Biologically Active Secondary Metabolites from the Fungi

Studies on the epipolythiodioxopiperazine alkaloid verticillin D: Scaled production, streamlined purification, and absolute configuration

Verticillins, epipolythiodioxopiperazine alkaloids that were first described over 50 years ago, have undergone extensive cytotoxic and pharmacological evaluations over the last decade. However, of the 27 verticillin analogues in the literature, the chemistry of verticillin D, which has two additional secondary hydroxy moieties, relative to verticillin A, has remained largely unexplored since its discovery in 1999. With the goal of advancing our understanding of verticillin D, there were three main objectives with this study: improving production, streamlining purification, and assigning absolute configuration via X-ray crystallography. To begin, the production of verticillin D was analyzed across seven fungal strains, and the top producer was further assessed under two fermentation conditions. Clonostachys rosea (strain MSX51257) biosynthesized the highest amount of verticillin D, with production peaking between 15 and 25 days on rice media. Interestingly, in contrast to similar studies that yield verticillin A, the biosynthesis of verticillin D was not accompanied by a suite of structurally related verticillin analogues. As such, the purification of verticillin D was more rapid and could be accomplished without the use of HPLC. These materials were used, in part, to determine the absolute configuration of verticillin D via X-ray crystallography, allowing for assignment of the asymmetric centers at both the 13 and 13' positions as R, which has never been accomplished. This is only the third report of an X-ray structure of a verticillin analogue.

Bioinformatics assisted construction of the link between biosynthetic gene clusters and secondary metabolites in fungi

Fungal secondary metabolites are considered as important resources for drug discovery. Despite various methods being employed to facilitate the discovery of new fungal secondary metabolites, the trend of identifying novel secondary metabolites from fungi is inevitably slowing down. Under laboratory conditions, the majority of biosynthetic gene clusters, which store information for secondary metabolites, remain inactive. Therefore, establishing the link between biosynthetic gene clusters and secondary metabolites would contribute to understanding the genetic logic underlying secondary metabolite biosynthesis and alleviating the current challenges in discovering novel natural products. Bioinformatics methods have garnered significant attention due to their powerful capabilities in data mining and analysis, playing a crucial role in various aspects. Thus, we have summarized successful cases since 2016 in which bioinformatics methods were utilized to establish the link between fungal biosynthetic gene clusters and secondary metabolites, focusing on their biosynthetic gene clusters and associated secondary metabolites, with the goal of aiding the field of natural product discovery.

New natural products from Aspergillus candidus NRRL 5214 and their glycosylation by Streptomyces chromofuscus ATCC 49982

Fungi represent a rich source of bioactive natural products. In this study, we present the isolation and identification of two new diphenyl ethers, named aspergilluscandidus A (1) and aspergilluscandidus B (2), along with a known compound terphenyllin (3), from the fungal strain Aspergillus candidus NRRL 5214. The chemical structures of compounds 1-3 were characterized through extensive 1D and 2D NMR analysis. Compounds 1 and 3 were subsequently biotransformed into two new glycosides, namely aspergilluscandidus C (4) and terphenyllin-4″-O-β-d-glucuronide (5) by the actinomycete strain Streptomyces chromofuscus ATCC 49982. The cytotoxicity assay revealed that the glycosylated products 4 and 5 exhibited significantly improved activity against the glioblastoma 33 cell line compared to their respective substrates, decreasing the IC50 from 8.15 ± 1.09 μM (1) to 5.41 ± 0.30 μM (4) and from 88.29 ± 10.54 μM (3) to 31.25 ± 4.20 μM (5), respectively. Our study emphasizes A. candidus NRRL 5214 as a promising source of new natural products and presents an effective strategy for modifying both diphenyl ether and p-terphenyl compounds using S. chromofuscus ATCC 49982 to enhance their cytotoxicity activity.

An Update of Fungal Endophyte Diversity and Strategies for Augmenting Therapeutic Potential of their Potent Metabolites: Recent Advancement

Endophytic fungi represent a significant renewable resource for the discovery of pharmaceutically important compounds, offering substantial potential for new drug development. Their ability to address the growing issue of drug resistance has drawn attention from researchers seeking novel, nature-derived lead molecules that can be produced on a large scale to meet global demand. Recent advancements in genomics, metabolomics, bioinformatics, and improved cultivation techniques have significantly aided the identification and characterization of fungal endophytes and their metabolites. Current estimates suggest there are approximately 1.20 million fungal endophytes globally, yet only around 16% (190,000) have been identified and studied in detail. This underscores the vast untapped potential of fungal endophytes in pharmaceutical research. Research has increasingly focused on the transformation of bioactive compounds by fungal endophytes through chemical and enzymatic processes. A notable example is the anthraquinone derivative 6-O-methylalaternin, whose cytotoxic potential is enhanced by the addition of a hydroxyl group, sharing structural similarities with its parent compound macrosporin. These structure-bioactivity studies open up new avenues for developing safer and more effective therapeutic agents by synthesizing targeted derivatives. Despite the immense promise, challenges remain, particularly in the large-scale cultivation of fungal endophytes and in understanding the complexities of their biosynthetic pathways. Additionally, the genetic manipulation of endophytes for optimized metabolite production is still in its infancy. Future research should aim to overcome these limitations by focusing on more efficient cultivation methods and deeper exploration of fungal endophytes' genetic and metabolic capabilities to fully harness their therapeutic potential.

Bikaverin as a molecular weapon: enhancing Fusarium oxysporum pathogenicity in bananas via rhizosphere microbiome manipulation

BACKGROUND

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), poses a severe threat to global banana production. Secondary metabolites are critical tools employed by pathogens to interact with their environment and modulate host-pathogen dynamics. Bikaverin, a red-colored polyketide pigment produced by several Fusarium species, has been studied for its pharmacological properties, but its ecological roles and impact on pathogenicity remain unclear.

RESULTS

This study investigated the role of bikaverin in Foc TR4, focusing on its contribution to pathogenicity and its interaction with the rhizosphere microbiome. Pathogenicity assays under sterile and autoclaved conditions demonstrated that bikaverin does not directly contribute to pathogenicity by affecting the infection process or damaging host tissues. Instead, bikaverin indirectly enhances Foc TR4's pathogenicity by reshaping the rhizosphere microbiome. It suppresses beneficial plant growth-promoting rhizobacteria, such as Bacillus, while promoting the dominance of fungal genera, thereby creating a microbial environment beneficial for pathogen colonization and infection. Notably, bikaverin biosynthesis was found to be tightly regulated by environmental cues, including acidic pH, nitrogen scarcity, and microbial competition. Co-culture with microbes such as Bacillus velezensis and Botrytis cinerea strongly induced bikaverin production and upregulated expression of the key bikaverin biosynthetic gene FocBik1. In addition, the identification of bikaverin-resistant Bacillus BR160, a strain with broad-spectrum antifungal activity, highlights its potential as a biocontrol agent for banana wilt management, although its stability and efficiency under field conditions require further validation.

CONCLUSIONS

Bikaverin plays an indirect yet important role in the pathogenicity of Foc TR4 by manipulating the rhizosphere microbiome. This ecological function underscores its potential as a target for sustainable disease management strategies. Future research should focus on elucidating the molecular mechanisms underlying bikaverin-mediated microbial interactions, using integrated approaches such as transcriptomics and metabolomics. Together, these findings provide a foundation for novel approaches to combat banana wilt disease and enhance crop resistance. Video Abstract.

