Paraconiothins A-J: Sesquiterpenoids from the Endophytic Fungus Paraconiothyrium brasiliense ECN258

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.

Diversity of Endophytes of Actinidia arguta in Different Seasons

The seasonal changes in environmental conditions can alter the growth states of host plants, thereby affecting the living environment of endophytes and forming different endophytic communities. This study employs Illumina MiSeq next-generation sequencing to analyze the 16SrRNA and ITS rDNA of endophytes in 24 samples of Actinidia arguta stem tissues across different seasons. The results revealed a high richness and diversity of endophytes in Actinidia arguta, with significant seasonal variations in microbial community richness. This study identified 897 genera across 36 phyla for bacteria and 251 genera across 8 phyla for fungi. Notably, 69 bacterial genera and 19 fungal genera significantly contributed to the differences in community structure across seasons. A distinctive feature of coexistence in the endophytic community, both specific and conservative across different seasons, was observed. The bacterial community in winter demonstrated significantly higher richness and diversity compared to the other seasons. Environmental factors likely influence the optimal timing for endophyte colonization. Solar radiation, temperature, precipitation, and relative humidity significantly impact the diversity of endophytic bacteria and fungi. In addition, seasonal variations show significant differences in the nutritional modes of fungal endophytes and the degradation, ligninolysis, and ureolysis functions of bacterial endophytes. This study elucidates the potential role of endophytes in assisting Actinidia arguta in adapting to seasonal changes and provides a theoretical basis for further exploration of functional microbial strains.

Terpenoids from the endophytic fungus Microdiplodia sp. and their anti-inflammatory activities

Motivated by the potential anti-inflammatory effect of the crude extract of endophytic fungus Microdiplodia sp. CJ01 derived from Camellia sinensis, chemical investigation of the extract of Microdiplodia sp. CJ01 led to the isolation and identification of sixteen terpenoids, including five undescribed eremophilane sesquiterpenoids named microdiplodins A-E (1-5), one undescribed meroterpenoid 13-carboxymacrophorin A (13), seven known eremophilane sesquiterpenoids (6-12), and three known meroterpenoids (14-16). The structures of these compounds were elucidated based on extensive spectroscopic analysis, including nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) data. Their absolute configurations were determined by calculational and experimental electronic circular dichroism (ECD) data. Anti-inflammatory activity assays revealed that compounds 3, 4, 14-16 exhibited moderate inhibitory effects on the production of nitric oxide (NO) in the lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells.

Antifungal and antifeedant terpenoids from Paraphaeosphaeria sp. cultured by extract of host Ginkgo biloba

Five undescribed terpenoids including a polyketide-terpenoid hybrid paraphaone, and four eremophilane sesquiterpenoids, paraphaterpenes A-D, as well as two known compounds were isolated from the endophytic fungus Paraphaeosphaeria sp. cultured by extract of host Ginkgo biloba L. The structures were established by spectroscopic analyses, and the single-crystal X-ray diffraction. The antifungal activity of Paraphaeosphaeria sp. cultured by extract of G. biloba against the plant pathogen Alternaria alternata was significant and higher than that of PDB medium. Tested compounds indicated antifeedant activities against silkworms with feeding deterrence index at 10-70%. Paraphaone, paraphaterpenes A, C, D and alternariol methyl ether showed significant antifungal activities against the phytopathogens A. alternata, Aspergillus fumigatus, and entomopathogen Beauveria bassiana with MICs ≤4 μg/mL. And the preliminary structure-activity relationship of eremophilane sesquiterpenoids was exhibited. The culture of Paraphaeosphaeria sp. by host G. biloba medium afforded agricultural antibiotics.

A taxonomic assessment of novel and remarkable fungal species in Didymosphaeriaceae (Pleosporales, Dothideomycetes) from plant litter

