Herpotrichones A and B, Two Intermolecular [4 + 2] Adducts with Anti-Neuroinflammatory Activity from a Herpotrichia Species

Fungal Coculture of Herpotrichia sp. and Trametes versicolor Induces Production of Diverse Metabolites with Anti-Parkinson's Neuroprotective Activity

Co-cultivation of isopod-associated fungi Herpotrichia sp. SF09 and Trametes versicolor SF09A led to the reciprocal induction of thirteen new compounds (1-7 and 9-13) with diverse architectures. Importantly, compounds 1 and 2 are rare fungal sesquiterpene-saccharide hybrids incorporating a xylopyranose moiety, compound (±)-3 represents the first example of a natural linear sesquiterpene racemate, and compound 7 is a rare α-pyrone derivative with a xylopyranose motif. Their structures were elucidated by analysis of NMR and mass spectrometry data, and their absolute configurations were determined by Mosher's method, microscale derivatization, and single-crystal X-ray diffraction, as well as ECD calculations. All the isolated compounds ameliorated MPP+-induced oxidative damage in PC12 cells in a dose-dependent fashion. Among them, compounds 5 and 15 showed significant protective action against neuronal injury by MPP+ at 5 μM. Meanwhile, transcriptome sequencing was performed to evaluate the molecular mechanism of the neuroprotective activity for compound 5. Results indicated that compound 5 might mitigate MPP+-induced neuronal injury through the regulation of multiple signaling pathways, including the PI3K-Akt and MAPK pathways. Our findings suggested that compound 5 could be a promising neuroprotective agent for the treatment of Parkinson's disease.

Herpotrichone A Exerts Neuroprotective Effects by Relieving Ferroptosis

Inhibition of oxidative stress and ferroptosis is currently considered to be a promising therapeutic approach for neurodegenerative diseases. Herpotrichones, a class of compounds derived from insect symbionts, have shown potential for neuroprotective activity with low toxicity. However, the specific mechanisms through which herpotrichones exert their neuroprotective effects remain to be fully elucidated. In this study, the natural [4 + 2] adducts herpotrichone A (He-A) and its new analogues were isolated from the isopod-associated fungus Herpotrichia sp. SF09 and exhibited significantly protective effects in H2O2-, 6-OHDA-, and RSL3-stimulated PC12 cells and LPS-stimulated BV-2 cells. Moreover, He-A was able to relieve ferroptotic cell death in RSL3-stimulated PC12 cells and 6-OHDA-induced zebrafish larvae. Interestingly, He-A can activate antioxidant elements and modulate the SLC7A11 pathway without capturing oxidic free radical and chelating iron. These findings highlight He-A as a novel hit that protects against ferroptosis-like neuronal damage in the treatment of neurodegenerative diseases.

Abietane-Type Diterpenoids from the Arils of Torreya grandis

A chemical investigation of the arils of Torreya grandis led to the isolation of seven abietane-type diterpenoids (compounds 1-7) including three previously undescribed compounds, one unreported natural product, and three known analogs. The structures of these compounds were determined by means of spectroscopy, single-crystal X-ray diffraction, and ECD spectra. An antibacterial activity assay showed that compounds 5 and 6 had significant inhibitory effects on methicillin-resistant Staphylococcus aureus, with MIC values of 100 μM. Moreover, compounds 1, 3, 4, and 7 exhibited anti-neuroinflammatory activity in LPS-stimulated BV-2 microglia cells, with the IC50 values ranging from 38.4 to 67.9 μM.

New Pyranone Derivatives and Sesquiterpenoid Isolated from the Endophytic Fungus Xylaria sp. Z184

