Butenolide derivatives from Aspergillus terreus selectively inhibit butyrylcholinesterase

Two undescribed butenolide derivatives, asperteretal J (1) and K (2), together with 13 known ones (3-15) were isolated from an endophytic fungus Aspergillus terreus SGP-1, the fermentation product of which exhibited selective inhibitory activity toward butyrylcholinesterase. The structures of the new compounds were elucidated based on HRMS and NMR data, and the absolute configurations were determined by specific optical rotation comparison. All compounds were evaluated for cholinesterase inhibitory effects with galantamine as a positive control. Compounds 4-8 selectively inhibited butyrylcholinesterase with IC₅₀ values of 18.4-45.8 µM in a competitive manner, with Ki values of 12.3-38.2 µM. The structure-activity relationship was discussed. Molecular docking and dynamic simulation of the inhibitor-enzyme complex were performed to better understand the interactions.

Aspergillus ochraceus: Metabolites, Bioactivities, Biosynthesis, and Biotechnological Potential

Fungus continues to attract great attention as a promising pool of biometabolites. Aspergillus ochraceus Wilh (Aspergillaceae) has established its capacity to biosynthesize a myriad of metabolites belonging to different chemical classes, such as isocoumarins, pyrazines, sterols, indole alkaloids, diketopiperazines, polyketides, peptides, quinones, polyketides, and sesquiterpenoids, revealing various bioactivities that are antimicrobial, cytotoxic, antiviral, anti-inflammatory, insecticidal, and neuroprotective. Additionally, A. ochraceus produces a variety of enzymes that could have variable industrial and biotechnological applications. From 1965 until June 2022, 165 metabolites were reported from A. ochraceus isolated from different sources. In this review, the formerly separated metabolites from A. ochraceus, including their bioactivities and biosynthesis, in addition, the industrial and biotechnological potential of A. ochraceus are highlighted.

Secondary Metabolite Variation and Bioactivities of Two Marine Aspergillus Strains in Static Co-Culture Investigated by Molecular Network Analysis and Multiple Database Mining Based on LC-PDA-MS/MS

Co-culture is known as an efficient way to explore the metabolic potential of fungal strains for new antibiotics and other therapeutic agents that could counter emerging health issues. To study the effect of co-culture on the secondary metabolites and bioactivities of two marine strains, Aspergillus terreus C23-3 and Aspergillus. unguis DLEP2008001, they were co-cultured in live or inactivated forms successively or simultaneously. The mycelial morphology and high-performance thin layer chromatography (HPTLC) including bioautography of the fermentation extracts were recorded. Furthermore, the agar cup-plate method was used to compare the antimicrobial activity of the extracts. Based on the above, liquid chromatography-photodiode array-tandem mass spectrometry (LC-PDA-MS/MS) together with Global Natural Products Social molecular networking (GNPS) and multiple natural products database mining were used to further analyze their secondary metabolite variations. The comprehensive results showed the following trends: (1) The strain first inoculated will strongly inhibit the growth and metabolism of the latter inoculated one; (2) Autoclaved A. unguis exerted a strong inducing effect on later inoculated A. terreus, while the autoclaved A. terreus showed high stability of its metabolites and still potently suppressed the growth and metabolism of A. unguis; (3) When the two strains are inoculated simultaneously, they both grow and produce metabolites; however, the A. terreus seemed to be more strongly induced by live A. unguis and this inducing effect surpassed that of the autoclaved A. unguis. Under some of the conditions, the extracts showed higher antimicrobial activity than the axenic cultures. Totally, A. unguis was negative in response but potent in stimulating its rival while A. terreus had the opposite effect. Fifteen MS detectable and/or UV active peaks showed different yields in co-cultures vs. the corresponding axenic culture. GNPS analysis assisted by multiple natural products databases mining (PubChem, Dictionary of Natural Products, NPASS, etc.) gave reasonable annotations for some of these peaks, including antimicrobial compounds such as unguisin A, lovastatin, and nidulin. However, some of the peaks were correlated with antagonistic properties and remain as possible novel compounds without mass or UV matching hits from any database. It is intriguing that the two strains both synthesize chemical 'weapons' for antagonism, and that these are upregulated when needed in competitive co-culture environment. At the same time, compounds not useful in this antagonistic setting are downregulated in their expression. Some of the natural products produced during antagonism are unknown chlorinated metabolites and deserve further study for their antimicrobial properties. In summary, this study disclosed the different responses of two Aspergillus strains in co-culture, revealed their metabolic variation, and displayed new opportunities for antibiotic discovery.