Fungal taxonomy has a long history and changed significantly in the last few decades. Most recent studies have witnessed morphology combined with DNA-based molecular analyses as the main research tool for fungal species identification. During field surveys, some interesting Didymosphaeriaceae species were found from plant litter in China and Thailand. Morphology combined with phylogenetic analyses (Bayesian and maximum likelihood) of ITS, LSU, SSU, tef1-α, and tub2 loci was used to identify fungal taxa. In this article, three new species and six new host records are described. The new species, Montagnula acaciae, Paraconiothyrium zingiberacearum, and Paraphaeosphaeria brachiariae, can be distinguished from other species of the respective genera based on their distinct size differences (ascomata, asci, and ascospores) and DNA sequence data. The new host records, Montagnula jonesii, Paraconiothyrium fuckelii, Spegazzinia deightonii, and S. tessarthra are reported from Ficus benjamina, Dimocarpus longan, Hedychium coronarium, and Acacia auriculiformis respectively, for the first time. Also, Paraconiothyrium archidendri and P. brasiliense are reported for the first time from Magnolia sp. in China. Moreover, Paraconiothyrium rosae is synonymized under P. fuckelii based on close phylogeny affinities and morphological characteristics. In-depth morphological descriptions, micrographs, and phylogenetic trees are provided to show the placement of new taxa.

Antitobacco Mosaic Virus Activity of a New Eremophilane Glucoside From the Leaves of Nicotiana tabacum L

A new eremophilane-type sesquiterpene glucoside, 13-hydroxycapsidiol 3- O- β-D-glucoside (1), was isolated from the leaves of Nicotiana tabacum L. The structure of this new metabolite was determined by one-dimensional (1D) and 2D nuclear magnetic resonance (NMR) spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and comparison with values reported in the literature. Compound 1 was the second glycosylated eremophilane sesquiterpenoid isolated from plants of the Solanaceae family and exhibited a more potent anti-tobacco mosaic virus (anti-TMV) activity, with an inhibition rate of 39.4% at 20 μM, than the positive control ningnanmycin (34.8%).

Cumulative Data of 1H and 13C NMR Signals and Specific Rotations of Eremophilane Sesquiterpenoids. 1. Bicyclic Eremophilanes (1)

1H and 13C Nuclear Magnetic Resonance (NMR) signals and specific rotations of eremophilane sesquiterpenoids are cumulated as a series of review articles. In the first chapter of this review, 332 bicyclic eremophilanes, namely with no furan or lactone rings (except for epoxides), without 3-OR functionality (except for hydroxy, acetoxy, and carbonyl) are listed in tables. These data may help chemists working in the area of natural products chemistry as well as synthetic scientists.

Brasilterpenes A-E, Bergamotane Sesquiterpenoid Derivatives with Hypoglycemic Activity from the Deep Sea-Derived Fungus Paraconiothyrium brasiliense HDN15-135

Five bergamotane sesquiterpenoid derivatives, brasilterpenes A-E (1-5), bearing an unreported spiral 6/4/5 tricyclic ring system, were isolated from the deep sea-derived ascomycete fungus Paraconiothyrium brasiliense HDN15-135. Their structures, including absolute configurations, were established by extensive spectroscopic methods complemented by single-crystal X-ray diffraction analyses, electronic circular dichroism (ECD), and density-functional theory (DFT) calculations of nuclear magnetic resonance (NMR) data including DP4+ analysis. The hypoglycemic activity of these compounds was assessed using a diabetic zebrafish model. Brasilterpenes A (1) and C (3) significantly reduced free blood glucose in hyperglycemic zebrafish in vivo by improving insulin sensitivity and suppressing gluconeogenesis. Moreover, the hypoglycemic activity of compound 3 was comparable to the positive control, anti-diabetes drug rosiglitazone. These results suggested brasilterpene C (3) had promising anti-diabetes potential.

Bioactive terpenoids derived from plant endophytic fungi: An updated review (2011-2020)

Plant endophytes have been considered as novel sources of naturally occurring compounds with various biological activities, including cytotoxic, antimicrobial, anti-inflammatory, anticancer, herbicides, antileishmanial and antioxidant. A variety of specialised products, comprising terpenoids, alkaloids, polyketides, phenolic compounds, coumarins, and quinone derivatives have been reported from various strains. An increasing number of products, especially terpenoids, are being isolated from endophytes. Herein, the isolated new terpenoids from plant endophytic fungi, their hosts, as well as biological activities, from January 2011 until the end of 2020 are reviewed. In this period, 516 terpenoids are classified into monoterpenes (5), sesquiterpenes (299), diterpenes (76), sesterterpens (22), meroterpenes (83), triterpenes (29), and other terpenoids (2), were isolated from different plant endophytic fungi species.

