Effects of drugs on mushroom poisoning induced in the rat by Cortinarius speciosissimus

Orellanine: From Fungal Origin to a Potential Future Cancer Treatment

Fungal metabolites represent an underutilized resource in the development of novel anticancer drugs. This review will focus on the promising fungal nephrotoxin orellanine, found in mushrooms including Cortinarius orellanus (Fools webcap). Emphasis will be placed on its historical significance, structural features, and associated toxicomechanics. Chromatographic methods for analysis of the compound and its metabolites, its synthesis, and chemotherapeutic potential are also discussed. Although orellanine's exceptional selectivity for proximal tubular cells is well documented, the mechanics of its toxicity in kidney tissue remains disputed. Here, the most commonly proposed hypotheses are detailed in the context of the molecule's structure, the symptoms seen following ingestion, and its characteristic prolonged latency period. Chromatographic analysis of orellanine and its related substances remains challenging, while biological evaluation of the compound is complicated by uncertainty regarding the role of active metabolites. This has limited efforts to structurally refine the molecule; despite numerous established methods for its synthesis, there is minimal published material on how orellanine's structure might be optimized for therapeutic use. Despite these obstacles, orellanine has generated promising data in preclinical studies of metastatic clear cell renal cell carcinoma, leading to the early 2022 announcement of phase I/II trials in humans.

Human and experimental toxicology of orellanine

Orellanine is a nephrotoxic toxin produced by some mushroom species of the Cortinarius genus, typically found in Europe and North America. The nephrotoxicity of Cortinarius orellanus is well known and was first recognized in the 1950s when this mushroom was identified as the cause of a mass poisoning in Poland. Typically, onset of symptoms is delayed for 1-2 weeks after ingestion. Some patients suffer mild gastrointestinal discomfort in the latency period before developing signs of renal impairment due to severe interstitial nephritis, acute focal tubular damage, and interstitial fibrosis. There is no specific antidote to orellanine poisoning. The mainstay of treatment is the prevention of secondary complications of kidney failure, adequate dialysis and, in the case of incomplete recovery, management of chronic renal insufficiency. : In this work, we aim to review about Cortinarius species, including epidemiological studies, chemical structure, toxicokinetics, toxic doses, mechanisms of toxicity, diagnosis, prognosis, and treatment options.

Clinical symptomatology and management of mushroom poisoning

Among poisonous mushrooms, a small number may cause serious intoxication and even fatalities in man. Humans may become symptomatic after a mushroom meal for rather different reasons: (1) ingestion of mushrooms containing toxins, (2) large amounts of mushrooms may be hard to digest, (3) immunological reactions to mushroom-derived antigens, (4) ingestion of mushrooms causing ethanol intolerance, and (5) vegetative symptoms may occur whenever a patient realizes that there might be a possibility of ingestion of a toxic mushroom after a mushroom meal. Based on the classes of toxins and their clinical symptoms, seven different types of mushroom poisoning can be distinguished: (1) phalloides, (2) orellanus, (3) gyromitra, (4) muscarine, (5) pantherina, (6) psilocybin, and (7) gastrointestinal mushroom syndrome. Two other entities of adverse reactions to mushrooms are (8) coprinus and (9) paxillus syndrome. Phalloides, orellanus, gyromitra and paxillus syndrome may lead to serious poisoning, which generally requires treatment of the patient in an intensive care unit. Diagnosis of mushroom poisoning is primarily based on anamnestic data, identification of mushrooms from leftovers of the mushroom meal, spore analysis, and/or chemical analysis. Therapeutic strategies include primary detoxification by induced emesis, gastric lavage and activated charcoal, secondary detoxification, symptomatic treatment and rarely specific antidotes. Owing to progressing fulminant hepatic failure, lethality associated with phalloides syndrome is still high (5-20%). Basic treatment includes administration of silibinin and penicillin G, although controlled studies on its therapeutic efficacy are still lacking. In serious phalloides syndrome, orthotopic liver transplantation has to be considered. Fortunately, the prognosis in most other mushroom poisonings is excellent.

Mushroom poisoning caused by species of the genus Cortinarius Fries

Symptomatology, clinical characteristics and pathogenesis of mushroom poisoning caused by Cortinarius species are surveyed. The isolation of a bipyridine--orellanine--from Cortinarius orellanus is held to be responsible for the nephrotoxicity of this species as well as the closely related C. speciosissimus. The present knowledge on the toxicity of structurally related and well-known bipyridines such as paraquat and diquat is brought up and found comparable to orellanine toxicity. Pharmacokinetic experiments on the nephrotoxic bipyridines suggest that haemoperfusion is a rational therapy of intoxicated persons, even several days after mushroom ingestion.