Pyrrolizidine alkaloids: their occurrence in Spanish honey collected from purple viper's bugloss (Echium spp.)

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 Alkaloids from Monofloral and Multifloral Italian Honey

Pyrrolizidine alkaloids (PAs) are secondary metabolites produced by plants as a self-defense against insects. After bioactivation in the liver, some PAs can cause acute or chronic toxicity in humans. The aim of this study was to determine the presence of PAs in 121 samples of monofloral and multifloral honey from three different Italian regions (Friuli-Venezia Giulia, Marche and Calabria) to meet the European Food Safety Authority (EFSA) suggestion. An in-house liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was validated according to European Union Reference Laboratory (EURL) performance criteria. This method allowed the detection and quantification of 35 PAs. Of the 121 honey samples, 38 (31%), mostly from Calabria, contained PAs. The total content of the PAs ranged from 0.9 µg/kg to 33.1 µg/kg. In particular, echimidine was the most prevalent PA. A rapid human exposure assessment to PAs in honey and a risk characterization was performed using the EFSA RACE tool. The assessment highlighted a potential health concern only for toddlers who frequently consume elevated quantities of honey. This study showed a low presence of PAs in Italian honey; however, the importance of continuously monitoring these compounds is stressed, along with the suggestion that the relevant authorities establish maximum limits to guarantee support for producers and consumer safety.

Pyrrolizidine Alkaloid Extraction and Analysis: Recent Updates

Pyrrolizidine alkaloids are natural secondary metabolites that are mainly produced in plants, bacteria, and fungi as a part of an organism's defense machinery. These compounds constitute the largest class of alkaloids and are produced in nearly 3% of flowering plants, most of which belong to the Asteraceae and Boraginaceae families. Chemically, pyrrolizidine alkaloids are esters of the amino alcohol necine (which consists of two fused five-membered rings including a nitrogen atom) and one or more units of necic acids. Pyrrolizidine alkaloids are toxic to humans and mammals; thus, the ability to detect these alkaloids in food and nutrients is a matter of food security. The latest advances in the extraction and analysis of this class of alkaloids are summarized in this review, with special emphasis on chromatographic-based analysis and determinations in food.

High abundance of pyrrolizidine alkaloids in bee pollen collected in July 2019 from Southern Germany

Pyrrolizidine alkaloids (PA) are secondary plant defense compounds and known pre-toxins when containing a 1,2-double bond. They are commonly produced by various plants and may thus be present in bee pollen which may be consumed by humans as food supplements. In this study, PA were determined in bee pollen samples from 57 locations in Southern Germany sampled by means of pollen traps in July 2019. Samples were analyzed by using palynological methodology and solid-phase extraction (SPE) followed by LC-MS/MS. In total, 52 pollen samples featured total pyrrolizidine alkaloids (ΣPA) with concentrations up to 48,000 ng/g bee pollen, while the N-oxides (NO) echinatine-NO and rinderine-NO clearly dominated. In contrast, the palynological analysis only detected 33 samples with pollen from PA-producing plants. Accordingly, the results showed that palynological analysis is not sufficient to determine PA in pollen. In addition, a risk assessment was followed to estimate the risk of the detected PA concentrations to humans.

Comparative analysis of the main medicinal substances and applications of Echium vulgare L. and Echium plantagineum L.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Echium vulgare L. and Echium plantagineum L. originated in the Mediterranean, and were later domesticated in Africa, America, Asia, Europe and Oceania, where they were widely used to treat many diseases including cough, urinary tract infection, fever, inflammation and muscle strain.

AIM OF THE STUDY

The purpose of this review is to provide scientific literature on the traditional uses, bioactive chemical components and pharmacological activities of two species of Echium, and to critically analyze the information provided, so as to understand the current work on these two species and explore the possible prospect of this plant in pharmaceutical research.