Transcriptome analysis of Beauveria bassiana interaction with Nicotiana benthamiana reveals signatures of N. Benthamiana growth promotion and enhanced defense responses

Many entomopathogenic fungi form intimate (epi- and endo-phytic) associations with that plant that can stimulate plant growth and /or improve resistance to pathogens and insect pests. However, little is known concerning global gene networks that mediate such responses. Nicotiana benthamiana seedlings were artificially colonized by the entomogenous fungus, Beauveria bassiana, and the root tissues were examined via comparative transcriptome analyses performed versus fungal cells grown in vitro on dried root biomass. Plant hormone pathways, and genes involved in photosynthesis, immune defense response, and nutrient metabolism were triggered in roots after fungal colonization. Fungal differentially expressed genes during plant colonization included plant cell wall-degrading enzymes, and those involved in lipid metabolism, detoxification, and fungal cell wall remodeling, the latter suggesting reduction in the exposure of pathogen related molecular patterns to avoid perception by the plant immune system. Fungal metabolic genes involved in amino acid, nitrogen, sulfur and carbohydrate assimilation were activated, nutrient exchange with the plant host. Exchange was confirmed by detection of sulfur in the seedling that was increased by the fungal colonization. A set of fungal secondary metabolism-associated genes were also upregulated during the plant interaction, which might contribute to plant resistance against pathogens or/and insect pest. In addition, B. bassiana expressed a suite of effector/elicitor genes consistent with triggering plant growth and/or immune defense response pathways. These results revealed global gene networks active in both the plants and the fungus as a consequence of their symbiotic interaction, and provides insights into the molecular determinants and physiological responses affected.

Marine Natural Products in Inflammation-Related Diseases: Opportunities and Challenges

In recent decades, the potentiality of marine natural products (MNPs) in the medical field has been increasingly recognized. Natural compounds derived from marine microorganisms, algae, and invertebrates have shown significant promise for treating inflammation-related diseases. In this review, we cover the three primary sources of MNPs and their diverse and unique chemical structures and bioactivities. This review aims to summarize the progress of MNPs in combating inflammation-related diseases. Moreover, we cover the functions and mechanisms of MNPs in diseases, highlighting their functions in regulating inflammatory signaling pathways, cellular stress responses, and gut microbiota, among others. Meanwhile, we focus on key technologies and scientific methods to address the current limitations and challenges in MNPs.

Mycochemical composition and antioxidant activity of root endophytic aquatic hyphomycetes isolated from the riparian area of Kumaun Himalaya, India

Endophytic fungi are essential sources of various bioactive natural compounds. The present study is aimed to investigate the chemical composition and antioxidant compounds of the root endophytic aquatic hyphomycetous fungi Tetracladium setigerum isolated from the roots of Barberries aristata growing in the riparian area of Nainital, Kumaun Himalaya. The chemical profiling was done by GC-MS analysis. The presence of 32 compounds characterised the fungal extract. 1, 2-Benzenedicarboxylic acid, diethyl ester; Bis(2-ethylhexyl) phthalate; and Bicyclo [3.2.1]octan-4-on-1-carbonsaeure,6-(6,10dimethyl-1,5,9-undecatrien-2-yl)-8-methyl-, ethyl ester were reported as major compounds in the ethyl acetate extract of T. setigerum. The antioxidant capacity of the extract was assessed by DPPH, MCA, and FRAP assay. In antioxidant analysis, the ethyl acetate extract of T. setigerum presents IC50, 42.34 µg/ml, and 46.90 µg/ml using DPPH and MCA, respectively. The tested extract also showed effective antioxidant activity 436.71 ± 9.3 mg AAE/g of the dry extract using FRAP assay.

Three new metabolites from the endophyte Fusarium proliferatum T2-10

One new cyclopeptide, cyclo-(L-Trp-L-Phe-L-Phe) (1), one new 2-pyridone derivative, fusarone A (3), and one new natural indole derivative, ethyl 3-indoleacetate (4), along with six known compounds were isolated from the endophytic fungus Fusarium proliferatum T2-10. The planar structures of three new compounds were identified by spectral methods including 1D and 2D NMR techniques, and the absolute configuration of compound 1 was elucidated by Marfey-MS method. In addition, all compounds were evaluated for their cytotoxic and antibacterial activities in vitro. Compound 2 showed remarkable cytotoxic activities against two human hepatoma cell lines SMMC7721 and HepG2 with IC50 values of 5.89 ± 0.74 and 6.16 ± 0.52 μM, and showed moderate antibacterial activities against Staphylococcus aureus and Enterococcus faecalis with MIC values of 7.81 and 15.62 μg/mL, respectively.

5,6-Dihydro-5,6-Epoxymultiplolide A, Cytosporone C, and Uridine Production by Diaporthe hongkongensis, an Endophytic Fungus from Minquartia guianensis

Endophytic fungi are valuable sources of bioactive secondary metabolites, with potential applications in pharmaceutical and agricultural fields. This study investigates the metabolic potential of Diaporthe hongkongensis, an endophytic fungus isolated from Minquartia guianensis. To date, no secondary metabolites have been identified from this species, highlighting the novelty of this research and its contribution to understanding the chemical diversity of endophytic fungi. The fungus was cultivated on parboiled rice under static and dark conditions for 28 days, leading to the isolation of the following three compounds: 5,6-dihydro-5,6-epoxymultiplolide A (1), cytosporone C (2), and uridine (3). Structural identification was carried out using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The results revealed the metabolic versatility of D. hongkongensis, as demonstrated by its ability to produce structurally diverse substances with biological relevance. Hence, it describes the first isolation of secondary metabolites from the endophytic fungus D. hongkongensis, marking a significant step in understanding its chemical profile. The identification of a known antifungal compound and a lactone derivative underscores the biosynthetic potential of this endophytic fungus, while the isolation of a nucleoside expands the chemical repertoire of fungal metabolites, suggesting possible roles in cellular metabolism and stress adaptation. These findings highlight the role of endophytic fungi as prolific sources of structurally diverse and potentially bioactive natural products, supporting further exploration of their biotechnological applications.

ATP deficiency triggers ganoderic acids accumulation via fatty acid β-oxidation pathway in Ganoderma lucidum

BACKGROUND

Ganoderic acids (GAs), recognized as significant triterpenoid bioactive components in Ganoderma lucidum, exhibit a broad spectrum of pharmacological activities, including immunomodulation, anti-cancer, and anti-aging properties. Despite their significant pharmacological potential, the low yield of GAs from natural sources has emerged as a critical bottleneck hindering their broader application in the pharmaceutical and health care industries. Previous studies have suggested that environmental perturbations can influence energy metabolism, potentially impacting the biosynthesis of bioactive compounds. However, the specific influence of environmental changes on energy metabolism and subsequent effects on GAs synthesis in G. lucidum remains an understudied area.

RESULTS

We demonstrated that intracellular ATP deficiency significantly influences GAs accumulation induced by alterations in energy metabolism. Intracellular ATP deficiency was consistently observed under all four known conditions that induce GAs accumulation: heat stress (HS), nitrogen limitation, treatment with 50 µM methyl jasmonate (MeJA), and treatment with 200 µM salicylic acid (SA). Consistent with these findings, silencing the ATP synthase beta subunit (ATPsyn-beta) or treating with oligomycin (Oli), an ATP synthase inhibitor, increased GAs accumulation and induced intracellular ATP deficiency in G. lucidum. Our results revealed an increase in the GAs biosynthetic pathway and increased levels of the GAs precursor acetyl-CoA in mycelia with intracellular ATP deficiency. Enhanced fatty acid β-oxidation was identified as the primary source of additional acetyl-CoA, indicating that this process, induced by intracellular ATP deficiency, is crucial for GAs accumulation.

CONCLUSIONS

This study demonstrated that changes in intracellular ATP content respond to environmental perturbations and impact the biosynthesis of GAs, holding substantial implications for production practices. Modulating ATP levels could increase GAs yields, cater to market demands, and reduce costs. The research also furnishes a scientific foundation for optimizing cultivation conditions, employing genetic engineering to refine biosynthetic pathways, and leveraging environmental control to boost production efficiency.

Fungi: Pioneers of chemical creativity - Techniques and strategies to uncover fungal chemistry

Natural product discovery from fungi for drug development and description of novel chemistry has been a tremendous success. This success is expected to accelerate even further, owing to the advent of sophisticated technical advances of technical advances that recently led to the discovery of an unparalleled biodiversity in the fungal kingdom. This review aims to give an overview on i) important secondary metabolite-derived drugs or drug leads, ii) discuss the analytical and strategic framework of how natural product discovery and drug lead identification transformed from earlier days to the present, iii) how knowledge of fungal biology and biodiversity facilitates the discovery of new compounds, and iv) point out endeavors in understanding fungal secondary metabolite chemistry in order to systematically explore fungal genomes by utilizing synthetic biology. An outlook is given, underlining the necessity for a collaborative and cooperative scenario to harness the full potential of the fungal secondary metabolome.