Fungal Naphthalenones; Promising Metabolites for Drug Discovery: Structures, Biosynthesis, Sources, and Pharmacological Potential

Fungi are well-known for their abundant supply of metabolites with unrivaled structure and promising bioactivities. Naphthalenones are among these fungal metabolites, that are biosynthesized through the 1,8-dihydroxy-naphthalene polyketide pathway. They revealed a wide spectrum of bioactivities, including phytotoxic, neuro-protective, cytotoxic, antiviral, nematocidal, antimycobacterial, antimalarial, antimicrobial, and anti-inflammatory. The current review emphasizes the reported naphthalenone derivatives produced by various fungal species, including their sources, structures, biosynthesis, and bioactivities in the period from 1972 to 2021. Overall, more than 167 references with 159 metabolites are listed.

Chaetomugilins and Chaetoviridins—Promising Natural Metabolites: Structures, Separation, Characterization, Biosynthesis, Bioactivities, Molecular Docking and Molecular Dynamics

Fungi are recognized as luxuriant metabolic artists that generate propitious biometabolites. Historically, fungal metabolites have largely been investigated as leads for various therapeutic agents. Chaetomugilins and the closely related chaetoviridins are fungal metabolites, and each has an oxygenated bicyclic pyranoquinone core. They are mainly produced by various Chaetomaceae species. These metabolites display unique chemical features and diversified bioactivities. The current review gives an overview of research about fungal chaetomugilins and chaetoviridins regarding their structures, separation, characterization, biosynthesis, and bioactivities. Additionally, their antiviral potential towards the SARS-CoV-2 protease was evaluated using docking studies and molecular dynamics (MD) simulations. We report on the docking and predictive binding energy estimations using reported crystal structures of the main protease (PDB ID: 6M2N, 6W81, and 7K0f) at variable resolutions—i.e., 2.20, 1.55, and 1.65 Å, respectively. Chaetovirdin D (43) exhibited highly negative docking scores of −7.944, −8.141, and −6.615 kcal/mol, when complexed with 6M2N, 6W81, and 7K0f, respectively. The reference inhibitors exhibited the following scores: −5.377, −6.995, and −8.159 kcal/mol, when complexed with 6M2N, 6W81, and 7K0f, respectively. By using molecular dynamics simulations, chaetovirdin D’s stability in complexes with the viral protease was analyzed, and it was found to be stable over the course of 100 ns.

Terretonin as a New Protective Agent against Sepsis-Induced Acute Lung Injury: Impact on SIRT1/Nrf2/NF-κBp65/NLRP3 Signaling

Endophytic fungi are proving to be an excellent source of chemical entities with unique structures and varied bioactivities. Terretonin (TE) and its structurally related derivatives are a class of meroterpenoids, possessing the same unique tetracyclic core skeleton, which have been reported from the Aspergillus genus. This study was carried out to assess the potential protective effects of TE separated from the endophytic fungus A. terreus against LPS (lipopolysaccharide)-induced ALI (acute lung injury) in mice. The results revealed that TE alleviated pulmonary edema as it lowered both the W/D lung ratio and protein content. The inflammatory response represented by inflammatory cell infiltration into the lung tissues was greatly repressed by TE. That was supported by the improved histopathological results and also by the reduced level of myeloperoxidase in the lung. TE showed a potent antioxidant activity as it attenuated lipid peroxidative markers (malondialdehyde, 4-hydroxynonenal, and protein carbonyl) and enhanced endogenous antioxidants (reduced glutathione, superoxide dismutase, and catalase) in lung tissues. Similarly, TE increased the mRNA expression of SIRT1, Nrf2, and its genes (HO-1, NQO1, and GCLm). On the other hand, TE restrained the activation of NF-κB (nuclear factor-κB) in the lung. Consequently, TE depressed the pro-inflammatory cytokines: nitric oxide (NOx), TNF-α (tumor necrosis factor-α), and interleukins (IL-6 and -1β). Additionally, TE inhibited NLRP3 signaling and interrupted apoptosis by decreasing the levels of proapoptotic markers (Bax and caspase-3) and increasing the level of an anti-apoptotic marker (Bcl-2). In conclusion, TE had a remarkable protective potential on LPS-induced lung damage via antioxidant and anti-inflammatory mechanisms. This finding encourages further investigations on this promising candidate.

