RESUMEN

Over 1,000 pyrrolizidine alkaloids (PAs) and their N-oxides (PA-N-oxides) occur in 3% of all flowering plants. PA-N-oxides are toxic when reduced to their parent PAs, which are bioactivated into pyrrole intermediates that generate protein- and DNA-adducts resulting in liver toxicity and carcinogenicity. Literature data for senecionine N-oxide in rats indicate that the relative potency (REP) value of this PA-N-oxide compared to its parent PA senecionine varies with the endpoint used. The first endpoint was the ratio between the area under the concentration-time curve (AUC) for senecionine upon dosing senecionine N-oxide or an equimolar dose of senecionine, while the second endpoint was the ratio between the amount for pyrrole-protein adducts formed under these conditions. This study aimed to investigate the mode of action underlying this endpoint dependent REP value for senecionine N-oxide with physiologically based kinetic (PBK) modeling. Results obtained reveal that limitation of 7-GS-DHP adduct formation due to GSH depletion, resulting in increased pyrrole-protein adduct formation, occurs more likely upon high dose oral PA administration than upon an equimolar dose of PA-N-oxide. At high dose levels, this results in a lower REP value when based on pyrrole-protein adduct levels than when based on PA concentrations. At low dose levels, the difference no longer exists. Altogether, the results of the study show how the REP value for senecionine N-oxide depends on dose and endpoint used, and that PBK modeling provides a way to characterize REP values for PA-N-oxides at realistic low dietary exposure levels, thus reducing the need for animal experiments.

RESUMEN

OBJECTIVE To improve the quality standard of Yi medicine Gynura japonica， and to evaluate its quality. METHODS Using 15 batches of G. japonica from different producing areas as samples， the contents of water， total ash， acid- insoluble ash and water-soluble extract were determined according to the method stated in part Ⅳ of Chinese Pharmacopoeia （2020 edition）. The contents of total alkaloid （calculated by senecionine） was determined by UV spectrophotometry. The contents of senecionine and seneciphylline were determined by HPLC. Using above 7 indexes as evaluation indexes， cluster heat map analysis， principal component analysis （PCA） and entropy weight approximation ideal ranking （TOPSIS） were used to evaluate the quality of medicinal material comprehensively. RESULTS Among 15 batches of G. japonica， the moisture contents were 8.88%-12.60%， the total ash contents were 4.43%-11.02%， the acid-insoluble ash contents were 0.56%-3.45%， the water-soluble extract contents were 21.71%-53.91%， the total alkaloid contents （calculated by senecionine） were 0.15%-0.39%， and the contents of senecionine and seneciphylline were 0.01% -0.05% and 0.01%-0.06% respectively. According to the results of various indicators， it was preliminarily proposed that the water content in the sample of G. japonica should not exceed 13.00%， the total ash content should not exceed 11.50%， the acid-insoluble ash content should not exceed 3.70%， the water-soluble extract should not be less than 20.70%， the total alkaloid content should not be less than 0.15%， the contents of senecionine and seneciphylline should not be less than 0.01% both. The results of cluster heat map analysis showed that the 15 batches of samples could be divided into four categories； the results of PCA and TOPSIS showed that the samples with high-quality ranking were jsq-2， jsq-5， jsq-6 and jsq-10， and the samples with low-quality ranking were jsq-4， jsq-13 and jsq-14. CONCLUSIONS In this study， the quantitative analysis method of total alkaloids （calculated by senecionine）， senecionine and seneciphylline in G. japonica is established， and the limits of each index are preliminarily determined. Among 15 batches of samples， the qualities of medicinal material collected from Linza Village of Ganluo County of Liangshan Yi Autonomous Prefecture， Machangping Village of Luojishan Town of Puge County of Liangshan Yi Autonomous Prefecture and other places are better.

