Bioaccumulation and Distribution of Indospicine and Its Foregut Metabolites in Camels Fed Indigofera spicata

In vitro experiments have demonstrated that camel foregut-fluid has the capacity to metabolize indospicine, a natural toxin which causes hepatotoxicosis, but such metabolism is in competition with absorption and outflow of indospicine from the different segments of the digestive system. Six young camels were fed Indigofera spicata (337 µg indospicine/kg BW/day) for 32 days, at which time three camels were euthanized. The remaining camels were monitored for a further 100 days after cessation of this indospicine diet. In a retrospective investigation, relative levels of indospicine foregut-metabolism products were examined by UHPLC-MS/MS in plasma, collected during both accumulation and depletion stages of this experiment. The metabolite 2-aminopimelamic acid could be detected at low levels in almost all plasma samples, whereas 2-aminopimelic acid could not be detected. In the euthanized camels, 2-aminopimelamic acid could be found in all tissues except muscle, whereas 2-aminopimelic acid was only found in the kidney, pancreas, and liver tissues. The clearance rate for these metabolites was considerably greater than for indospicine, which was still present in plasma of the remaining camels 100 days after cessation of Indigofera consumption.

Assessing the risk of residues of the toxin indospicine in bovine muscle and liver from north-west Australia

Indospicine is a natural toxin occurring only in Indigofera plant species, including the Australian native species I. linnaei. These perennial legumes are resistant to drought and palatable to grazing livestock including cattle. Indospicine accumulates in the tissues (including muscle) of animals grazing Indigofera and these residues persist for several months after exposure. Dogs are particularly sensitive to indospicine with reports in past decades of hepatotoxicosis and mortalities in dogs after dietary exposure to indospicine-contaminated horse and camel meat. The risk for human consumption is not known, and the current study was undertaken to assess indospicine levels in cattle going to slaughter from divergent regions of Western Australia, and to predict the likelihood of significant residues being present. Muscle and corresponding liver samples from 776 cattle originating from the Kimberley and Pilbara Regions in the tropical north of the state, where I. linnaei is prevalent, and 640 cattle from the South West and South Coast Regions in the temperate south west of the state, where the plant is not known to occur, were collected at abattoirs over four seasons in 2015-2017. Indospicine levels were measured by LC-MS/MS and ranged from below detection to 3.63 mg/kg. No indospicine residues were detected in any of the animals originating from the South West and South Coast Regions. Prevalence of indospicine residues in cattle from the Kimberley Region was as high as 33% in spring and 91% in autumn, with positive animals being present in most consignments and on most properties. The average prevalence of indospicine residues from the Kimberley and Pilbara Regions throughout the survey period was 63%. @Risk best fit probability distributions showed ninety-fifth percentile (P95) indospicine concentrations of 0.54 mg/kg for muscle and 0.77 mg/kg for liver in cattle originating from the Kimberley and Pilbara Regions during the survey period. When considered with average Australian meat consumption data, the estimated consumer exposure from this P95 muscle was 0.32 μg indospicine/kg bw/day, which compared favourably with our calculated provisional tolerable daily intake (PTDI) of 1.3 μg indospicine/kg bw/day. However canine exposure is of potential concern, with active working dog exposure calculated to exceed this PTDI by a factor of 25, based on a P95 indospicine concentration of 0.54 mg/kg in muscle.

Release of Indospicine from Contaminated Camel Meat following Cooking and Simulated Gastrointestinal Digestion: Implications for Human Consumption

Indospicine, a hepatotoxic arginine analog, occurs in leguminous plants of the Indigofera genus and accumulates in the tissues of grazing animals that consume these plants. Furthermore, indospicine has caused toxicity in dogs following consumption of indospicine-contaminated meat; however, the potential impact on human health is unknown. The present study was designed to determine the effect of simulated human gastrointestinal digestion on the release and degradation of indospicine from contaminated camel meat following microwave cooking. Results showed no significant (p > 0.05) indospicine degradation during cooking or in vitro digestion. However, approximately 70% indospicine was released from the meat matrix into the liquid digesta during the gastric phase (in the presence of pepsin) and increased to >90% in the intestinal phase (with pancreatic enzymes). Following human consumption of contaminated meat, this soluble and more bioaccessible fraction of intact indospicine could be readily available for absorption by the small intestine, potentially circulating indospicine throughout the human body to tissues where it could accumulate and cause detrimental toxic effects.