METHODS

Systematic review and meta-analysis were conducted according to Prisma guidelines, and the related literatures searched on Google Academic, Science Direct, Baidu Scholars and China National Knowledge Infrastructure (CNKI) up to June 2021 were reviewed. The key words used are: Echium, E.vulgare, E.plantagineum, plant components, chemical components, pharmacological activities, pharmaceutical products and applications. Thereafter all eligible studies are analyzed and summarized in this review. The selection of manuscripts is based on the following inclusion criteria: the article has years of research or publication, is published in English, Portuguese or Spanish and Chinese, and there are keywords in the title, abstract, keywords or full text of the article. For the selection of manuscripts, first, select articles according to titles, then summarize them, and finally, analyze the full text of the publication. Elimination criteria: 1. Duplicate reports; 2. There are research design defects and poor quality; 3. Incomplete data and unclear ending effect; 4. The statistical method is wrong and cannot be corrected.

RESULTS

The pharmacological characteristics of E.vulgare and E.plantagineum can basically support their traditional use, but the medicinal substances contained in them are quite different in composition and content, and the development and application of corresponding products are also different.

CONCLUSIONS

At present, there is little clinical data about drugs related to the two species, and more research is needed in the future, especially human experiments and clinical trials, to evaluate the cellular and molecular mechanisms based on pharmacological, biological activity and safety studies, and to provide more powerful scientific basis for their traditional medicinal properties. In addition, the further application and development of the medicinal products of E.vulgare and E.plantagineum still need to be precise and identified, so as to give full play to their medicinal potential.

Comfrey (Symphytum spp.) as a feed supplement in pig nutrition contributes to regional resource cycles

In smallholder agriculture, the fast-growing and perennial accumulator plant comfrey (Symphytum spp.) was used to supply pigs with protein and minerals. Comfrey leaves show similar values in dry matter as soybean or blue lupine in crude protein content, but much higher levels of calcium and phosphorus. However, in terms of increased efficiency in animal husbandry, comfrey has been displaced by mainly soybean and cereals. Due to its profile of macro- and micronutrients the use of comfrey could have the potential to re-establish local resource cycles and help remediate over-fertilized soils. The aim of the study was to evaluate whether a modern pig breed accepts a continuous feed supplement of dried comfrey leaves. After an initial adaptation period post-weaning, German Landrace piglets were subjected to either a standard control diet or a diet supplemented with 15% dried comfrey leaves for 4 weeks. Body weight was reduced in comfrey-supplemented piglets compared to controls, which might be attributed to reduced palatability in the experimental setting. Nevertheless, comfrey-supplemented piglets exhibited adequate bone mineralization and intestinal integrity. The microbiome profile in feces and digesta revealed higher diversity in comfrey-supplemented piglets compared to controls, with pronounced effects on the abundances of Treponema and Prevotella. This may be due to described bio-positive components of the comfrey plant, as data suggest that the use of comfrey leaves may promote intestinal health. Digestive tract phosphorus levels were reduced in piglets receiving comfrey supplementation, which may ultimately affect phosphorus levels in manure. Results indicate that comfrey leaves could serve as a feed component in integrated agricultural systems to establish regional nutrient cycles. The trial provides a basis for further work on comfrey as a regionally grown protein source and effective replacement for rock mineral supplements.

Fluorescent lateral flow immunoassay based on gold nanocluster for detection of pyrrolizidine alkaloids