RESUMEN

1,2-unsaturated Pyrrolizidine Alkaloids (PAs) are secondary plant metabolites that occur as food contaminants. Upon consumption, they can cause severe liver damage. PAs have been shown to induce apoptosis, to have cytotoxic and genotoxic effects, and to impair bile acid homeostasis in the human hepatoma cell line HepaRG. The major mode of action of PAs is DNA- and protein-adduct formation. Beyond that, nuclear receptor activation has only been observed for one receptor and two PAs, yielding the possibility that other cellular mediators are involved in PA-mediated toxicity. Here, the mode of action of Senecionine (Sc), a prominent and ubiquitous representative of hepatotoxic PAs, was investigated by analyzing 7 hepatic microRNAs (miRNAs) in HepaRG cells. Ultimately, 11 target genes that were predicted with Ingenuity Pathway Analysis software (IPA) were found to be significantly downregulated, while their assigned miRNAs showed significant upregulation of gene expression. According to IPA, these targets are positively correlated with apoptosis and cellular death and are involved in diseases such as hepatocellular carcinoma. Subsequent antagomiR-inhibition analysis revealed a significant correlation between PA-induced miRNA-4434 induction and P21-Activated Kinase-1 (PAK1) downregulation. PAK1 downregulation is usually associated with cell cycle arrest, suggesting a new function of Sc-mediated toxicity in human liver cells.

RESUMEN

Hepatotoxicity induced by herbal medicines such as Gynura japonica, which contains large amount of pyrrolizidine alkaloids (PAs) such as senecionine (SEN), is among the most serious problems of herbal drug-induced liver injury, yet there is no effective treatment in clinic. We have previously reported that ritonavir (the well-known CYP3A4 inhibitor) protected rats against Gynura japonica-induced liver injury in rats, which was closely related to the inhibition of the metabolic activation of PAs. A large number of lignans have been identified in Schisandrae Chinensis Fructis and are reported to attenuate drug-induced liver injuries by modulating the drug metabolism enzymes. Therefore, the present study investigated the protective effect and potential mechanism of schisandrol A (SoA, a representative lignan identified in Schisandrae Chinensis Fructis) against SEN-induced hepatotoxicity in mice. All experiments were approved by the Animal Research Committee of Shanghai University of Traditional Chinese Medicine (PZSHUTCM210604002). Animal welfare and the animal experimental protocols were strictly consistent with related ethics regulations of Shanghai University of Traditional Chinese Medicine. Liver injury was induced by a single gavage of SEN (150 μmol·kg-1); mice in the protection group were gavaged with SoA (116 μmol·kg-1) 7 days before SEN treatment. The results show that SoA dramatically alleviated SEN-induced liver injury in mice. Mice in the protection group showed decreased serum activities for alanine aminotransferase and aspartate aminotransferase; in addition, the hepatic necrosis and sinusoidal hemorrhage in SEN-treated mice were markedly attenuated in the protection group. The serum contents of SEN metabolites in mice were decreased. In vitro studies were performed by using human liver microsomes and proved that SoA inhibits CYP3A4 to decrease the metabolism of SEN. These studies indicate that SoA attenuated SEN-induced liver injury in mice, which was closely related to the inhibition of the metabolic activation of SEN. These results provide a better understanding of the relationship between CYP3A4 and PA-induced toxicity. This work also will be helpful in developing effective treatments for SEN-induced liver injury based on inhibition of its metabolic activation, and in making reasonable evaluations of the safety of herbal medicines containing PAs such as G. japonica.

RESUMEN

Pyrrolizidine alkaloids (PAs) are a large group of botanical toxins of concern, as they are considered genotoxic carcinogens, with long-term dietary exposure presenting an elevated risk of liver cancer. PAs can contaminate honey through honeybees visiting the flowers of PA-containing plant species. A program of monitoring New Zealand honey has been undertaken over several years to build a comprehensive dataset on the concentration, regional and seasonal distribution, and botanical origin of 18 PAs and PA N-oxides. A bespoke probabilistic exposure model has then been used to assess the averaged lifetime dietary risk to honey consumers, with exposures at each percentile of the model characterized for risk using a margin of exposure from the Joint World Health Organization and United Nations Food and Agriculture Organization Expert Committee on Food Additives (JECFA) Benchmark Dose. Survey findings identify the typical PA types for New Zealand honey as lycopsamine, echimidine, retrorsine and senecionine. Regional and seasonal variation is evident in the types and levels of total PAs, linked to the ranges and flowering times of certain plants. Over a lifetime basis, the average exposure an individual will receive through honey consumption is considered within tolerable levels, although there are uncertainties over high and brand-loyal consumers, and other dietary contributors. An average lifetime risk to the general population from PAs in honey is not expected. However, given the uncertainties in the assessment, risk management approaches to limit or reduce exposures through honey are still of value.

