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.

Pyrrolizidine Alkaloids-Pros and Cons for Pharmaceutical and Medical Applications

Heterocyclic organic compounds named pyrrolizidine alkaloids (PAs) belong to a group of alkaloids and are synthesized by either plants or microorganisms. Therefore, they are naturally occurring secondary metabolites. They are found in species applied in the pharmaceutical and food industries, thus a thorough knowledge of their pharmacological properties and toxicology to humans is of great importance for their further safe employment. This review is original because it synthesizes knowledge of plant and microbial PAs, which is unusual in the scientific literature. We have focused on the Boraginaceae family, which is unique due to the exceptional richness and diversity of its PAs in plant species. We have also presented the microbial sources of PAs, both from fungi and bacteria. The structure and metabolism of PAs have been discussed. Our main aim was to summarize the effects of PAs on humans, including both negative, toxic ones, mainly concerning hepatotoxicity and carcinogenicity, as well as potentially positive ones for pharmacological and medical applications. We have collected the results of studies on the anticancer activity of PAs from plant and microbial sources (mainly Streptomyces strains) and on the antimicrobial activity of PAs on different strains of microorganisms (bacteria and fungi). Finally, we have suggested potential applications and future perspectives.

Clinicopathological characteristics and diagnosis of hepatic sinusoidal obstruction syndrome caused by Tusanqi - Case report and literature review

Tusanqi-induced hepatic sinusoidal obstruction syndrome (HSOS) is caused by exposure to pyrrolizidine alkaloids (PAs) and manifests as abdominal distension, liver pain, ascites, jaundice, and hepatomegaly. Pathologically, hepatic congestion and sinusoidal occlusion are observed in HSOS. We summarized the clinical characteristics of 124 patients with HSOS caused by Tusanqi in China between 1980 and 2019, along with those of 831 patients from seven English case series. The main clinical manifestations of PA-HSOS included abdominal pain, ascites, and jaundice. Common imaging features included characteristic heterogeneous density, slender hepatic veins, and other nonspecific changes. The acute stage is primarily manifested as hepatic sinus congestion and necrosis. Meanwhile, the persistence of hepatic sinus congestion and the onset of perisinusoidal fibrosis were observed during the repair stage. Finally, the persistence of hepatic sinusoidal fibrosis and resultant central hepatic vein occlusion were observed in the chronic stage. The new Nanjing standard for PA-HSOS incorporates the history of PA consumption and imaging features and eliminates weight gain and the serum total bilirubin value. Preliminary clinical validation of the Nanjing standard for PA-HSOS diagnosis revealed a sensitivity and specificity of 95.35 and 100%, respectively.

An Intramolecular Hydroaminomethylation-Based Approach to Pyrrolizidine Alkaloids under Microwave-Assisted Heating

A general method for the synthesis of pyrrolizidine derivatives using an intramolecular hydroaminomethylation protocol (HAM) under microwave (MW) dielectric heating is reported. Starting from a 3,4-bis(benzyloxy)-2-[(benzyloxy)methyl]-5-vinylpyrrolidine, MW-assisted intramolecular HAM in the presence of gaseous H2 and CO gave the natural alkaloid hyacinthacine A2 protected as benzyl ether. The same approach gave a lentiginosine analogue starting from the corresponding vinyl N-hydroxypyrrolidine. The nature of the reaction products and the yields were strongly influenced by the relative stereochemistry of the starting pyrrolidines, as well as by the catalyst/ligand employed. The use of ethanol as a solvent provides environmentally friendly conditions, while the ligand/catalyst system can be recovered by separating the alkaloid product with an SCX column and recycling the ethanolic solution. HAM worked up to three times with the recycled catalyst solution without any significant impact on yield.

