A new sesquiterpene lactone from fungus Eutypella sp. D-1

Genome Mining Leads to Diverse Sesquiterpenes with Anti-inflammatory Activity from an Arctic-Derived Fungus

With the advancement of bioinformatics, the integration of genome mining with efficient separation technology enables the discovery of a greater number of novel bioactive compounds. The deletion of the key gene responsible for triterpene cyclase biosynthesis in the polar strain Eutypella sp. D-1 instigated metabolic shunting, resulting in the activation of dormant genes and the subsequent production of detectable, new compounds. Fifteen sesquiterpenes were isolated from the mutant strain, with eight being new compounds. The structural elucidation of these compounds was obtained through a combination of HRESIMS, NMR spectroscopy, and ECD calculations, revealing six distinct skeleton types. Compound 7 possessed a unique skeleton of 5/10 macrocyclic ether structure. Based on the gene functions and newly acquired secondary metabolites, the metabolic shunting pathway in the mutant strain was inferred. Compounds 6, 8, 11, 14, and 15 exhibited anti-inflammatory effects without cytotoxicity through the release of nitric oxide from lipopolysaccharide-stimulated RAW264.7 cells. Notably, acorane-type sesquiterpene 8 inhibited nitric oxide production and modulated the MAPK and NLRP3/caspase-1 signaling pathways. Compound 8 also alleviated the CuSO4-induced systemic neurological inflammation symptoms in a transgenic fluorescent zebrafish model.

Chemical structures, biological activities, and biosynthetic analysis of secondary metabolites of the Diatrypaceae family: A comprehensive review

The family Diatrypaceae is a less well-known group within the order Xylariales (Ascomycota). Initially, the focus on its metabolites was related to the pathogenicity of one of its members, Eutypa lata. To date, a total of 254 natural products have been identified from Diatrypaceae strains. These compounds include terpenoids, sterols, polyketones, phenols, and acetylene aromatic compounds, which have shown anticancer, cytotoxic, anti-inflammatory, antimicrobial, and antiviral activities. The complex and diverse structural types, along with the diverse bioactivities, highlight the potential of Diatrypaceae as a valuable source of bioactive natural products. In this review, a deep analysis of the biosynthesis of pimarane diterpenes and scoparasin-type cytochalasins is provided, coupled with a compilation of the biosynthetic pathways of aromatic acetylene compounds in filamentous fungi. This comprehensive review not only enhances our understanding of the natural product chemistry, biological activities, and biosynthesis of secondary metabolites from the Diatrypaceae family but also promotes the exploitation and development of important bioactive compounds and potential strains.

Eutypellaolides A-J, Sesquiterpene diversity expansion of the polar fungus Eutypella sp. D-1

Eight new 12,8-eudesmanolide sesquiterpenes, eutypellaolides A-H (1-8), and two new eudesmane-type sesquiterpenes, eutypellaolides I-J (9-10), along with four known 12,8-eudesmanolide compounds 11-14, were isolated from the culture extract of the polar fungus Eutypella sp. D-1 by one strain many compounds (OSMAC) approach. The structures of these compounds were determined through comprehensive spectroscopic data and experimental and calculated ECD analysis. Antibacterial, immunosuppressive, and PTP1B inhibition activities of these compounds were evaluated. Compounds 1 and 11 exhibited strong inhibitory activities against Bacillus subtilis and Staphylococcus aureus, with each showing an MIC value of 2 μg/mL. Compound 9 displayed weak immunosuppressive activity against ConA-induced T-cell proliferation with an inhibitory rate of 61.7% at a concentration of 19.8 μM. Compounds 5, 11, and 14 exhibited weak PTP1B inhibition activities with IC50 values of 44.8, 43.2, and 49.5 μM, respectively.

Pimarane-Type Diterpenes with Anti-Inflammatory Activity from Arctic-Derived Fungus Eutypella sp. D-1

The Arctic-derived fungus Eutypella sp. D-1 can produce numerous secondary metabolites, and some compounds exhibit excellent biological activity. Seven pimarane-type diterpenes, including three new compounds eutypellenone F (1), libertellenone Y (2), and libertellenone Z (3), and four known compounds (4-7), were isolated from fermentation broth of Eutypella sp. D-1 by the OSMAC strategy of adding ethanol as a promoter in the culture medium. Compound 2 has a rare tetrahydrofuran-fused pimarane diterpene skeleton. The anti-inflammatory activity of all compounds was evaluated. Compounds 3-6 showed a significant inhibitory effect on cell NO release at 10 μmol/L by in vitro experiments, of which 3-5 had inhibitory rates over 60% on nitric oxide (NO) release. Subsequently, the anti-inflammatory activity of 3-5 was evaluated based on a zebrafish model, and the results showed that 3 had a significant inhibitory effect on inflammatory cells migration at 40 μmol/L, while 4 and 5 had a significant inhibitory effect at 20 μmol/L. Moreover, compounds 3-5 have the same conjugated double bond structure, which may be an important group for these compounds to exert anti-inflammatory activity.