The fungus Xylaria sp. Z184, harvested from the leaves of Fallopia convolvulus (L.) Á. Löve, has been isolated for the first time. Chemical investigation on the methanol extract of the culture broth of the titles strain led to the discovery of three new pyranone derivatives, called fallopiaxylaresters A-C (1-3), and a new bisabolane-type sesquiterpenoid, named fallopiaxylarol A (4), along with the first complete set of spectroscopic data for the previously reported pestalotiopyrone M (5). Known pyranone derivatives (6-11), sesquiterpenoids (12-14), isocoumarin derivatives (15-17), and an aromatic allenic ether (18) were also co-isolated in this study. All new structures were elucidated by the interpretation of HRESIMS, 1D, 2D NMR spectroscopy, and quantum chemical computation approach. The in vitro antimicrobial, anti-inflammatory, and α-glucosidase-inhibitory activities of the selected compounds and the crude extract were evaluated. The extract was shown to inhibit nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine RAW264.7 macrophage cells, with an inhibition rate of 77.28 ± 0.82% at a concentration of 50 μg/mL. The compounds 5, 7, and 8 displayed weak antibacterial activity against Staphylococcus areus subsp. aureus at a concentration of 100 μM.

Polyarylisocyanides Derived from an Alkyne-Pd(II) Catalyst as Robust Alignment Media with Excellent Enantiodiscimination

The development of chiral alignment media for measuring anisotropic NMR parameters provides an opportunity to determine the absolute configuration of chiral molecules without the need for derivatization. However, chiral alignment media with a high and robust enantiodiscriminating property for a wide range of chiral molecules are still scarce. In this study, we synthesized cholesterol-end-functionalized helical polyisocyanides from a chiral monomer using a cholesterol-based alkyne-Pd(II) initiator. These stereoregular polyisocyanides form stable and weak anisotropic lyotropic liquid crystals (LLCs) in dichloromethane systems, exhibiting highly optical activities in both single left- and right-handed helices. The preparation process of the media was straightforward, and the aligning property of the LLCs could be controlled by adjusting the concentration and temperature. Using the chiral polyisocyanides, we extracted the residual dipolar coupling for an enantiomeric pair of isopinocampheol (IPC), as well as a number of pharmaceutical molecules, demonstrating excellent enantiodiscriminating properties for a broad range of chiral compounds.

Weakly aligned Ti3C2Tx MXene liquid crystals: measuring residual dipolar coupling in multiple co-solvent systems

Residual Dipolar Coupling (RDC), acquired relying on weakly alignment media, is highly valuable for the structural elucidation of organic molecules. Arising from the striking features of no background signals and low critical concentrations, two-dimensional (2D) liquid crystals (LCs) show the clear advantages of acting as alignment media to measure RDCs. So far, creating multisolvent compatible 2D LC media through a simple and versatile method is still formidably challenging. Herein, we report the rapid creation of aligned media based on the Ti₃C₂T_x MXene, which self-aligned in multiple co-solvents including CH₃OH-H₂O, DMSO-H₂O, DMF-H₂O, and acetone-H₂O. We demonstrated the applicability of these aligned media for the RDC measurement of small organic molecules with different polarities and solubilities. Notably, Ti₃C₂T_x MXene LCs without chemical modification enabled RDC measurements on aromatic molecules. The straightforward preparation of Ti₃C₂T_x media and its compatibility with multiple solvents will push RDC measurement as a routine methodology for structural elucidation. It may also facilitate the investigation of solvation effects on conformational dynamics.

Sesquiterpenoids from Inula britannica and Their Potential Effects against Triple-Negative Breast Cancer Cells

Flowers of Inula britannica commercially serve as pharmaceutical herbs in the manufacturing of medicinal products. In the current study, sesquiterpenoids of I. britannica flowers’ extract and their potential effects against triple-negative breast cancer (TNBC) cells were investigated. Eight structurally diverse sesquiterpenoids, including one sesquiterpenoid dimer (1) and seven sesquiterpenoid monomers (2−8) were isolated from this source. The structures of all compounds were elucidated by 1D/2D NMR data, and their absolute configurations were discerned by single crystal X-ray diffraction. All of the compounds were tested for their potential effects against TNBC. Specifically, 5 displayed strong antiproliferative potency against TNBC cells with a high selective index (SI) on MCF-7 cells (SI > 4 of IC50 on MDA-MB-468/IC50 on MCF-7), and dimer 1 (IC50 = 8.82 ± 0.85 μM) showed better antiproliferative potency against MCF-7 cells than the other monomers did (2−8) (IC50 > 20 μM). To our best knowledge, compound 5 is the first sesquiterpenoid targeting TNBC cells.