Liquorice Extract and 18β-Glycyrrhetinic Acid Protect Against Experimental Pyrrolizidine Alkaloid-Induced Hepatotoxicity in Rats Through Inhibiting Cytochrome P450-Mediated Metabolic Activation

Misuse of pyrrolizidine alkaloid (PA)-containing plants or consumption of PA-contaminated foodstuffs causes numerous poisoning cases in humans yearly, while effective therapeutic strategies are still limited. PA-induced liver injury was initiated by cytochrome P450 (CYP)-mediated metabolic activation and subsequent formation of adducts with cellular proteins. Liquorice, a hepato-protective herbal medicine, is commonly used concurrently with PA-containing herbs in many compound traditional Chinese medicine formulas, and no PA-poisoning cases have been reported with this combination. The present study aimed to investigate hepato-protective effects of liquorice aqueous extract (EX) and 18β-glycyrrhetinic acid (GA, the primary bioactive constituent of liquorice) against PA-induced hepatotoxicity and the underlying mechanism. Histopathological and biochemical analysis demonstrated that both single- and multiple-treatment of EX (500 mg/kg) or GA (50 mg/kg) significantly attenuated liver damage caused by retrorsine (RTS, a representative hepatotoxic PA). The formation of pyrrole-protein adducts was significantly reduced by single- (30.3% reduction in liver; 50.8% reduction in plasma) and multiple- (32.5% reduction in liver; 56.5% reduction in plasma) treatment of GA in rats. Single- and multiple-treatment of EX also decreased the formation of pyrrole-protein adducts, with 30.2 and 31.1% reduction in rat liver and 51.8 and 53.1% reduction in rat plasma, respectively. In addition, in vitro metabolism assay with rat liver microsomes demonstrated that GA reduced the formation of metabolic activation-derived pyrrole-glutathione conjugate in a dose-dependent manner with the estimated IC₅₀ value of 5.07 µM. Further mechanism study showed that GA inhibited activities of CYPs, especially CYP3A1, the major CYP isoform responsible for the metabolic activation of RTS in rats. Enzymatic kinetic study revealed a competitive inhibition of rat CYP3A1 by GA. In conclusion, our findings demonstrated that both EX and GA exhibited significant hepato-protective effects against RTS-induced hepatotoxicity, mainly through the competitive inhibition of CYP-mediated metabolic activation of RTS.

High-performance counter-current chromatography purification and off-line mass spectrometry monitoring and identification of pyrrolizidine alkaloid markers of tropical Ghanaian honey

The nutritional and medicinal properties of honey have been well-documented. However, honey has occasionally been contaminated with hepatotoxic pyrrolizidine alkaloids as a result of bees foraging on the flowers of pyrrolizidine alkaloid plants. This study establishes a simple and rapid method to determine the marker pyrrolizidine alkaloids in honey using high-performance counter-current chromatography and an off-line electrospray ionization-tandem mass spectrometry, in order to identify the botanical sources responsible for the contamination. The honey sample was initially liquid-liquid extracted (sulfuric acid/hexane, 2:3, v/v) to enrich the pyrrolizidine alkaloids and subsequently purified by a semi-preparative high-performance counter-current chromatography using a solvent system, hexane/butanol/1% aqueous ammonia, 1:1:2, v/v, based on partition coefficient measurements of the target alkaloids. The recovered fractions were profiled by injecting them sequentially into an off-line electrospray ionization-tandem mass spectrometry device to monitor the preparative molecular weight based on elution and extrusion modes. The monitored lycopsamine-type pyrrolizidine alkaloids and their N-oxides (m/z 300, 316; lycopsamine, intermedine, rinderine, and echinatine) were used as the phytochemical markers to identify plants like Chromolaena odorata, Ageratum spp., or Heliotropium spp. to be responsible for the pyrrolizidine alkaloid contamination. Identification of these pyrrolizidine alkaloid plants could guide beekeepers in locating their beehives in order to minimize their potential liver damaging effects.

Phosphine-Catalyzed (4+1) Annulation: Rearrangement of Allenylic Carbamates to 3-Pyrrolines through Phosphonium Diene Intermediates

We have developed a phosphine-catalyzed (4+1) annulative rearrangement for the preparation of 3-pyrrolines from allenylic carbamates via phosphonium diene intermediates. We employed this methodology to synthesize an array of 1,3-disubstituted- and 1,2,3-trisubstituted-3-pyrrolines, including the often difficult to prepare 2-alkyl variants. A mechanistic investigation employing allenylic acetates and mononucleophiles unexpectedly unveiled that a phosphine-catalyzed (4+1) reaction for the construction of cyclopentene products, previously reported by Tong, might not occur through a phosphonium diene, as had been proposed, but rather through multiple mechanisms working in concert. Consequently, our phosphine-catalyzed rearrangement is most likely the first transformation to involve the unequivocal formation of a phosphonium diene intermediate along the reaction pathway. To demonstrate the synthetic utility of this newly developed reaction, we have completed concise formal syntheses of the pyrrolizidine alkaloids (±)-trachelanthamidine and (±)-supinidine.

