Highly oxygenated isoprenylated cyclohexanoids from the fungus Parastagonospora nodorum SN15

Discovery of Novel Phenolic Compounds from Eutypa lata Through OSMAC Approach: Structural Elucidation and Antibiotic Potential

Among grapevine trunk diseases, Eutypa dieback, caused by the fungus Eutypa lata, is one of the most critical ones, due to its widespread infection in vineyards and the lack of effective treatments. This fungus is a vascular pathogen that enters grapevines through pruning wounds. The infection process is associated with phytotoxic metabolites produced by the fungus, and as such, the identification of new metabolites from different culture conditions and broths could provide valuable insights into the fungus's enzymatic system and help its control. For the purposes of this study, the OSMAC (one strain, many compounds) approach was applied to investigate the secondary metabolism of E. lata strain 311 isolated from Vitis vinifera plants in Spain. A total of twenty metabolites were isolated, including five reported for the first time from E. lata and four that are newly identified compounds in the literature: eulatagalactoside A, (R)-2-(4'-hydroxy-3'-methylbut-1'-yn-1'-yl)-4-(hydroxymethyl)phenol, (S)-7-hydroxymethyl-3-methyl-2,3-dihydro-1-benzoxepin-3-ol, and (3aR,4S,5R,7aS)-4,5-dihydroxy-6-((R)-3'-methylbuta-1',3'-dien-1'-ylidene)hexahydrobenzo[d][1,3]dioxol-2-one. These compounds were extracted from fermentation broths using silica gel column chromatography and high-performance liquid chromatography (HPLC). Their structures were elucidated through extensive 1D and 2D NMR spectroscopy, along with high-resolution electrospray ionization mass spectrometry (HRESIMS). Compounds were evaluated for phytotoxicity against Phaseolus vulgaris, with only eulatagalactoside A producing white spots after 48 h. Additionally, the antibacterial activity against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae of selected compounds was tested. The compounds (R)-2-(4'-hydroxy-3'-methylbut-1'-yn-1'-yl)-4-(hydroxymethyl)phenol and (S)-7-(hydroxymethyl)-3-methyl-2,3-dihydrobenzo[b]oxepin-3-ol showed the most significant antimicrobial activity against Gram-positive bacteria, inhibiting S. aureus by over 75%, with IC50 values of 511.4 µg/mL and 617.9 µg/mL, respectively.

The cytochalasans: potent fungal natural products with application from bench to bedside

Covering: 2000-2023Cytochalasans are a fascinating class of natural products that possess an intricate chemical structure with a diverse range of biological activities. They are known for their complex chemical architectures and are often isolated from various fungi. These compounds have attracted attention due to their potential pharmacological properties, including antimicrobial, antiviral, and anticancer effects. For decades, researchers have studied these molecules to better understand their mechanisms of action and to explore their potential applications in medicine and other fields. This review article aims to shed light over the period 2000-2023 on the structural diversities of 424 fungal derived cytochalasans, insights into their biosynthetic origins, pharmacokinetics and their promising therapeutic potential in drug discovery and development.

New Hydrogenated Phenanthrene Glycosides from the Edible Vegetable Elatostema tenuicaudatum W.T.Wang with DPP-IV Inhibitory and Hepatoprotective Activity

Based on molecular networking-guided isolation, 15 previously undescribed hydrogenated phenanthrene glycosides, including eight hexahydro-phenanthrenone glycosides, four tetrahydro-phenanthrenone glycosides, one dihydro-phenanthrenol glycoside, two dimers, and two known dihydrophenanthrene glycosides, were isolated from Elatostema tenuicaudatum W.T.Wang, a popular regional edible vegetable at the northwest region of Vietnam. Their chemical structures were determined using extensive spectroscopic data: NMR and ECD calculations. Notably, the crude extract, along with compounds 5, 6, 8, and 14, demonstrated dipeptidyl peptidase IV inhibitory activity with IC50 values of 220.5 ± 39.6 μg/mL, 141.7 ± 15.6, 151.2 ± 11.8, 107.9 ± 19.6, and 71.9 ± 8.9 μM, respectively. Molecular docking indicates compound 14 possesses the highest binding affinity with DPP-IV. Besides, compounds 1, 9, 11, and 14 exhibited significant hepatoprotective effects in acetaminophen-induced hepatotoxicity in HepG2. These findings suggested that E. tenuicaudatum can serve as a beneficial vegetable for individuals at risk of diabetes and chronic liver disease.