Chemical and Nutritional Composition of Terminalia ferdinandiana (Kakadu Plum) Kernels: A Novel Nutrition Source

Terminalia ferdinandiana (Kakadu plum) is a native Australian fruit. Industrial processing of T. ferdinandiana fruits into puree generates seeds as a by-product, which are generally discarded. The aim of our present study was to process the seed to separate the kernel and determine its nutritional composition. The proximate, mineral and fatty acid compositions were analysed in this study. Kernels are composed of 35% fat, while proteins account for 32% dry weight (DW). The energy content and fiber were 2065 kJ/100 g and 21.2% DW, respectively. Furthermore, the study showed that kernels were a very rich source of minerals and trace elements, such as potassium (6693 mg/kg), calcium (5385 mg/kg), iron (61 mg/kg) and zinc (60 mg/kg) DW, and had low levels of heavy metals. The fatty acid composition of the kernels consisted of omega-6 fatty acid, linoleic acid (50.2%), monounsaturated oleic acid (29.3%) and two saturated fatty acids namely palmitic acid (12.0%) and stearic acid (7.2%). The results indicate that T. ferdinandiana kernels have the potential to be utilized as a novel protein source for dietary purposes and non-conventional supply of linoleic, palmitic and oleic acids.

Accumulation and depletion of indospicine in calves (Bos taurus) fed creeping indigo (Indigofera spicata)

Prolonged consumption of Indigofera pasture plants can cause both hepatotoxicosis and reproductive losses in grazing animals with the responsible toxin indospicine forming persistent tissue residues. Separate accumulation and depletion feeding trials were undertaken in calves fed Indigofera spicata (3 mg indospicine/kg bodyweight) to ascertain the appearance and elimination of indospicine from various tissues. In the accumulation trial indospicine concentrations increased throughout the 42-day feeding period with maximum levels of 15 mg/L in plasma and 19 and 33 mg/kg in liver and muscle, respectively. In the depletion trial, calves were fed I. spicata for 35 days, after which the plant was withdrawn from the diet. The rate of elimination was relatively slow with estimates of half-life being 31, 25 and 20 days for muscle, liver and plasma, respectively. Indospicine levels measured in bovine tissues in this trial are comparable with levels in horsemeat and camel meat reported to cause fatal hepatoxicity in dogs, a species known to be susceptible to this toxin. The persistence of indospicine residues in bovine tissues and the widespread distribution of Indigofera species in tropical and sub-tropical grazing lands warrant further investigation, as indospicine has been established as causing reproductive losses and likely contributes to calf losses in these regions.

NIRS Calibration of Aflatoxin in Maize

The aim of this study is to determine the value of near-infrared spectroscopy (NIRS) as a diagnostic tool for aflatoxin contamination, specifically to rapidly predict levels of aflatoxin, either quantitatively or qualitatively, in ground maize. Maize was collected from inoculated field trials conducted across four sites in Kenya. Inoculated and uninoculated maize ears were harvested, milled, and prepared for NIRS scanning and wet chemistry-based aflatoxin quantification. Several statistical and machine learning techniques were compared. Absorbance at a single bandwidth explained 34 % of the variation in levels of aflatoxin using a regression model while a partial least-squares (PLS) method showed that NIR measurements could explain 42 % of the variation in aflatoxin levels. To compare various methods for their ability to classify samples with high (>100 ppb) levels of aflatoxin, various additional procedures were applied. The k-nearest neighbour classification method yielded sensitivity and specificity values of 0.75 and 0.52 respectively, compared with the support vector machine method with estimates of 0.81 and 0.68, whereas PLS could achieve values of 0.82 and 0.72 respectively. The corresponding false positive and false negative values are still unacceptable for NIRS to be used with confidence, as ~18 % of contaminated ground maize samples would be accepted and 28 % of good maize would be discarded or declared contaminated or downgraded. However, such calibrations could be useful in breeding programs without access to wet chemistry analysis, seeking to rank entries semiquantitatively.