Mycophenolate mofetil exerts broad-spectrum antiviral activity against coronaviruses including SARS-CoV-2

BACKGROUND

New anti-coronavirus drugs are continuously being developed to address the serious long-term challenge posed by numerous SARS-CoV-2 variants. The clinical immunosuppressants mycophenolate mofetil (MMF) and mycophenolic acid (MPA) have been reported to have anti-coronavirus activities. However, systematic studies have not been conducted to evaluate their activities and mechanisms against pan-coronaviruses, including SARS-CoV-2.

METHODS

The antiviral effect of MMF and MPA was determined by qRT-PCR assay, Western blotting, and immunofluorescence assay. The IMPDH inhibition effect of MMF was determined by cellular thermal shift assay and Western blotting.

RESULTS

We showed that MMF and MPA had broad-spectrum inhibitory effect against coronavirus, including HCoV-229E, HCoV-OC43, and SARS-CoV-2 ancestral strain and its variants. In terms of characteristics, MMF acted in the early stages of viral infection and inhibited viral replication by blocking purine nucleotide synthesis through interaction with inosine-5'-monophosphate dehydrogenase (IMPDH). Therefore, the antiviral effect of MMF can be reversed by exogenous guanosine. Additionally, MMF in combination with molnupiravir, GC376 or E64d showed synergistic antiviral effects.

CONCLUSION

MMF and MPA exerted broad-spectrum anti-coronavirus effects by inhibiting IMPDH activity. MMF had a synergistic antiviral effect when combined with other drugs, showing its potential clinical antiviral applications.

3-Furoic Acid from Sea-Derived Aspergillus luchuensis Hy-6 as a Valuable Lead Compound against Plant-Parasitic Nematodes in Cucumber

Root-knot nematodes pose a significant threat to crop growth and yield, thereby impacting global food security. Here, the sea-derived Aspergillus luchuensis hy-6 was identified as a producer of 3-furoic acid by liquid chromatography-mass spectrometry. Low doses of 3-furoic acid, an acidic compound with strong nematicidal activity, can reduce the motility, lifespan, and egg hatchability of nematodes in a dose-dependent manner. Additionally, 3-furoic acid was found to affect the chemotaxis of Meloidogyne incognita toward cucumber by decreasing the root's attractive activity to the nematodes. Metabolomic analyses indicated that the functional abnormalities in lipid metabolism may represent a critical molecular mechanism underlying severe metabolic dysfunction. Importantly, a significant enhancement in control efficacy was achieved through a simple structural modification, particularly with pent-4-en-1-yl furan-3-carboxylate (A1), which was superior to that of 3-furoic acid. These findings validated the potential of 3-furoic acid as a promising lead in the development of eco-friendly nematicides.

Fungal Metabolomics: A Comprehensive Approach to Understanding Pathogenesis in Humans and Identifying Potential Therapeutics

Metabolomics has emerged as a transformative tool in the study of microbes, including pathogenic fungi, facilitating the identification of unique metabolic profiles that elucidate their pathogenic mechanisms, host interactions, and treatment resistance. This review highlights key applications of metabolomics in understanding fungal metabolites essential for human virulence, such as mycotoxins produced by various fungal species, including Aspergillus fumigatus (gliotoxin, fumagillins) and Candida species (phenylethyl alcohol, TCA cycle metabolites), and secondary metabolites that contribute to pathogenicity. It also explores the metabolic adaptations of fungi in relation to drug resistance and biofilm formation, revealing alterations in key metabolic pathways during infection, as seen in C. albicans and C. auris. Furthermore, metabolomics aids in deciphering host-pathogen interactions, showcasing how fungi like Cryptococcus neoformans and Candida modify host metabolism to promote survival and evade immune responses. The study of antifungal resistance mechanisms has also benefited from metabolomic approaches, identifying specific metabolite patterns that signify resistance, such as in Candida albicans and Candidozyma (Candida) auris, and informing new therapeutic strategies. The integration of metabolomics with other omics technologies is paving the way for a comprehensive understanding of fungal biology and pathogenesis. Such multi-omics approaches are crucial for discovering new therapeutic targets and developing innovative antifungal treatments. Thus, the purpose of this review is to provide an overview of how metabolomics is revolutionizing our understanding of fungal pathogenesis, drug resistance, and host interactions, and to highlight its potential for identifying new therapeutic targets and improving antifungal strategies.

Chemical constituents from marine medicinal brown alga-derived Scytalidium lignicola SC228

In this study, a marine medicinal brown alga Sargassum cristaefolium-derived fungal strain Scytalidium lignicola SC228 has been isolated and identified. Column chromatography of the extracts from liquid-fermented products of the fungal strain was carried out, and led to the purification of eight compounds. Their structures were characterized by spectroscopic analysis, and the absolute configurations were further established by single X-ray diffraction analysis and modified Mosher's method as four previously undescribed compounds, namely scytabenzofurans A-C (1-3), and (3S,4S)-5-chloro-3,4-dihydro-4,6,8-trihydroxy-3-methyl-1H-2-benzopyran-1-one (4), along with four known compounds 5-8. All the isolates were subjected to anti-inflammatory and anti-angiogenic assays. Compounds 1-4, 7, and 8 showed moderate nitric oxide production inhibitory activities in lipopolysaccharide-activated BV-2 microglial cells with IC50 in the range of 19.6 ± 0.1 to 49.0 ± 1.2 μM in comparison with that of curcumin (IC50 = 2.7 ± 0.3 μM). Compounds 5-7 exhibited moderate to potent inhibitory effects on EPCs growth with IC50 in the range of 0.5 ± 0.1 to 42.7 ± 0.9 μM as compared to sorafenib (IC50 = 5.50 ± 1.50 μM).

Efficacy of Trichoderma longibrachiatum SC5 Fermentation Filtrate in Inhibiting the Sclerotinia sclerotiorum Growth and Development in Sunflower

Sclerotinia sclerotiorum is a destructive pathogen responsible for sunflower sclerotinia rot, resulting in substantial yield and economic losses worldwide. Trichoderma species have demonstrated the capacity to inhibit plant pathogen growth through the production of secondary metabolites. However, there are fewer recent studies focusing on the application of Trichoderma metabolites in inhibiting S. sclerotiorum growth and development and controlling sunflower sclerotinia rot disease. Our results showed that five Trichoderma strains (SC5, T6, TN, P6, and TS3) exhibited mycelial growth inhibition higher than 60% in dual culture assays out of the 11 tested strains. The Trichoderma SC5 fermentation filtrate exhibited superior efficacy compared to other strains, achieving a 94.65% inhibition rate of mycelial growth on S. sclerotiorum, 96% inhibition of myceliogenic germination of sclerotia, and 81.05% reduction in the oxalic acid content of S. sclerotiorum, while significantly increasing the cell membrane permeability. In addition, the Trichoderma SC5 fermentation filtrate significantly decreased the activities of polygalacturonase and pectin methyl-galacturonic enzymes and even caused S. sclerotiorum hyphae to swell, branch, twist, lyse, and inhibited the production and development of sclerotia. Moreover, the Trichoderma SC5 fermentation filtrate downregulated genes expression that associated with the growth and infection of S. sclerotiorum. The control efficacies of the protective and curative activities of the Trichoderma SC5 fermentation filtrate were 95.45% and 75.36%, respectively, on detached sunflower leaves at a concentration of 8 mg/mL. Finally, the Trichoderma SC5 was identified as Trichoderma longibrachiatum through morphological and phylogenetic analysis. Our research indicates that the T. longibrachiatum SC5 can be considered a promising biological control candidate against S. sclerotiorum and controlling the sunflower sclerotinia rot disease, both in vitro and in vivo.

Modifications of Prenyl Side Chains in Natural Product Biosynthesis

In recent years, there has been a growing interest in understanding the enzymatic machinery responsible for the modifications of prenyl side chains and elucidating their roles in natural product biosynthesis. This interest stems from the pivotal role such modifications play in shaping the structural and functional diversity of natural products, as well as from their potential applications to synthetic biology and drug discovery. In addition to contributing to the diversity and complexity of natural products, unique modifications of prenyl side chains are represented by several novel biosynthetic mechanisms. Representative unique examples of epoxidation, dehydrogenation, oxidation of methyl groups to carboxyl groups, unusual C-C bond cleavage and oxidative cyclization are summarized and discussed. By revealing the intriguing chemistry and enzymology behind these transformations, this comprehensive and comparative review will guide future efforts in the discovery, characterization and application of modifications of prenyl side chains in natural product biosynthesis.

