Phenolic bisabolane and cuparene sesquiterpenoids with anti-inflammatory activities from the deep-sea-derived Aspergillus sydowii MCCC 3A00324 fungus

Anti-necroptosis and anti-ferroptosis compounds from the Deep-Sea-Derived fungus Aspergillus sp. MCCC 3A00392

Eight undescribed (1-8) and 46 known compounds (9-54) were isolated from the deep-sea-derived Aspergillus sp. MCCC 3A00392. Compounds 1-3 were three novel oxoindolo diterpenoids, 4-6 were three bisabolane sesquiterpenoids, while 7 and 8 were two monocyclic cyclopropanes. Their structures were established by exhaustive analyses of the HRESIMS, NMR, and theoretical calculations of the NMR data and ECD spectra. Compounds 10, 33, 38, and 39 were able to inhibit tumor necrosis factor (TNF)-induced necroptosis in murine L929 cell lines. Functional experiments verified that compounds 10 and 39 inhibited necroptosis by downregulating the phosphorylation of RIPK3 and MLKL. Moreover, compound 39 also reduced the phosphorylation of RIPK1. Compounds 10, 33, and 34 displayed potent inhibitory activities against RSL-3 induced ferroptosis with the EC50 value of 3.0 μM, 0.4 μM, and 0.1 μM, respectively. Compound 10 inhibited ferroptosis by the downregulation of HMOX1, while compounds 33 and 34 inhibited ferroptosis through regulation of NRF2/SLC7A11/GCLM axis. However, these compounds only showed weak effect in either the necroptosis or ferroptosis relative mouse disease models. Further studies of pharmacokinetics and pharmacodynamics might improve their in vivo bioactivities.

Two Pairs of New Bisabolane-Type Sesquiterpenoids from Aspergillus sydowii

Two pairs of new bisabolane-type sesquiterpenoids, (+)-aspersydowin A (7S) [(+)-1], (-)-aspersydowin A (7R) [(-)-1], (+)-aspersydowin B (7S,11S) [(+)-2], (-)-aspersydowin B (7R,11R) [(-)-2], along with six known compounds (1-8) were isolated from the fungus Aspergillus sydowii. Compounds 1 and 2 are enantiomers resolved by the Chiralpak IC, using a hexane- propan-2-ol mobile phase. The structure of 1 and 2 with absolute configuration were assigned tentatively by 1D (1 H, 13 C, and DEPT) & 2D (HSQC, 1 H-1 H COSY, HMBC, and NOESY) NMR data analyses and ECD calculations. Compounds 1-8 were screened for the biological activities in vitro. The results showed that compounds 3, 4 and 8 exhibited immunosuppressive activities with IC50 values of 10.9, 17.6 and 13.4 μM, respectively.

Bisabolane-type sesquiterpenoids and bacillibactin from the marine-derived fungus Aspergillus sydowii SCSIO 41041 and their enzyme inhibiting activity

Twelve compounds, including eleven bisabolane-type sesquiterpenoids (1 - 11), and one bacillibactin (12) were identified from marine-derived fungus Aspergillus sydowii SCSIO 41041 isolated from Creseis acicula. The chemical structures were elucidated by the basis of spectroscopic evidences, including HRESIMS, NMR and optical rotation. Biologically, all compounds were evaluated for their acetyl cholin-esterase (AChE) enzyme, pancreatic lipase (PL) enzyme, neuraminidase (NA) and phosphodiesterase 4 (PDE4) inhibitory activities. Compound 12 displayed significant inhibitory activity against neuraminidase (NA) with an IC50 value of 24.0 μM, which was equivalent to the positive drug oseltamivir phosphate (IC50 value of 20.0 μM). And the NA inhibitory activity was confirmed by molecular docking analysis.