In Vitro Biodegradation of Hepatotoxic Indospicine in Indigofera spicata and Its Degradation Derivatives by Camel Foregut and Cattle Rumen Fluids

The known accumulation of the hepatotoxin indospicine in tissues of camels and cattle grazing Indigofera pasture plants is unusual in that free amino acids would normally be expected to be degraded during the fermentation processes in these foregut fermenters. In this study, in vitro experiments were carried out to examine the degradability of indospicine of Indigofera spicata by camel and cattle foregut microbiota. In the first experiment, a 48 h in vitro incubation was carried out using foregut fluid samples that were collected from 15 feral camels and also a fistulated cow. Degradability of indospicine ranged between 97% and 99%, with the higher value of 99% for camels. A pooled sample of foregut fluids from three camels that were on a roughage diet was used in a second experiment to examine the time-dependent degradation of indospicine present in the plant materials. Results indicated that camels' foregut fluids have the ability to biodegrade ∼99% of the indospicine in I. spicata within 48 h of incubation and produced 2-aminopimelamic acid and 2-aminopimelic acid. The time-dependent degradation analysis showed rapid indospicine degradation (65 nmol/h) during the first 8-18 h of incubation followed by a slower degradation rate (12 nmol/h) between 18 and 48 h. Indospicine degradation products were also degraded toward the end of the experiment. The results of these in vitro degradation studies suggest that dietary indospicine may undergo extensive degradation in the foregut of the camel, resulting in trace levels after 48 h. The retention time for plant material in the camel foregut varies depending on feed quality, and the results of this study together with the observed accumulation of indospicine in camel tissues suggest that, although indospicine can be degraded by foregut fermentation, this degradation is not complete before the passage of the digesta into the intestine.

Tools for Defusing a Major Global Food and Feed Safety Risk: Nonbiological Postharvest Procedures To Decontaminate Mycotoxins in Foods and Feeds

Mycotoxin contamination of foods and animal feeds is a worldwide problem for human and animal health. Controlling mycotoxin contamination has drawn the attention of scientists and other food and feed stakeholders all over the world. Despite best efforts targeting field and storage preventive measures, environmental conditions can still lead to mycotoxin contamination. This raises a need for developing decontamination methods to inactivate or remove the toxins from contaminated products. At present, decontamination methods applied include an array of both biological and nonbiological methods. The targeted use of nonbiological methods spans from the latter half of last century, when ammoniation and ozonation were first used to inactivate mycotoxins in animal feeds, to the novel techniques being developed today such as photosensitization. Effectiveness and drawbacks of different nonbiological methods have been reported in the literature, and this review examines the utility of these methods in addressing food safety. Particular consideration is given to the application of such methods in the developing world, where mycotoxin contamination is a serious food safety issue in staple crops such as maize and rice.

Thermo-alkaline Treatment as a Practical Degradation Strategy To Reduce Indospicine Contamination in Camel Meat

Ingestion of indospicine-contaminated camel and horse meat has caused fatal liver injury to dogs in Australia, and it is currently not known if such contaminated meat may pose a human health risk upon dietary exposure. To date, indospicine-related research has tended to focus on analytical aspects, with little information on post-harvest management of indospicine-contaminated meat. In this study, indospicine degradation was investigated in both aqueous solution and also contaminated meat, under a range of conditions. Aqueous solutions of indospicine and indospicine-contaminated camel meat were microwaved (180 °C) or autoclaved (121 °C) with the addition of food-grade additives [0.05% (v/v) acetic acid or 0.05% (w/v) sodium bicarbonate] for 0, 15, 30, and 60 min. An aqueous sodium bicarbonate solution demonstrated the greatest efficacy in degrading indospicine, with complete degradation after 15 min of heating in a microwave or autoclave; concomitant formation of indospicine degradation products, namely, 2-aminopimelamic and 2-aminopimelic acids, was observed. Similar treatment of indospicine-contaminated camel meat with aqueous sodium bicarbonate resulted in 50% degradation after 15 min of heating in an autoclave and 100% degradation after 15 min of heating in a microwave. The results suggest that thermo-alkaline aqueous treatment has potential as a pragmatic post-harvest handling technique in reducing indospicine levels in indospicine-contaminated meat.