Characterization of a New Insecticidal Benzothiazole Derivative from Aspergillus sp. 1022LEF against the Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

The fall armyworm Spodoptera frugiperda is considered one of the most destructive crop pests, posing a significant threat to food and crop security. In this study, we conducted a chemical investigation of the endophytic fungus Aspergillus sp. 1022LEF, leading to the identification of a previously unreported benzothiazole derivative, 6-(2-hydroxyethyl)benzo[d]thiazol-4-ol (HBT). Its structure was unambiguously characterized using extensive spectroscopic methods, including 1D and 2D NMR data, HRESIMS data, and single-crystal X-ray diffraction analysis. The insecticidal assay revealed that HBT possessed remarkable activity against S. frugiperda with an LC50 value of 0.24 mg/mL. Further transcriptomic and proteomic analyses revealed that HBT induced mortality in S. frugiperda by impeding DNA replication and protein synthesis, influencing mitochondria-mediated autophagy, and perturbing hormone synthesis, thereby disrupting the fundamental biosynthetic processes. HBT demonstrated high activity in controlling S. frugiperda, which highlighted its potential use as a lead in the development of biopesticides.

Filamentous fungi as emerging cell factories for the production of aromatic compounds

Microbial production of aromatic compounds from renewable feedstocks has gained increasing interest as a means towards sustainable production of chemicals. The potential of filamentous fungi for production of aromatic compounds has nonetheless not yet been widely exploited. Notably, many filamentous fungi can naturally break down lignin and metabolize lignin-derived aromatic compounds. A few examples where a fungal cell factory, often of Aspergillus spp., is used to produce an aromatic compound, typically through the conversion of one compound to another, have already been reported. In this review, we summarize fungal biosynthesis of biotechnologically interesting aromatic compounds. The focus is on compounds produced from the shikimate pathway. Biorefinery-relevant efforts for valorizing residual biomass or lignin derived compounds are also discussed. The advancement in engineering tools combined with the increasing amounts of data supporting the discovery of new enzymes and development of new bioprocesses has led to an increased range of potential production hosts and products. This is expected to translate into a wider utilization of fungal cell factories for production of aromatic compounds.

Revealing the metabolic potential and environmental adaptation of nematophagous fungus, Purpureocillium lilacinum, derived from hadal sediment

The extreme environment shapes fungi in deep-sea sediments with novel metabolic capabilities. The ubiquity of fungi in deep-sea habitats supports their significant roles in these ecosystems. However, there is limited research on the metabolic activities and adaptive mechanisms of filamentous fungi in deep-sea ecosystems. In this study, we investigated the biological activities, including antibacterial, antitumor and nematicidal activity of Purpureocillium lilacinum FDZ8Y1, isolated from sediments of the Mariana Trench. A key feature of P. lilacinum FDZ8Y1 was its tolerance to high hydrostatic pressure (HHP), up to 110 MPa. We showed that HHP affected its vegetative growth, development, and production of secondary metabolites, indicating the potential for discovering novel natural products from hadal fungi. Whole-genome sequencing of P. lilacinum FDZ8Y1 revealed the metabolic potential of this piezotolerant fungus in carbon (carbohydrate metabolism), nitrogen (assimilatory nitrate reduction and protein degradation) and sulfur cycling processes (assimilatory sulfate reduction). Transcriptomic analysis under elevated HHP showed that P. lilacinum FDZ8Y1 may activate several metabolic pathways and stress proteins to cope with HHP, including fatty acid metabolism, the antioxidant defense system, the biosynthetic pathway for secondary metabolites, extracellular enzymes and membrane transporters. This study provides valuable insights into the metabolic potential and adaptation mechanisms of hadal fungi to the challenging conditions of the hadal environment.

Structurally diverse indole alkaloids with cytotoxicity from Lonicera Japonica-associated endophytic fungus Penicillium ochrochloron YT2022-65

Natural products, especially fungal secondary metabolites, have been served as valuable sources of drug leads in pharmaceutical industry. Medicinal plants-associated endophytic fungi possess a well-developed secondary metabolism. In this study, chemical investigation on Penicillium ochrochloron YT2022-65, an endophytic fungus associated with Lonicera Japonica, led to the isolation of six structurally diversified indole alkaloids, including a new one, namely peniochroloid A (1), as well as five previously reported alkaloids, flavonoid B (2), brocaeloid C (3), isoroquefortine C (4), roquefortine C (5), and dihydrocarneamide A (6). Their structures, including the absolute configuration of 1, were determined by a combined analysis of HRESIMS, NMR spectroscopic data, and calculation of the optical rotation. Their cytotoxicity against A549, HepG2, MCF-7, and THP-1 cell lines were evaluated in vitro. The new compound 1 was found to possess considerable cytotoxicity against MCF-7 and THP-1 cell lines with IC50 values of 10.2 and 11.0 μM, respectively.

Antibacterial and Antifungal Activity of Metabolites from Basidiomycetes: A Review

Background/Objectives: The search for new antimicrobial molecules is important to expand the range of available drugs, as well as to overcome the drug resistance of pathogens. One of the promising sources of antibacterial and antifungal metabolites is basidial fungi, which have wide biosynthetic capabilities. Methods: The review summarized the results of studying the antimicrobial activity of extracts and metabolites from basidiomycetes published from 2018-2023. Results: In all studies, testing for antibacterial and antifungal activity was carried out in in vitro experiments. To obtain the extracts, mainly the fruiting bodies of basidiomycetes, as well as their mycelia and culture liquid were used. Antimicrobial activity was found in aqueous, methanol, and ethanol extracts. Antimicrobial metabolites of basidiomycetes were isolated mainly from the submerged culture of basidiomycetes. Metabolites active against Gram-positive and Gram-negative bacteria and mycelial and yeast-like fungi were identified. Conclusions: Basidiomycete extracts and metabolites have shown activity against collectible strains of bacteria and fungi and multi-resistant and clinical strains of pathogenic bacteria. The minimum inhibitory concentration (MIC) values of the most active metabolites ranged from 1 to 16.7 µg/mL.

Genomic insights into Aspergillus tamarii TPD11: enhancing polyphyllin production and uncovering potential therapeutic applications

BACKGROUND

The excavation and utilization of endophytic fungi from medicinal plants is highly important for the development of new drugs. The endophytic fungus Aspergillus tamarii TPD11, which was isolated and obtained by the authors in the previous stage, can produce a variety of polyphyllins with important potential applications in hemostasis, inflammation and antitumor activities; however, the genomic information of TPD11 is still unknown.

RESULTS

In this study, we sequenced and assembled the whole genome of the endophytic fungus A. tamarii TPD11, resolved the genome evolutionary relationships of 24 Aspergillus strains, and phylogenetic analysis of the genomes of 16 strains revealed the evolutionary differences between Aspergillus and Penicillium and the mechanisms of genome expansion and contraction. CAZy annotation analysis revealed that TPD11 obtains nutrients mainly by ingesting starch from the host plant. TPD11 has a biosynthesis-related gene cluster for the synthesis of squalestatin S1, and the silencing of this biosynthesis-related gene cluster might increase the content of polyphyllin. Annotation of 11 UDP-glycosyltransferase genes helps to further reveal the biosynthetic pathway of polyphyllin. In addition, secondary metabolism gene cluster and CAZy analyses confirmed the potential probiotic, insecticidal and antimicrobial activities of TPD11 on host plants.

CONCLUSIONS

This study reveals the intrinsic mechanism by which endophytic fungi increase the content of polyphyllin, which provides a basis for the synthetic synthesis of the natural product polyphyllin.

