Clavaric acid: a triterpenoid inhibitor of farnesyl-protein transferase from Clavariadelphus truncatus

Characterization of Polysaccharide Extracts of Four Edible Mushrooms and Determination of In Vitro Antioxidant, Enzyme Inhibition and Anticancer Activities

Mushroom polysaccharides are important bioactive compounds derived from mushrooms with various beneficial properties. In this study, the chemical characterization and bioactivities of polysaccharide extracts from four different edible mushrooms, Clavariadelphus truncatus Donk, Craterellus tubaeformis (Fr.) Quél., Hygrophorus pudorinus (Fr.) Fr., and Macrolepiota procera (Scop.) Singer were studied. Glucose (13.24-56.02%), galactose (14.18-64.05%), mannose (2.18-18.13%), fucose (1.21-5.78%), and arabinose (0.04-5.43%) were identified in all polysaccharide extracts by GC-MS (gas chromatography-mass spectrometry). FT-IR (Fourier transform infrared spectroscopy) confirmed the presence of characteristic carbohydrate patterns. 1H NMR suggested that all polysaccharide extracts had α- and β-d-mannopyranose, d-glucopyranose, d-galactopyranose, α-l-arabinofuranose, and α-l-fucopyranose residues. Approximate molecular weights of polysaccharide extracts were determined by HPLC (high-performance liquid chromatography). The best antioxidant activity was found in M. procera polysaccharide extract in DPPH• (1,1-diphenyl-2-picrylhydrazyl) scavenging (39.03% at 800 μg/mL), CUPRAC (cupric reducing antioxidant capacity) (A0.50: 387.50 μg/mL), and PRAP (phosphomolybdenum reducing antioxidant power) (A0.50: 384.08 μg/mL) assays. C. truncatus polysaccharide extract showed the highest antioxidant activity in ABTS•+ scavenging (IC50: 734.09 μg/mL), β-carotene-linoleic acid (IC50: 472.16 μg/mL), and iron chelating (IC50: 180.35 μg/mL) assays. Significant anticancer activity was found in C. truncatus polysaccharide extract on HT-29 (IC50: 46.49 μg/mL) and HepG2 (IC50: 48.50 μg/mL) cell lines and H. pudorinus polysaccharide extract on the HeLa cell line (IC50: 51.64 μg/mL). Also, H. pudorinus polysaccharide extract possessed prominent AChE (acetylcholinesterase) inhibition activity (49.14% at 200 μg/mL).

New autophagy-modulating lanostane-type triterpenoids from a hallucinogenic poisonous mushroom Gymnopilus orientispectabilis

Gymnopilus orientispectabilis, also known as "big laughter mushroom," is a hallucinogenic poisonous mushroom that causes excessive laughter upon ingestion. From the fruiting bodies of G. orientispectabilis, eight lanostane-type triterpenoids (1-8), including seven novel compounds: gymnojunols A-G (2-8), were isolated. The chemical structures of these new compounds (2-8) were determined by analyzing their 1D and 2D NMR spectra and HR-EISMS, and their absolute configurations were unambiguously assigned by quantum chemical ECD calculations and a computational method coupled with a statistical procedure (DP4+). Upon evaluating autophagic activity, compounds 2, 6, and 7 increased LC3B-II levels in HeLa cells to a similar extent as bafilomycin, an autophagy inhibitor. In contrast, compound 8 decreased the levels of both LC3B-I and LC3B-II, and a similar effect was observed following treatment with rapamycin, an autophagy inducer. Our findings provide experimental evidence for new potential autophagy modulators in the hallucinogenic poisonous mushroom G. orientispectabilis.

Telomere-to-Telomere Genome Assembly of Tibetan Medicinal Mushroom Ganoderma leucocontextum and the First Copia Centromeric Retrotransposon in Macro-Fungi Genome

A complete telomere-to-telomere (T2T) genome has been a longstanding goal in the field of genomic research. By integrating high-coverage and precise long-read sequencing data using multiple assembly strategies, we present here the first T2T gap-free genome assembly of Ganoderma leucocontextum strain GL72, a Tibetan medicinal mushroom. The T2T genome, with a size of 46.69 Mb, consists 13 complete nuclear chromosomes and typical telomeric repeats (CCCTAA)n were detected at both ends of 13 chromosomes. The high mapping rate, uniform genome coverage, a complete BUSCOs of 99.7%, and base accuracy exceeding 99.999% indicate that this assembly represents the highest level of completeness and quality. Regions characterized by distinct structural attributes, including highest Hi-C interaction intensity, high repeat content, decreased gene density, low GC content, and minimal or no transcription levels across all chromosomes may represent potential centromeres. Sequence analysis revealed the first Copia centromeric retrotransposon in macro-fungi genome. Phylogenomic analysis identified that G. leucocontextum and G. tsugae diverged from the other Ganoderma species approximately 9.8-17.9 MYA. The prediction of secondary metabolic clusters confirmed the capability of this fungus to produce a substantial quantity of metabolites. This T2T gap-free genome will contribute to the genomic 'dark matter' elucidation and server as a great reference for genetics, genomics, and evolutionary studies of G. leucocontextum.