Deciphering the potential of Cymbopogon citratus (DC.) Stapf as an anti-obesity agent: phytochemical profiling, in vivo evaluations and molecular docking studies

Based on its anti-inflammatory and antioxidant properties, Cymbopogon citratus (DC) Stapf is commonly used in traditional and modern medicine to cure different diseases. The present study investigates the potential of C. citratus organic extract as an anti-obesity drug in a HCHFD (high-carbohydrate, high-fat diet) model for obese rats. Its negative hypolipidemic effect has been confirmed through biochemical and histological methods. Fifty male albino rats were randomly divided into five groups (10 rats each) Group I (Control group), Group II (HCHFD group), Group III (C. citratus group), Group IV (HCHFD + C. citratus group) and Group V (HCHFD + Orlistat group). Serum glucose levels and lipid profiles were quantified using a spectrophotometer. Insulin, apelin, and adiponectin parameters were measured using ELISA (enzyme-linked immunosorbent assay) kits, while real-time PCR following extraction and purification was used for apelin, apelin receptor genes (APJ), and adiponectin gene expression evaluation. Besides, C. citratus methanolic extract was subjected to untargeted metabolic profiling via RP-HPLC-QTOF-MS and MS/MS, disclosing the presence of 52 secondary metabolites where they mainly belonged to phenolic compounds viz., flavones and hydroxycinnamic acids, among other metabolites with predominance of derivatives of luteolin and O-coumaroyl-O-feruloylglycerol. Our findings were further strengthened by computational-based virtual screening protocols that included molecular docking (MDock) and Structure-Activity Relationships (SARs). The MDock studies revealed that the three main flavone-containing metabolites, each with a luteolin C6-glycosylation core featuring two sugar units (16, 25, and 31), outperformed the positive control (8EH, a triazole derivative) known to bind to the APJ protein. These metabolites exhibited exceptional binding affinities, with estimated free binding energy (ΔGB) values of -9 kcal mol-1 or lower, likely due to potential hydrogen bond interactions with the Arg168 residue of the APJ protein. Additionally, the pharmacokinetic, physicochemical, and toxicity profiles of the 11 major metabolites from C. citratus leaf extract were assessed, revealing a profile like that of the positive control in the three selected flavone metabolites. Based on the acquired data, it can be concluded that C. citratus shows strong potential as a hypolipidemic agent and could play a significant role in managing obesity and mitigating its associated complications.

Investigating the antiviral therapeutic potentialities of marine polycyclic lamellarin pyrrole alkaloids as promising inhibitors for SARS-CoV-2 and Zika main proteases (Mpro)

The new coronavirus variant (SARS-CoV-2) and Zika virus are two world-wide health pandemics. Along history, natural products-based drugs have always crucially recognized as a main source of valuable medications. Considering the SARS-CoV-2 and Zika main proteases (Mpro) as the re-production key element of the viral cycle and its main target, herein we report an intensive computer-aided virtual screening for a focused list of 39 marine lamellarins pyrrole alkaloids, against SARS-CoV-2 and Zika main proteases (Mpro) using a set of combined modern computational methodologies including molecular docking (MDock), molecule dynamic simulations (MDS) and structure-activity relationships (SARs) as well. Indeed, the molecular docking studies had revealed four promising marine alkaloids including [lamellarin H (14)/K (17)] and [lamellarin S (26)/Z (39)], according to their notable ligand-protein energy scores and relevant binding affinities with the SARS-CoV-2 and Zika (Mpro) pocket residues, respectively. Consequentially, these four chemical hits were further examined thermodynamically though investigating their MD simulations at 100 ns, where they showed prominent stability within the accommodated (Mpro) pockets. Moreover, in-deep SARs studies suggested the crucial roles of the rigid fused polycyclic ring system, particularly aromatic A- and F- rings, position of the phenolic -OH and δ-lactone functionalities as essential structural and pharmacophoric features. Finally, these four promising lamellarins alkaloids were investigated for their in-silico ADME using the SWISS ADME platform, where they displayed appropriated drug-likeness properties. Such motivating outcomes are greatly recommending further in vitro/vivo examinations regarding those lamellarins pyrrole alkaloids (LPAs).Communicated by Ramaswamy H. Sarma.