A New NPolyketide from Marine-Derived Paraconiothyrium sp

A new polyketide, paraconthone A (1) was obtained from the fermentation culture of Paraconiothyrium sp., together with two known compounds (2-3). Their structures were elucidated by spectroscopic analyses, including 1D- and 2D-NMR experiments, HR-ESI-MS, ECD calculation and by comparison with reported data. Compounds 1 to 3 were evaluated for their cytotoxic, anti-inflammation and antimicrobial activities in vitro, and 1 to 3 showed weak anti-microbial activities.

Citreobenzofuran D–F and Phomenone A–B: Five Novel Sesquiterpenoids from the Mangrove-Derived Fungus Penicillium sp. HDN13-494

Five new sesquiterpenoids, citreobenzofuran D–F (1–3) and phomenone A–B (4–5), along with one known compound, xylarenone A (6), were isolated from the culture of the mangrove-derived fungus Penicillium sp. HDN13-494. Their structures were deduced from extensive spectroscopic data, high-resolution electrospray ionization mass spectrometry (HRESIMS), and electronic circular dichroism (ECD) calculations. Furthermore, the absolute structures of 1 were determined by single-crystal X-ray diffraction analysis. Citreobenzofuran E–F (2–3) are eremophilane-type sesquiterpenoids with rare benzofuran frameworks, while phomenone A (4) contains a rare thiomethyl group, which is the first report of this kind of sesquiterpene with sulfur elements in the skeleton. All the compounds were tested for their antimicrobial and antitumor activity, and phomenone B (5) showed moderate activity against Bacillus subtilis, with an MIC value of 6.25 μM.

Natural Products Targeting Liver X Receptors or Farnesoid X Receptor

Nuclear receptors (NRs) are a superfamily of transcription factors induced by ligands and also function as integrators of hormonal and nutritional signals. Among NRs, the liver X receptors (LXRs) and farnesoid X receptor (FXR) have been of significance as targets for the treatment of metabolic syndrome-related diseases. In recent years, natural products targeting LXRs and FXR have received remarkable interests as a valuable source of novel ligands encompassing diverse chemical structures and bioactive properties. This review aims to survey natural products, originating from terrestrial plants and microorganisms, marine organisms, and marine-derived microorganisms, which could influence LXRs and FXR. In the recent two decades (2000-2020), 261 natural products were discovered from natural resources such as LXRs/FXR modulators, 109 agonists and 38 antagonists targeting LXRs, and 72 agonists and 55 antagonists targeting FXR. The docking evaluation of desired natural products targeted LXRs/FXR is finally discussed. This comprehensive overview will provide a reference for future study of novel LXRs and FXR agonists and antagonists to target human diseases, and attract an increasing number of professional scholars majoring in pharmacy and biology with more in-depth discussion.

Two new ɑ-pyrone derivatives from the endophytic Diaporthe sp. ECN371

Diaportholides A (1) and B (2), two polyketides with ɑ-pyrone moieties, were isolated from the cultures of an endophytic Diaporthe sp. ECN371 isolated from Orixa japonica, together with four known polyketides, phomopsolide B (3), phomopsolidones A (4) and B (5), and 5-[(1R)-1-hydroxyethyl]-γ-oxo-2-furanbutanoic acid (6). The structures of 1 and 2 were determined by extensive analysis of NMR and MS spectroscopic data. Furthermore, the structure of 2 was confirmed by analyzing the single-crystal X-ray diffraction data. The luciferase reporter gene assay revealed that among all isolated compounds (1-6), 3, a known ɑ-pyrone derivative, exhibited agonistic activity against the peroxisome proliferator-activated receptor ɑ, which is an important regulator of lipid metabolism in humans.

Eremophilane Sesquiterpenoids with Antibacterial and Anti-inflammatory Activities from the Endophytic Fungus Septoria rudbeckiae