Unraveling the Polysaccharide Biosynthesis Potential of Ganoderma lucidum: A Chromosome-Level Assembly Using Hi-C Sequencing

Ganoderma lucidum exhibits the ability to synthesize a diverse range of biologically active molecules with significant pharmaceutical potential, including xylomannan and fucogalactan, which have demonstrated antitumor activity. However, there exists considerable intra-species variability in the capacity to produce these metabolites at high concentrations, likely reflecting the high genomic diversity observed from a limited number of strains sequenced to date. We employed high-throughput shotgun sequencing to obtain the complete genome sequence of G. lucidum strain 5.1, which is distinguished by its remarkable xylomannan synthesis capabilities. Through the utilization of semi-automatic reordering based on conformation capture (Hi-C) data, we substantially enhanced the assembly process, resulting in the generation of 12 chromosome-level scaffolds with a cumulative length of 39 Mbp. By employing both de novo and homology-based approaches, we performed comprehensive annotation of the genome, thereby identifying a diverse repertoire of genes likely involved in polysaccharide biosynthesis. The genome sequence generated in this study serves as a valuable resource for elucidating the molecular mechanisms underlying the medicinal potential of Ganoderma species, discovering novel pharmaceutically valuable compounds, and elucidating the ecological mechanisms of the species. Furthermore, the chromosome contact map obtained for the first time for this species extends our understanding of 3D fungal genomics and provides insights into the functional and structural organization within the fungal kingdom.

Identification of Virulence Factors in Entomopathogenic Aspergillus flavus Isolated from Naturally Infected Rhipicephalus microplus

Aspergillus flavus has been found to be an effective entomopathogenic fungus for various arthropods, including ticks. In particular, natural fungal infections in cattle ticks show promise for biocontrol of the Rhipicephalus (Boophilus) microplus tick, which is a major ectoparasite affecting cattle worldwide. Our study aimed to elucidate the specific entomopathogenic virulence factors encoded in the genome of an A. flavus strain isolated from naturally infected cattle ticks. We performed morphological and biochemical phenotyping alongside complete genome sequencing, which revealed that the isolated fungus was A. flavus related to the L morphotype, capable of producing a range of gene-coded entomopathogenic virulence factors, including ribotoxin, aflatoxin, kojic acid, chitinases, killer toxin, and satratoxin. To evaluate the efficacy of this A. flavus strain against ticks, we conducted experimental bioassays using healthy engorged female ticks. A morbidity rate of 90% was observed, starting at a concentration of 105 conidia/mL. At a concentration of 107 conidia/mL, we observed a 50% mortality rate and a 21.5% inhibition of oviposition. The highest levels of hatch inhibition (30.8%) and estimated reproduction inhibition (34.64%) were achieved at a concentration of 108 conidia/mL. Furthermore, the tick larval progeny that hatched from the infected tick egg masses showed evident symptoms of Aspergillus infection after incubation.

Potential of Secondary Metabolites of Diaporthe Species Associated with Terrestrial and Marine Origins

Diaporthe species produce versatile secondary metabolites (SMs), including terpenoids, fatty acids, polyketides, steroids, and alkaloids. These structurally diverse SMs exhibit a wide range of biological activities, including cytotoxic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, and phytotoxic activities, which could be exploited in the medical, agricultural, and other modern industries. This review comprehensively covers the production and biological potencies of isolated natural products from the genus Diaporthe associated with terrestrial and marine origins. A total of 275 SMs have been summarized from terrestrial (153; 55%) and marine (110; 41%) origins during the last twelve years, and 12 (4%) compounds are common to both environments. All secondary metabolites are categorized predominantly on the basis of their bioactivities (cytotoxic, antibacterial, antifungal, and miscellaneous activity). Overall, 134 bioactive compounds were isolated from terrestrial (92; 55%) and marine (42; 34%) origins, but about half the compounds did not report any kind of activity. The antiSMASH results suggested that Diaporthe strains are capable of encoding a wide range of SMs and have tremendous biosynthetic potential for new SMs. This study will be useful for future research on drug discovery from terrestrial and marine natural products.