Molecular docking analysis of doronine derivatives with human COX-2

Cyclooxygenase-2 (COX-2) is linked to inflammation. Therefore, it is of interest to design and develop novel inhibitors for COX-2. Hence, we report the molecular docking based binding features of doronine derivatives (desacetyldoronine, floradnin, onetine, 22310115, 21159807) with the human Cyclooxygenase-2 as potential inhibitors. A pyrrolizidine alkaloid doronine a molecular constituents of Emilia sonchifolia is an herbal alternative to known drugs in the prophylaxis of inflammation. We report the molecular docking, pharmacophore, ADMET and molecular properties analysis data of doronine and its similar compounds. Docking and ADMET Data shows that COX-2 binds with doronine with optimal features for further consideration.

Analysis of Pyrrolizidine Alkaloids in Queensland Honey: Using Low Temperature Chromatography to Resolve Stereoisomers and Identify Botanical Sources by UHPLC-MS/MS

Pyrrolizidine alkaloids (PAs) are a diverse group of plant secondary metabolites with known varied toxicity. Consumption of 1,2-unsaturated PAs has been linked to acute and chronic liver damage, carcinogenicity and death, in livestock and humans, making their presence in food of concern to food regulators in Australia and internationally. In this survey, honey samples sourced from markets and shops in Queensland (Australia), were analysed by high-resolution Orbitrap UHPLC-MS/MS for 30 common PAs. Relationships between the occurrence of pyrrolizidine alkaloids and the botanical origin of the honey are essential as pyrrolizidine alkaloid contamination at up to 3300 ng/g were detected. In this study, the predominant alkaloids detected were isomeric PAs, lycopsamine, indicine and intermedine, exhibiting identical MS/MS spectra, along with lesser amounts of each of their N-oxides. Crucially, chromatographic UHPLC conditions were optimised by operation at low temperature (5 °C) to resolve these key isomeric PAs. Such separation of these isomers by UHPLC, enabled the relative proportions of these PAs present in honey to be compared to alkaloid levels in suspect source plants. Overall plant pyrrolizidine alkaloid profiles were compared to those found in honey samples to help identify the most important plants responsible for honey contamination. The native Australian vines of Parsonsia spp. are proposed as a likely contributor to high levels of lycopsamine in many of the honeys surveyed. Botanical origin information such as this, gained via low temperature chromatographic resolution of isomeric PAs, will be very valuable in identifying region of origin for honey samples.

Pyrrolizidine Alkaloids of Blue Heliotrope (Heliotropium amplexicaule) and Their Presence in Australian Honey

Blue heliotrope (Heliotropium amplexicaule) is an invasive environmental weed that is widely naturalized in eastern Australia and has been implicated as a source of pyrrolizidine alkaloid (PA) poisoning in livestock. Less well-documented is the potential of such carcinogenic alkaloids to contaminate honey from bees foraging on this plant species. In this study, the PA profile of H. amplexicaule plant material, determined by HRAM LC-MS/MS, revealed the presence of nine PAs and PA-N-oxides, including several PAs and PA-N-oxides of the indicine class, which have not previously been reported. The predominant alkaloid, indicine, represents 84% of the reduced PA content, with minor alkaloids identified as intermedine and the newly reported helioamplexine, constituting 7 and 9%, respectively. NMR analysis confirmed the identity of helioamplexine as a previously unreported indicine homologue. This is the first report of the isolation of intermedine, helioamplexine, and 3'-O-angelylindicine from H. amplexicaule. Also described is the identification of N-chloromethyl analogues of the major alkaloids as isolation-derived artifacts from reactions with dichloromethane. Analysis of regional-market honey samples revealed a number of honey samples with PA profiles analogous to that seen in H. amplexicaule, with measured PA contents of up to 2.0 μg of PAs per gram of honey. These results confirm the need for honey producers to be aware of H. amplexicaule as a potential PA source, most particularly in products where honey is sourced from a single location.