Fourteen eremophilane sesquiterpenoids (1-14), including nine new congeners, septoreremophilanes A-I (1-9), together with three known sesquiterpenes (15-17), two known tetralone derivatives (18, 19), and two known cholesterol analogues (20, 21), were isolated from the endophytic fungus Septoria rudbeckiae. Compounds 1-6 and 7a belong to the family of the highly oxygenated eremophilane sesquiterpenoids with a 6/6/5 tricyclic system and bearing a hemiacetal moiety. The inhibitions of all metabolites against eight bacteria were estimated in vitro, and nine new metabolites (1-9) were tested for antineuroinflammatory activity. Notably, the effects of 4 against Pseudomonas syringae pv. actinidae and 20 against Bacillus cereus displayed potent inhibitory, with the MIC values of 6.25 and 6.25 μM, respectively. Further, scanning electron microscopy analyses indicated that 4 and 20 were to change the outer configuration of bacterial cells, respectively, and the investigations demonstrated that 4 and 20 may act as potential structure templates for the development of the agrochemical bactericides. Additionally, compound 6 displayed potent inhibition of NO generation in lipopolysaccharide-induced BV-2 microglial cells (IC₅₀ = 12.0 ± 0.32 μM), and the conceivable anti-inflammatory mechanisms implicated were also investigated by molecular docking. Thus, the bioactive metabolites of the strain S. rudbeckiae may serve as a novel resource to be developed.

The genus Paraconiothyrium: species concepts, biological functions, and secondary metabolites

The genus Paraconiothyrium has worldwide distribution with diverse host habitats and exhibits potential utilisation as biocontrol agent, bioreactor and antibiotic producer. In this review, we firstly comprehensively summarise the current taxonomic status of Paraconiothyrium species, including their category names, morphological features, habitats, and multigene phylogenetic relationships. Some Paraconiothyrium species possess vital biological functions and potential applications in medicine, agriculture, industry, and environmental protection. A total of 147 secondary metabolites have been reported so far from Paraconiothyrium, among which 95 are novel. This paper serves to provide an overview of their diverse structures with chemical classification and biological activities. To date, 27 species of Paraconiothyrium have been documented; however, only seven have been investigated for their secondary metabolites or biological functions. Our review is expected to draw more attention to this genus for providing a taxonomic reference, discovering extensive biological functions, and searching in-depth for new bioactive natural products.

Cadinane- and drimane-type sesquiterpenoids produced by Paecilomyces sp. TE-540, an endophyte from Nicotiana tabacum L., are acetylcholinesterase inhibitors

Sesquiterpenoids with diverse skeleton types are regarded as potential lead compounds in pharmacological and other applications. Herein, we report the discovery of two new cadinane-type sesquiterpenoids, paecilacadinol A (1) and B (2); two new drimane-type sesquiterpenoids, ustusol D (3) and ustusol E (4); and six known analogs (5-10) from the endophytic fungus Paecilomyces sp. TE-540, enriching the structural diversity of naturally occurring sesquiterpenoids. Their planar structures were determined on the basis of detailed interpretation of 1D and 2D NMR spectroscopy and HRESIMS data, while their stereochemical structures were established by X-ray crystallographic analyses for 1 and 3-8 and theoretical calculations for 2. Notably, compounds 1 and 2 represent novel examples of cadinane-type sesquiterpenoids with ether bonds formed by intramolecular dehydration. Compounds 5 and 6 showed moderate activities against acetylcholinesterase (AChE), with IC50 values of 43.02 ± 6.01 and 35.97 ± 2.12 μM, respectively. Docking analysis predicted that 5 bound well in the catalytic pocket of AChE via hydrophobic interactions with Trp84, Gly117, Ser122, and Tyr121 residues, while 6 was located with Asp72 and Ser122 residues.

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

Two new azaphilones, namely muyocopronones A (1) and B (2), were isolated from the cultures of an endophytic fungus Muyocopron laterale ECN279. Their structures were elucidated by extensive spectroscopic analysis. Their absolute configurations were determined using the modified Mosher’s method and through comparisons of experimental and calculated electronic circular dichroism data. In addition, muyocopronone B (2) was found to exhibit a weak antibacterial activity against some Gram-positive bacteria.

Absolute configurations of talaromycones A and B, α-diversonolic ester, and aspergillusone B from endophytic Talaromyces sp. ECN211

Talaromycones A (1) and B (2), new xanthenediones, were isolated from the cultures of Talaromyces sp. ECN211, an endophytic fungus, along with α-diversonolic ester (3), aspergillusone B (4), glauconic acid (5), and rosellisin (6). The planar structures of 1 and 2 were elucidated by extensive spectroscopic analyses. Furthermore, the absolute configurations of 1–4 were determined by single-crystal X-ray diffraction and electronic circular dichroism spectroscopy (ECD). In addition, the crystallographic data for 5 were updated for the first time in over 50 years.