Pholiols E-K, lanostane-type triterpenes from Pholiota populnea with anti-inflammatory properties

Investigation of the chloroform and ethyl acetate extracts of the edible mushroom Pholiota populnea led to the isolation of eight triterpenes, the undescribed natural products pholiols E-K and the known (+)-clavaric acid. HRESIMS and 1D and 2D NMR spectroscopy were employed to determine the structures of the undescribed compounds. The NOESY spectra were used to assign the relative configurations of triterpenes. The isolated compounds were screened for their anti-inflammatory activity on cyclooxygenase (COX-1 and COX-2), and lipoxygenase (5-LOX and 15-LOX) inhibitory assays. Dose-response investigations revealed that lanostane derivatives exhibited moderate 5-LOX and COX-2 inhibitory activities, with pholiol F (IC₅₀ 194.5 μM against 5-LOX and 439.8 μM against COX-2) the most active among the isolated compounds. Our findings indicated that P. populnea is an abundant source of new bioactive lanostane-type triterpenes.

The First Telomere-to-Telomere Chromosome-Level Genome Assembly of Stagonospora tainanensis Causing Sugarcane Leaf Blight

The sexual morph Leptosphaeria taiwanensis Yen and Chi and its asexual morph Stagonospora tainanensis W. H. Hsieh is an important necrotrophic fungal phytopathogen, which causes sugarcane leaf blight, resulting in loss of cane tonnage and sucrose in susceptible sugarcane varieties. Decoding the genome and understanding of the basis of virulence is vitally important for devising effective disease control strategies. Here, we present a 38.25-Mb high-quality genome assembly of S. tainanensis strain StFZ01, denovo assembled with 10.19 Gb Nanopore sequencing long reads (~267×) and 3.82 Gb Illumina short reads (~100×). The genome assembly consists of 12 contigs with N50 of 2.86 Mb of which 5 belong to the telomere to telomere (T2T) chromosome. It contains 13.20% repeat sequences, 12,543 proteins, and 12,206 protein-coding genes with the BUSCO completeness 99.18% at fungi (n = 758) and 99.87% at ascomycota (n = 1706), indicating the high accuracy and completeness of our gene annotations. The virulence analysis in silico revealed the presence of 2379 PHIs, 599 CAZys, 248 membrane transport proteins, 191 cytochrome P450 enzymes, 609 putative secreted proteins, and 333 effectors in the StFZ01 genome. The genomic resources presented here will not only be helpful for development of specific molecular marker and diagnosis technique, population genetics, molecular taxonomy, and disease managements, it can also provide a significant precise genomic reference for investigating the ascomycetous genome, the necrotrophic lifestyle, and pathogenicity in the future.

Bioprospecting Trichoderma: A Systematic Roadmap to Screen Genomes and Natural Products for Biocontrol Applications

Natural products derived from microbes are crucial innovations that would help in reaching sustainability development goals worldwide while achieving bioeconomic growth. Trichoderma species are well-studied model fungal organisms used for their biocontrol properties with great potential to alleviate the use of agrochemicals in agriculture. However, identifying and characterizing effective natural products in novel species or strains as biological control products remains a meticulous process with many known challenges to be navigated. Integration of recent advancements in various "omics" technologies, next generation biodesign, machine learning, and artificial intelligence approaches could greatly advance bioprospecting goals. Herein, we propose a roadmap for assessing the potential impact of already known or newly discovered Trichoderma species for biocontrol applications. By screening publicly available Trichoderma genome sequences, we first highlight the prevalence of putative biosynthetic gene clusters and antimicrobial peptides among genomes as an initial step toward predicting which organisms could increase the diversity of natural products. Next, we discuss high-throughput methods for screening organisms to discover and characterize natural products and how these findings impact both fundamental and applied research fields.

13C nuclear magnetic resonance data of lanosterol derivatives--profiling the steric topology of the steroid skeleton via substituent effects on its 13C NMR

The (13)C NMR spectra of over 24 tetracyclic triterpenoid derivatives have been structurally analyzed. The (13)C NMR chemical shifts allow one to probe the steric topology of the rigid steroid skeleton and inductive effects of its substituents. Use of deuterium labeling in chemical shift assignment and B-ring aromatic terpenoids are also featured.

