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.

The Health and Clinical Benefits of Medicinal Fungi

The human uses of mushrooms and cultured mycelium products for nutrition and medicine are detailed and supported by available human studies, which in many cases are clinical trials published in peer-reviewed journals. The major medically active immunomodulating compounds in the cell walls-chitin, beta-glucans, and glycoproteins, as well as lower weight molecules-nitrogen-containing compounds, phenolics, and terpenes-are discussed in relation to their current clinical uses. The nutritional content and foods derived from mushrooms, particularly related to their medical benefits, are discussed. High-quality major nutrients such as the high amounts of complete protein and prebiotic fibers found in edible and medicinal fungi and their products are presented. Mushrooms contain the highest amount of valuable medicinal fiber, while dried fruiting bodies of some fungi have up to 80% prebiotic fiber. These fibers are particularly complex and are not broken down in the upper gut, so they can diversify the microbiome and increase the most beneficial species, leading to better immune regulation and increasing normalizing levels of crucial neurotransmitters like serotonin and dopamine. Since the growth of medicinal mushroom products is expanding rapidly worldwide, attention is placed on reviewing important aspects of mushroom and mycelium cultivation and quality issues relating to adulteration, substitution, and purity and for maximizing medicinal potency. Common questions surrounding medicinal mushroom products in the marketplace, particularly the healing potential of fungal mycelium compared with fruiting bodies, extraction methods, and the use of fillers in products, are all explored, and many points are supported by the literature.

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 [...].

Various Techniques for One-Pot Synthesis of 1,3,5-Triazine (s-Triazine) Derivatives: A Review

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Recent studies have shown that one-pot synthesis is a boon for triazines synthesis. One-pot processes had significant success in carrying out complex reactions under mild and eco-friendly conditions. One-pot synthesis is environmentally benign and more economical than other processes in triazines synthesis. The triazine scaffold has provided the starting key point for the design and development of pharmaceutical molecules with wide range of biomedical applications. This review highlights the various methodologies involved for one-pot synthesis of 1,3,5-triazine scaffolds.

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

A catalyst-free one-pot synthetic methodology was developed for the preparation of 1,3,5-triazine-2,4-dithione derivatives through three-component reactions of arylaldehydes, thiourea, and orthoformates. The procedure tolerated a diverse range of arylaldehydes and orthoformates and provided a rapid entry to a variety of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones (29 examples). The synthetic strategy relies on the dual role of thiourea in the cyclization with the aldehydes and the alkylation via an intermediate imidate formation. The structures of 1,3,5-triazine-2,4-dithione derivatives were characterized by spectroscopic techniques as well as by single crystal X-ray diffraction.

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.

Thermally induced formal [4+2] cycloaddition of 3-aminocyclobutenones with electron-deficient alkynes: facile and efficient synthesis of 4-pyridones

A thermally induced novel formal [4+2] cycloaddition of cyclobutenones with electron-deficient alkynes under metal-free conditions has been developed. The reaction provides a straightforward and efficient method for the synthesis of 4-pyridone derivatives in a single step.

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).

A novel chloro-substituted pentenamide from the fruiting bodies of Amanita virgineoides

One unusual chloro-substituted pentenamide, (3R)-4-chloro-3-hydroxy-4-pentenamide (1), together with 11 known compounds (2-12) were isolated from the fruiting bodies of Amanita virgineoides. The structure of 1 including the absolute configuration was characterized by extensive spectroscopic analyses and quantum calculation. Compound 1 displayed no obvious activity against herpes simplex virus (HSV), human enterovirus 71 (EV71) or coxsackievirus B3 (CVB3).

A new cyclic dipeptide from cultures of Coprinus plicatilis

Three cyclic dipeptides (1-3), including one new compound (1) were isolated from cultures of the basidiomycetes Coprinus plicatilis. Their structures were elucidated by spectroscopic methods, including extensive 2D NMR techniques. At the same time, all compounds were tested for their cytotoxicities against five human cancer cell lines.