An ultrasensitive and rapid fluorescent immunoassay based on a broad-spectrum monoclonal antibody (mAb) was developed to detect pyrrolizidine alkaloids (PAs) in honey samples. First, Discovery Studio software was used to analyze and predict the target hapten, and retrorsine (RTS) was selected to react with succinic anhydride (HS) for hapten synthesization. A sensitive and broad-spectrum monoclonal antibody (mAb 13E1) was obtained for nine PAs. Then, fluorescent gold nanoclusters (AuNCs) were conjugated with mAb as a label probe and used in establishing a qualitative and quantitative lateral flow immunoassay (AuNCs-LFIA) for the determination of four PAs (retrorsine, platyphylline, senecionine, integerrimine) in honey within 14 min. The limits of detection (LOD) were 0.083 μg/kg. The recovery in spiked honey samples were 87.98-119.57%, with coefficients of variation of ≤ 11.5%. A total of 45 commercial import honey samples from nine different countries were tested through AuNCs-LFIA and UPLC-MS/MS method, and satisfactory consistency (R2 = 0.995) was obtained. The rates of positive samples were 55.56% (25/45), and the average concentrations of four PAs were 3.24-46.47 μg/kg. This ultrasensitive multi-PA method provides an alternative analytical tool for evaluating the human risk posed by the consumption of PA-contaminated honey.

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.

Monitoring of pyrrolizidine alkaloids in beehive products and derivatives on the Belgian market

Pyrrolizidine alkaloids (PAs) and related N-oxides (PANOs) are secondary plant metabolites thought to be found in approximately 3% of the flowering plants worldwide and exhibiting hepatotoxic properties to humans. As a consequence, beehive products are prone to be contaminated with those compounds by bees foraging PA-producing plants. Downstream contamination can also occur through food items containing honey. Analytical methods based on UHPLC separation and MS/MS detection were developed with a focus on very low LOQs and validated for the analysis of 16 PAs and 14 PANOs in honey, honey-based candies and snacks, as well as beehive product-based food supplements. A maximum level of 182 ng/g of PAs was detected in a Mediterranean honey, and high levels of heliotrine-type compounds were reported for the first time. An extensive sampling of honeys harvested in Belgium was performed (N = 374), the concentration levels were more limited with a maximum of 60 ng/g, and the contamination pattern was dominated by senecionine-type PAs. The PA levels in honey-based candies and snacks were very low, with respective maxima of 7.61 ng/g and 0.36 ng/g. Seventy-five percent among the pre-dosed food supplements based on beehive products were contaminated, with a maximum of 43 ng/g. The highest level was detected in a bee-collected pollen sample (1672 ng/g). The analytical results were consistent with the previously reported data for beehive products and confirmed that PA/PANO contamination in these food commodities is recurrent.

Straightforward Determination of Pyrrolizidine Alkaloids in Honey through Simplified Methanol Extraction (QuPPE) and LC-MS/MS Modes

Contamination of honey with toxic pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) was assessed by dilution with acidic methanol and analysis through liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) in three different modes. The hybrid linear trap/triple quadrupole (LC-QTRAP) instrument was used in precursor ion scan (PIS), enhanced product ion scan (EPI), and multiple reaction monitoring (MRM) mode. The parent ions from ions at m/z 120 or 138 amus, characteristic of all the toxic PAs and PANOs in the sample were first scanned by PIS. Then, the presence of each contaminant at specific retention times through its MS2 spectrum was confirmed by EPI. Finally, they were quantified in the MRM mode. The method was validated: recoveries 86-111%, relative standard deviation (RSD) <20%, at 20 and 40 μg/kg, except retrorsine, which showed a RSD of 30% at 20 μg/kg. Honey samples were analyzed and five of them showed levels of 40 μg/kg for the sum (PAs + PANOs). This approach allows the simultaneous determination of PAs and PANOs in honey, even if their chemical standards are not available.

Pyrrolizidine Alkaloids: Chemistry, Pharmacology, Toxicology and Food Safety

Pyrrolizidine alkaloids (PA) are widely distributed in plants throughout the world, frequently in species relevant for human consumption. Apart from the toxicity that these molecules can cause in humans and livestock, PA are also known for their wide range of pharmacological properties, which can be exploited in drug discovery programs. In this work we review the current body of knowledge regarding the chemistry, toxicology, pharmacology and food safety of PA.