Search for Protein Farnesyltransferase Inhibitors of Microbial Origin: Our Strategy and Results as well as the Results Obtained by Other Groups

Mutant ras oncogenes are associated with various human tumors, being found in approximately 25% of all human cancers. Since its identification, the enzyme Ras protein farnesyltransferase (PFTase), which catalyzes the initial step of Ras-processing, has been viewed as a most promising target for cancer therapy. Consequently, a number of synthetic and natural small molecules have been searched and developed according to this concept during the 1990s. Among these, microbial metabolites have provided diverse structural classes of compounds which exhibit PFTase inhibitory activity. This article reviews our work on PFTase inhibitors originating from microbial metabolites, and the results of similar works carried out by several other research groups.

Synthetic Studies toward Highly Functionalized 5β-Lanosterol Derivatives: A Versatile Approach Utilizing Anionic Cycloaddition

Stereoselective synthesis of the potentially biologically valuable 5beta-lanosteroidal-type backbone was achieved via anionic cycloaddition. Synthesis of the two new bicyclic Nazarov intermediates 14 and 40 and their cycloaddition with chiral cyclohexenone 25 and further functional group manipulations resulted in highly functionalized tetracyclic intermediates 28 and 44. These synthetic intermediates could lead to the total synthesis of new lanosterol-based inhibitors.

New fungal metabolite geranylgeranyltransferase inhibitors with antifungal activity

Geranylgeranyltransferase I (GGTase I) catalyzes the post-translational transfer of lyophilic diterpenoid geranylgeranyl to the cysteine residue of proteins terminating with a CaaX motif such as Rho1p and Cdc42p. It has been shown that GGTase I activity is essential for viability of Saccharomyces cerevisiae and hence its inhibition is a potential antifungal target. From natural product screening, a number of azaphilones including one novel analog were isolated as broad-spectrum inhibitors of GGTase I. Isolation, structure elucidation, GGTase I inhibitory activities and antifungal activities of these compounds are described.

Agrobacterium tumefaciens-mediated transformation of the antitumor clavaric acid-producing basidiomycete Hypholoma sublateritium

The basidiomycete Hypholoma sublateritium produces clavaric acid, an antitumor isoprenoid compound. Arthrospores of this fungus were transformed by Agrobacterium tumefaciens-mediated conjugation. Five plasmids carrying different regulatory sequences to drive expression of the hph (hygromycin phosphotransferase) gene were tested. The promoter used was critically important in order to express heterologous genes in H. sublateritium. Constructions carrying the Agaricus bisporus glyceraldehyde-3-phosphate dehydrogenase promoter (P gpd) showed a good transformation efficiency, whereas constructions with the gpd promoter from ascomycetes were ineffective. Transformant clones showed a random integration pattern of plasmid DNA. Most transformants showed a single integrated copy of the transforming plasmid, but about 1.5% showed double or multiple integrations. All the analyzed transformants were mitotically stable and maintained the integrated exogenous DNA in the absence of antibiotic. The green fluorescent protein gene was expressed from the A. bisporus gpd promoter, as shown by RT-PCR studies, but no significant fluorescence was observed. Transformation of H. sublateritium opens the way for the genetic manipulation of clavaric acid biosynthesis in this fungus.

Chemistry and structure-activity relationship of HIV-1 integrase inhibitor integracide B and related natural products

Integracides, 4,4-dimethylergostane triterpenoids, are inhibitors of HIV-1 integrase, a critical enzyme in replication of HIV-1. The chemistry and structure-activity relationship of integracide B and related natural products are described. A charged group, e.g., a sulfate, carboxyl, or amino, is required for the HIV-1 integrase activity. These compounds showed HIV-1 integrase activity with IC(50) values in the range 4.8-15 muM and exhibited antiviral activity in a viral spread assay, but with only a small or no therapeutic window.

Modeling of binding modes and inhibition mechanism of some natural ligands of farnesyl transferase using molecular docking

Several natural inhibitors of farnesyl transferase have been reported in the literature: some compounds are competitive with farnesyl pyrophosphate (FPP), whereas other ones are competitive with Ras proteins, even though it is usually hard to highlight their inhibition mechanism, which is still unknown for several natural compounds. The aim of this work is to show that the molecular docking analysis can be successfully used to underline the inhibition mechanism of these natural compounds. First, the selected compounds were subjected to a detailed docking analysis, by means of BioDock, a program able to reveal the most likely binding mode for each ligand. By comparing these results with the binding sites for the natural substrates, earlier determined, it was possible to highlight the site specificity and the inhibition mechanism of the selected compounds. In addition, it is possible to relate the binding mode of these molecules with their lipole values, which is appreciably less for peptidomimetics than for FPP mimetic and reveals a straightforward method to predict and to understand the inhibition mechanism of these natural derivatives.