Genetic stability of ectomycorrhizal fungi is not affected by cryopreservation at -130 °C or cold storage with repeated sub-cultivations over a period of 2 years

Cryopreservation is considered the most reliable method for storage of filamentous fungi including ectomycorrhizal (ECM) fungi. A number of studies, however, have reported genetic changes in fungus cultures following cryopreservation. In the present study, the genetic stability of six ECM fungus isolates was analyzed using amplified fragment length polymorphism (AFLP). The isolates were preserved for 2 years either by cryopreservation (at -130 °C) or by storage at 4 °C with regular sub-cultivation. A third preservation treatment consisting of isolates maintained on Petri dishes at 22-23 °C for 2 years (i.e., without any sub-cultivation) was included and used as a control. The differences observed in AFLP patterns between the three preservation methods remained within the range of the total error generated by the AFLP procedure (6.85%). Therefore, cryopreservation at -130 °C and cold storage with regular sub-cultivation did not affect the genetic stability of the ECM fungus isolates, and both methods can be used for the routine storage of ECM fungus isolates over a period of 2 years.

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.

Trapping of Transient Zwitterionic Intermediates by N-Acylpyridinium Salts: A Palladium-Catalyzed Diastereoselective Three-Component Reaction

We developed a palladium-catalyzed diastereoselective three-component reaction of N-aryl diazoamides, pyridine, and chloroformate, which proceeded through trapping of transient zwitterionic intermediates by in situ formed N-acylpyridinium salts in a regioselective 1,4-addition fashion. This reaction can rapidly provide a library of biologically relevant 4-(2-oxoindolin-3-yl)-1,4-dihydropyridine derivatives in high yields (up to 98%) with moderate to excellent diastereoselectivities (up to >95:5 dr) under mild reaction conditions.

Griseofulvin Derivative and Indole Alkaloids from Penicillium griseofulvum CPCC 400528

A new griseofulvin derivative, 4'-demethoxy-4'-N-isopentylisogriseofulvin (1), three new indole alkaloids, 2-demethylcyclopiamide E (2), 2-demethylsperadine F (3), and clopiamine C (4), and five known metabolites (5-9) were isolated from Penicillium griseofulvum CPCC 400528. Compound 1 is the first reported griseofulvin analogue with an N-isopentane group and the first example of a naturally occurring N-containing griseofulvin analogue. Their structures and absolute configurations were elucidated through extensive spectroscopic analyses, calculated ECD, and single-crystal X-ray diffraction (Cu Kα). The possible biogenetic pathway of 1-3 was proposed. Compounds 1, 2, and 5 exhibited anti-HIV activities with IC₅₀ values of 33.2, 20.5, and 12.6 μM, respectively.

Biosynthesis and molecular engineering of templated natural products

Bioactive small molecules that are produced by living organisms, often referred to as natural products (NPs), historically play a critical role in the context of both medicinal chemistry and chemical biology. How nature creates these chemical entities with stunning structural complexity and diversity using a limited range of simple substrates has not been fully understood. Focusing on two types of NPs that share a highly evolvable ‘template’-biosynthetic logic, we here provide specific examples to highlight the conceptual and technological leaps in NP biosynthesis and witness the area of progress since the beginning of the twenty-first century. The biosynthesis of polyketides, non-ribosomal peptides and their hybrids that share an assembly-line enzymology of modular multifunctional proteins exemplifies an extended ‘central dogma’ that correlates the genotype of catalysts with the chemotype of products; in parallel, post-translational modifications of ribosomally synthesized peptides involve a number of unusual biochemical mechanisms for molecular maturation. Understanding the biosynthetic processes of these templated NPs would largely facilitate the design, development and utilization of compatible biosynthetic machineries to address the challenge that often arises from structural complexity to the accessibility and efficiency of current chemical synthesis.

