Abstract
Species in the mushroom genus Lepiota can cause fatal mushroom poisonings due to their content of amatoxins such as α-amanitin. Previous studies of the toxin composition of poisonous Lepiota species relied on analytical methods of low sensitivity or resolution. Using liquid chromatography coupled to UV absorbance and mass spectrometry, we analyzed the spectrum of peptide toxins present in six Italian species of Lepiota, including multiple samples of three of them collected in different locations. Field taxonomic identifications were confirmed by sequencing of the internal transcribed spacer (ITS) regions. For comparison, we also analyzed specimens of Amanita phalloides from Italy and California, a specimen of A. virosa from Italy, and a laboratory-grown sample of Galerina marginata. α-Amanitin, β-amanitin, amanin, and amaninamide were detected in all samples of L. brunneoincarnata, and α-amanitin and γ-amanitin were detected in all samples of L. josserandii. Phallotoxins were not detected in either species. No amatoxins or phallotoxins were detected in L. clypeolaria, L. cristata, L. echinacea, or L. magnispora. The Italian and California isolates of A. phalloides had similar profiles of amatoxins and phallotoxins, although the California isolate contained more β-amanitin relative to α-amanitin. Amaninamide was detected only in A. virosa.
Highlights
The amatoxins, such as α-amanitin, are a group of bicyclic octapeptides produced by some species of mushrooms
In order to redress the relative scarcity of information regarding the distribution and abundance of the amatoxins and phallotoxins in the genus Lepiota, especially using modern methods of higher sensitivity and resolution, we analyzed six species of Lepiota for their toxin content by liquid chromatography-mass spectrometry (LC-MS)
The species of Lepiota and Amanita were identified in the field by expert mycologists and the identification were confirmed by DNA sequencing of the internal transcribed spacer (ITS) regions and comparison to nucleotide sequences in GenBank (Figure S1)
Summary
The amatoxins, such as α-amanitin, are a group of bicyclic octapeptides produced by some species of mushrooms (phylum Basidiomycota, class Agaricomycetes, order Agaricales) They account for the majority of fatal mushroom poisonings throughout the world. Further diversity among the amatoxins arises from differences in hydroxylations of the side chains, which include 4-hydroxyPro, γ,δ-dihydroxyIle, and 6-hydroxyTrp (Figure 1A) The phallotoxins, such as phalloidin and phallacidin, are a related class of bicyclic heptapeptides that contain a Trp-Cys cross-bridge. In order to redress the relative scarcity of information regarding the distribution and abundance of the amatoxins and phallotoxins in the genus Lepiota, especially using modern methods of higher sensitivity and resolution, we analyzed six species of Lepiota for their toxin content by liquid chromatography-mass spectrometry (LC-MS)
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