Programmable alignment media from self-assembled oligopeptide amphiphiles for the measurement of independent sets of residual dipolar couplings in organic solvents

NMR spectroscopy in anisotropic media has emerged as a powerful technique for the structural elucidation of organic molecules. Its application requires weak alignment of analytes by means of suitable alignment media. Although a number of alignment media, that are compatible with organic solvents, have been introduced in the last 20 years, acquiring a number of independent, non-linearly related sets of anisotropic NMR data from the same organic solvent system remains a formidable challenge, which is however crucial for the alignment simulations and deriving dynamic and structural information of organic molecules unambiguously. Herein, we introduce a programmable strategy to construct several distinct peptide-based alignment media by adjusting the amino acid sequence, which allows us to measure independent sets of residual dipolar couplings (RDCs) in a highly efficient and accurate manner. This study opens a new avenue for de novo structure determination of organic compounds without requiring prior structural information.

We report a programmable strategy to construct multi-alignment media via peptide self-assembly for the measurement of independent sets of residual dipolar couplings (RDCs).

Biosynthesis of Fungal Natural Products Involving Two Separate Pathway Crosstalk

Fungal natural products (NPs) usually possess complicated structures, exhibit satisfactory bioactivities, and are an outstanding source of drug leads, such as the cholesterol-lowering drug lovastatin and the immunosuppressive drug mycophenolic acid. The fungal NPs biosynthetic genes are always arranged within one single biosynthetic gene cluster (BGC). However, a rare but fascinating phenomenon that a crosstalk between two separate BGCs is indispensable to some fungal dimeric NPs biosynthesis has attracted increasing attention. The hybridization of two separate BGCs not only increases the structural complexity and chemical diversity of fungal NPs, but also expands the scope of bioactivities. More importantly, the underlying mechanism for this hybridization process is poorly understood and needs further exploration, especially the determination of BGCs for each building block construction and the identification of enzyme(s) catalyzing the two biosynthetic precursors coupling processes such as Diels–Alder cycloaddition and Michael addition. In this review, we summarized the fungal NPs produced by functional crosstalk of two discrete BGCs, and highlighted their biosynthetic processes, which might shed new light on genome mining for fungal NPs with unprecedented frameworks, and provide valuable insights into the investigation of mysterious biosynthetic mechanisms of fungal dimeric NPs which are constructed by collaboration of two separate BGCs.

Self-assembly of Helical Polymers and Oligomers to Create Liquid Crystalline Alignment for Anisotropic NMR Parameters

The measurement of anisotropic residual dipolar couplings (RDCs) parameters for the structure elucidation of organic molecules relies on suitable alignment media. Employment of self-assembled liquid crystalline systems to create anisotropic alignment can be an effective way to realize aligned samples and acquire RDCs. This Mini-review highlights the recent advances on amino acid-based helical polymers and supramolecular oligomers forming rigid, rod-like structures that aggregate into ordered liquid crystalline phases, including amino acid-based helical polyisocyanides, polyacetylenes, polypeptides, and oligopeptides assembled alignment media. The methodology for the determination of anisotropic liquid crystals was briefly discussed, and a summary of recent research progress in the enantiodifferentiation of helical polymers aligned media was followed. In addition, the self-assembled mechanism of oligopeptides and their RDCs structural analysis were also described. This article is protected by copyright. All rights reserved.

Imidazolylacetophenone oxime-based multifunctional neuroprotective agents: Discovery and structure-activity relationships

Alzheimer's disease (AD) possesses a complex pathogenetic mechanism. Nowadays, multitarget agents are considered to have potential in effectively treating AD via triggering molecules in functionally complementary pathways at the same time. Here, based on the screening (∼1400 compounds) against neuroinflammation, an imidazolylacetophenone oxime ether (IOE) was discovered as a novel hit. In order to obtain SARs, a series of imidazolylacetophenone oxime derivatives were constructed, and their C=N bonds were confirmed as the Z configuration by single crystals. These derivatives exhibited potential multifunctional neuroprotective effects including anti-neuroinflammatory, antioxidative damage, metal-chelating, inhibition of acetylcholinesterase (AChE) properties. Among these derivatives, compound 12i displayed the most potent inhibitory activity against nitric oxide (NO) production with EC₅₀ value of 0.57 μM 12i can dose-dependently suppress the expression of iNOS and COX-2 but not change the expression of HO-1 protein. Moreover, 12i exhibited evidently neuroprotective effects on H₂O₂-induced PC12 cells damage and ferroptosis without cytotoxicity at 10 μM, as well as selectively metal chelating properties via chelating Cu²⁺. In addition, 12i showed a mixed-type inhibitory effect on AChE in vitro. The structure-activity relationships (SARs) analysis indicated that dioxolane groups on benzene ring and rigid oxime ester can improve the activity. Parallel artificial membrane permeation assay (PAMPA) also verified that 12i can overcome the blood-brain barrier (BBB). Overall, this is the first report on imidazolylacetophenone oxime-based multifunctional neuroprotective effects, suggesting that this type of compounds might be novel multifunctional agents against AD.

