N-containing compounds of macromycetes

Purpurascenines A-C, Azepino-Indole Alkaloids from Cortinarius purpurascens: Isolation, Biosynthesis, and Activity Studies on the 5-HT2A Receptor

Three previously undescribed azepino-indole alkaloids, named purpurascenines A-C (1-3), together with the new-to-nature 7-hydroxytryptophan (4) as well as two known compounds, adenosine (5) and riboflavin (6), were isolated from fruiting bodies of Cortinarius purpurascens Fr. (Cortinariaceae). The structures of 1-3 were elucidated based on spectroscopic analyses and ECD calculations. Furthermore, the biosynthesis of purpurascenine A (1) was investigated by in vivo experiments using 13C-labeled sodium pyruvate, alanine, and sodium acetate incubated with fruiting bodies of C. purpurascens. The incorporation of 13C into 1 was analyzed using 1D NMR and HRESIMS methods. With [3-13C]-pyruvate, a dramatic enrichment of 13C was observed, and hence a biosynthetic route via a direct Pictet-Spengler reaction between α-keto acids and 7-hydroxytryptophan (4) is suggested for the biosynthesis of purpurascenines A-C (1-3). Compound 1 exhibits no antiproliferative or cytotoxic effects against human prostate (PC-3), colorectal (HCT-116), and breast (MCF-7) cancer cells. An in silico docking study confirmed the hypothesis that purpurascenine A (1) could bind to the 5-HT2A serotonin receptor's active site. A new functional 5-HT2A receptor activation assay showed no functional agonistic but some antagonistic effects of 1 against the 5-HT-dependent 5-HT2A activation and likely antagonistic effects on putative constitutive activity of the 5-HT2A receptor.

Indole Alkaloids from Psychoactive Mushrooms: Chemical and Pharmacological Potential as Psychotherapeutic Agents

Neuropsychiatric diseases such as depression, anxiety, and post-traumatic stress represent a substantial long-term challenge for the global health systems because of their rising prevalence, uncertain neuropathology, and lack of effective pharmacological treatments. The approved existing studies constitute a piece of strong evidence whereby psychiatric drugs have shown to have unpleasant side effects and reduction of sustained tolerability, impacting patients' quality of life. Thus, the implementation of innovative strategies and alternative sources of bioactive molecules for the search for neuropsychiatric agents are required to guarantee the success of more effective drug candidates. Psychotherapeutic use of indole alkaloids derived from magic mushrooms has shown great interest and potential as an alternative to the synthetic drugs currently used on the market. The focus on indole alkaloids is linked to their rich history, their use as pharmaceuticals, and their broad range of biological properties, collectively underscoring the indole heterocycle as significant in drug discovery. In this review, we aim to report the physicochemical and pharmacological characteristics of indole alkaloids, particularly those derived from magic mushrooms, highlighting the promising application of such active ingredients as safe and effective therapeutic agents for the treatment of neuropsychiatric disorders.

Lanostane triterpenoids from the fungus Physisporinus vitreus and their inhibitory activity against nitric oxide production

Eight undescribed lanostane triterpenoids, physivitrins A-H, along with four known analogues, were isolated from cultures of the fungus Physisporinus vitreus. Their structures were elucidated on the basis of extensive spectroscopic methods, in which the absolute configuration of physivitrin A was elucidated using electronic circular dichroism calculation and nuclear magnetic resonance (NMR) calculation with DP4+ analysis. Physivitrins B and C showed inhibitory activities against nitric oxide (NO) production in LPS-activated RAW264.7 macrophages with IC₅₀ values of 7.5 and 23.5 μM, respectively. Meanwhile, proinflammatory cytokines (TNF-α, iNOS and IL-1β) mRNA expression was also inhibited by physivitrin B significantly.

Secondary Metabolites from Fungi-In Honor of Prof. Dr. Ji-Kai Liu's 60th Birthday

It is our pleasure and privilege to serve as Guest Editors for this Special Issue of the Journal of Fungi in honor of Professor Ji-Kai Liu's 60th birthday [...].