Bright Side of Fusarium oxysporum: Secondary Metabolites Bioactivities and Industrial Relevance in Biotechnology and Nanotechnology

Fungi have been assured to be one of the wealthiest pools of bio-metabolites with remarkable potential for discovering new drugs. The pathogenic fungi, Fusarium oxysporum affects many valuable trees and crops all over the world, producing wilt. This fungus is a source of different enzymes that have variable industrial and biotechnological applications. Additionally, it is widely employed for the synthesis of different types of metal nanoparticles with various biotechnological, pharmaceutical, industrial, and medicinal applications. Moreover, it possesses a mysterious capacity to produce a wide array of metabolites with a broad spectrum of bioactivities such as alkaloids, jasmonates, anthranilates, cyclic peptides, cyclic depsipeptides, xanthones, quinones, and terpenoids. Therefore, this review will cover the previously reported data on F. oxysporum, especially its metabolites and their bioactivities, as well as industrial relevance in biotechnology and nanotechnology in the period from 1967 to 2021. In this work, 180 metabolites have been listed and 203 references have been cited.

New Alkaloids From a Hawaiian Fungal Strain Aspergillus felis FM324

Two new alkaloids tryptoquivaline Y (1) and pseurotin I (2), together with eight known compounds (3-10), were purified from a fungal strain Aspergillus felis FM324, which was isolated from a Hawaiian beach soil sample. The absolute configuration and physicochemical data of tryptoquivaline Z (3) were reported for the first time here in this paper. Compound 1 is an uncommon tryptoquivaline analog containing a 3-O-isobutanoyl group. The structures of the new compounds 1-2 and known compound 3 were elucidated through HRESIMS, NMR spectroscopy and ECD analysis. All the compounds were evaluated for their antiproliferative, antibacterial and NF-κB inhibitory activities. Compound 4 showed weak antibacterial activity against Staphylococcus aureus, methicillin resistant Staphylococcus aureus and Bacillus subtilis with the same MIC value of 59.2 µM. Compounds 3 and 2 inhibited NF-κB with IC50 values of 26.7 and 30.9 μM, respectively.

Naturally Occurring Isocoumarins Derivatives from Endophytic Fungi: Sources, Isolation, Structural Characterization, Biosynthesis, and Biological Activities

Recently, the metabolites separated from endophytes have attracted significant attention, as many of them have a unique structure and appealing pharmacological and biological potentials. Isocoumarins represent one of the most interesting classes of metabolites, which are coumarins isomers with a reversed lactone moiety. They are produced by plants, microbes, marine organisms, bacteria, insects, liverworts, and fungi and possessed a wide array of bioactivities. This review gives an overview of isocoumarins derivatives from endophytic fungi and their source, isolation, structural characterization, biosynthesis, and bioactivities, concentrating on the period from 2000 to 2019. Overall, 307 metabolites and more than 120 references are conferred. This is the first review on these multi-facetted metabolites from endophytic fungi.

A New Pentacyclic Ergosteroid from Fungus Aspergillus sp. SCSIO41211 Derived of Mangrove Sediment Sample

Chemical investigation of the fungus Aspergillus sp. SCSIO41211 derived of mangrove sediment sample afforded a ergostane-type pentacyclic steroid, (22 S, 23 R)-12α,14α,23α-trihydroxy-16,22-epoxy-ergosta-4,8-dien-3,11-dione (1), together with seven known compounds, flavacol (2), aspergilliamide (3), ochratoxin A methyl ester (4), ochratoxin A ethyl ester (5), dihydroaspyrone (6), aspilactonol E (7) and aspilactonol F (8). The structures were determined on the basis of NMR and MS analysis. The isolated compounds were tested for their antiviral activity against H3N2 and EV71 viruses, cytotoxic, and antituberculosis effects. Among them, compounds 2 and 5 showed significant cytotoxicity against ten human cancer cell lines. None of the compounds displayed a significant antiviral activity against H3N2 and EV71 viruses nor antimycobacterial activities.