Diversity of African fungi, chemical constituents and biological activities

Besides plants and animals, the fungal kingdom consists of several species characterized by various forms and applications. Fungi are amazing producers of bioactive natural products with applications in medicine and agriculture. Though this kingdom has been extensively investigated worldwide, it remains relatively underexplored in Africa. To address the knowledge gaps, encourage research interest, and suggest opportunities for the discovery of more bioactive substances from African fungi, we considered it appropriate to extensively review the research work carried out on African fungi since 1988. This review summarizes the diversity and distribution of fungi throughout Africa, the secondary metabolites yet reported from studied fungi, their biological activities and, the countries where they were collected. The studied fungi originated from eleven African countries and were mainly endophytic fungi and higher fungi (macrofungi). Their investigation led to the isolation of five hundred and three (503) compounds with polyketides representing the main class of secondary metabolites. The compounds exhibited varied biological activities with antibacterial and antiproliferative properties being the most prominent.

Verticillins: fungal epipolythiodioxopiperazine alkaloids with chemotherapeutic potential

Covering: 1970 through June of 2023Verticillins are epipolythiodioxopiperazine (ETP) alkaloids, many of which possess potent, nanomolar-level cytotoxicity against a variety of cancer cell lines. Over the last decade, their in vivo activity and mode of action have been explored in detail. Notably, recent studies have indicated that these compounds may be selective inhibitors of histone methyltransferases (HMTases) that alter the epigenome and modify targets that play a crucial role in apoptosis, altering immune cell recognition, and generating reactive oxygen species. Verticillin A (1) was the first of 27 analogues reported from fungal cultures since 1970. Subsequent genome sequencing identified the biosynthetic gene cluster responsible for producing verticillins, allowing a putative pathway to be proposed. Further, molecular sequencing played a pivotal role in clarifying the taxonomic characterization of verticillin-producing fungi, suggesting that most producing strains belong to the genus Clonostachys (i.e., Bionectria), Bionectriaceae. Recent studies have explored the total synthesis of these molecules and the generation of analogues via both semisynthetic and precursor-directed biosynthetic approaches. In addition, nanoparticles have been used to deliver these molecules, which, like many natural products, possess challenging solubility profiles. This review summarizes over 50 years of chemical and biological research on this class of fungal metabolites and offers insights and suggestions on future opportunities to push these compounds into pre-clinical and clinical development.

Progress in the Study of Natural Antimicrobial Active Substances in Pseudomonas aeruginosa

The prevalence of antimicrobial resistance reduces the effectiveness of antimicrobial drugs in the prevention and treatment of infectious diseases caused by pathogens such as bacteria, fungi, and viruses. Microbial secondary metabolites have been recognized as important sources for new drug discovery and development, yielding a wide range of structurally novel and functionally diverse antimicrobial drugs for the treatment of a variety of diseases that are considered good producers of novel antimicrobial drugs. Bacteria produce a wide variety of antimicrobial compounds, and thus, antibiotics derived from natural products still dominate over purely synthetic antibiotics among the antimicrobial drugs developed and introduced over the last four decades. Among them, Pseudomonas aeruginosa secondary metabolites constitute a richly diverse source of antimicrobial substances with good antimicrobial activity. Therefore, they are regarded as an outstanding resource for finding novel bioactive compounds. The exploration of antimicrobial compounds among Pseudomonas aeruginosa metabolites plays an important role in drug development and biomedical research. Reports on the secondary metabolites of Pseudomonas aeruginosa, many of which are of pharmacological importance, hold great promise for the development of effective antimicrobial drugs against microbial infections by drug-resistant pathogens. In this review, we attempt to summarize published articles from the last twenty-five years (2000-2024) on antimicrobial secondary metabolites from Pseudomonas aeruginosa.

Global Analysis of Natural Products Biosynthetic Diversity Encoded in Fungal Genomes

Fungal secondary metabolites (SMs) represent an invaluable source of therapeutic drugs. Genomics-based approaches to SM discovery have revealed a vast and largely untapped biosynthetic potential within fungal genomes. Here, we used the publicly available fungal genome sequences from the NCBI public database, as well as tools such as antiSMASH, BIG-SLiCE, etc., to analyze a total of 11,598 fungal genomes, identifying 293,926 biosynthetic gene clusters (BGCs), which were subsequently categorized into 26,825 gene cluster families (GCFs). It was discovered that only a tiny fraction, less than 1%, of these GCFs could be mapped to known natural products (NPs). Some GCFs that only contain a single BGC internally are crucial for the biodiversity of fungal biosynthesis. Evident patterns emerged from our analysis, revealing popular taxa as prominent sources of both actual and potential biosynthetic diversity. Our study also suggests that the genus rank distribution of GCF is generally consistent with NP diversity. It is noteworthy that genera Xylaria, Hypoxylon, Colletotrichum, Diaporthe, Nemania, and Calonectria appear to possess a higher potential for SM synthesis. In addition, 7213 BGCs match possible known compound structures, and homologous gene clusters of well-known drugs can be located in different genera, facilitating the development of derivatives that share structural similarity to these drugs and may potentially possess similar biological activity. Our study demonstrated the various types of fungi with mining potential, assisting researchers in prioritizing their research efforts and avoiding duplicate mining of known resources to further explore fungal NP producers.

Exploration of diverse secondary metabolites from Penicillium brasilianum by co-culturing with Armillaria mellea

Bioinformatic analysis revealed that the genomes of ubiquitous Penicillium spp. might carry dozens of biosynthetic gene clusters (BGCs), yet many clusters have remained uncharacterized. In this study, a detailed investigation of co-culture fermentation including the basidiomycete Armillaria mellea CPCC 400891 and the P. brasilianum CGMCC 3.4402 enabled the isolation of five new compounds including two bisabolene-type sesquiterpenes (arpenibisabolanes A and B), two carotane-type sesquiterpenes (arpenicarotanes A and B), and one polyketide (arpenichorismite A) along with seven known compounds. The assignments of their structures were deduced by the extensive analyses of detailed spectroscopic data, electronic circular dichroism spectra, together with delimitation of the biogenesis. Most new compounds were not detected in monocultures under the same fermentation conditions. Arpenibisabolane A represents the first example of a 6/5-fused bicyclic bisabolene. The bioassay of these five new compounds exhibited no cytotoxic activities in vitro against three human cancer cell lines (A549, MCF-7, and HepG2). Moreover, sequence alignments and bioinformatic analysis to other metabolic pathways, two BGCs including Pb-bis and Pb-car, responsible for generating sesquiterpenoids from co-culture were identified, respectively. Furthermore, based on the chemical structures and deduced gene functions of the two clusters, a hypothetic metabolic pathway for biosynthesizing induced sesquiterpenoids was proposed. These results demonstrated that the co-culture approach would facilitate bioprospecting for new metabolites even from the well-studied microbes. Our findings would provide opportunities for further understanding of the biosynthesis of intriguing sesquiterpenoids via metabolic engineering strategies. KEY POINTS: • Penicillium and Armillaria co-culture facilitates the production of diverse secondary metabolites • Arpenibisabolane A represents the first example of 6/5-fused bicyclic bisabolenes • A hypothetic metabolic pathway for biosynthesizing induced sesquiterpenoids was proposed.

Wheldone Revisited: Structure Revision Via DFT-GIAO Chemical Shift Calculations, 1,1-HD-ADEQUATE NMR Spectroscopy, and X-ray Crystallography Studies

Wheldone is a fungal metabolite isolated from the coculture of Aspergillus fischeri and Xylaria flabelliformis, displaying cytotoxic activity against breast, melanoma, and ovarian cancer cell lines. Initially, its structure was characterized as an unusual 5-methyl-bicyclo[5.4.0]undeca-3,5-diene scaffold with a 2-hydroxy-1-propanone side chain and a 3-(2-(1-hydroxyethyl)-2-methyl-2,5-dihydrofuran-3-yl)acrylic acid moiety. Upon further examination, minor inconsistencies in the data suggested the need for the structure to be revisited. Thus, the structure of wheldone has been revised using an orthogonal experimental-computational approach, which combines 1,1-HD-ADEQUATE NMR experiments, DFT-GIAO chemical shift calculations, and single-crystal X-ray diffraction (SCXRD) analysis of a semisynthetic p-bromobenzylamide derivative, formed via a Steglich-type reaction. The summation of these data now permits the unequivocal assignment of both the structure and absolute configuration of the natural product.

