Biologically active components of poisonous mushrooms

Natural Bridged Bicyclic Peptide Macrobiomolecules from Celosia argentea and Amanita phalloides

Bridged peptide macrobicycles (BPMs) from natural resources belong to types of compounds that are not investigated fully in terms of their formation, pharmacological potential and stereo-chemical properties. This division of biologically active congeners with multiple circular rings, has merits over other varieties of peptide molecules. BPMs form one of the most hopeful grounds for establishment of drugs because of their close resemblance and biocompatibility to proteins, and these bio-actives are debated as feasible realistic tools in diverse biomedical applications. Despite huge potential, poor metabolic stability and cell permeability limit the therapeutic success of macrocyclic peptides. In this review, we have comprehensively explored major bicyclic peptides sourced from plants and mushrooms including βs-leucyl-tryptophano-histidine bridged and tryptophano-cysteine bridged peptide macrobicycles. The unique structural features, structure activity relationship, synthetic routes, bioproperties and therapeutic potential of the natural BPMs are also discussed.

Extensive screening of cyclopeptide toxins in mushrooms by ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry

A non-target screening method of cyclopeptide toxins and their analogues in mushroom was developed, using ultra-high-performance liquid chromatography coupled with quadrupole Orbitrap mass spectrometry (UHPLC-Q-Orbitrap MS) followed by mass spectrometry databases retrieval and software tools analysis for the candidate analogues. Three cyclopeptide toxins in the toxic mushroom Amanita rimosa were firstly screened without standard, and two of them were unknown analogues which were tentatively identified by the accurate masses, isotopic patterns and characteristic fragments. A validated quantitative method was performed to rapidly quantify three major cyclopeptide toxins in the Amanita rimosa sample including α-manitin, β-amanitin and phalloidin, and their contents were detected to be 4.52 mg/kg, 2.37 mg/kg and 2.53 mg/kg, respectively. The developed method has good selectivity and sensitivity for rapid and comprehensive screening the cyclopeptide toxins and their analogues in mushrooms at trace levels. Successful non-target screening of trace cyclopeptide toxin analogues will guarantee the food safety in mushrooms consumption.

Mushroom-Derived Indole Alkaloids

Mushrooms are known to produce over 140 natural products bearing an indole heterocycle. In this review, the isolation of these mushroom-derived indole alkaloids is discussed, along with their associated biological activities.

Molybdophyllysin, a toxic metalloendopeptidase from the tropical toadstool, Chlorophyllum molybdites

A toxic protein, dubbed molybdophyllysin, was isolated from the tropical toadstool Chlorophyllum molybdites by following its lethal effect in mice. Analysis of the protein using SDS-PAGE revealed a single 23-kDa band. Sequence analysis of molybdophyllysin tryptic fragments showed that this protein is highly homologous to metalloendopeptidases (MEPs) obtained from edible mushrooms, such as Grifola frondosa, Pleurotus ostreatus, and Armillaria mellea. These proteins include a HEXXH+D zinc-binding motif known as aspzincin. Accordingly, molybdophyllysin is a member of the deuterolysin family of zinc proteases. Molybdophyllysin retained its proteolytic activity at temperatures up to 60°C with an optimum pH of 7.0. The activity was inhibited by both 1,10-phenanthroline and N-bromosuccinimide, but molybdophyllysin exhibited strong resistance to SDS.

Laccase and lectin activities of intracellular proteins produced in a submerged culture of the xylotrophic basidiomycete Lentinus edodes

The white-rot fungus Lentinus edodes produced D-melibiose-specific lectins and two laccase forms in a lignin-containing medium. The maxima of laccase and lectin activities coincided, falling within the period of active mycelial growth. The enzymes and lectins were isolated and purified by gel filtration followed by anion-exchange chromatography. The L. edodes lectins were found to be able to stabilize the activity of the fungus's own laccases. Lectin activity during the formation of lectin-enzyme complexes remained unchanged.

Explaining Dioscorides' “Double Difference”: Why Are Some Mushrooms Poisonous, and Do They Signal Their Unprofitability?

The adaptive significance of toxins in mushrooms has received very little consideration, although it is clear that poisons have appeared (and/or disappeared) many times in mushrooms' evolutionary history. One possibility is that poisons have evolved in some mushroom species to deter their consumption by would-be fungivores before spore dispersal. If this is so, then one might expect poisonous mushrooms to signal their unprofitability in some way. In this study, we have conducted the first formal analysis of the ecological and morphological traits associated with edible and poisonous mushrooms in North America and Europe. Poisonous mushrooms do not tend to be more colorful or aggregated than edible mushrooms, but they are more likely to exhibit distinctive odors even when phylogenetic relationships are accounted for. This raises the intriguing possibility that some poisonous species of mushrooms have evolved warning odors (and perhaps tastes) to enhance avoidance learning by fungivores.