Cadinane sesquiterpenoids from the fungus Antrodiella albocinnamomea and their inhibitory activity against nitric oxide production

Seven previously undescribed cadinane sesquiterpenoids, albocinnamins A‒G, were isolated from the fungus Antrodiella albocinnamomea. Their structures with absolute configurations were elucidated on the basis of extensive spectroscopic methods, as well as single crystal X-ray diffraction. Cadinane sesquiterpenoids were reported from A. albocinnamomea for the first time. All of these sesquiterpenoids possess an unusual ether ring with minor modifications. Albocinnamins D and G showed certain inhibitory activities against nitric oxide production in LPS-activated RAW264.7 macrophages with IC₅₀ values of 26.1 and 19.2 μM, respectively.

Sesquiterpenes with diverse skeletons from histone deacetylase inhibitor modified cultures of the basidiomycete Cyathus stercoreus (Schwein.) De Toni HFG134

Epigenetic modifiers are proved to be effective specialized products-mining tools by rationally regulating the gene expression of fungal biosynthetic pathways. Chemical investigation on the histone deacetylase inhibitor (HDI) vorinostat (also known as SAHA)-modified cultures of the basidiomycete Cyathus stercoreus (Schwein.) De Toni (Nidulariaceae) led to the isolation of nine previously undescribed sesquiterpenes, and four previously described ones. The structures of the nine undescribed compounds were determined by extensive NMR spectroscopic analysis, HRESIMS analysis, as well as ECD and NMR calculations. Notably, the isolated sesquiterpenes are exclusive or overproduced from the epigenetic modified cultures compared to the negative control cultures. Additionally, the skeleton types of the isolated sesquiterpenes include protoilludalane, illudalane, 1,11-seco-protoilludalane, 10,11-seco-illudalane, and 14(11→10)abeo-illudalane. It is noteworthy that the 14(11→10)abeo-illudalane skeleton is reported for the first time. Cystercorodiol A, 4-O-acetylcybrodol, cystercorotone, and cybrodol showed weak inhibitory activity against the bacterium Escherichia coli ATCC25922 with the inhibitory rates 34.7%, 33.0%, 32.3%, and 29.6% at the concentration 200 μM, respectively. This study suggested that epigenetic modifiers are also an effective tool for specialized metabolite-mining in basidiomycetes.

Sesquiterpenoids Specially Produced by Fungi: Structures, Biological Activities, Chemical and Biosynthesis (2015-2020)

Fungi are widely distributed in the terrestrial environment, freshwater, and marine habitat. Only approximately 100,000 of these have been classified although there are about 5.1 million characteristic fungi all over the world. These eukaryotic microbes produce specialized metabolites and participate in a variety of ecological functions, such as quorum detection, chemical defense, allelopathy, and maintenance of symbiosis. Fungi therefore remain an important resource for the screening and discovery of biologically active natural products. Sesquiterpenoids are arguably the richest natural products from plants and micro-organisms. The rearrangement of the 15 high-ductility carbons gave rise to a large number of different skeletons. At the same time, abundant structural variations lead to a diversification of biological activity. This review examines the isolation, structural determination, bioactivities, and synthesis of sesquiterpenoids that were specially produced by fungi over the past five years (2015-2020).

Does the chemistry of fungal pigments demand the existence of photoactivated defense strategies in basidiomycetes?

The well-known photosensitizers hypericin, harmane, and emodin are typical pigments of certain mushroom species-is this a coincidence or an indication towards a photoactivated defense mechanism in the phylum Basidiomycota? This perspective article explores this hypothesis by cross-linking the chemistry of fungal pigments with structural requirements from known photosensitizers and insights from photoactivated strategies in the kingdom Plantae. Thereby, light is shed on a yet unexplored playground dealing with ecological questions, photopharmaceutical opportunities, and biotechnological potentials.