Penidihydrocitrinins A-C: New Polyketides from the Deep-Sea-Derived Penicillium citrinum W17 and Their Anti-Inflammatory and Anti-Osteoporotic Bioactivities

Three new polyketides (penidihydrocitrinins A-C, 1-3) and fourteen known compounds (4-17) were isolated from the deep-sea-derived Penicillium citrinum W17. Their structures were elucidated by comprehensive analyses of 1D and 2D NMR, HRESIMS, and ECD calculations. Compounds 1-17 were evaluated for their anti-inflammatory and anti-osteoporotic bioactivities. All isolates exhibited significant inhibitory effects on LPS-stimulated nitric oxide production in murine brain microglial BV-2 cells in a dose-response manner. Notably, compound 14 displayed the strongest effect with the IC50 value of 4.7 µM. Additionally, compounds 6, 7, and 8 significantly enhanced osteoblast mineralization, which was comparable to that of the positive control, purmorphamine. Furthermore, these three compounds also suppressed osteoclastogenesis in a dose-dependent manner under the concentrations of 2.5 μM, 5.0 μM, and 10 μM.

Secondary Metabolites, Biological Activities, and Industrial and Biotechnological Importance of Aspergillus sydowii

Marine-derived fungi are renowned as a source of astonishingly significant and synthetically appealing metabolites that are proven as new lead chemicals for chemical, pharmaceutical, and agricultural fields. Aspergillus sydowii is a saprotrophic, ubiquitous, and halophilic fungus that is commonly found in different marine ecosystems. This fungus can cause aspergillosis in sea fan corals leading to sea fan mortality with subsequent changes in coral community structure. Interestingly, A. sydowi is a prolific source of distinct and structurally varied metabolites such as alkaloids, xanthones, terpenes, anthraquinones, sterols, diphenyl ethers, pyrones, cyclopentenones, and polyketides with a range of bioactivities. A. sydowii has capacity to produce various enzymes with marked industrial and biotechnological potential, including α-amylases, lipases, xylanases, cellulases, keratinases, and tannases. Also, this fungus has the capacity for bioremediation as well as the biocatalysis of various chemical reactions. The current work aimed at focusing on the bright side of this fungus. In this review, published studies on isolated metabolites from A. sydowii, including their structures, biological functions, and biosynthesis, as well as the biotechnological and industrial significance of this fungus, were highlighted. More than 245 compounds were described in the current review with 134 references published within the period from 1975 to June 2023.

Structure Revisions of Phenolic Bisabolane Sesquiterpenes and a Ferroptosis Inhibitor from the Marine-Derived Fungus Aspergillus versicolor YPH93

Seven new phenolic bisabolane sesquiterpenoids (1-7), along with 10 biogenetically related analogues (8-17), were obtained from the deep-sea-derived fungus Aspergillus versicolor YPH93. The structures were elucidated based on extensive analyses of the spectroscopic data. Compounds 1-3 are the first examples of phenolic bisabolanes that contain two hydroxy groups attached to the pyran ring. The structures of sydowic acid derivatives (1-6 and 8-10) were carefully studied, leading to the structure revisions of six known analogues, including a revision of the absolute configuration for sydowic acid (10). All metabolites were evaluated for their effects on ferroptosis. Compound 7 exerted inhibition on erastin/RSL3-induced ferroptosis with EC50 values ranging from 2 to 4 μM, while it exhibited no effects on TNFα-induced necroptosis or H2O2-induced cell necrosis.

Phaeosphamides A and B, Cytotoxic Cyclodecadepsipeptides from the Mangrove-Derived Fungus Phaeosphaeriopsis sp. S296

Chemical examination of the fermented broth of the mangrove-derived fungus Phaeosphaeriopsis sp. S296 resulted in the isolation of two new cyclodecadepsipeptides, namely phaeosphamides A (1) and B (2), as well as one known congener Sch 217048 (3). The structures of new metabolites, including absolute configurations, were established on the basis of extensive spectroscopic data analyses, chemical conversion, and Marfey’s method. The 2-hydroxy-3-methylpentanoic acid (Hmp) moiety and pipecolic acid (Pip) unit in structures were rarely discovered in nature. Interestingly, compounds 1–3 are examples of peptides discovered from the fungal genus Phaeosphaeriopsis for the first time. All identified compounds were evaluated for their cytotoxicity against five tumor cell lines of AGS, BEL-7402, HepG2, B16, and BIU87. Among them, compound 1 showed inhibitory activities against these tumor cell lines with IC₅₀ values ranging from 5.14 to 66.38 μM. A further mechanistic investigation found that 1 arrested AGS cells in the G2 phase and induced their apoptosis in a dose-dependent manner.

