Extrarenal and direct renal actions of atractyloside contribute to its acute nephrotoxicity in pentobarbital-anesthetized dogs

Direct and indirect targets of carboxyatractyloside, including overlooked toxicity toward nucleoside diphosphate kinase (NDPK) and mitochondrial H+ leak

CONTEXT

The toxicity of atractyloside/carboxyatractyloside is generally well recognized and commonly ascribed to the inhibition of mitochondrial ADP/ATP carriers, which are pivotal for oxidative phosphorylation. However, these glycosides may 'paralyze' additional target proteins.

OBJECTIVE

This review presents many facts about atractyloside/carboxyatractyloside and their plant producers, such as Xanthium spp. (Asteraceae), named cockleburs.

METHODS

Published studies and other information were obtained from databases, such as 'CABI - Invasive Species Compendium', 'PubMed', and 'The World Checklist of Vascular Plants', from 1957 to December 2022. The following major keywords were used: 'carboxyatractyloside', 'cockleburs', 'hepatotoxicity', 'mitochondria', 'nephrotoxicity', and 'Xanthium'.

RESULTS

In the third decade of the twenty first century, public awareness of the severe toxicity of cockleburs is still limited. Such toxicity is often only perceived by specialists in Europe and other continents. Interestingly, cocklebur is among the most widely distributed invasive plants worldwide, and the recognition of new European stands of Xanthium spp. is provided here. The findings arising from field and laboratory research conducted by the author revealed that (i) some livestock populations may instinctively avoid eating cocklebur while grazing, (ii) carboxyatractyloside inhibits ADP/GDP metabolism, and (iii) the direct/indirect target proteins of carboxyatractyloside are ambiguous.

CONCLUSIONS

Many aspects of the Xanthium genus still require substantial investigation/revision in the future, such as the unification of the Latin nomenclature of currently distinguished species, bur morphology status, true fruit (achene) description and biogeography of cockleburs, and a detailed description of the physiological roles of atractyloside/carboxyatractyloside and the toxicity of these glycosides, mainly toward mammals. Therefore, a more careful interpretation of atractyloside/carboxyatractyloside data, including laboratory tests using Xanthium-derived extracts and purified toxins, is needed.

A validated method for quantifying atractyloside and carboxyatractyloside in blood by HPLC-HRMS/MS, a non-fatal case of intoxication with Atractylis gummifera L

Atractyloside (ATR) and carboxyatractyloside (CATR) are diterpene glycosides that are responsible for the toxicity of several Asteraceae plants around the world. Mediterranean gum thistle (Atractylis gummifera L.) and Zulu impila (Callilepis laureola DC.), in particular, are notoriously poisonous and the cause of many accidental deaths, some suicides and even some murders. There is no current method for measuring the two toxins in biological samples that meet the criteria of specificity required in forensic medicine. We have endeavored to fill this analytical gap. Analysis was carried out using a solid-phase extraction and a high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry detection. The method was validated in the whole blood with quantification limits of 0.17 and 0.15 µg/L for ATR and CATR, respectively. The method was applied to a non-fatal case of intoxication with A. gummifera. To the best of the authors' knowledge, this is the first time that a concentration of ATR and CATR in blood (883.1 and 119.0 µg/L, respectively) and urine (230.4 and 140.3 µg/L, respectively) is reported. ATR and CATR were quantified in A. gummifera roots by the standard method addition (3.7 and 5.4 mg/g, respectively).

Carboxyatractyloside poisoning in humans

OBJECTIVE

Cocklebur (Xanthium strumarium) is an herbaceous annual plant with worldwide distribution. The seeds contain the glycoside carboxyatractyloside, which is highly toxic to animals. We describe nine cases of carboxyatractyloside poisoning in humans which, to our knowledge, has not previously been reported. The clinical, laboratory and histopathological findings and our therapeutic approach are also discussed.

SUBJECTS AND METHODS

The patients presented with acute onset abdominal pain, nausea and vomiting, drowsiness, palpitations, sweating and dyspnoea. Three of them developed convulsions followed by loss of consciousness and death.