The Novel Compounds with Biological Activity Derived from Soil Fungi in the Past Decade

The secondary metabolites isolated from soil fungi have received more and more attention, especially new compounds that exhibited good biological activities. In this review, a total of 546 new compounds are included in the relevant literature since 2011. The new compounds are isolated from soil fungi, We divided these compounds into seven categories, including alkaloids, terpenoids, steroids, ketones, phenylpropanoids, quinones, esters, lactones, etc. In addition, the biological activities and structure-activity relationships of these compounds have also been fully discussed. The activities of these compounds are roughly divided into eight categories, including anticancer activity, antimicrobial activity, anti-inflammatory activity, antioxidant activity, antiviral activity, antimalarial activity, immunosuppressive activity and other activities. Since natural products are an important source of new drugs, this review may have a positive guiding effect on drug screening.

Antimicrobial Activity of Lactones

The development of bacterial resistance to antibiotics and the consequent lack of effective therapy is one of the biggest problems in modern medicine. A consequence of these processes is an urgent need to continuously design and develop novel antimicrobial agents. Among the compounds showing antimicrobial potential, lactones are a group to explore. For centuries, their antimicrobial activities have been used in folk medicine. Currently, novel lactone compounds are continuously described in the literature. Some of those structures exhibit high antimicrobial potential and some are an inspiration for design and synthesis of future drugs. This paper describes recent developments on antimicrobial lactones with smaller ring sizes, up to seven membered ε-lactones. Their isolation from natural sources, chemical synthesis, synergistic activity with antibiotics, and effects on quorum sensing are presented herein.

Optimization of Protoplast Preparation and Establishment of Genetic Transformation System of an Arctic-Derived Fungus Eutypella sp

Arctic-derived fungus Eutypella sp. D-1 has attracted wide attention due to its huge ability to synthesize secondary metabolites. However, current studies only focus on stimulating its production of new secondary metabolites by OSMAC strategies, and the relationship between secondary metabolites and biosynthetic gene clusters (BGCs) has not been explored. In this study, the preparation and regeneration conditions of Eutypella sp. D-1 protoplasts were explored to lay a foundation for the study of genetic transformation of this fungus. Orthogonal experiment showed that the optimal preparation conditions were 0.75 M NaCl, 20 g/L of lysing enzyme, and 20 g/L of driselase, 28°C for 6 h. The maximum yield of Eutypella sp. D-1 protoplasts could reach 6.15 × 10⁶ cells·ml⁻¹, and the concentration of osmotic stabilizer NaCl was the most important factor for Eutypella sp. D-1 protoplasts. The results of FDA staining showed that the prepared protoplasts had good activity. Besides, the best protoplasts regeneration medium was YEPS, whose maximum regeneration rate is 36%. The mediums with nitrogen sources, such as SR and RM, also had good effects on the Eutypella sp. D-1 protoplast regeneration, indicating that nitrogen sources played an important role on the Eutypella sp. D-1 protoplast regeneration. Subsequent transformation experiments showed that hygromycin resistance genes (hrg) could be successfully transferred into the genome of Eutypella sp. D-1, indicating that the prepared protoplasts could meet the needs of subsequent gene manipulation and research. This study lays a foundation for the genetic transformation of Eutypella sp. D-1.

Chemical epigenetic manipulation triggers the production of sesquiterpenes from the deep-sea derived Eutypella fungus

Chemical epigenetic manipulation of a deep-sea-derived Eutypella sp. fungus by the co-treatment with a histonedeacetylase inhibitor (suberohydroxamic acid, SBHA) and a DNA methyltransferase inhibitor (5-azacytidine, 5-Aza), resulted in the activation of a sesquiterpene-related biosynthetic gene cluster. Chromatographic separation of the elicitor-treated cultures led the isolation of 21 sesquiterpenes, including 17 undescribed compounds, eutypeterpenes A-Q. Their structures were identified by the extensive analysis of the spectroscopic data, including the single-crystal X-ray diffraction, chemical conversion, and the calculated NMR and ECD data for configurational assignments. Eutypeterpene A is a first bergamotene-type sesquiterpene incorporated with a dioxolanone unit, and eutypeterpenes O-Q with a cyclopentane ring represent an undescribed subtype of sesquiterpenes. The bioassay results showed that most compounds exert inhibitory effects against the lipopolysaccharide (LPS)-induced NO production in RAW 264.7 macrophages, and eutypeterpene N is the most active. This study demonstrates that the epigenetic manipulation is an effective approach to trigger the production of cryptic metabolites from deep-sea derived fungus. The significant inhibition against LPS-induced NO production in vitro suggests eutypeterpenes to be potential for the development as anti-inflammatory agents.

Sesquiterpenes and Steroids from an Endophytic Eutypella scoparia

A chemical investigation on the EtOAc extract of the endophytic fungus Eutypella scoparia SCBG-8 led to the isolation of eight new sesquiterpenes eutyscoparins A-H (1-8), one C-28 steroid eutyscoparene A (9), one triterpenoid eutyscoparene B (10), six known terpenoids, and two known steroids. Their structures including absolute configurations were established on the basis of spectroscopic data analysis, single-crystal X-ray diffraction experiments, and electronic circular dichroism (ECD) calculations. Compound 7 displayed antibacterial activity against S. aureus and MRSA (methicillin-resistant Staphylococcus aureus) with MIC values of 6.3 μg/mL.