Heterobasidion annosum Induces Apoptosis in DLD-1 Cells and Decreases Colon Cancer Growth in In Vivo Model

Application of substances from medicinal mushrooms is one of the interesting approaches to improve cancer therapy. In this study, we commenced a new attempt in the field of Heterobasidion annosum (Fr.) Bref. sensu lato to further extend our knowledge on this basidiomycete fungus. For this purpose, analysis of the active substances of Heterobasidion annosum methanolic extract and also its influence on colorectal cancer in terms of in vitro and in vivo experiments were performed. In vivo studies on mice were conducted to verify its acute toxicity and to further affirm its anticancer potential. Results indicated that all the most common substances of best known medicinal mushrooms that are also responsible for their biological activity are present in tested extracts. In vitro tests showed a high hemocompatibility and a significant decrease in viability and proliferation of DLD-1 cells in a concentration-dependent manner of Heterobasidion annosum extract. The studies performed on xenograft model of mice showed lower tendency of tumor growth in the group of mice receiving Heterobasidion annosum extract as well as mild or moderate toxicity. Obtained results suggest beneficial potential of Heterobasidion annosum against colon cancer as cytotoxic agent or as adjuvant anticancer therapy.

The Pictet-Spengler Reaction Updates Its Habits

The Pictet-Spengler reaction (P-S) is one of the most direct, efficient, and variable synthetic method for the construction of privileged pharmacophores such as tetrahydro-isoquinolines (THIQs), tetrahydro-β-carbolines (THBCs), and polyheterocyclic frameworks. In the lustro (five-year period) following its centenary birthday, the P-S reaction did not exit the stage but it came up again on limelight with new features. This review focuses on the interesting results achieved in this period (2011-2015), analyzing the versatility of this reaction. Classic P-S was reported in the total synthesis of complex alkaloids, in combination with chiral catalysts as well as for the generation of libraries of compounds in medicinal chemistry. The P-S has been used also in tandem reactions, with the sequences including ring closing metathesis, isomerization, Michael addition, and Gold- or Brønsted acid-catalyzed N-acyliminium cyclization. Moreover, the combination of P-S reaction with Ugi multicomponent reaction has been exploited for the construction of highly complex polycyclic architectures in few steps and high yields. The P-S reaction has also been successfully employed in solid-phase synthesis, affording products with different structures, including peptidomimetics, synthetic heterocycles, and natural compounds. Finally, the enzymatic version of P-S has been reported for biosynthesis, biotransformations, and bioconjugations.

Nor-guanacastepene pigments from the Chilean mushroom Cortinarius pyromyxa

For the first time, the pigment composition of basidiocarps from the Chilean mushroom Cortinarius pyromyxa was studied under various aspects like phylogeny, chemistry and antibiotic activity. A molecular biological study supports the monotypic position of C. pyromyxa in subgenus Myxacium, genus Cortinarius. Four undescribed diterpenoids, named pyromyxones A-D, were isolated from fruiting bodies of C. pyromyxa. Their chemical structures were elucidated based on comprehensive one- and two-dimensional NMR spectroscopic analysis, ESI-HRMS measurements, as well as X-ray crystallography. In addition, the absolute configurations of pyromyxones A-D were established with the aid of J_H,H, NOESY spectra and quantum chemical CD calculation. The pyromyxones A-D possess the undescribed nor-guanacastane skeleton. Tested pyromyxones A, B, and D exhibit only weak activity against gram-positive Bacillus subtilis and gram-negative Aliivibrio fischeri as well as the phytopathogenic fungi Botrytis cinerea, Septoria tritici and Phytophthora infestans.

Heterocyclic Compounds from the Mushroom Albatrellus confluens and Their Inhibitions against Lipopolysaccharides-Induced B Lymphocyte Cell Proliferation

Eight hetereocyclic compounds conflamides B-I with an unprecedented skeleton and their precursor conflamide A were isolated from the mushroom Albatrellus confluens. Their structures and absolute configurations were determined by use of NMR studies, total synthesis, and calculated ECD spectra. Conflamides D and E were found to exhibit potent inhibition against LPS-induced B lymphocyte cell proliferation with IC₅₀ values 1.48 and 5.71 μM, respectively.

Albatredines A and B, a pair of epimers with unusual natural heterocyclic skeletons from edible mushroom Albatrellus confluens

A chemical study of the common species Albatrellus confluens present in Yunnan province, southwest China led to the identification of a pair of epimers named albatredines A (1) and B (2). They feature a natural unprecedented 1,2,4-oxadiazolidin-5-one skeleton. The acyl substitution pattern and complete configurational assignments were deduced from the comparison between experimental and theoretical ¹³C NMR and ECD data, respectively. Bioassay results showed that compound 1 exhibited a weak immunosuppressive activity against the concanavalin A-induced T lymphocyte cell proliferation (IC₅₀ 2.99 μM).