Biosynthesis of Sesquiterpenes in Basidiomycetes: A Review

Sesquiterpenes are common small-molecule natural products with a wide range of promising applications and are biosynthesized by sesquiterpene synthase (STS). Basidiomycetes are valuable and important biological resources. To date, hundreds of related sesquiterpenoids have been discovered in basidiomycetes, and the biosynthetic pathways of some of these compounds have been elucidated. This review summarizes 122 STSs and 2 fusion enzymes STSs identified from 26 species of basidiomycetes over the past 20 years. The biological functions of enzymes and compound structures are described, and related research is discussed.

Antiviral Cyclopropane Acids from Deep-Sea-Derived Fungus Aspergillus sydowii

Four novel monocyclic cyclopropane acids, namely, sydocyclopropanes A–D (1–4), along with one known congener hamavellone B (5), were isolated from the Aspergillus sydowii MCCC 3A00324 fungus, which was isolated from the deep-sea sediment. The gross structures of novel compounds were established by detailed analyses of the spectroscopic data (HRESIMS and NMR spectra), and their absolute configurations were resolved on the basis of the quantum chemical calculations of ECD and NMR data, in association with DP4+ probability analyses. Sydocyclopropanes A–D, featuring the 1,1,2,3-tetrasubstituted cyclopropane nucleus with different lengthy alkyl side chains, were discovered in nature for the first time. All compounds exhibited antiviral activities against A/WSN/33 (H1N1), with IC₅₀ values ranging from 26.7 to 77.2 μM, of which compound 1 exhibited a moderate inhibitory effect (IC₅₀ = 26.7 μM).

Bisabolane Sesquiterpenes with Anti-Inflammatory Activities from the Endophytic Fungus Penicillium citrinum DF47

Seven new bisabolane-type sesquiterpenes (1-7), namely penicibisabolanes A-G, together with eight known analogs (8-15) were obtained from the AcOEt extract of the millet fermentation broth of the endophytic fungus Penicillium citrinum DF47, which was isolated from the fresh root of Codonopsis pilosula (Franch.) Nannf. The gross structures of new metabolites were determined on the basis of the spectroscopic data (HR-ESI-MS, 1D and 2D NMR spectra), while their absolute configurations were resolved by comparison of the experimental and calculated ECD spectra, in association with specific rotation data. Compound 1 is a rare seco-trinor-bisabolane sesquiterpene found in nature, while 3 is the first example of phenolic bisabolanes bearing a methoxy group at C-1. All the isolates were evaluated their inhibitory effects against NO production in lipopolysaccharides (LPS) stimulated RAW264.7 cells. Among them, compounds 7 and 13 showed moderately anti-inflammatory effects with the inhibitory rate more than 50 % at the concentration of 20 μM.

Chemistry and Bioactivity of Marine-Derived Bisabolane Sesquiterpenoids: A Review

Natural products, characterized by intriguing scaffold diversity and structural complexity, as well as significant agricultural and medicinal activities, have been a valuable source of agrochemicals/drugs development and have historically made a huge contribution to pharmacotherapy. Structurally, bisabolanes are a family of naturally occurring sesquiterpenoids that featured a hexatomic ring core incorporating with eight continuous carbons, which cause high structural variability along the alkyl side chain to form abundant functionalities. Moreover, apart from their interesting structures, bisabolanes have shown multitudinous bioactivities. Bisabolanes are distributed in a variety of marine invertebrates, terrestrial plant, and microbial sources. Interestingly, bisabolanes characterized from marine environment possess unique characteristics both structurally and biologically. A total of 296 newly-discovered bisabolanes were searched. Among them, 94 members were isolated from marine organisms. This review particularly focuses on the new bisabolanes characterized from marine organisms (covering from 2000 to 2021), including marine-derived fungi, algae, soft corals, and sponges, with emphasis on the diversity of their chemical structures as well as the novelty and differences between terrestrial and marine sources. Moreover, a wide range of bioactivities of marine-derived bisabolanes, including antimicrobial, anti-inflammatory, enzyme inhibitory, and cytotoxic properties, are presented herein, which is considered to be a promising resource for the discovery of new drug leads and agrochemicals.