Bioactive metabolites from the Arctic fungus Nectria sp. B-13

Two new cyclohexanone derivatives, nectriatones A-B (1-2), and one new natural product, nectriatone C (3), together with three known phenolic sesquiterpene derivatives (4-6), were isolated from the culture of Nectria sp. B-13 obtained from high-latitude soil of the Arctic. The structures of all compounds were unambiguously elucidated by extensive spectroscopic analysis, as well as by comparison with the literature. These compounds were evaluated in cytotoxic and antibacterial activities. Compounds 1-6 showed cytotoxicities against SW1990, HCT-116, MCF-7, and K562 cells, with IC₅₀ values in the range of 0.43 to 42.64 μM. Only compound 4 exhibited antibacterial activity against Escherichisa coli, Bacillus subtilis, and Staphylococcus aureus (MIC 4.0, 2.0, and 4.0 μg/ml, respectively).

Diversity of biologically active secondary metabolites from endophytic and saprotrophic fungi of the ascomycete order Xylariales

Covering: up to December 2017 The diversity of secondary metabolites in the fungal order Xylariales is reviewed with special emphasis on correlations between chemical diversity and biodiversity as inferred from recent taxonomic and phylogenetic studies. The Xylariales are arguably among the predominant fungal endophytes, which are the producer organisms of pharmaceutical lead compounds including the antimycotic sordarins and the antiparasitic nodulisporic acids, as well as the marketed drug, emodepside. Many Xylariales are "macromycetes", which form conspicuous fruiting bodies (stromata), and the metabolite profiles that are predominant in the stromata are often complementary to those encountered in corresponding mycelial cultures of a given species. Secondary metabolite profiles have recently been proven highly informative as additional parameters to support classical morphology and molecular phylogenetic approaches in order to reconstruct evolutionary relationships among these fungi. Even the recent taxonomic rearrangement of the Xylariales has been relying on such approaches, since certain groups of metabolites seem to have significance at the species, genus or family level, respectively, while others are only produced in certain taxa and their production is highly dependent on the culture conditions. The vast metabolic diversity that may be encountered in a single species or strain is illustrated based on examples like Daldinia eschscholtzii, Hypoxylon rickii, and Pestalotiopsis fici. In the future, it appears feasible to increase our knowledge of secondary metabolite diversity by embarking on certain genera that have so far been neglected, as well as by studying the volatile secondary metabolites more intensively. Methods of bioinformatics, phylogenomics and transcriptomics, which have been developed to study other fungi, are readily available for use in such scenarios.

Libertellenones O-S and Eutypellenones A and B, Pimarane Diterpene Derivatives from the Arctic Fungus Eutypella sp. D-1

Seven new pimarane-type diterpene derivatives, libertellenones O-S (1-5) and eutypellenones A and B (6 and 7), together with two known compounds (8 and 9), were isolated from the culture of Eutypella sp. D-1 obtained from high-latitude soil of the Arctic. Their structures were elucidated from spectroscopic data, as well as experimental and calculated electronic circular dichroism (ECD) analysis. Structurally, compounds 1-5 possess a cyclopropyl-fused pimarane diterpene moiety, whereas compounds 6 and 7 share an unusual cyclobutyl-fused pimarane diterpene skeleton. Compounds 1-9 exhibited cytotoxicities against HeLa, MCF-7, HCT-116, PANC-1, and SW1990 cells, with IC₅₀ values in the range of 0.3 to 29.4 μM. Compounds 6 and 7 could dose-dependently inhibit the activity of NF-κB and exhibited significantly inhibitory effects on nitric oxide production induced by lipopolysaccharide.

Novel Natural Products from Extremophilic Fungi

Extremophilic fungi have been found to develop unique defences to survive extremes of pressure, temperature, salinity, desiccation, and pH, leading to the biosynthesis of novel natural products with diverse biological activities. The present review focuses on new extremophilic fungal natural products published from 2005 to 2017, highlighting the chemical structures and their biological potential.

Bioactive Pimarane Diterpenes from the Arctic Fungus Eutypella sp. D-1

Two new pimarane diterpenes, libertellenone M (1) and libertellenone N (2), together with five known compounds were isolated from the culture extract of Eutypella sp. D-1 derived from high-latitude soil of the Arctic. The structures of these compounds were determined by spectroscopic data as well as experimental and calculated electronic circular dichroism (ECD) analysis. Antimicrobial and cytotoxic activities of the isolated compounds were evaluated. Compound 3 exhibited weak antibacterial activity against Escherichia coli, Bacillus subtilis, and Vibrio vulnificus, each with MIC values of 16 μg/mL. Compounds 2 and 3 showed moderate cytotoxic activity against K562 and MCF-7 cell lines with IC₅₀ values of 7.67 and 9.57 μm, respectively.