Identification and Characterization of a δ-Cadinol Synthase Potentially Involved in the Formation of Boreovibrins in Boreostereum vibrans of Basidiomycota

Sesquiterpenoids are very common among natural products. A large number of sesquiterpene synthase genes have been cloned and functionally characterized. However, until now there is no report about the δ-cadinol synthase predominantly forming δ-cadinol (syn. torreyol) from farnesyl diphosphate. Sesquiterpenoids boreovibrins structurally similar to δ-cadinol were previously isolated from culture broths of the basidiomycete fungus Boreostereum vibrans. This led us to expect a corresponding gene coding for a δ-cadinol synthase that may be involved in the biosynthesis of boreovibrins in B. vibrans. Here we report the cloning and heterologous expression of a new sesquiterpene synthase gene from B. vibrans. The crude and purified recombinant enzymes, when incubating with farnesyl diphosphate as substrate, gave δ-cadinol as its principal product and thereby identified as a δ-cadinol synthase. A new sesquiterpene synthase gene was cloned from the basidiomycete fungus Boreostereum vibrans and heterologously expressed in E. coli. The purified recombinant enzyme gave δ-cadinol as its principal product from farnesyl diphosphate and thereby identified as a δ-cadinol synthase (BvCS).

Geleganidines A-C, Unusual Monoterpenoid Indole Alkaloids from Gelsemium elegans

The first rotameric monoterpenoid indole alkaloids (MIAs), 1a and 1b, and two unusual dimeric MIAs, 2 and 3, with new dimerization patterns, together with their putative biosynthetic intermediates 4-7, were isolated from the roots of Gelsemium elegans. Compounds 2 and 3 represent the first natural aromatic azo- and the first urea-linked dimeric MIAs, respectively. Their structures and absolute configurations were elucidated by means of NMR spectroscopy, single-crystal X-ray diffraction, and electronic circular dichroism data analyses. The interconverting mechanism of rotamers 1a and 1b was studied by density functional theory computation. Compounds 2 and 3 showed moderate cytotoxic activity against MCF-7 and PC-12 cells, respectively. In addition, a plausible biosynthesis pathway for the new alkaloids was proposed on the basis of the coexistence of their biosynthetic precursors.

A Viscidane Diterpene and Polyacetylenes from Cultures of Hypsizygus marmoreus

Investigation on the cultures of Hypsizygus marmoreus resulted in the isolation of a new viscidane diterpene, 8-oxoviscida-3,11(18)-diene-13,14,15,19-tetraol (1) and two new polyacetylenes, (E)-10-(1,1-dimethyl-2-propenyloxy)-2-decene-4,6,8-triyn-1-ol (2) and 10-(1,1-dimethyl-2-propenyloxy)deca-4,6,8-triyn-1-ol (3), together with two known polyacetylenes, (E)-2-decen-4,6,8-triyn-1-ol (4) and 4,6,8-decatriyn-1-ol (5). Their structures were elucidated on the basis of extensive spectroscopic studies. Compound 1 is the first finding of viscidane diterpene in mushrooms. Compounds 1, 3 and 5 were tested for cytotoxicity against human tumor cell lines HL-60, SMMC-7721, A-549, MCF-7 and SW-480. None of the compounds showed cytotoxic activity (IC50 > 40 µM).

A New Ergostane Triterpenoid from Cultures of the Basidiomycete Inocybe lilacina

A new ergostane triterpenoid (4α-methylergost-8,24(28)-dien-3,7,11-trione, 1) together with four known compounds (2–5) were isolated from cultures of the basidiomycete Inocybe lilacina. The structure of the new compound was established on the basis of IR, 1D and 2D NMR spectroscopic and MS experiments.

An efficient method for the construction of polysubstituted 4-pyridones via self-condensation of β-keto amides mediated by P2O5 and catalyzed by zinc bromide

A self-condensation cyclization reaction mediated by phosphorus pentoxide (P2O5) and catalyzed by zinc bromide (ZnBr2) is presented for the synthesis of polysubstituted 4-pyridones and 2-pyridones from β-keto amides. A variety of β-keto amides are used in this approach, and a wide range of functionalized 4-pyridones and 2-pyridones were obtained in good to excellent yields. When employing the N-aryl β-keto amides as the substrates in this protocol, 4-pyridones are resulted, however, when using N-aliphatic-substituted β-keto amides as the partners of N-aryl β-keto amides under the same conditions, 2-pyridones are afforded.