Level of natural hepatotoxin (Indospicine) contamination in Australian camel meat

Camel meat production for human consumption and pet food manufacture accounts for a relatively small part of overall red meat production in Australia. Reliable statistical data for the Australian production and consumption of camel meat are not available; however, it is estimated that 300,000 feral camels roam within the desert of central Australia, with an annual usage of more than 3000 camels for human consumption, 2000 for pet food manufacture and a smaller number for live export. Despite a small Australian camel meat production level, the usage of camel meat for pet food has been restricted in recent years due to reports of serious liver disease and death in dogs consuming camel meat. This camel meat was found to contain residues of indospicine, a non-proteinogenic amino acid found in certain Indigofera spp., and associated with mild to severe liver disease in diverse animals after dietary exposure to this hepatotoxin. The extent of indospicine-contaminated Australian camel meat was previously unknown, and this study ascertains the prevalence of such residue in Australian camel meat. In this study, indospicine levels in ex situ (95 samples collected from an abattoir in Queensland) and in situ (197 samples collected from camels after field culling in central Australia) camel meat samples were quantitated using a validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The quantitation results showed 46.7% of the in situ- and 20.0% of the ex situ-collected camel meat samples were contaminated by indospicine (more than the limit of detection (LOD) of 0.05 mg kg^-1 fresh weight). The overall indospicine concentration was higher (p < 0.05) in the in situ-collected samples. Indospicine levels detected in the present study are considered to be low; however, a degree of caution must still be exercised, since the tolerable daily intake for indospicine is currently not available for risk estimation.

Seasonal and Species Variation of the Hepatotoxin Indospicine in Australian Indigofera Legumes As Measured by UPLC-MS/MS

Livestock industries have maintained a keen interest in pasture legumes because of the high protein content and nutritive value. Leguminous Indigofera plant species have been considered as having high feeding values to be utilized as pasture, but the occurrence of the toxic constituent indospicine in some species has restricted this utility. Indospicine has caused both primary and secondary hepatotoxicosis and also reproductive losses, but has only previously been determined in a small number of Indigofera species. This paper validates a high-throughput ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to determine the indospicine content of various Indigofera species found in Australian pasture. Twelve species of Indigofera together with Indigastrum parviflorum plants were collected and analyzed. Of the 84 samples analyzed, *I. spicata (the asterisk indicates a naturalized species) contained the highest indospicine level (1003 ± 328 mg/kg DM, n = 4) followed by I. linnaei (755 ± 490 mg/kg DM, n = 51). Indospicine was not detected in 9 of the remaining 11 species and at only low levels (<10 mg/kg DM) in 2 of 8 I. colutea specimens and in 1 of 5 I. linifolia specimens. Indospicine concentrations were below quantitation levels for other Indigofera spp. (I. adesmiifolia, I. georgei, I. hirsuta, I. leucotricha, *I. oblongifolia, I. australis, and I. trita) and Indigastrum parviflorum. One of the more significant findings to emerge from this study is that the indospicine content of I. linnaei is highly variable (from 159 to 2128 mg/kg DM, n = 51) and differs across both regions and seasons. Its first regrowth after spring rain has a higher (p < 0.01) indospicine content than growth following more substantial summer rain. The species collected include the predominant Indigofera in Australia pasture, and of these, only *I. spicata and I. linnaei contain high enough levels of indospicine to pose a potential toxic threat to grazing herbivores.