Insect Antifeedant Components of Senecio fistulosus var. fistulosus-Hualtata

From a bioactive methanolic extract of Senecio fistulosus, the antifeedant effects of the alkaloidal and non-alkaloidal fractions were tested against the insects Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi, with the non-alkaloidal fraction being antifeedant. The phytochemical study of the non-alkaloidal fraction of S. fistulosus, resulted in the isolation of four compounds, two 9-oxo-furanoeremophilanes (1, 2), an eremophilanolide, 1β,10β-epoxy-6-acetoxy-8α-hydroxy-eremofil-7(11)-en-8β,12-olide (3) and a maaliol derivative (4). The alkaloidal fraction yielded two known pyrrolizidine alkaloids (5, 6). Compounds 1, 3 and 4 are new natural products. Furanoeremophilane 2 was a strong antifeedant against S. littoralis and maaliane 4 inhibited the settling of M. persicae.

Gynura Rhizoma containing pyrrolizidine alkaloids induces the hepatic sinusoidal obstruction syndrome in mice via upregulating fibrosis-related factors

Recently, hepatic sinusoidal obstruction syndrome (HSOS) caused by herbal preparations containing pyrrolizidine alkaloids (PAs), such as Gynura Rhizoma (Tusanqi), has gained global attention. However, the lack of a reliable and reproducible animal model has greatly hampered mechanistic studies. Therefore, we aimed to establish a reproducible HSOS mouse model and investigate the hepatotoxic mechanism. The model was established by intragastrical administration of Gynura Rhizoma extract, i.e., 1.0 g extract/kg per day (equal to 16.7 g crude drug/kg per day based on extraction rate and 49.1 mg PA/kg per day based on the total PA content in the extract determined) for 40 successive days. Then, the mice were sacrificed, and their blood samples and livers were collected for analyses. Using hematoxylin-eosin (HE) and Masson staining, scanning electron microscopy imaging, clinical biomarkers, and other assays, we showed that the HSOS was successfully induced in our mouse model. Furthermore, we detected the key factors involved in liver fibrosis in the mice, revealing significantly increased hydroxyproline concentration; elevated expression of α-smooth muscle actin (α-SMA) and fibrosis-related genes such as Collagen-1, Collagen-3, Mmp2, Mmp13, Timp1, Timp3, and Activin, upregulated Smad3 phosphorylation, and increased serum TGF-β levels. Moreover, pro-inflammatory cytokines, including Tnf-α, Il-1β, and Il-6, were also increased in the model. All these results demonstrate the key roles of the TGF-β-Smad3 and inflammatory signaling pathways in this Gynura Rhizoma-induced HSOS mouse model, suggesting that blockade of fibrosis and/or inflammation should be an effective treatment for HSOS.

CT Features of Hepatic Veno-occlusive Disease: A Meta-analysis

RATIONALE AND OBJECTIVE

The computed tomography (CT) features of hepatic veno-occlusive disease (HVOD) could play a role in its diagnosis. We aimed to perform a meta-analysis of studies examining the CT features of HVOD.

METHODS

Relevant studies published up to May 3, 2017 were searched in major electronic databases. The extracted data included the proportion of various CT features in patients with HVOD. The meta-analysis was conducted using R 3.3.3 with the "meta" package.

RESULTS

Eleven studies were included. The studies involved 326 patients with a mean age range of 50.2-58.9 years, and the proportion of female patients ranged from 20% to 57.5%. The meta-analysis showed the pooled proportion of CT features: hepatic parenchyma with heterogeneous hypoattenuation (81.05%, 95% confidence interval [CI]: 56.97%-93.25%), patchy enhancement in the portal venous phase (87.09%, 95% CI: 75.15%-93.77%) with or without a narrow or invisible hepatic vein (71.02% 95% CI: 42.09%-89.20%), gallbladder wall edema (65.51%, 95% CI: 28.98%-89.84%), and patchy heterogeneous enhancement in the arterial phase (44.36%, 95% CI: 29.98%-59.76%) with or without slightly enlarged hepatic artery (56.61%, 95% CI: 40.62%-71.33%).