A chemical study of the common species Albatrellus confluens present in Yunnan province, southwest China led to the identification of a pair of epimers named albatredines A (1) and B (2).

New Acetylenic Acids and Derivatives from the Edible Mushroom Craterellus lutescens (Cantharellaceae)

Thirteen new acetylenic acids and their derivatives, craterellynes G-Q (1, 2, 4-10, 12, 13), 9-epi-craterellyne H (3), and 14-O-ethyl-craterellyne O (11), were isolated from the fruiting bodies of edible mushrooms Craterellus lutescens. The structures of these compounds were identified by various spectroscopic and chemical means. The stereoconfigurations of 1-13 were elucidated by the combination of acetonide formation, J-based configuration analysis, and modified Mosher's method. Craterellyne I exhibited cytotoxicities against human cancer strains and inhibition of nitric oxide (NO) production, as well as weak antimicrobial activity against Candida albicans.

Chemical Constituents and Their Bioactivities of Mushroom Phellinus rhabarbarinus

Phellinus rhabarbarinus soaked in wine has folk usages by local residents of Ailao mountain of Yunnan province, China, which were to daub the wound to prevent infection and to drink to enhance immunity and treat other diseases such as cough, gastritis, and cancer. Systemic investigation on the chemical constituents of fruiting bodies of P. rhabarbarinus resulted in the isolation of 11 lanostane triterpenoids (1-10) including three new ones, namely, phellibarins A-C (1-3), together with five ergosterols (11-15). This is the first time reporting secondary metabolites of P. rhabarbarinus. Compounds 2, 3, 7, and 8 showed inhibitory activities against nitric oxide (NO) production in LPS-activated RAW264.7 macrophages, whereas compounds 2-4, 6, 7, and 10 exhibited cytotoxicities against human cancer cell lines. The results of this assessment suggested that the lanostane triterpenoids in fruiting bodies of P. rhabarbarinus played key roles in its folk usages.

Differential metabolic responses of Beauveria bassiana cultured in pupae extracts, root exudates and its interactions with insect and plant

Beauveria bassiana is a kind of world-wide entomopathogenic fungus and can also colonize plant rhizosphere. Previous researches showed differential expression of genes when entomopathogenic fungi are cultured in insect or plant materials. However, so far there is no report on metabolic alterations of B. bassiana in the environments of insect or plant. The purpose of this paper is to address this problem. Herein, we first provide the metabolomic analysis of B. bassiana cultured in insect pupae extracts (derived from Euproctis pseudoconspersa and Bombyx mori, EPP and BMP), plant root exudates (derived from asparagus and carrot, ARE and CRE), distilled water and minimal media (MM), respectively. Principal components analysis (PCA) shows that mycelia cultured in pupae extracts and root exudates are evidently separated and individually separated from MM, which indicates that fungus accommodates to insect and plant environments by different metabolic regulation mechanisms. Subsequently, orthogonal projection on latent structure-discriminant analysis (OPLS-DA) identifies differential metabolites in fungus under three environments relative to MM. Hierarchical clustering analysis (HCA) is performed to cluster compounds based on biochemical relationships, showing that sphingolipids are increased in BMP but are decreased in EPP. This observation further implies that sphingolipid metabolism may be involved in the adaptation of fungus to different hosts. In the meantime, sphingolipids are significantly decreased in root exudates but they are not decreased in distilled water, suggesting that some components of the root exudates can suppress sphingolipid to down-regulate sphingolipid metabolism. Pathway analysis finds that fatty acid metabolism is maintained at high level but non-ribosomal peptides (NRP) synthesis is unaffected in mycelia cultured in pupae extracts. In contrast, fatty acid metabolism is not changed but NRP synthesis is high in mycelia cultured in root exudates and distilled water. This indicates that fungal fatty acid metabolism is enhanced when contacting insect, but when in the absence of insect hosts NRP synthesis is increased. Ornithine, arginine and GABA are decreased in mycelia cultured in pupae extracts and root exudates but remain unchanged in distilled water, which suggests that they may be associated with fungal cross-talk with insects and plants. Trehalose and mannitol are decreased while adenine is increased in three conditions, signifying carbon shortage in cells. Together, these results unveil that B. bassiana has differential metabolic responses in pupae extracts and root exudates, and metabolic similarity in root exudates and distilled water is possibly due to the lack of insect components.