Accumulation, Persistence, and Effects of Indospicine Residues in Camels Fed Indigofera Plant

Indospicine (l-2-amino-6-amidinohexanoic acid) is a natural hepatotoxin found in all parts of some Indigofera plants such as Indigofera linnaei and Indigofera spicata. Several studies have documented a susceptibility to this hepatotoxin in different species of animals, including cattle, sheep, dogs, and rats, which are associated with mild to severe liver disease after prolonged ingestion. However, there is little published data on the effects of this hepatotoxin in camels, even though Indigofera plants are known to be palatable to camels in central Australia. The secondary poisoning of dogs after prolonged dietary exposure to residual indospicine in camel muscle has raised additional food safety concerns. In this study, a feeding experiment was conducted to investigate the in vivo accumulation, excretion, distribution, and histopathological effects of dietary indospicine on camels. Six young camels (2-4 years old), weighing 270-390 kg, were fed daily a roughage diet consisting of Rhodes grass hay and lucerne chaff, supplemented with Indigofera and steam-flaked barley. Indigofera (I. spicata) was offered at 597 mg DM/kg body weight (bw)/day, designed to deliver 337 μg indospicine/kg bw/day, and fed for a period of 32 days. Blood and muscle biopsies were collected over the period of the study. Concentrations of indospicine in the plasma and muscle biopsy samples were quantitated by validated ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The highest concentrations in plasma (1.01 mg/L) and muscle (2.63 mg/kg fresh weight (fw)) were found at necropsy (day 33). Other tissues were also collected at necropsy, and analysis showed ubiquitous distribution of indospicine, with the highest indospicine accumulation detected in the pancreas (4.86 ± 0.56 mg/kg fw) and liver (3.60 ± 1.34 mg/kg fw), followed by the muscle, heart, and kidney. Histopathological examination of liver tissue showed multiple small foci of predominantly mononuclear inflammatory cells. After cessation of Indigofera intake, indospicine present in plasma in the remaining three camels had a longer terminal elimination half-life (18.6 days) than muscle (15.9 days), and both demonstrated monoexponential decreases.

In vitro experimental environments lacking or containing soil disparately affect competition experiments of Aspergillus flavus and co-occurring fungi in maize grains

In vitro experimental environments are used to study interactions between microorganisms, and to predict dynamics in natural ecosystems. This study highlights that experimental in vitro environments should be selected to match closely the natural environment of interest during in vitro studies to strengthen extrapolations about aflatoxin production by Aspergillus and competing organisms. Fungal competition and aflatoxin accumulation were studied in soil, cotton wool or tube (water-only) environments, for Aspergillus flavus competition with Penicillium purpurogenum, Fusarium oxysporum or Sarocladium zeae within maize grains. Inoculated grains were incubated in each environment at two temperature regimes (25 and 30°C). Competition experiments showed interaction between the main effects of aflatoxin accumulation and the environment at 25°C, but not so at 30°C. However, competition experiments showed fungal populations were always interacting with their environments. Fungal survival differed after the 72-h incubation in different experimental environments. Whereas all fungi incubated within the soil environment survived, in the cotton wool environment none of the competitors of A. flavus survived at 30°C. With aflatoxin accumulation, F. oxysporum was the only fungus able to interdict aflatoxin production at both temperatures. This occurred only in the soil environment and fumonisins accumulated instead. Smallholder farmers in developing countries face serious mycotoxin contamination of their grains, and soil is a natural reservoir for the associated fungal propagules, and a drying and storage surface for grains on these farms. Studying fungal dynamics in the soil environment and other environments in vitro can provide insights into aflatoxin accumulation post-harvest.

Banana peel: an effective biosorbent for aflatoxins

This work reports the application of banana peel as a novel bioadsorbent for in vitro removal of five mycotoxins (aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A). The effect of operational parameters including initial pH, adsorbent dose, contact time and temperature were studied in batch adsorption experiments. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pHpzc) analysis were used to characterise the adsorbent material. Aflatoxins' adsorption equilibrium was achieved in 15 min, with highest adsorption at alkaline pH (6-8), while ochratoxin has not shown any significant adsorption due to surface charge repulsion. The experimental equilibrium data were tested by Langmuir, Freundlich and Hill isotherms. The Langmuir isotherm was found to be the best fitted model for aflatoxins, and the maximum monolayer coverage (Q0) was determined to be 8.4, 9.5, 0.4 and 1.1 ng mg(-1) for AFB1, AFB2, AFG1 and AFG2 respectively. Thermodynamic parameters including changes in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined for the four aflatoxins. Free energy change and enthalpy change demonstrated that the adsorption process was exothermic and spontaneous. Adsorption and desorption study at different pH further demonstrated that the sorption of toxins was strong enough to sustain pH changes that would be experienced in the gastrointestinal tract. This study suggests that biosorption of aflatoxins by dried banana peel may be an effective low-cost decontamination method for incorporation in animal feed diets.