Asunto(s)

RESUMEN

Pyrrolizidine alkaloids (PAs) are produced by plants as secondary compounds that are the most widely distributed natural toxins. There have been many cases of human toxicity caused by consumption of toxic plant species, as herbal teas and grain or grain products contaminated with PA-containing seeds have been reported. Companies that produce dried spices and tea leaves should examine the PA level in their products. For the first time in the literature, a simple and inexpensive electrochemical assay based on a single-use sensor was introduced for quantitative determination of senecionine (SEN) in the most frequently contaminated food sources. SEN was immobilized on a pencil graphite electrode surface by the passive adsorption technique. Differential pulse voltammetry (DPV) was used to evaluate the oxidation signal of SEN, which was observed to be around +0.95 V. The oxidation signal was specific to the SEN in the sample, and the current value was proportional to its concentration. The selectivity of our assay was also tested in the presence of other similar PAs such as intermedine, lycopsamine, and heliotrine. The detection limit is calculated by developed assay and found to be 5.45 µg/mL, which is an acceptable concentration value of SEN occurring at toxic levels for consumers. As an application of the developed sensor in food products, the electrochemical detection of SEN was successfully performed in flour and herbal tea products.

RESUMEN

The honey bee pollen/nectar diet is rich in bioactive phytochemicals and recent studies have demonstrated the potential of phytochemicals to influence honey bee disease resistance. To unravel the role of dietary phytochemicals in honey bee health it is essential to understand phytochemical uptake, bioavailability, and metabolism but presently limited knowledge exists. With this study we aim to build a knowledge foundation. For 5 days, we continuously fed honey bees on eight individual phytochemicals and measured the concentrations in whole and dissected bees by HPLC-MS/MS. Ample phytochemical metabolization was observed, and only 6-30% of the consumed quantities were recovered. Clear differences in metabolization rates were evident, with atropine, aucubin, and triptolide displaying significantly slower metabolism. Phytochemical gut uptake was also demonstrated, and oral bioavailability was 4-31%, with the highest percentages observed for amygdalin, triptolide, and aucubin. We conclude that differences in the chemical properties and structure impact phytochemical uptake and metabolism.

Asunto(s)

RESUMEN

In recent years, there has been an increase in the incidence of herbal-induced liver injury due to the accidental ingestion of herbal medicines containing pyrrolizidine alkaloids (PAs) in domestic. Salvianolic acid B (Sal B), a hydrophilic component in Salvia miltiorrhiza Bge., shows activities of anticoagulation, antioxidation, and other pharmacological activities. This research aims to investigate the protective effect of Sal B on hepatotoxicity induced by senecionine (SEN) and its potential mechanism. The animal experiment was approved by the Experimental Animal Ethical Committee of Shanghai University of Traditional Chinese Medicine, and all mice have received humane care in compliance with the institutional animal care guidelines. Mice were treated with Sal B (10 mg·kg-1) 3 days before and 1 day after SEN (50 mg·kg-1) treatment. The animals were sacrificed 48 h after SEN administration. As a result, Sal B effectively ameliorated SEN-induced liver injury. The mice in the group treated with Sal B showed lower serum activities of alanine aminotransferase and aspartate aminotransferase, less hepatic sinusoidal hemorrhage, and reduced hepatocyte necrosis. Besides, contents of pyrrole-protein adducts, the marker for PA-induced toxicity, were also decreased in serum. The key factors related to coagulation, oxidative stress, and liver fibrosis were further analyzed. It was found that Sal B inhibited the coagulant system by reducing the expression of plasminogen activator inhibitor-1. Sal B also modulated glutathione and superoxide dismutase levels and improved the anti-oxidative defense system. In addition, Sal B decreased the excessive deposition of extracellular matrix and inhibited the progression of liver fibrosis via down-regulating several key factors related to liver fibrosis, including matrix metalloproteinase 9, transforming growth factor-β1, signal transducer and activator of transcription 3, and chemokine 1. In conclusion, Sal B ameliorated SEN-induced liver injury in mice by regulating the blood coagulation system, improving oxidative stress, and modulating liver fibrosis-related factors. Our present study pointed to the possibility of utilizing salvianolic acid B for protection against PA-induced liver injury clinically.