Recent advances in the discovery, biosynthesis, and therapeutic potential of isocoumarins derived from fungi: a comprehensive update

Microorganisms still remain the main hotspots in the global drug discovery avenue. In particular, fungi are highly prolific producers of vast structurally diverse specialized secondary metabolites, which have displayed a myriad of biomedical potentials. Intriguingly, isocoumarins is one distinctive class of fungal natural products polyketides, which demonstrated numerous remarkable biological and pharmacological activities. This review article provides a comprehensive state-of-the-art over the period 2000-2022 about the discovery, isolation, classifications, and therapeutic potentials of isocoumarins exclusively reported from fungi. Indeed, a comprehensive list of 351 structurally diverse isocoumarins were documented and classified according to their fungal sources [16 order/28 family/55 genera] where they have been originally discovered along with their reported pharmacological activities wherever applicable. Also, recent insights around their proposed and experimentally proven biosynthetic pathways are also briefly discussed.

Chemical diversity, medicinal potentialities, biosynthesis, and pharmacokinetics of anthraquinones and their congeners derived from marine fungi: a comprehensive update

Marine fungi receive excessive attention as prolific producers of structurally unique secondary metabolites, offering promising potential as substitutes or conjugates for current therapeutics, whereas existing research has only scratched the surface in terms of secondary metabolite diversity and potential industrial applications as only a small share of bioactive natural products have been identified from marine-derived fungi thus far. Anthraquinones derived from filamentous fungi are a distinct large group of polyketides containing compounds which feature a common 9,10-dioxoanthracene core, while their derivatives are generated through enzymatic reactions such as methylation, oxidation, or dimerization to produce a large variety of anthraquinone derivatives. A considerable number of reported anthraquinones and their derivatives have shown significant biological activities as well as highly economical, commercial, and biomedical potentialities such as anticancer, antimicrobial, antioxidant, and anti-inflammatory activities. Accordingly, and in this context, this review comprehensively covers the state-of-art over 20 years of about 208 structurally diverse anthraquinones and their derivatives isolated from different species of marine-derived fungal genera along with their reported bioactivity wherever applicable. Also, in this manuscript, we will present in brief recent insights centred on their experimentally proved biosynthetic routes. Moreover, all reported compounds were extensively investigated for their in-silico drug-likeness and pharmacokinetics properties which intriguingly highlighted a list of 20 anthraquinone-containing compounds that could be considered as potential drug lead scaffolds.

The chemistry and biology of fungal meroterpenoids (2009-2019)

Fungal meroterpenoids are secondary metabolites from mixed terpene-biosynthetic origins. Their intriguing chemical structural diversification and complexity, potential bioactivities, and pharmacological significance make them attractive targets in natural product chemistry, organic synthesis, and biosynthesis. This review provides a systematic overview of the isolation, chemical structural features, biological activities, and fungal biodiversity of 1585 novel meroterpenoids from 79 genera terrestrial and marine-derived fungi including macrofungi, Basidiomycetes, in 441 research papers in 2009-2019. Based on the nonterpenoid starting moiety in their biosynthesis pathway, meroterpenoids were classified into four categories (polyketide-terpenoid, indole-, shikimate-, and miscellaneous-) with polyketide-terpenoids (mainly tetraketide-) and shikimate-terpenoids as the primary source. Basidiomycota produced 37.5% of meroterpenoids, mostly shikimate-terpenoids. The genera of Ganoderma, Penicillium, Aspergillus, and Stachybotrys are the four dominant producers. Moreover, about 56% of meroterpenoids display various pronounced bioactivities, including cytotoxicity, enzyme inhibition, antibacterial, anti-inflammatory, antiviral, antifungal activities. It's exciting that several meroterpenoids including antroquinonol and 4-acetyl antroquinonol B were developed into phase II clinically used drugs. We assume that the chemical diversity and therapeutic potential of these fungal meroterpenoids will provide biologists and medicinal chemists with a large promising sustainable treasure-trove for drug discovery.