RESULTS

Laboratory findings showed raised liver enzymes, indicating severe hepatocellular damage. BUN and creatinine levels were raised, especially in the fatal cases who also displayed findings of consumption coagulopathy. CPK-MB values indicative of myocardial injury were also raised, especially in the fatal cases. Three of the patients died within 48 hours of ingesting carboxyatractyloside. Post-mortem histopathology of the liver confirmed centrilobular hepatic necrosis and renal proximal tubular necrosis, secondary changes owing to increased permeability and microvascular haemorrhage in the cerebrum and cerebellum, and leucocytic infiltrates in the muscles and various organs including pancreas, lungs and myocardium.

CONCLUSIONS

Carboxyatractyloside poisoning causes multiple organ dysfunction and can be fatal. Coagulation abnormalities, hyponatraemia, marked hypoglycaemia, icterus and hepatic and renal failure are signs of a poor prognosis. No antidote is available and supportive therapy is the mainstay of treatment.

Atractylis gummifera L. poisoning: an ethnopharmacological review

Atractylis gummifera L. (Asteraceae) is a thistle located in the Mediterranean regions. Despite the plant's well-known toxicity, its ingestion continues to be a common cause of poisoning. The toxicity of Atractylis gummifera resides in atractyloside and carboxyatractyloside, two diterpenoid glucosides capable of inhibiting mitochondrial oxidative phosphorylation. Both constituents interact with a mitochondrial protein, the adenine nucleotide translocator, responsible for the ATP/ADP antiport and involved in mitochondrial membrane permeabilization. Poisoned patients manifest characteristic symptoms such as nausea, vomiting, epigastric and abdominal pain, diarrhoea, anxiety, headache and convulsions, often followed by coma. No specific pharmacological treatment for Atractylis gummifera intoxication is yet available and all the current therapeutic approaches are only symptomatic. In vitro experiments showed that some compounds such as verapamil, or dithiothreitol could protect against the toxic effects of atractyloside, but only if administered before atractyloside exposure. New therapeutic approaches could come from immunotherapy research: some studies have already tried to produce polyclonal Fab fragments against the toxic components of Atractylis gummifera.

The biochemistry and toxicity of atractyloside: a review

Atractyloside poisoning is an infrequent but often fatal form of herbal poisoning, which occurs worldwide but especially in Africa and the Mediterranean regions. The primary mechanism of atractyloside poisoning is known to be inhibition of the mitochondrial ADP transporter. Poisoning in humans may present with either acute hepatic or renal pathology and it is possible that there is a second, different mechanism of toxicity to the hepatocyte. Atractyloside in large amounts gives rise to massive necrosis, but in vitro studies have shown that at lower doses cells progress to apoptosis. Simple methods for the detection of atractyloside poisoning are at present restricted to thin-layer chromatography in urine and are useful only in the case of severe poisoning. Immunoassays, high-performance liquid chromatography, nuclear magnetic resonance, and a recently developed high-performance liquid chromatography/mass spectrometry method have yet to be applied to clinical diagnoses. There is at present no treatment, but a fuller understanding of the mechanisms of toxicity may lead to the application of a number of compounds that are effective in vitro.