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.

Two new drimane sesquiterpenoids from cultures of the basidiomycete Trichaptum biforme

Two new drimane sesquiterpenoids (1 and 2), as well as five known compounds (3–7), were isolated from the basidiomycete Trichaptum biforme. The structures of new compounds were elucidated by extensive spectroscopic methods, and the known compounds were identified by comparing their spectroscopic data with those reported in the literature. The cytotoxicities results against five human cancer cell lines of compounds 1 and 2 were negligible.

Four new sesquiterpenoids from cultures of the fungus Funalia trogii

Four new drimane sesquiterpenoids, named as funatrols A-D, together with isodrimenediol, were isolated from cultures of the fungus Funalia trogii. The new structures were elucidated by means of spectroscopic methods. All compounds were tested for their cytotoxicities against five human cancer cell lines.

Five new 5,6-seco-tremulane sesquiterpenoids from the basidiomycete Conocybe siliginea

Five new 5,6-seco-tremulane sesquiterpenoids (1–5), as well as three known analogues (6–8), were isolated from the basidiomycete Conocybe siliginea. The structures of new compounds were elucidated by extensive spectroscopic methods. The known compounds were identified by comparing their spectroscopic data with those reported in the literature.

Two new triterpenoids from the fungus Perenniporia maackiae

Two new triterpenoids, 3β-(2-methoxy-oxalyloxy)-24-methylene-lanost-8-en-21-oic acid (1) and 3β-(2-methoxy-oxalyloxy)-15α-hydroxy-24-methylene-lanost-8-en-21-oic acid (2), were isolated from cultures of the fungus Perenniporia maackiae, together with two previously known triterpenoids (3 and 4). Their structures were determined by spectroscopic methods, including 1D and 2D NMR, and MS analyses. All compounds were evaluated for their cytotoxic activities on five tumor cell lines.

N-containing compounds of macromycetes

This review surveys the chemical, biological, and mycological literature dealing with the isolation, structural elucidation, biological activities, and synthesis of nitrogen-containing compounds from the fruiting bodies or the culture broths of macromycetes.

Two new chamigrane metabolites from fermentation broth of Steccherinum ochraceum

Two new chamigrane-type metabolites named steperoxides C (1) and D (2) were isolated from the basidiomycetes Steccherinum ochraceum. The structures of 1 and 2 were established on the basis of spectral methods (MS, IR, ID and 2D NMR experiments). Compounds 2 showed significant antimicrobial activity against Staphylococcus aureus at 10 and 5 μg/disk.

A new isoprenyl phenyl ether riboside from the culture of basidiomycete Laccaria amethystea

A new isoprenyl phenyl ether riboside, 3-(3-methylbut-2-enyloxy)-4-O-alpha-D-ribofuranose benzoic acid methyl ester (1), was isolated from the culture of basidiomycete Laccaria amethystea. The structure of 1 was elucidated on the basis of extensive spectroscopic analysis.

Two new sesquiterpenoids from basidiomycete Agrocybe salicacola

Two new aromadendrane-type sesquiterpenoids (1 and 2), together with a known aromadendrane sesquiterpenoid (3), were isolated from the culture of basidiomycete Agrocybe salicacola. The structures and relative configurations of the new compounds were determined by spectroscopic methods and single-crystal X-ray crystallographic analysis.

Toxicity of Non-protein Amino Acids to Humans and Domestic Animals

Non-protein amino acids are common in plants and are present in widely consumed animal feeds and human foods such as alfalfa ( Medicago sativa), which contains canavanine, and lentil ( Lens culinaris), which contains homoarginine. Some occur in wild species that are inadvertently harvested with crop species. Some nonprotein amino acids and metabolites can be toxic to humans, e.g. Lathyrus species contain a neurotoxic oxalyl-amino acid. Some potential toxins may be passed along a food chain via animal intermediates. The increased interest in herbal medicines in the Western countries will increase exposure to such compounds.