Pyrrolizidine Alkaloids in Honey: Determination with Liquid Chromatography-mass Spectrometry Method

INTRODUCTION

Pyrrolizidine alkaloids (PAs) are probably the most widespread toxins of natural origin. More than 6,000 plant species produce these toxic compounds. Bees can forage on flowers of plants producing PAs, which leads to contamination of honey with the toxic compounds. To determine the contamination of honey with PAs, a sensitive method based on liquid chromatography coupled with mass spectrometry has been developed.

MATERIAL AND METHODS

PAs were extracted with 0.05 M sulphuric acid and purified with MCX cartridges. A solvent mixture consisting of ethyl acetate, methanol, acetonitrile, ammonia, and triethylamine (8:1:1:0.1:0.1, v/v) was used to wash alkaloids from the cartridges. After evaporation the residues were reconstituted in water and methanol mixture and subjected to LC-MS analysis.

RESULTS

The developed method was validated according to SANTE/11945/2015 requirements. The recovery was from 80.6% to 114.5%. The repeatability ranged from 2.3% to 14.6%, and the reproducibility was from 4.9% to 17.7%.

CONCLUSIONS

A new method for the determination of PAs in honey has been developed and validated. All evaluated parameters were in accordance with the SANTE/11945/2015 guidance document. Out of 50 analysed honey samples, 16 (32%) were positive for the content of at least one PA.

Pyrrolizidine alkaloids: occurrence, biology, and chemical synthesis

Covering: 2013 up to the end of 2015This review covers the isolation and structure of new pyrrolizidines; pyrrolizidine biosynthesis; biological activity, including the occurrence of pyrrolizidines as toxic components or contaminants in foods and beverages; and formal and total syntheses of naturally-occurring pyrrolizidine alkaloids and closely related non-natural analogues.

Pyrrolizidine Alkaloids from Echium vulgare in Honey Originate Primarily from Floral Nectar

Pyrrolizidine alkaloids (PAs) in honey can be a potential human health risk. So far, it has remained unclear whether PAs in honey originate from pollen or floral nectar. We obtained honey, nectar, and plant pollen from two observation sites where Echium vulgare L. was naturally abundant. The PA concentration of honey was determined by targeted analysis using a high pressure liquid chromatography-mass spectrometry system (HPLC-MS/MS), allowing the quantification of six different PAs and PA-N-oxides present in E. vulgare. Echium-type PAs were detected up to 0.153 μg/g in honey. Nectar and plant pollen were analyzed by nontargeted analysis using ultrahigh pressure liquid chromatography-high resolution-mass spectrometry (UHPLC-HR-MS), allowing the detection of 10 alkaloids in small size samples. Echium-type PAs were detected between 0.3-95.1 μg/g in nectar and 500-35000 μg/g in plant pollen. The PA composition in nectar and plant pollen was compared to the composition in honey. Echimidine (+N-oxide) was the main alkaloid detected in honey and nectar samples, while echivulgarine (+N-oxide) was the main PA found in plant pollen. These results suggest that nectar contributes more significantly to PA contamination in honey than plant pollen.

Pyrrolizidine alkaloids in herbal teas for infants, pregnant or lactating women

A general contamination of tea with pyrrolizidine alkaloids (PA) has just become known. Here, we report the application and modification of a new HPLC-ESI-MS/MS sum parameter method to quantitate PA content of herbal teas intended for infants, pregnant and lactating women. Using p-toluenesulfonyl isocyanate for derivatization and a stable isotope labeled internal standard, the total retronecine-/heliotridine-type PA content of the samples is expressed in form of a single sum parameter (retronecine equivalents: RE). The new methods were applied to analyze 44 tea samples for such consumer groups. Thirty eight products (86%) were tested PA positive showing PA concentrations ranging from 0 to 391 μg RE/kg (average: 50 μg RE/kg). The dataset is discussed in the view of the current discussion on PA in the food chain with special focus on those particular vulnerable consumer groups.