Bioactivity-driven fungal metabologenomics identifies antiproliferative stemphone analogs and their biosynthetic gene cluster

INTRODUCTION

Fungi biosynthesize chemically diverse secondary metabolites with a wide range of biological activities. Natural product scientists have increasingly turned towards bioinformatics approaches, combining metabolomics and genomics to target secondary metabolites and their biosynthetic machinery. We recently applied an integrated metabologenomics workflow to 110 fungi and identified more than 230 high-confidence linkages between metabolites and their biosynthetic pathways.

OBJECTIVES

To prioritize the discovery of bioactive natural products and their biosynthetic pathways from these hundreds of high-confidence linkages, we developed a bioactivity-driven metabologenomics workflow combining quantitative chemical information, antiproliferative bioactivity data, and genome sequences.

METHODS

The 110 fungi from our metabologenomics study were tested against multiple cancer cell lines to identify which strains produced antiproliferative natural products. Three strains were selected for further study, fractionated using flash chromatography, and subjected to an additional round of bioactivity testing and mass spectral analysis. Data were overlaid using biochemometrics analysis to predict active constituents early in the fractionation process following which their biosynthetic pathways were identified using metabologenomics.

RESULTS

We isolated three new-to-nature stemphone analogs, 19-acetylstemphones G (1), B (2) and E (3), that demonstrated antiproliferative activity ranging from 3 to 5 µM against human melanoma (MDA-MB-435) and ovarian cancer (OVACR3) cells. We proposed a rational biosynthetic pathway for these compounds, highlighting the potential of using bioactivity as a filter for the analysis of integrated-Omics datasets.

CONCLUSIONS

This work demonstrates how the incorporation of biochemometrics as a third dimension into the metabologenomics workflow can identify bioactive metabolites and link them to their biosynthetic machinery.

Preliminary Bioactivity Assessment of Myrothecium Species (Stachybotryaceae) Crude Extracts against Aedes aegypti (Diptera: Culicidae): A First Approach from This Phytopathogenic Fungi

Mosquitoes, as insect vectors, play a crucial role in transmitting viruses and parasites, leading to millions of human deaths in tropical and subtropical regions worldwide. This study aimed to evaluate the effects of ethanolic extracts of three species within the genus Myrothecium (M. roridum, M. dimerum, and M. nivale) on Aedes aegypti mosquito larvae to assess the inhibitory effect on growth and development, as well as to determine mortality. We quantify the average lethal concentrations and provide a qualitative characterization of the chemical groups responsible for their potential. Phytochemical screening revealed the presence of alkaloids, flavonoids, and terpenoids in the ethanolic extracts of the three fungal species. Tannins were found only in the extracts of M. dimerum and M. roridum. We observed a clear dependence of the effects of the crude extracts on mosquito larvae on the concentrations used and the duration of exposure. The toxic effect was observed after 48 h at a concentration of 800 ppm for both M. dimerum and M. nivale, while M. roridum showed effectiveness after 72 h. All three species within the genus Myrothecium exhibited 100% biological activity after 72 h of exposure at 600 ppm. At lower concentrations, there was moderate growth and development inhibitory activity in the insect life cycle. The study highlights the effectiveness of crude Myrothecium extracts in combating mosquito larvae, with effects becoming apparent between 48 and 72 h of exposure. This initial approach underscores the potential of the fungus's secondary metabolites for further in-depth analysis of their individual effects or synergies between them.

Chemoenzymatic asymmetric total synthesis of naturally occurring resorcylic acid lactones hamigeromycins F and G

Asymmetric total synthesis of two naturally occurring resorcylic acid lactones (RALs), hamigeromycins F and G, was achieved for the first time. The synthetic strategy involved a late-stage intramolecular macrolactonization achieved with a transesterification reaction. Stereocenters (C10' and C6') in both the molecules were accessed via an enzymatic kinetic resolution reaction. The penta-substituted aromatic core present in hamigeromycins F and G was accessed using vanillin as a precursor. The crucial E-olefinic unsaturated bond at C1'-C2' was constructed with a stereoselective Julia-Kocienski olefination reaction.

Isolation and structure determination of a new bisabolane-type sesquiterpenoid with cytotoxicity from Penicillium oxalicum MZY-202312-521

Endophytic fungi can produce attractive secondary metabolites with various biological activities that have contributed significantly to pharmacotherapy. In this study, three bisabolane-type sesquiterpenoids, including a new one, namely, inonotic acid C (1), together with previously reported compounds (S)-(+)-11-dehydrosydonic acid (2) and sydonic acid (3), were isolated from a marine algal-derived endophytic fungus Penicillium oxalicum MZY-202312-521. Their structures were determined by means of extensive spectroscopic analyses. The absolute configurations of inonotic acid C (1) were established by single-crystal X-ray diffraction method. In vitro cytotoxic experiments on human A549, MCF-7, HeLa, and HepG2 carcinoma cell lines were carried out. The new compound inonotic acid C (1) was found to possess strong inhibitory activity against the MCF-7 cell line, with an IC50 value of 7.7 μM.

Discovery of novel secondary metabolites from the basidiomycete Lentinus cf. sajor-caju and their inhibitory effects on Staphylococcus aureus biofilms

Three novel derivatives of microporenic acid, microporenic acids H-J, were identified from submerged cultures of a Lentinus species obtained from a basidiome collected during a field trip in the tropical rainforest in Western Kenya. Their structures were elucidated via HR-ESIMS spectra and 1D/2D NMR spectroscopic analyses, as well as by comparison with known derivatives. Applying biofilm assays based on crystal violet staining and confocal microscopy, two of these compounds, microporenic acids H and I, demonstrated the ability to inhibit biofilm formation of the opportunistic pathogen Staphylococcus aureus. Thereby, they were effective in a concentration range that did not affect planktonic growth. Additionally, microporenic acid I enhanced the anti-biofilm activity of the antibiotics vancomycin and gentamicin when used in combination. This opens up possibilities for the use of these compounds in combination therapy to prevent the formation of S. aureus biofilms.

Bio-synthesis, purification and structural analysis of Cyclosporine-A produced by Tolypocladium inflatum with valorization of agro-industrial wastes

Cyclosporine A (CyA) holds significant importance as a strategic immunosuppressive drug for organ transplant patients. In this study, we aimed to produce pure and cost-effective Cyclosporine A (CyA) by fermenting a culture medium containing dairy sludge, using Tolypocladium inflatum PTCC 5253. Following the fermentation stage, ethyl acetate extraction and fast protein liquid chromatography were employed for sample purification. The initial evaluation of the effectiveness of CyA obtained from these processes was performed through bioassay, wherein the antimicrobial clear zone diameter was found to be larger compared to the sample obtained from the fermentation culture. The concentration of CyA was determined using high-performance liquid chromatography, yielding values of 334 mg/L, 456 mg/L, and 578 mg/L for the fermented, extracted, and purified samples, respectively. Further analysis utilizing liquid chromatography tandem mass spectrometry (LC/MS/MS) confirmed a purity of 91.9% and proper agreement with the standard sample based on the ion intensity of Z/m 1205. To validate the structure of CyA, nuclear magnetic resonance spectroscopy, Fourier-transform infrared (FT-IR), and Raman spectroscopy were employed. X-ray diffraction and differential scanning calorimetry analyses demonstrated that the purified CyA exhibited a crystal structure similar to the standard sample, characterized by two broad peaks at 2θ = 9° and 20°, and comparable glass transition temperatures (57-68 °C for the purified sample; 53-64 °C for the standard sample). Dynamic light scattering analysis confirmed a uniform particle size distribution in both the purified and standard samples. The zeta potentials of the purified and standard samples were determined to be - 25.8 ± 0.16 and - 23.63 ± 0.12 mV, respectively. Our results demonstrate that dairy sludge can serve as a suitable culture medium for the production of (CyA).

Lachnuoic Acids A-F: Ambuic Acid Congeners from a Saprotrophic Lachnum Species

Chemical prospection of an extract derived from a saprotrophic fungus Lachnum sp. IW157 resulted in the isolation and characterization of six unprecedentedly reported ambuic acid analogues named lachnuoic acids A-F (1-6). Chemical structures of 1-6 were determined based on comprehensive 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry. The relative configurations of 1-3 were defined by ROESY spectroscopic analyses while their absolute configurations were unambiguously determined by Mosher's esters method. All isolated compounds were subjected to cytotoxic, antimicrobial, antibiofilm and nematicidal activity assays where only lachnuoic acid A (1) revealed potent antimicrobial activity against Staphylococcus aureus and Bacillus subtilis at MIC values of 16.6 and 8.3 μg/mL, respectively.