Injury-induced biosynthesis of methyl-branched polyene pigments in a white-rotting basidiomycete

A stereaceous basidiomycete was investigated with regard to its capacity to produce yellow pigments after physical injury of the mycelium. Two pigments were isolated from mycelial extracts, and their structures were elucidated by ESIMS and one- and two-dimensional NMR methods. The structures were identified as the previously undescribed polyenes (3Z,5E,7E,9E,11E,13Z,15E,17E)-18-methyl-19-oxoicosa-3,5,7,9,11,13,15,17-octaenoic acid (1) and (3E,5Z,7E,9E,11E,13E,15Z,17E,19E)-20-methyl-21-oxodocosa-3,5,7,9,11,13,15,17,19-nonaenoic acid (2). Stable-isotope feeding with [1-(13)C]acetate and l-[methyl-(13)C]methionine demonstrated a polyketide backbone and that the introduction of the sole methyl branch is most likely S-adenosyl-l-methionine-dependent. Dose-dependent inhibition of Drosophila melanogaster larval development was observed with both polyenes in concentrations between 12.5 and 100 μM. GI50 values for 1 and 2 against HUVEC (K-562 cells) were 71.6 and 17.4 μM (15.4 and 1.1 μM), respectively, whereas CC50 values for HeLa cells were virtually identical (44.1 and 45.1 μM).

Pictet-Spengler reaction-based biosynthetic machinery in fungi

The Pictet-Spengler (PS) reaction constructs plant alkaloids such as morphine and camptothecin, but it has not yet been noticed in the fungal kingdom. Here, a silent fungal Pictet-Spenglerase (FPS) gene of Chaetomium globosum 1C51 residing in Epinephelus drummondhayi guts is described and ascertained to be activable by 1-methyl-L-tryptophan (1-MT). The activated FPS expression enables the PS reaction between 1-MT and flavipin (fungal aldehyde) to form "unnatural" natural products with unprecedented skeletons, of which chaetoglines B and F are potently antibacterial with the latter inhibiting acetylcholinesterase. A gene-implied enzyme inhibition (GIEI) strategy has been introduced to address the key steps for PS product diversifications. In aggregation, the work designs and validates an innovative approach that can activate the PS reaction-based fungal biosynthetic machinery to produce unpredictable compounds of unusual and novel structure valuable for new biology and biomedicine.

Two new ylangene-type sesquiterpenoids from cultures of the fungus Postia sp

Two new ylangene-type sesquiterpenoids, postinins A (1) and B (2), were isolated from cultures of the fungus Postia sp. Structures 1 and 2 were elucidated on the basis of extensive spectroscopic analysis. The bioactivity evaluation showed that both compounds had significant inhibitory activities against protein tyrosine phosphatase 1B, and SH2-containing cytoplasmic tyrosine phosphatase-1 and -2 with IC₅₀ values of 1.6-6.2 μg/ml.

Physical Properties and Molecular Conformations of Indole Alkaloids and Model Protein Interactions – Theoretical vs. Experimental Study

The physical properties and molecular structure of five natural indole alkaloids (IAs) and their interaction with protein targets have been studied, experimentally and theoretically. Electronic absorption (EAs) and CD spectroscopy, electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), as well as imaging mass spectrometric techniques (IMS) were used, analyzing the isolated alkaloids and corresponding IAs/protein molecular complexes. Theoretical quantum chemical DFT calculations were also applied. The mechanism of their biological activity and structure-activity relationship as potential neurologically active compounds were studied, using the model interactions with 5HT2A receptors. The gas-phase stable molecular fragments of the IAs are discussed comparing the experimental mass spectrometric data and theoretical quantum chemical DFT calculations of the different molecular fragments of the IAs.