RESUMEN

Drug-induced liver injury and herbal preparations containing pyrrolizidine alkaloid (PA) have gained global attention. The purpose of this research was to investigate the effects and mechanisms of Alismatis Rhizoma, a traditional Chinese medicine, to protect against acute liver injury in mice induced by senecionine (SEN), a representative toxic PA compound. All experiments were approved by the Animal Research Committee of Shanghai University of Traditional Chinese Medicine. Animal welfare and the animal experimental protocols were strictly consistent with related ethics regulations of Shanghai University of Traditional Chinese Medicine. Acute liver injury was induced by a single intragastric administration of SEN (50 mg·kg-1). Mice in the protection groups received intragastric administration of Alismatis Rhizoma water extract (WE, 18 g·kg-1 per day) or ethanol extract (EE, 18 g·kg-1 per day) 5 days before SEN treatment. The results show that Alismatis Rhizoma extracts can significantly attenuate acute liver injury in mice. Mice in the protection groups showed decreased serum activities of alanine aminotransferase and aspartate aminotransferase, as well as decreased total bile acids. In addition, the infiltration of inflammatory cells, sinusoidal hemorrhage, and hepatic necrosis in SEN-treatment mice was clearly attenuated in the protection groups. Interestingly, EE showed a better effect than WE. The content of principal bile acids in serum and the mRNA and protein expression of key factors related to bile acid metabolism were also measured. Alismatis Rhizoma up-regulated the bile acid transporters and drug metabolism enzymes, consistent with the observed bile acid homeostasis and alleviation of SEN-induced injury to hepatocytes. The present study points to the possibility of utilizing Alismatis Rhizoma for protection against liver injury caused by drugs and preparations containing PA.

RESUMEN

Pyrrolizidine alkaloids (PAs) are carcinogenic phytochemicals, inducing liver tumors in experimental rodents. We previously determined that (±)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), 7-glutathione-DHP, 7-cysteine-DHP, 7-N-acetylcysteine-DHP, and 1-CHO-DHP are DNA reactive pyrrolic metabolites potentially associated with PA-induced liver tumor initiation. In this study, we developed an LC/MS/MS multiple reaction monitoring (MRM) mode method to identify and quantify these metabolites formed from the metabolism of senecionine, a carcinogenic PA, by mouse, rat, and human liver microsomes, and primary rat hepatocytes. Together with the chemically prepared standards of these metabolites, this represents an accurate and convenient LC/MS/MS analytical method for quantifying these five reactive pyrrolic metabolites in biological systems.

Asunto(s)

RESUMEN

Pyrrolizidine alkaloids (PAs) are heterocyclic secondary metabolites with a typical pyrrolizidine motif predominantly produced by plants as defense chemicals against herbivores. They display a wide structural diversity and occur in a vast number of species with novel structures and occurrences continuously being discovered. These alkaloids exhibit strong hepatotoxic, genotoxic, cytotoxic, tumorigenic, and neurotoxic activities, and thereby pose a serious threat to the health of humans since they are known contaminants of foods including grain, milk, honey, and eggs, as well as plant derived pharmaceuticals and food supplements. Livestock and fodder can be affected due to PA-containing plants on pastures and fields. Despite their importance as toxic contaminants of agricultural products, there is limited knowledge about their biosynthesis. While the intermediates were well defined by feeding experiments, only one enzyme involved in PA biosynthesis has been characterized so far, the homospermidine synthase catalyzing the first committed step in PA biosynthesis. This review gives an overview about structural diversity of PAs, biosynthetic pathways of necine base, and necic acid formation and how PA accumulation is regulated. Furthermore, we discuss their role in plant ecology and their modes of toxicity towards humans and animals. Finally, several examples of PA-producing crop plants are discussed.

Asunto(s)

RESUMEN

Awareness about pyrrolizidine alkaloids (PAs) and tropane alkaloids (TAs) in food was recently raised by the European Food Safety Authority stressing the lack of data and gaps of knowledge required to improve the risk assessment strategy. The present study aimed at the elaboration and validation of a method to determine PAs and TAs in honey. QuEChERS sample treatment and liquid chromatography coupled to hybrid high resolution mass spectrometry, were used. The method resulted in good linearity (R2>0.99) and low limits of detection and quantification, ranging from 0.04 to 0.2µgkg-1 and from 0.1 to 0.7µgkg-1 respectively. Recoveries ranged from 92.3 to 114.8% with repeatability lying between 0.9 and 15.1% and reproducibility between 1.1 and 15.6%. These performances demonstrate the selectivity and sensitivity of the method for simultaneous trace detection and quantification of PAs and TAs in honey, verified through the analysis of forty commercial samples.