Sesquiterpenes and α-pyrones from an endophytic fungus Xylaria curta YSJ-5

Chemical investigation of the culture extract of an endophyte Xylaria curta YSJ-5 from Alpinia zerumbet (Pers.) Burtt. et Smith resulted in the isolation of eight previously undescribed compounds including five eremophilane sesquiterpenes xylarcurenes A-E, one norsesquiterpene xylarcurene F, and two α-pyrone derivatives xylarpyrones A-B together with eight known related derivatives. Their chemical structures were extensively established based on the 1D- and 2D-NMR spectroscopic analysis, modified Mosher's method, electronic circular dichroism calculations, single-crystal X-ray diffraction experiments, and the comparison with previous literature data. All these compounds were tested for in vitro cytotoxic, anti-inflammatory, α-glucosidase inhibitory, and antibacterial activities. As a result, 6-pentyl-4-methoxy-pyran-2-one was disclosed to display significant antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus with minimal inhibitory concentration value of 6.3 μg/mL.

Isolation, Characterization, and Bioherbicidal Potential of the 16-Residue Peptaibols from Emericellopsis sp. XJ1056

Eco-friendly bioherbicides are urgently needed for managing the problematic weed Amaranthus retroflexus. A mass spectrometry- and bioassay-guided screening approach was employed to identify phytotoxic secondary metabolites from fungi for the development of such bioherbicides. This effort led to the discovery of six phytotoxic 16-residue peptaibols, including five new compounds (2-6) and a known congener (1), from Emericellopsis sp. XJ1056. Their planar structures were elucidated through the analysis of tandem mass and NMR spectroscopic data. The absolute configurations of the chiral amino acids were determined by advanced Marfey's method and chiral-phase liquid chromatography-mass spectrometry (LC-MS) analysis. Bioinformatic analysis and targeted gene disruption identified the biosynthetic gene cluster for these peptaibols. Compounds 1 and 2 significantly inhibited the radicle growth of A. retroflexus seedlings, and 1 demonstrated potent postemergence herbicidal activity against A. retroflexus while exhibiting minimal toxicity to Sorghum bicolor. Structure-activity relationship analysis underscored the importance of trans-4-hydroxy-l-prolines at both the 10th and 13th positions for the herbicidal activities of these peptaibols.

Formation of Bridged Disulfide in Epidithiodioxopiperazines

Epidithiodioxopiperazine (ETP) alkaloids, featuring a 2,5-diketopiperazine core and transannular disulfide bridge, exhibit a broad spectrum of biological activities. However, the structural complexity has prevented efficient chemical synthesis and further clinical research. In the past few decades, many achievements have been made in the biosynthesis of ETPs. Here, we discuss the biosynthetic progress and summarize them as two comprehensible metabolic principles for better understanding the complex pathways of α, α'- and α, β'-disulfide bridged ETPs. Specifically, we systematically outline the catalytic machineries to install α, α'- and α, β'-disulfide by flavin-containing oxygenases. This concept would contribute to the medical and industrial applications of ETPs.

Multi-omics approaches to understand pathogenicity during potato early blight disease caused by Alternaria solani

Potato early blight (PEB), a foliar disease of potato during the growing period, caused by Alternaria sp., is common in major potato-producing areas worldwide. Effective agents to control this disease or completely resistant potato varieties are absent. Large-scale use of fungicides is limited due to possibility of increase in pathogen resistance and the requirements of ecological agriculture. In this study, we focused on the composition and infection characteristics of early blight pathogens in Yunnan Province and screened candidate pathogenesis-related pathways and genes. We isolated 85 strains of Alternaria sp. fungi from typical early blight spots in three potato-growing regions in Yunnan Province from 2018 to 2022, and identified 35 strains of Alternaria solani and 50 strains of Alternaria alternata by morphological characterization and ITS sequence comparison, which were identified as the main and conditional pathogens causing early blight in potato, respectively. Scanning electron microscope analysis confirmed only A. solani producing appressorium at 4 h after inoculation successfully infected the leaf cells. Via genome assembly and annotation, combine transcriptome and proteomic analysis, the following pathogenicity-related unit, transcription factors and metabolic pathway were identified: (1) cell wall-degrading enzymes, such as pectinase, keratinase, and cellulase; (2) genes and pathways related to conidia germination and pathogenicity, such as ubiquitination and peroxisomes; and (3) transcription factors, such as Zn-clus, C2H2, bZIP, and bHLH. These elements were responsible for PEB epidemic in Yunnan.

Predicting fungal secondary metabolite activity from biosynthetic gene cluster data using machine learning

Fungal secondary metabolites (SMs) contribute to the diversity of fungal ecological communities, niches, and lifestyles. Many fungal SMs have one or more medically and industrially important activities (e.g., antifungal, antibacterial, and antitumor). The genes necessary for fungal SM biosynthesis are typically located right next to each other in the genome and are known as biosynthetic gene clusters (BGCs). However, whether fungal SM bioactivity can be predicted from specific attributes of genes in BGCs remains an open question. We adapted machine learning models that predicted SM bioactivity from bacterial BGC data with accuracies as high as 80% to fungal BGC data. We trained our models to predict the antibacterial, antifungal, and cytotoxic/antitumor bioactivity of fungal SMs on two data sets: (i) fungal BGCs (data set comprised of 314 BGCs) and (ii) fungal (314 BGCs) and bacterial BGCs (1,003 BGCs). We found that models trained on fungal BGCs had balanced accuracies between 51% and 68%, whereas training on bacterial and fungal BGCs had balanced accuracies between 56% and 68%. The low prediction accuracy of fungal SM bioactivities likely stems from the small size of the data set; this lack of data, coupled with our finding that including bacterial BGC data in the training data did not substantially change accuracies currently limits the application of machine learning approaches to fungal SM studies. With >15,000 characterized fungal SMs, millions of putative BGCs in fungal genomes, and increased demand for novel drugs, efforts that systematically link fungal SM bioactivity to BGCs are urgently needed.IMPORTANCEFungi are key sources of natural products and iconic drugs, including penicillin and statins. DNA sequencing has revealed that there are likely millions of biosynthetic pathways in fungal genomes, but the chemical structures and bioactivities of >99% of natural products produced by these pathways remain unknown. We used artificial intelligence to predict the bioactivities of diverse fungal biosynthetic pathways. We found that the accuracies of our predictions were generally low, between 51% and 68%, likely because the natural products and bioactivities of only very few fungal pathways are known. With >15,000 characterized fungal natural products, millions of putative biosynthetic pathways present in fungal genomes, and increased demand for novel drugs, our study suggests that there is an urgent need for efforts that systematically identify fungal biosynthetic pathways, their natural products, and their bioactivities.

Neosetophomone B induces apoptosis in multiple myeloma cells via targeting of AKT/SKP2 signaling pathway

Multiple myeloma (MM) is a hematologic malignancy associated with malignant plasma cell proliferation in the bone marrow. Despite the available treatments, drug resistance and adverse side effects pose significant challenges, underscoring the need for alternative therapeutic strategies. Natural products, like the fungal metabolite neosetophomone B (NSP-B), have emerged as potential therapeutic agents due to their bioactive properties. Our study investigated NSP-B's antitumor effects on MM cell lines (U266 and RPMI8226) and the involved molecular mechanisms. NSP-B demonstrated significant growth inhibition and apoptotic induction, triggered by reduced AKT activation and downregulation of the inhibitors of apoptotic proteins and S-phase kinase protein. This was accompanied by an upregulation of p21Kip1 and p27Cip1 and an elevated Bax/BCL2 ratio, culminating in caspase-dependent apoptosis. Interestingly, NSP-B also enhanced the cytotoxicity of bortezomib (BTZ), an existing MM treatment. Overall, our findings demonstrated that NSP-B induces caspase-dependent apoptosis, increases cell damage, and suppresses MM cell proliferation while improving the cytotoxic impact of BTZ. These findings suggest that NSP-B can be used alone or in combination with other medicines to treat MM, highlighting its importance as a promising phytoconstituent in cancer therapy.