Structures and absolute configurations of butenolide derivatives from the isopod-associated fungus Pidoplitchkoviella terricola

In this research, twenty aromatic and branched aliphatic polyketides, including seven previously undescribed butenolide derivatives, piterriones A-G and one known analogue, along with twelve known altenusin derivatives, were isolated from the isopod-associated fungus Pidoplitchkoviella terricola. Their structures were elucidated by analysis of NMR (1D and 2D) and mass spectrometry data, and their absolute configurations were determined by Mosher's method, microscale derivatization, and comparison of their specific rotations and ECD spectra. Dihydroaltenuene B exhibited mushroom tyrosinase inhibitory activity with an IC₅₀ value of 38.33 ± 1.59 μM, which was comparable to that of the positive control, kojic acid (IC₅₀ = 39.72 ± 1.34 μM). A molecular-docking study disclosed the hydrogen bonding interactions between the 3-OH and 4'-OH of dihydroaltenuene B and the His244, Met280 and Gly281 residues of tyrosinase.

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.

Chemical characterization and multifunctional neuroprotective effects of sesquiterpenoid-enriched Inula britannica flowers extract

Dried flowers of Inula britannica commercially serve as pharmaceutical/nutraceutical herbs in the manufacture of medicinal products and functional tea that has been reported to possess extensive biological property. However, the neuroprotective constituents in I. britannica flowers are not known. In the current study, phytochemicals of sesquiterpenoid-enriched I. britannica flowers extract and their potential multifunctional neuroprotective effects were investigated. Nineteen structurally diverse sesquiterpenoids, including two new sesquiterpenoid dimers, namely, inubritanolides A and B (1, 2), and four new sesquiterpenoid monomers (3-6), namely, 1-O-acetyl-6-O-chloracetylbritannilactone (3), 6-methoxybritannilactone (4), 1-hydroxy-10β-methoxy-4αH-1,10-secoeudesma-5(6),11(13)-dien-12,8β-olide (5) and 1-hydroxy-4αH-1,10-secoeudesma-5(6),10(14),11(13)-trien-12,8β-olide (6), as well as 13 known congeners (7-19) were isolated from this source. The structures of compounds 1-6 were elucidated by 1D- and 2D- NMR and HR-ESI-MS data, and their absolute configurations were discerned by electronic circular dichroism (ECD) data analysis and single crystal X-ray diffraction. Interestingly, inubritannolide A (1) is a new type [4 + 2] Diels-Alder dimer featuring a hepta-membered cycloether skeleton. Most of the compounds showed potential multifunctional neuroprotective effects, including antioxidative, anti-neuroinflammatory, and microglial polarization properties. Specifically, 1 and 6 displayed slight strong neuroprotective potency against different types of neuronal cells mediated by various inducers including H₂O₂, 6-hydroxydopamine (6-OHDA), and lipopolysaccharide (LPS). Overall, this is the first report on multifunctional neuroprotective effects of sesquiterpenoid-enriched I. britannica flowers extract, which supports its potential pharmaceutical/nutraceutical application in neurodegenerative diseases.