CONCLUSION

Hepatic parenchyma with heterogeneous hypoattenuation and patchy enhancement with or without narrowing or an invisible hepatic vein in the portal venous or equilibrium phase may be the most important CT feature for diagnosing HVOD.

Variability of Pyrrolizidine Alkaloid Occurrence in Species of the Grass Subfamily Pooideae (Poaceae)

Pyrrolizidine alkaloids (PAs) are a class of secondary metabolites found in various unrelated angiosperm lineages including cool-season grasses (Poaceae, subfamily Pooideae). Thesinine conjugates, saturated forms of PA that are regarded as non-toxic, have been described to occur in the two grass species Lolium perenne and Festuca arundinacea (Poaceae, subfamily Pooideae). In a wider screen, we tested various species of the Pooideae lineage, grown under controlled conditions, for their ability to produce thesinine conjugates or related structures. Using an LC-MS based targeted metabolomics approach we were able to show that PA biosynthesis in grasses is limited to a group of very closely related Pooideae species that produce a limited diversity of PA structures. High variability in PA levels was observed even between individuals of the same species. These individual accumulation patterns are discussed with respect to a possible function and evolution of this type of alkaloid.

Incidence of Pyrrolizidine Alkaloids in Herbal Medicines from German Retail Markets: Risk Assessments and Implications to Consumers

The occurrence of potentially toxic pyrrolizidine alkaloids (PAs) in herbal medicines (HMs) is currently intensely being discussed in Europe. Pyrrolizidine alkaloids, particularly the 1,2-unsaturated PAs, are undesired compounds in HMs due to their potential hepatotoxic and carcinogenic properties. In this study, 98 widely patronized HMs from six popular German retail supermarkets/drugstores, as well as from pharmacies, were analyzed by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry for the presence of PAs. The results showed that about 63% of the HMs were PA positive, whereas the average PA concentration of the samples was 201 μg/kg, the highest concentration of PAs (3270 μg/kg) was attributed to a product that was purchased from the pharmacy and contained Hypericum perforatum L. (St. John's Wort) as an active ingredient. In addition, H. perforatum-containing products were frequently contaminated with PAs from Echium spp., while both Cynara cardunculus L. products and fixed-combination products of Gentiana lutea L., Rumex acetosa L., Verbena officinalis L., Sambucus nigra L., and Primula veris L. products were commonly contaminated with PAs of Senecio spp. The study showed that H. perforatum, C. cardunculus, Urtica dioica L., and fixed-combination products were frequently contaminated with PA levels above the recommended values of both the German and European Medicines Agencies. Copyright © 2017 John Wiley & Sons, Ltd.

7-N-Acetylcysteine-pyrrole conjugate-A potent DNA reactive metabolite of pyrrolizidine alkaloids

Plants containing pyrrolizidine alkaloids (PAs) are widespread throughout the world and are the most common poisonous plants affecting livestock, wildlife, and humans. PAs require metabolic activation to form reactive dehydropyrrolizidine alkaloids (dehydro-PAs) that are capable of alkylating cellular DNA and proteins, form (±)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-DNA and DHP-protein adducts, and lead to cytotoxicity, genotoxicity, and tumorigenicity. In this study, we determined that the metabolism of riddelliine and monocrotaline by human and rat liver microsomes in the presence of N-acetylcysteine both produced 7-N-acetylcysteine-DHP (7-NAC-DHP) and DHP. Reactions of 7-NAC-DHP with 2'-deoxyguanosine (dG), 2'-deoxyadenosine (dA), and calf thymus DNA in aqueous solution followed by enzymatic hydrolysis yielded DHP-dG and/or DHP-dA adducts. These results indicate that 7-NAC-DHP is a reactive metabolite that can lead to DNA adduct formation.

Survey of pyrrolizidine alkaloids in seven varieties of Lappula squarrosa: An alternative source of heart-healthy vegetable oil

INTRODUCTION

Growing demand for heart-healthy omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is putting stress on wild fish stocks. There is now a compelling need for new and novel sources of non-traditional seed oils containing high stearidonic acid (SDA), a precursor of EPA and DHA, to reduce this demand. The seed oil of Lappula squarrosa is one of the richest sources of SDA, however, the plant has been found to contain toxic pyrrolizidine alkaloids (PAs).