Synthesis of l-indospicine, [5,5,6-2H3]-l-indospicine and l-norindospicine

Indospicine is a non-proteogenic amino acid that accumulates as the free amino acid in livestock grazing Indigofera plant species and causes both reproductive losses and hepatotoxic effects.

Effect of increasing low-dose simplexin exposure in cattle consuming Pimelea trichostachya

Pimelea species (or desert riceflower) are small native plants endemic to the drier inland pastoral regions of Australia, which cause a unique syndrome in grazing cattle characterized by submandibular edema and edema in the brisket area as a result of right-sided heart failure attributed to the toxin simplexin, 1. Field evidence suggests that poisoning can occur through minor, inadvertent consumption of Pimelea plant material, but the minimum simplexin intake required to induce Pimelea poisoning is not known. In this study, mild Pimelea poisoning was induced at a daily dose of 12.5 mg Pimelea/kg body weight per day, equivalent to 2.5 μg simplexin/kg body weight per day, demonstrating the high potential toxicity of these plant species. Effects in all animals diminished with prolonged low-dose feeding, and it is postulated that these animals developed mechanisms for detoxifying simplexin, 1, possibly through rumen microbial adaptation or activation of liver enzymes.

Suspected pyrrolizidine alkaloid hepatotoxicosis in wild southern hairy-nosed wombats (Lasiorhinus latifrons)

Southern hairy-nosed wombats (Lasiorhinus latifrons) inhabiting degraded habitat in South Australia were recently identified with extensive hair loss and dermatitis and were in thin to emaciated body condition. Pathological and clinicopathological investigations on affected juvenile wombats identified a toxic hepatopathy suggestive of plants containing pyrrolizidine alkaloids, accompanied by photosensitive dermatitis. Hepatic disease was suspected in additional wombats on the basis of serum biochemical analysis. Preliminary toxicological analysis performed on scats and gastrointestinal contents from wombats found in this degraded habitat identified a number of toxic pyrrolizidine alkaloids consistent with ingestion of Heliotropeum europaeum. Although unpalatable, ingestion may occur by young animals due to decreased availability of preferred forages in degraded habitats and the emergence of weeds around the time of weaning of naive animals. Habitat degradation leading to malnutrition and ingestion of toxic weed species is a significant welfare issue in this species.

Determination of hepatotoxic indospicine in Australian camel meat by ultra-performance liquid chromatography-tandem mass spectrometry

Indospicine is a hepatotoxic amino acid found in Indigofera plant spp. and is unusual in that it is not incorporated into protein but accumulates as the free amino acid in the tissues (including muscle) of animals consuming these plants. Dogs are particularly sensitive to indospicine, and secondary poisoning of dogs has occurred from the ingestion of indospicine-contaminated horse meat and more recently camel meat. In central Australia, feral camels are known to consume native Indigofera species, but the prevalence of indospicine residues in their tissues has not previously been investigated. In this study, a method was developed and validated with the use of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine the level of indospicine in camel meat samples using isotopically labeled indospicine as an internal standard. UPLC-MS/MS analysis showed that the method is reproducible, with high recovery efficiency and a quantitation limit of 0.1 mg/kg. Camel meat samples from the Simpson Desert were largely contaminated (≈50%) by indospicine with levels up to 3.73 mg/kg (fresh weight) determined. However, the majority of samples (95%) contained less than 1 mg/kg indospicine.

Chemical studies of rectal gland secretions of some species ofBactrocera dorsalis complex of fruit flies (diptera: Tephritidae)

Male-produced rectal gland secretions of a number of species now considered to be members of theBactrocera dorsalis complex of fruit flies have been examined by combined gas chromatography-mass spectrometry. The structures of a number of previously unreported compounds have been confirmed by synthesis and Chromatographic comparisons. Compounds identified in these secretions include fatty acids, esters, amides, keto alcohols, diols and spiroacetals. These chemical findings are in agreement with taxonomic revisions based on other criteria.