Asunto(s)

RESUMEN

Pyrrolizidine alkaloids (PAs) are a group of compounds found in various plants and some of them are widely consumed in the world as herbal medicines and food supplements. PAs are potent hepatotoxins that cause irreversible liver injury in animals and humans. However, the mechanisms by which PAs induce liver injury are not clear. In the present study, we determined the hepatotoxicity and molecular mechanisms of senecionine, one of the most common toxic PAs, in primary cultured mouse and human hepatocytes as well as in mice. We found that senecionine administration increased serum alanine aminotransferase levels in mice. H&E and TUNEL staining of liver tissues revealed increased hemorrhage and hepatocyte apoptosis in liver zone 2 areas. Mechanistically, senecionine induced loss of mitochondrial membrane potential, release of mitochondrial cytochrome c as well as mitochondrial JNK translocation and activation prior to the increased DNA fragmentation and caspase-3 activation in primary cultured mouse and human hepatocytes. SP600125, a specific JNK inhibitor, and ZVAD-fmk, a general caspase inhibitor, alleviated senecionine-induced apoptosis in primary hepatocytes. Interestingly, senecionine also caused marked mitochondria fragmentation in hepatocytes. Pharmacological inhibition of dynamin-related protein1 (Drp1), a protein that is critical to regulate mitochondrial fission, blocked senecionine-induced mitochondrial fragmentation and mitochondrial release of cytochrome c and apoptosis. More importantly, hepatocyte-specific Drp1 knockout mice were resistant to senecionine-induced liver injury due to decreased mitochondrial damage and apoptosis. In conclusion, our results uncovered a novel mechanism of Drp1-mediated mitochondrial fragmentation in senecionine-induced liver injury. Targeting Drp1-mediated mitochondrial fragmentation and apoptosis may be a potential avenue to prevent and treat hepatotoxicity induced by PAs.

Asunto(s)

RESUMEN

Jacobaea aquatica (Asteraceae) growing in wet grasslands with low management intensity is regarded as a noxious weed with pyrrolizidine alkaloids (PAs), which cause health problems to livestock. The influence of different management practices on the production of PAs and on the proportion of J. aquatica in the fodder was studied. Five cutting regimes were applied during 4 years on permanent plots in lower Austria. The toxicity of the fodder was assessed by recording dry weight and alkaloid content of J. aquatica and total aboveground biomass. Different cutting regimes had significant effects on the PA content of J. aquatica and on its proportion in the fodder. The content of J. aquatica was lowest in fodder of June and October cuts and highest in second cuts in July and August. Total alkaloid contents exceeding 100 mg/kg were found in fodder harvested in July and August. After cutting, the toxic plants regenerated quickly and produced new flowering stalks within 4-5 weeks. Six macrocylic PAs were evaluated, with Z-erucifoline as the most abundant compound. The alkaloid levels were highest in plants cut during summer when flowering plants were present. Consequently, this fodder should not be fed to livestock over a long period of time.

RESUMEN

Hepatic sinusoidal obstruction syndrome (HSOS), characterized by hepatomegaly, ascites and hyperbilirubinemia, is caused by toxic injury to hepatic sinusoidal endothelial cells. One major etiology of HSOS in China is the intake of products containing pyrrolizidine alkaloids (PA) such as Tusanqi. The manifestations of patients with HSOS are usually non-specific, presenting with abnormal liver function and portal hypertension. Diagnosis of the disease depends mostly on liver histopathology when clinical and imaging data are not sufficient. A history of Tusanqi intake is mostly important for the diagnosis. Due to a lack of effective, evidence-based treatments for HSOS, avoiding the mistaken use of PA-containing products including Tusanqi is important for the prevention of HSOS.

Asunto(s)

RESUMEN

OBJECTIVE: To investigate the metabolic profile of senecionine in rats. METHODS: Liquid chromatography-tandem mass spectrometry (LC-MSn) mass spectrometry was used for the analysis of senecionine and its metabolites in rats bile, urine, and feces after a single oral dose of senecionine. RESULTS: In total 38 metabolites were identified, including oxidation products, hydroxylation products, hydrolysis products, sulfation products, glucuronidation products, and GSH-conjugations. And metabolites were found to be more abundant in bile and urine than those in feces. CONCLUSION: Senecionine undergoes extensive metabolism in rats.