Acautalides A-C, Neuroprotective Diels-Alder Adducts from Solid-State Cultivated Acaulium sp. H-JQSF

The solid-state cultivation of Acaulium sp. H-JQSF isolated from Armadillidium vulgare produces acautalides A-C (1-3) as skeletally unprecedented Diels-Alder adducts of a 14-membered macrodiolide to an octadeca-9,11,13-trienoic acid. The acautalide structures, along with the intramolecular transesterifications of 1-acylglycerols, were elucidated by mass spectrometry, nuclear magnetic resonance, chemical transformation, and single-crystal X-ray diffraction. Compounds 1-3 were found to be neuroprotective with antiparkinsonic potential in the 1-methyl-4-phenylpyridinium-challenged nematode model, with the magnitude impacted by the glycerol esterification.

Alkylated Salicylaldehydes and Prenylated Indole Alkaloids from the Endolichenic Fungus Aspergillus chevalieri and Their Bioactivities

Sixteen metabolites, including seven C₇-alkylated salicylaldehyde derivatives (1-7) and nine prenylated indole alkaloids (8-16), three of which are new, namely, asperglaucins A and B (1 and 2) and neoechinulin F (8), were separated from the endolichenic fungus Aspergillus chevalieri SQ-8. Asperglaucin A (1) represents an unusual phthalide-like derivative with a benzo[c]thiophen-1(3H)-one scaffold. All compounds were assessed in vitro for antibacterial, antineuroinflammatory, and antioxidant activities. Notably, asperglaucins A and B exhibited potent antibacterial activities against two plant pathogens Pseudomonas syringae pv actinidae (Psa) and Bacillus cereus, with an MIC value of 6.25 μM; further SEM analyses illustrated that the possible bacteriostatic mechanisms for compounds 1 and 2 were to alter the external structure of B. cereus and Psa, and to cause the rupture or deformation of the cell membranes, respectively, and the results suggest that compounds 1 and 2 may serve as potential promising candidates for lead compounds of agrochemical bactericides. Furthermore, compounds 6 and 10 significantly inhibited nitric oxide production with an IC₅₀ value of ca. 12 μM, and the possible anti-inflammatory mechanisms involved were also studied by molecular docking. Finally, the tested phenolics 3-5 showed significant antioxidative effects. Thus, strain SQ-8 represents a novel resource of these bioactive metabolites to be utilized.

Structurally Diverse Sesquiterpenoids with Anti-neuroinflammatory Activity from the Endolichenic Fungus Cryptomarasmius aucubae

Two new sterpurane sesquiterpenoids named sterpurol D (1) and sterpurol E (2), and one skeletally new sesquiterpene, cryptomaraone (3), bearing a 5,6-fused bicyclic ring system, along with five known ones, sterpurol A (4), sterpurol B (5), paneolilludinic Acid (6), murolane-2α, 9β-diol-3-ene (7) and (-)-10,11-dihydroxyfarnesol (8) were isolated from an endolichenic fungus Cryptomarasmius aucubae. The structures of the new compounds were elucidated by analysis of NMR spectroscopic spectra and HRESIMS data. The absolute configurations of 1 and 2 were established by spectroscopic data analysis and comparison of specific optical rotation, as well as the biosynthetic consideration. Additionally, compounds 1, 2, 4-6, and 8 showed significant nitric oxide (NO) production inhibition in Lipopolysaccharide (LPS)-induced BV-2 microglial cells with the IC50 values ranging from 9.06 to 14.81 μM.

Anti-neuroinflammatory polyoxygenated lanostanoids from Chaga mushroom Inonotus obliquus

Chaga mushroom, Inonotus obliquus, was used as food and nutrient food and traditional herbs in Russia, China and Japan, with anti-inflammatory and anticancer activities. Chemical investigations of the fruiting bodies of Chaga were carried to uncover the bioactive metabolites. As a result, seven undescribed lanostane-type triterpenoids, namely inonotusols H-N, were isolated, and all lanostanoids remarkably inhibited NO production in lipopolysaccharide-stimulated BV-2 microglial cells. Of these, inonotusols I and L presented the most potent inhibitory effects on inducible nitric oxide synthase (iNOS) and NO production without any significant cytotoxicity. Molecular docking studies confirmed the capacity of inonotusols I and L to interact with iNOS protein. Structure-activity relationships were also discussed. These results indicated that the potential anti-inflammatory effects of inonotusols I and L in microglial BV-2 cells may be imparted through suppression of iNOS. These results may support the use of I. obliquus for food and medicinal application.

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