Omphalotus olearius: Jack o’Lantern Mushroom Identification & Info

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The scientific name for Jack-o’Lantern is Omphalotus illudens, this mushroom is a basidiomycete [1]. Investigations of the properties from this mushroom were published back early in the 1900s when this fungus was more commonly known then as Clitocybe illudens [2] [3]. Original studies also suggested that there was a synonymy between Omphalotus illudens and Omphalotus olearious however, DNA examination confirms they are two distinct species [4]. The Jack-o’Lantern mushroom is large and strikingly bright orange. It is found in clumps usually on large stumps of wood or fallen branches and the decaying roots of deciduous trees. Jack-o’Lantern is a poisonous mushroom and when ingested can cause diarrhoea and vomiting [5]. It has been known for its toxic properties in Japan for some time with occasional fatalities, thought to be linked to its similar appearance to edible mushrooms [6].

Jack-o’Lantern Mushroom Identification and Description

Cap: 3-20cm; starts convex with a central “nipple” before flattening.

Gills: Bright orange; features true gills running down the stem; crowded. Gills are said by some to be mildly bioluminescent and can be seen to glow green in the dark; others argue that this is a myth.

Stem: 3-13cm long; 1- 2cm wide.

Smell: Reasonably strong; not unpleasant.

Taste: Not distinctive.

Spores: Ellipsoid-globular.

Spore color: White to a pale yellow.

Edibility: Poisonous and should not be ingested.

Habitat: Found in clusters; Europe (Central and Northern) and sometimes North America; late summer and fall.

Ecology: Saprobic.

Jack-o’Lantern Medicinal Properties

Anti-bacterial properties

Omphalotus illudens is the source of a number of sesquiterpenes, of which some were identified pre-1950s as having anti-bacterial properties [1], although the specific factors responsible were not known at the time. Bacterial growth inhibition was observed, in dishes with the presence of components from Omphalotus illudens, following the application of cultures of Staphylococcus aureus, Mycobacterium smegma. A greater effect was seen in the presence of Mycobacterium smegma but very little growth inhibition was observed in the presence of Escherichia coli. The first identified sesquiterpenes were illuden S and illuden M [8] and they were identified as the components of  Omphalotus illudens responsible for the anti-bacterial properties observed in vitro.

Anti-viral properties

Investigation and analysis of the mature fruiting bodies of Omphalotus illudens identified anti-viral properties in an assay using HSV-1 (Herpes Simplex Virus Type 1) in vitro. The specific component of the mushroom thought to be responsible for the anti-viral properties was illudin S1 [9].

Anti-tumour Properties

Illudins S and Illudins M are incredibly cytotoxic products of Omphalotus illudens [10] and as such have been examined for their use as anti-tumorigenic therapeutics. They have shown selective toxicity for cancers including leukaemia, breast, lung and ovarian [11]. The toxic effects from ingestion of Omphalotus illudens mean that it cannot be taken directly however, less toxic chemically modified variations to the compounds are of interest. ­Irofulven is semi-synthetic derivative of the illuden S isolated from Omphalotus illudens. [12]. Irofulven is a patented drug that has been used in clinical trials looking at anti-tumor properties. The drug is a semi-synthetic compound based on illudin S a sesquiterpene known to be a toxic compound found in Omphalotus illudens [13]. Trials have provided varied results, with some positive effects of irofulven seen in hormone-refractory prostate cancer [14]. A new study is in place looking at specific biomarkers in late stage prostate cancer and the effectiveness of Irofulven administration.

Jacko Lantern Mushroom Toxicity, Safety & Side Effects

Jack-o’Lantern (Omphalotus illudens) is poisonous and should not be consumed. Please take medical advice immediately if the mushroom is ingested as it may cause sickness, diarrhoea and/or affect liver function [7].

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  1. McMorris, T.C., et al., Sesquiterpenes from the basidiomycete Omphalotus illudens. J Nat Prod, 2000. 63(11): p. 1557-9.
  2. Clark, E.D. and C.S. Smith, Toxicological Studies on the Mushrooms Clitocybe Illudens and Inocybe Infida. Mycologia, 1913. 5(4): p. 224-232.
  3. Anchel, M., A. Hervey, and W.J. Robbins, Antibiotic substances from Basidiomycetes+. VII. Clitocybe illudens. Proceedings of the National Academy of Sciences of the United States of America, 1950. 36(5): p. 300-305.
  4. Kirchmair, M., et al., Phylogeny of the genus Omphalotus based on nuclear ribosomal DNA-sequences. Mycologia, 2004. 96(6): p. 1253-1260.
  5. French, A.L. and L.K. Garrettson, Poisoning with the North American Jack O’Lantern mushroom, Omphalotus illudens. J Toxicol Clin Toxicol, 1988. 26(1-2): p. 81-8.
  6. McMorris, T.C., et al., Structure-activity relationships of illudins: analogs with improved therapeutic index. The Journal of Organic Chemistry, 1992. 57(25): p. 6876-6883.
  7. Vanden Hoek, T.L., et al., Jack o’lantern mushroom poisoning. Ann Emerg Med, 1991. 20(5): p. 559-61.
  8. McMorris, T.C. and M. Anchel, The Structures of the Basidiomycete Metabolites Illudin S and Illudin M. Journal of the American Chemical Society, 1963. 85(6): p. 831-832.
  9. Lehmann, V.K., et al., Illudin S, the sole antiviral compound in mature fruiting bodies of Omphalotus illudens. J Nat Prod, 2003. 66(9): p. 1257-8.
  10. Dick, R.A., X. Yu, and T.W. Kensler, NADPH alkenal/one oxidoreductase activity determines sensitivity of cancer cells to the chemotherapeutic alkylating agent irofulven. Clin Cancer Res, 2004. 10(4): p. 1492-9.
  11. Kelner, M.J., T.C. McMorris, and R. Taetle, Preclinical evaluation of illudins as anticancer agents: basis for selective cytotoxicity. J Natl Cancer Inst, 1990. 82(19): p. 1562-5.
  12. Staake, M.D., et al., Hydroxyurea derivatives of irofulven with improved antitumor efficacy. Bioorg Med Chem Lett, 2016. 26(7): p. 1836-8.
  13. Baekelandt, M., Irofulven (MGI Pharma). Curr Opin Investig Drugs, 2002. 3(10): p. 1517-26.
  14. Senzer, N., et al., Irofulven demonstrates clinical activity against metastatic hormone-refractory prostate cancer in a phase 2 single-agent trial. Am J Clin Oncol, 2005. 28(1): p. 36-42.

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