OBJECTIVE

In this study, the PA concentrations of seven varieties (A-G) of Lappula squarrosa were analysed to determine the most suitable varieties for commercial seed oil production.

METHODS

Whilst the clean-up procedure for the PAs in the roots, flowers and leaves was on diatomaceous earth columns and finally analysed with GC-EI-MS, that of the seeds was through SCX-SPE and a more sensitive HPLC-ESI-MS/MS sum parameter method was used in the analysis.

RESULTS

Altogether six PAs (supinine, amabiline, intermedine, lycopsamine and 3'-acetylintermedine) including one unknown retronecine-type PA were identified with variety C recording the lowest total PA concentration (4.64 mg seneciphylline equivalents (SE)/g dry weight (d.w.)). Besides, the total PA concentrations in the seeds of Lappula squarrosa varieties ranged between 2.88 μg PA/g and 10.36 μg PA/g d.w.

CONCLUSION

Based solely on overall PA concentrations and PA distribution, variety D (5.95 mg SE/g d.w.) was found to be a potential candidate for commercial seed oil cultivation.

The comparative toxicity of a reduced, crude comfrey (Symphytum officinale) alkaloid extract and the pure, comfrey-derived pyrrolizidine alkaloids, lycopsamine and intermedine in chicks (Gallus gallus domesticus)

Comfrey (Symphytum officinale), a commonly used herb, contains dehydropyrrolizidine alkaloids that, as a group of bioactive metabolites, are potentially hepatotoxic, pneumotoxic, genotoxic and carcinogenic. Consequently, regulatory agencies and international health organizations have recommended comfrey be used for external use only. However, in many locations comfrey continues to be ingested as a tisane or as a leafy vegetable. The objective of this work was to compare the toxicity of a crude, reduced comfrey alkaloid extract to purified lycopsamine and intermedine that are major constituents of S. officinale. Male, California White chicks were orally exposed to daily doses of 0.04, 0.13, 0.26, 0.52 and 1.04 mmol lycopsamine, intermedine or reduced comfrey extract per kg bodyweight (BW) for 10 days. After another 7 days chicks were euthanized. Based on clinical signs of poisoning, serum biochemistry, and histopathological analysis the reduced comfrey extract was more toxic than lycopsamine and intermedine. This work suggests a greater than additive effect of the individual alkaloids and/or a more potent toxicity of the acetylated derivatives in the reduced comfrey extract. It also suggests that safety recommendations based on purified compounds may underestimate the potential toxicity of comfrey.

Hirmi Valley liver disease: a disease associated with exposure to pyrrolizidine alkaloids and DDT

BACKGROUND & AIMS

Hirmi Valley liver disease was first reported in 2001 in Tigray, Ethiopia. 591 cases, including 228 deaths, were reported up to December 2009. The pyrrolizidine alkaloid acetyllycopsamine was detected in stored grain and residents reported adding the pesticide DDT (dichlorodiphenyldichloroethylene) directly to their food stores. We aimed to characterise the clinical features of the disease, and explore the role of these chemicals in its aetiology.

METHODS

32 cases were examined and full clinical histories taken. Nine cases underwent liver biopsy in hospitals. Serum and urine samples were collected from cases and controls. Urine was analysed for acetyllycopsamine by UPLC-MS. Total DDT in serum was measured by ELISA. Hepatotoxicity of DDT and acetyllycopsamine alone or in combination was explored in C57BL/6J mice.

RESULTS

Clinical presentation included epigastric pain, abdominal swelling, bloody diarrhoea, hepatomegaly, splenomegaly, and ascites. Histology revealed acute injury characterised by centrilobular necrosis or chronic injury with bile ductular reaction, cytomegaly and fibrosis but no hepatic vein occlusion. Acetyllycopsamine was detected in urine samples taken in the affected area with significantly greater concentrations in 45 cases than in 43 controls (p=0.02). High levels of DDT (>125 ppb) were detected in 78% of serum samples. In mice, DDT (3 × 75 mg/kg) significantly increased the hepatotoxicity (plasma ALT, p=0.0065) of acetyllycopsamine (750 mg/kg), and in combination induced liver pathology similar to Hirmi Valley liver disease including centrilobular necrosis and cytomegaly.