Crotalaria medicaginea associated with horse deaths in northern Australia: new pyrrolizidine alkaloids

Crotalaria medicaginea has been implicated in horse poisoning in grazing regions of central-west Queensland, which resulted in the deaths of more than 35 horses from hepatotoxicosis in 2010. Liver pathology was suggestive of pyrrolizidine alkaloidosis, and we report here the isolation of two previously uncharacterized pyrrolizidine alkaloids from C. medicaginea plant specimens collected from pastures where the horses died. The first alkaloid was shown by mass spectometric and NMR analyses to be 1β,2β-epoxy-7β-hydroxy-1α-methoxymethyl-8α-pyrrolizidine, which, like other alkaloids previously isolated from C. medicaginea, lacks the requisite functionality for hepatotoxcity. The second alkaloid isolated in this investigation was a new macrocyclic diester of otonecine, which we have named cromedine. The (1)H and (13)C NMR spectra of cromedine were fully assigned by 2D NMR techniques and allowed the constitution of the macrocyclic diester to be assigned unambiguously. C. medicaginea specimens implicated in this investigation do not belong to any of the three recognized Australian varieties (C. medicaginea var. neglecta, C. medicaginea var. medicaginea, and C. medicaginea var. linearis) and appear to be a local variant or form, referred to here as C. medicaginea (chemotype cromedine).

Residue potential of norsesquiterpene glycosides in tissues of cattle fed Austral bracken (Pteridium esculentum)

Austral bracken, Pteridium esculentum , occurs widely in Australian grazing lands and contains both the known carcinogen ptaquiloside and its hydroxy analogue, ptesculentoside, with untested carcinogenic potential. Calves were fed a diet containing 19% P. esculentum that delivered 1.8 mg of ptaquiloside and 4.0 mg of ptesculentoside per kilogram of body weight (bw) per day to explore the carcass residue potential of these compounds. Concentrations of ptaquiloside and ptesculentoside in the liver, kidney, skeletal muscle, heart, and blood of these calves were determined as their respective elimination products, pterosin B and pterosin G, by HPLC-UV analysis. Plasma concentrations of up to 0.97 μg/mL ptaquiloside and 1.30 μg/mL ptesculentoside were found, but were shown to deplete to <10% of these values within 24 h of bracken consumption. Both glycosides were also detected in all tissues assayed, with ptesculentoside appearing to be more residual than ptaquiloside. Up to 0.42 and 0.32 μg/g ptesculentoside was present in skeletal muscle and liver, respectively, 15 days after bracken consumption ended. This detection of residual glycosides in tissues of cattle feeding on Austral bracken raises health concerns for consumers and warrants further investigation.

Norsesquiterpene glycosides in bracken ferns (Pteridium esculentum and Pteridium aquilinum subsp. wightianum) from Eastern Australia: reassessed poisoning risk to animals

Austral bracken Pteridium esculentum contains three unstable norsesquiterpene glycosides: ptaquiloside, ptesculentoside, and caudatoside, in variable proportions. The concentration of each of the glycosides was determined in this study as their respective degradation products, pterosin B, pterosin G and pterosin A, by HPLC-UV analysis. Samples of P. esculentum collected from six sites in eastern Australia contained up to 17 mg of total glycoside/g DW, with both ptaquiloside and ptesculentoside present as major components accompanied by smaller amounts of caudatoside. Ratios of ptaquiloside to ptesculentoside varied from 1:3 to 4:3, but in all Australian samples ptesculentoside was a significant component. This profile differed substantially from that of P. esculentum from New Zealand, which contained only small amounts of both ptesculentoside and caudatoside, with ptaquiloside as the dominant component. A similar profile with ptaquiloside as the dominant glycoside was obtained for Pteridium aquilinum subsp. wightianum (previously P. revolutum ) from northern Queensland and also P. aquilinum from European sources. Ptesculentoside has chemical reactivity similar to that of ptaquiloside and presumably biological activity similar to that of this potent carcinogen. The presence of this additional reactive glycoside in Australian P. esculentum implies greater toxicity for consuming animals than previously estimated from ptaquiloside content alone.