Diaporaustalides A-L, Austalide Meroterpenoids from a Plant Endophytic Diaporthe sp

Twelve new austalide meroterpenoids (1-12) were isolated from the endophytic fungus Diaporthe sp. XC1211. Their structures were elucidated by extensive spectroscopic analysis. The absolute configurations of compounds 1, 3, 4, and 6 were established by single-crystal X-ray diffraction, whereas those for the others were established by experimental electronic circular dichroism (ECD) data analysis. Compounds 1-12 represent a rare class of austalides with a 24α-CH3. Compounds 2 and 5 demonstrated potent proliferation inhibitory effects against LPS-induced B cells with IC50 values of 6.7 (SI = 3.6) and 3.8 (SI > 13) μM, respectively. Compounds 2 and 5 decreased the secretion of IL-6 in LPS-induced B cells in a dose-dependent manner.

Aspertaichamide a, a novel cytotoxic prenylated indole alkaloid possessing a bicyclo[2.2.2]diazaoctane framework from a marine algal-derived endophytic fungus aspergillus taichungensis 299

Filamentous fungi belonging to the genus Aspergillus are prodigious producers of alkaloids, particularly prenylated indole alkaloids, that often exhibit structurally diversified skeletons and potent biological activities. In this study, five prenylated indole alkaloids possessing a bicyclo[2.2.2]diazaoctane core ring system, including a novel derivative, namely aspertaichamide A (1), as well as four known compounds, (+)-stephacidin A (2), sclerotiamide (3), (-)-versicolamide B (4), and (+)-versicolamide B (5), were isolated and identified from A. taichungensis 299, an endophytic fungus obtained from the marine red alga Gelidium amansii. The chemical structures of the compounds were elucidated by comprehensive NMR and HRESIMS spectroscopic analyses. In addition to the previously reported prenylated indole alkaloids, aspertaichamide A (1) was characterized as having an unusual ring structure with the fusion of a 3-pyrrolidone dimethylbenzopyran to the bicyclo[2.2.2]diazaoctane moiety, which was rare in these kinds of compounds. The absolute configuration of 1 was determined by TDDFT-ECD calculations. In vitro cytotoxic assays revealed that the novel compound 1 possessed selective cytotoxic activity against five human tumor cell lines (A549, HeLa, HepG2, HCT-116, and AGS), with IC50 values of 1.7-48.5 μM. Most importantly, compound 1 decreased the viability of AGS cells in a concentration-dependent manner with an IC50 value of 1.7 μM. Further studies indicated that 1 may induce AGS cells programmed cell death via the apoptotic pathway.

Tackling Nontuberculous Mycobacteria by Repurposable Drugs and Potential Leads from Natural Products

Nontuberculous Mycobacteria (NTM) refer to bacteria other than all Mycobacterium species that do not cause tuberculosis or leprosy, excluding the species of the Mycobacterium tuberculosis complex, M. leprae and M. lepromatosis. NTM are ubiquitous and present in soils and natural waters. NTM can survive in a wide range of environmental conditions. The direct inoculum of the NTM from water or other materials is most likely a source of infections. NTMs are responsible for several illnesses, including pulmonary alveolar proteinosis, cystic fibrosis, bronchiectasis, chronic obstructive pneumoconiosis, and pulmonary disease. Recent reports suggest that NTM species have become insensitive to sterilizing agents, antiseptics, and disinfectants. The efficacy of existing anti-NTM regimens is diminishing and has been compromised due to drug resistance. New and recurring cases of multidrug-resistant NTM strains are increasing. Thus, there is an urgent need for ant-NTM regimens with novel modes of action. This review sheds light on the mode of antimicrobial resistance in the NTM species. Then, we discussed the repurposable drugs (antibiotics) that have shown new indications (activity against NTM strains) that could be developed for treating NTM infections. Also, we have summarised recently identified natural leads acting against NTM, which have the potential for treating NTM-associated infections.

Stress in the microbiome-immune crosstalk

The gut microbiota exerts a mutualistic interaction with the host in a fragile ecosystem and the host intestinal, neural, and immune cells. Perturbations of the gastrointestinal track composition after stress have profound consequences on the central nervous system and the immune system. Reciprocally, brain signals after stress affect the gut microbiota highlighting the bidirectional communication between the brain and the gut. Here, we focus on the potential role of inflammation in mediating stress-induced gut-brain changes and discuss the impact of several immune cells and inflammatory molecules of the gut-brain dialogue after stress. Understanding the impact of microbial changes on the immune system after stress might provide new avenues for therapy.

Secondary Metabolites of Biscogniauxia: Distribution, Chemical Diversity, Bioactivity, and Implications of the Occurrence

The genus Biscogniauxia, a member of the family Xylariaceae, is distributed worldwide with more than 50 recognized taxa. Biscogniauxia species is known as a plant pathogen, typically acting as a parasite on tree bark, although certain members of this genus also function as endophytic microorganisms. Biscogniauxia endophytic strain has received attention in many cases, which includes constituent research leading to the discovery of various bioactive secondary metabolites. Currently, there are a total of 115 chemical compounds belonging to the class of secondary metabolites, and among these compounds, fatty acids have been identified. In addition, the strong pharmacological agents of this genus are (3aS,4aR,8aS,9aR)-3a-hydroxy-8a-methyl-3,5-dimethylenedecahydronaphto [2,3-b]furan-2(3H)-one (HDFO) (antifungal), biscopyran (phytotoxic activity), reticulol (antioxidant), biscogniazaphilone A and B (antimycobacterial), and biscogniauxone (Enzyme GSK3 inhibitor). This comprehensive research contributes significantly to the potential discovery of novel drugs produced by Biscogniauxia and holds promise for future development. Importantly, it represents the first-ever review of natural products originating from the Biscogniauxia genus.

Neurite Outgrowth-Inducing Drimane-Type Sesquiterpenoids Isolated from Cultures of the Polypore Abundisporus violaceus MUCL 56355

Abundisporin A (1), together with seven previously undescribed drimane sesquiterpenes named abundisporins B-H (2-8), were isolated from a polypore, Abundisporus violaceus MUCL 56355 (Polyporaceae), collected in Kenya. Chemical structures of the isolated compounds were elucidated based on exhaustive 1D and 2D NMR spectroscopic measurements and supported by HRESIMS data. The absolute configurations of the isolated compounds were determined by using Mosher's method for 1-4 and TDDFT-ECD calculations for 4 and 5-8. None of the isolated compounds exhibited significant activities in either antimicrobial or cytotoxicity assays. Notably, all of the tested compounds demonstrated neurotrophic effects, with 1 and 6 significantly increasing outgrowth of neurites when treated with 5 ng/mL NGF.

Alkaloid diversity expansion of a talent fungus Penicillium raistrichii through OSMAC-based cultivation

Introduction

Alkaloidal natural products are attractive for their broad spectrum of pharmaceutical bioactivities. In the present work, the highly productive saline soil derived fungus, Penicillium raistrichii, was subjected to the strategy of OSMAC (one strain many compounds) with changes of cultivation status. Then, the work-flow led to the expansion of the alkaloid chemical diversity and subsequently induced the accumulation of four undescribed alkaloids, named raistrimides A-D (1-4), including three β-carbolines (1-3), one 2-quinolinone (4), and one new natural product, 2-quinolinone (5), along with five known alkaloid chemicals (6-10).

Methods

A set of NMR techniques including 1H, 13C, HSQC and HMBC, along with other spectroscopic data of UV-Vis, IR and HRESIMS, were introduced to assign the plain structures of compounds 1-10. The absolute configuration of 1-3 were elucidated by means of X-ray crystallography or spectroscopic analyses on optical rotation values and experimental electronic circular dichroism (ECD) data. In addition, it was the first report on the confirmation of structures of 6, 7 and 9 by X-ray crystallography data. The micro-broth dilution method was applied to evaluate antimicrobial effect of all compounds towards Staphylococcus aureus, Escherichia coli, and Candida albicans.

Results and discussion

The results indicated compounds 1, 3 and 4 to be bioactive, which may be potential for further development of anti-antimicrobial agents. The finding in this work implied that OSMAC strategy was a powerful and effective tool for promotion of new chemical entities from P. raistrichii.