CONCLUSIONS

This novel form of disease appears to be caused by co-exposure to acetyllycopsamine and DDT.

Chemical defense: bestowal of a nuptial alkaloidal garment by a male moth on its mate

Males of the moth Cosmosoma myrodora (Arctiidae) acquire pyrrolizidine alkaloid by feeding on the excrescent fluids of certain plants (for instance, Eupatorium capillifolium). They incorporate the alkaloid systemically and as a result are protected against spiders. The males have a pair of abdominal pouches, densely packed with fine cuticular filaments, which in alkaloid-fed males are alkaloid laden. The males discharge the filaments on the female in bursts during courtship, embellishing her with alkaloid as a result. The topical investiture protects the female against spiders. Alkaloid-free filaments, from alkaloid-deprived males, convey no such protection. The males also transmit alkaloid to the female by seminal infusion. The systemic alkaloid thus received, which itself may contribute to the female's defense against spiders, is bestowed in part by the female on the eggs. Although paternal contribution to egg defense had previously been demonstrated for several arctiid moths, protective nuptial festooning of a female by its mate, such as is practiced by C. myrodora, appears to be without parallel among insects.

Chemical defense against predation in an insect egg

The larva of the green lacewing (Ceraeochrysa cubana) (Neuroptera, Chrysopidae) is a natural predator of eggs of Utetheisa ornatrix (Lepidoptera, Arctiidae), a moth that sequesters pyrrolizidine alkaloids from its larval foodplant (Fabaceae, Crotalaria spp.). Utetheisa eggs are ordinarily endowed with the alkaloid. Alkaloid-free Utetheisa eggs, produced experimentally, are pierced by the larva with its sharp tubular jaws and sucked out. Alkaloid-laden eggs, in contrast, are rejected. When attacking an Utetheisa egg cluster (numbering on average 20 eggs), the larva subjects it to an inspection process. It prods and/or pierces a small number of eggs (on average two to three) and, if these contain alkaloid, it passes "negative judgement" on the remainder of the cluster and turns away. Such generalization on the part of the larva makes sense, because the eggs within clusters differ little in alkaloid content. There is, however, considerable between-cluster variation in egg alkaloid content, so clusters in nature can be expected to range widely in palatability. To check each cluster for acceptability must therefore be adaptive for the larva, just as it must be adaptive for Utetheisa to lay its eggs in large clusters and to apportion alkaloid evenly among eggs of a cluster.

Female choice increases offspring fitness in an arctiid moth (Utetheisa ornatrix)

In Utetheisa ornatrix (Lepidoptera, Arctiidae), the female mates preferentially with larger males. Having a larger father results in the eggs being more richly endowed with defensive pyrrolizidine alkaloid (which the female receives from the male with the sperm package, in quantity proportional to the male's body mass, and passes on to the eggs); having a larger father also results in the sons and daughters themselves being larger (body mass is heritable in Utetheisa). We provide evidence herein that these consequences enhance the fitness of the offspring. Eggs sired by larger males are less vulnerable to predation (presumably because of their higher alkaloid content), whereas sons and daughters, by virtue of being larger, are, respectively, more successful in courtship and more fecund. The female Utetheisa, therefore, by being choosy, reaps both direct phenotypic and indirect genetic benefits.

Heritability of body mass, a sexually selected trait, in an arctiid moth (Utetheisa ornatrix)

In the moth Utetheisa ornatrix (Lepidoptera: Arctiidae), females mate preferentially with larger males. Large body mass is advantageous to both sexes: large males sire more young than small males, and large females have higher fecundity than small females. Here we report that body mass is heritable in both sexes, indicating that by choosing larger males females obtain genetic benefits for their offspring. Choosy females also receive extra nutrient and defensive alkaloid by way of their partner's spermatophores, but these gifts do not affect the heritability of body mass. These results indicate that by exercising mate choice female Utetheisa receive both direct phenotypic and indirect genetic benefits.