs contents of A. capillaris from different sources varied significantly. The method was successfully applied to the detection and risk evaluation of PAs-containing A. capillaris for the first time. This study should provide a meaningful reference for the rational and safe use of A. capillaris.

Primary and secondary pyrrolic metabolites of pyrrolizidine alkaloids form DNA adducts in human A549 cells

Humans and animals can be exposed to carcinogenic pyrrolizidine alkaloids (PAs) through consumption of plants commonly found in many parts of the world. Although the liver is the primary target organ for carcinogenic PAs, they have also induced lung tumors in rodents. Hepatic cytochrome P450 activity converts PAs into dehydro-PAs that can be hydrolyzed to dehydropyrrolizidine (DHP); these reactive pyrrolic metabolites can produce four characteristic DNA adducts associated with PA-induced liver tumor initiation in laboratory animals. We reported recently that these four DNA adducts are also formed when 7-glutathione-DHP (7-GS-DHP) or 7-cysteine-DHP is incubated with calf thymus DNA. Here we showed that the four characteristic DNA adducts were formed when human A549 brochoalveolar carcinoma cells were treated with three dehydro-PAs (dehydroriddelliine, dehydromonocrotaline, or dehydroretronecine) or with 7-GS-DHP or 7-cysteine-DHP. For comparison, two parent PAs (riddelliine and monocrotaline) and 7,9-di-glutathionine-DHP were studied. No DHP-DNA adducts were detected with these incubations, confirming that A549 lung carcinoma cells do not express cytochrome P450 enzymes required for metabolic activation of PAs. Our results show that primary and secondary pyrrolic metabolites of carcinogenic PAs produce characteristic DHP-containing DNA adducts in A549 lung cancer cells, suggesting that they are DNA reactive metabolites.

Scientific opinion on the safety of green tea catechins

The EFSA ANS Panel was asked to provide a scientific opinion on the safety of green tea catechins from dietary sources including preparations such as food supplements and infusions. Green tea is produced from the leaves of Camellia sinensis (L.) Kuntze, without fermentation, which prevents the oxidation of polyphenolic components. Most of the polyphenols in green tea are catechins. The Panel considered the possible association between the consumption of (-)-epigallocatechin-3-gallate (EGCG), the most relevant catechin in green tea, and hepatotoxicity. This scientific opinion is based on published scientific literature, including interventional studies, monographs and reports by national and international authorities and data received following a public 'Call for data'. The mean daily intake of EGCG resulting from the consumption of green tea infusions ranges from 90 to 300 mg/day while exposure by high-level consumers is estimated to be up to 866 mg EGCG/day, in the adult population in the EU. Food supplements containing green tea catechins provide a daily dose of EGCG in the range of 5-1,000 mg/day, for adult population. The Panel concluded that catechins from green tea infusion, prepared in a traditional way, and reconstituted drinks with an equivalent composition to traditional green tea infusions, are in general considered to be safe according to the presumption of safety approach provided the intake corresponds to reported intakes in European Member States. However, rare cases of liver injury have been reported after consumption of green tea infusions, most probably due to an idiosyncratic reaction. Based on the available data on the potential adverse effects of green tea catechins on the liver, the Panel concluded that there is evidence from interventional clinical trials that intake of doses equal or above 800 mg EGCG/day taken as a food supplement has been shown to induce a statistically significant increase of serum transaminases in treated subjects compared to control.