Biochemistry and toxicology of the diterpenoid glycoside atractyloside

Atractyloside (Atr) is a diterpenoid glycoside that occurs naturally in plants (many of which are used in ethnomedicines) found in Europe, Africa, South America, Asia and the far East. It is also present in animal grazing forage. Atr (and its analogues) may be present at levels as high as 600 mg/kg dried plant material. Consumption of the plants containing Atr or carboxyatractyloside (carboxyAtr) has caused fatal renal proximal tubule necrosis and/or centrilobular hepatic necrosis in man and farm animals. Although pure Atr and crude plant extracts disrupt carbohydrate homeostasis and induce similar pathophysiological lesions in the kidney and liver, it is also possible that the toxicity of Atr may be confounded by the presence of other natural constituents in plants. Atr competitively inhibits the adenine nucleoside carrier in isolated mitochondria and thus blocks oxidative phosphorylation. This has been assumed to explain changes in carbohydrate metabolism and the toxic effects in liver and kidney. Although the acute toxicity of Atr is well described, many aspects of Atr toxicity (subchronic and chronic toxicity, reproductive toxicity, mutagenicity and carcinogenicity) have not been investigated and pharmacokinetic and metabolism data are limited. In vitro proximal tubular cells are selectively sensitive to Atr, whereas other renal cell types are quite resistant. There are also differences in the response of liver and renal tissue to Atr. Thus, not all of the clinical, biochemical and morphological changes caused by Atr can simply be explained on the basis of inhibition of mitochondrial phosphorylation. The relevance to a wider human risk is shown by the presence of Atr analogues in dried roasted Coffea arabica beans (17.5 32 mg/kg). There are no data to help identify the risk of low dose chronic exposure in human coffee consumers, nor is there information on the levels of Atr or its analogues in other commonly consumed human foodstuffs.

Toxicity of atractyloside in precision-cut rat and porcine renal and hepatic tissue slices

Atractyloside (ATR) causes acute fatal renal and hepatic necrosis in animals and humans. Precision-cut renal cortical and hepatic slices (200 +/- 15 microns) from adult male Wistar rat and domestic pigs, incubated with ATR (0.2-2.0 mM) for 3 h at 37 degrees C, inhibited pyruvate-stimulated gluconeogenesis in a concentration- and time-dependent manner. p-Aminohippurate accumulation was significantly inhibited in both rat and pig renal cortical slices from 0.2 mM ATR (p < 0.05). There was a small decrease in mitochondrial reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium to formazan in both rat and pig kidney slices, which was significant at > or = 2 mM, but no changes in liver slices from either species. However, cellular ATP was significantly depleted at > or = 0.2 mM ATR in kidney and in liver slices from both species. ATR also caused a marked leakage of lactate dehydrogenase and alkaline phosphatase from both pig and rat kidney slices at all concentrations, but only lactate dehydrogenase was significantly elevated in liver slices from both species. ATR > or = 0.5 mM caused a significant increase in lipid peroxidation, but only in liver slices of both species, and > or = 0.2 mM ATR caused a marked depletion of reduced glutathione and significant increase in oxidized glutathione in both kidney and liver slices of both species. However, GSH to GSSG ratio was only significantly altered in the liver slices, indicating that oxidative stress may be the cause of toxicity in this organ. Both rat and pig tissue slices from the same organ responded similarly to ATR, although their basal biochemistry was different. ATR toxicity to both kidney and liver showed similar patterns but it appears that the mechanisms of toxicity are different. While cytotoxicity of ATR in kidney is only accompanied with GSH depletion, that of the liver is linked to both lipid peroxidation and GSH depletion. Striated muscle slices from both species were not affected by the highest ATR concentration. This further strengthens the argument that the molecular basis of ATR, target selective toxicity, is not a measure of the interaction between ATR and mitochondria and that other factors such as selective uptake are involved. Precision-cut tissue slices show organ-specific toxicity in kidney and liver from both rat and pig and suggest different mechanisms of injury for each organ.

Citrinin produces acute adverse changes in renal function and ultrastructure in pentobarbital-anesthetized dogs without concomitant reductions in [potassium]plasma