Antimicrobial and cytotoxic phenolic bisabolane sesquiterpenoids from the fungus Aspergillus flavipes 297

Phenolic bisabolane-type sesquiterpenoids (PBS) represent a rare class of natural products with diverse biological activities. In this study, chemical investigations of the fungus Aspergillus flavipes 297 resulted in the isolation and identification of seven PBS, including a pair of new enantiomers (+)-1a and (-)-1b, a new derivative 2, and five previously reported ones 3-7. The chemical structures of the isolated PBS were determined by extensive NMR and HRESIMS spectroscopic analysis. The absolute configurations of the separated enantiomers (+)-1a and (-)-1b were solved by comparison of the experimental ECD spectra with those of the TDDFT-ECD calculated spectra. The new compounds 1 and 2 represent rare cases of PBS bearing a methylsulfinyl group, which was distinct from the commonly-observed PBS structurally. All the isolated compounds 1-7 were evaluated their antimicrobial and cytotoxic activities. As a result, the tested compounds showed selective antimicrobial activity against several pathogenic bacteria and fungi with the MIC (minimum inhibiting concentrations) values ranging from 2 to 64 μg/mL. Moreover, enantiomers (+)-1a and (-)-1b, together with compound 2, exhibited promising cytotoxicity against MKN-45 and HepG2 cell lines, respectively, indicating that the methylsulfinyl substituent enhanced cytotoxicity to a certain degree.

Acremolin D, a new acremolin alkaloid from the deep-sea sediment derived Aspergillus sydowii fungus

Chemical investigation of the deep-sea-derived fungus Aspergillus sydowii MCCC 3A00324 led to the isolation of one new acremolin type alkaloid (acremolin D, 1) and five known alkaloids (2‒6). The planar structure of 1 was established by the extensive analyses of the NMR and HRESIMS data, while its absolute configuration was assigned by the comparison of the experimental and calculated ECD data. Acremolin D (1) represented the second analogue of acremolin found in nature. All compounds were evaluated for their cytotoxic activities against six human cancer cell lines (A549, Hela-S3, MCF-7, HepG2, K562, and SF-268). As a result, compounds 1 and 2 exhibited a certain inhibitory effects against the proliferation of the A549, Hela-S3, HepG2, and K562 cell lines at the concentration of 20 µM.

New Monoterpenoids and Polyketides from the Deep-Sea Sediment-Derived Fungus Aspergillus sydowii MCCC 3A00324

Chemical study of the secondary metabolites of a deep-sea-derived fungus Aspergillus sydowii MCCC 3A00324 led to the isolation of eleven compounds (1-11), including one novel (1) and one new (2) osmane-related monoterpenoids and two undescribed polyketides (3 and 4). The structures of the metabolites were determined by comprehensive analyses of the NMR and HRESIMS spectra, in association with quantum chemical calculations of the 13C NMR, ECD, and specific rotation data for the configurational assignment. Compound 1 possessed a novel monoterpenoid skeleton, biogenetically probably derived from the osmane-type monoperpenoid after the cyclopentane ring cleavage and oxidation reactions. Additionally, compound 3 was the first example of the α-pyrone derivatives bearing two phenyl units at C-3 and C-5, respectively. The anti-inflammatory activities of 1-11 were tested. As a result, compound 6 showed potent inhibitory nitric oxide production in lipopolysaccharide (LPS)-activated BV-2 microglia cells with an inhibition rate of 94.4% at the concentration of 10 µM. In addition, a plausible biosynthetic pathway for 1 and 2 was also proposed.