Phytotoxic Secondary Metabolites from Fungi

Fungal phytotoxic secondary metabolites are poisonous substances to plants produced by fungi through naturally occurring biochemical reactions. These metabolites exhibit a high level of diversity in their properties, such as structures, phytotoxic activities, and modes of toxicity. They are mainly isolated from phytopathogenic fungal species in the genera of Alternaria, Botrytis, Colletotrichum, Fusarium, Helminthosporium, and Phoma. Phytotoxins are either host specific or non-host specific phytotoxins. Up to now, at least 545 fungal phytotoxic secondary metabolites, including 207 polyketides, 46 phenols and phenolic acids, 135 terpenoids, 146 nitrogen-containing metabolites, and 11 others, have been reported. Among them, aromatic polyketides and sesquiterpenoids are the main phytotoxic compounds. This review summarizes their chemical structures, sources, and phytotoxic activities. We also discuss their phytotoxic mechanisms and structure-activity relationships to lay the foundation for the future development and application of these promising metabolites as herbicides.

Trinor- and tetranor-eremophilane sesquiterpenoids with anti-neuroinflammatory activity from cultures of the fungus Septoria rudbeckiae

Fifteen eremophilane sesquiterpenoids, including nine undescribed congeners, septeremophilane A-H, and chaetopenoid G, together with four conjugated unsaturated polyketide fatty acids, including an undescribed derivative, were isolated from cultures of the fungus Septoria rudbeckiae, a plant pathogenic fungus isolated from the halophyte Karelinia caspia. Septeremophilane A represents an unprecedented tetranor-eremophilane sesquiterpenoid with an α,β-unsaturated δ-lactone unit bearing a hemiacetal group, while septeremophilane B-H possesses a trinor-eremophilane skeleton. Their structures and absolute configurations were established based on spectroscopic data (NMR and HRESIMS), quantum chemical calculations and electronic circular dichroism (ECD) experiments. All metabolites were tested for nitric oxide (NO) production inhibition in lipopolysaccharide (LPS)-activated BV-2 microglial cells, while dendryphiellin D, septeremophilane D, and septeremophilane E were found to display significant inhibition, with IC₅₀ values of 11.9 ± 1.0, 8.5 ± 0.1, and 6.0 ± 0.2 μM, respectively.

Genomics-Driven Discovery of Phytotoxic Cytochalasans Involved in the Virulence of the Wheat Pathogen Parastagonospora nodorum

The etiology of fungal pathogenesis of grains is critical to global food security. The large number of orphan biosynthetic gene clusters uncovered in fungal plant pathogen genome sequencing projects suggests that we have a significant knowledge gap about the secondary metabolite repertoires of these pathogens and their roles in plant pathogenesis. Cytochalasans are a family of natural products of significant interest due to their ability to bind to actin and interfere with cellular processes that involved actin polymerization; however, our understanding of their biosynthesis and biological roles remains incomplete. Here, we identified a putative polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) gene cluster (phm) that was upregulated in the pathogen Parastagonospora nodorum during its infection on wheat. Overexpression of the transcription factor gene phmR encoded in the phm gene cluster resulted in the production of two leucine-derived cytochalasans, phomacins D and E (1 and 2, respectively), and an acetonyl adduct phomacin F. Heterologous expression of the PKS-NRPS gene phmA and the trans-enoyl reductase (ER) gene phmE in Aspergillus nidulans resulted in the production of a novel 2-pyrrolidone precursor prephomacin. Reverse genetics and wheat seedling infection assays showed that ΔphmA mutants exhibited significantly reduced virulence compared to the wild type. We further demonstrated that both 1 and 2 showed potent actin polymerization-inhibitory activities and exhibited potentially monocot-specific antigerminative activities. The findings from this study have advanced our knowledge based on the biosynthesis and biological roles of cytochalasans, the latter of which could have significant implications for our understanding of the molecular mechanisms of fungus-plant interactions.