Citrinin's nephrotoxicity was examined in pentobarbital-anesthetized dogs under conditions that minimized or avoided significant changes in a number of its actions that could indirectly and adversely affect renal function and ultrastructure, such as, (i) major acute reductions in blood pressure and renal blood flow and, (ii) emesis and diarrhea that could lead to dehydration and electrolyte imbalances, especially hypokalemia. Slow intravenous injection of 20 mumol citrinin/kg to pentobarbital-anesthetized dogs did not induce any alterations in renal tissue ultrastructure or in any of the 23 whole blood, plasma or renal function parameters that were monitored over a 6-h post-citrinin period. On the other hand, 80 mumol citrinin/kg produced significant increases in the hematocrit and in the renal excretion rates of protein and glucose; modest reductions were noted in CIN, RBF and excretion rate of inorganic phosphorus. In addition, 80 mumol citrinin/kg induced ultrastructural lesions in the cells of the S2 proximal tubular segment, the thick ascending limb, the distal convoluted tubule and the collecting ducts. The glomeruli, S1 and S3 cells of the proximal tubule and the thin descending and ascending limbs of Henle's loop were unaffected by both citrinin doses. The location and nature of the adverse ultrastructural lesions were most likely the result of the direct actions of citrinin (or a citrinin metabolite) since the effects of citrinin that could lead to indirect adverse renal effects were totally avoided or greatly minimized.

4-Maleimidohippuric acid--a tailor-made, direct, site-specific nephrotoxin: effects on renal function and ultrastructure in pentobarbital-anesthetized dogs

A model has been proposed to explain at least one of the possible pathways through which a xenobiotic might produce proximal tubule necrosis. The model is formulated on the idea that a compound must possess two structural features: (i) a carboxyl or amino acid moiety that would allow for selective uptake into proximal tubule cells via the strategically located antiluminal membrane-bound organic anion transport system or the luminal membrane-bound amino acid transport system(s), respectively, and (ii) a highly reactive moiety that can directly alkylate proximal tubular components, or a moiety that can be biotransformed within proximal tubular cells to such a substance. In an attempt to validate the proposed structural features as prerequisites for xenobiotic induction of proximal tubular necrosis, a novel compound, 4-maleimidohippuric acid (4-MHA), was synthesized which possesses an anionic group and a reactive moiety. Following the administration of 4-MHA directly into the renal artery of pentobarbital-anesthetized dogs, specific unilateral ultrastructural damage was noted only in the S1 and S2 cell types of the proximal tubule; the most notable renal function changes included proteinuria and glucosuria. Anionic, but non-alkylating, relatives of 4-MHA failed to alter renal function or ultrastructure. The specific proximal tubular toxicity of 4-MHA validates the proposed structural requirements for induction of proximal tubular necrosis.

S-(1,2-dichlorovinyl)-3-mercaptopropionic acid effects on renal function and ultrastructure in pentobarbital-anesthetized dogs: site-specific toxicity and evidence for its toxification via the pathway responsible for beta-oxidation of fatty acids

S-(1,2-dichlorovinyl)-3-mercaptopropionic acid (DCV-3-MPA) was equally nephrotoxic to spontaneously-respiring and mechanically-ventilated, pentobarbital-anesthetized dogs. Its nephrotoxicity was expressed as dose-dependent changes in key renal function parameters, in proximal tubular S1, S2 and S3 cellular architecture and in the ability of the kidneys to respond maximally to ethacrynic acid, an efficacious loop diuretic. The nephrotoxicity associated with DCV-3-MPA was not the result of extrarenal actions such as hypoxemia and subsequent renal tissue hypoxia because mechanical ventilation was not protective. Four lines of evidence suggested that DCV-3-MPA was taken-up by renal proximal tubular cells like a fatty acid and metabolized by the mitochondrial beta-oxidation pathway to a reactive nephrotoxic intermediate: (i) probenecid pretreatment, which reduces the renal uptake of many organic anions but fails to do so with anions of fatty acids, failed to modify the nephrotoxicity of DCV-3-MPA; (ii) the next higher and lower homologues of DCV-3-MPA (i.e., S-(1,2-dichlorovinyl)-4-mercaptobutanoic acid (DCV-4-MBA) and S-(1,2-dichlorovinyl)-mercaptoacetic acid (DCV-MAA)) cannot yield the same reactive intermediate as DCV-3-MPA upon beta-oxidation and neither was nephrotoxic; (iii) DCV-MAA was found in plasma and urine following administration of DCV-4-MBA and (iv) the renal mitochondria were reproducibly damaged by DCV-3-MPA whereas the peroxisomes, which are also capable of performing beta-oxidation of certain fatty acids, were unscathed.