Aspersterols A-D, Ergostane-Type Sterols with an Unusual Unsaturated Side Chain from the Deep-Sea-Derived Fungus Aspergillus unguis

Talarergosteroids A-C: Three Unusual Steroid-Polyketone Conjugates with Antifungal Activity from a Kandelia Obovata Derived Fungus Talaromyces sp

Three previously undescribed steroid-polyketone conjugates, talarergosteroids A-C (1-3), together with talarergosteroid D (4), which was first identified from a natural source, were isolated from a Kandelia Obovata derived fungus Talaromyces sp. SCNU-F0041. Compounds 1 and 2 bear a complicated 6/6/6/5/6/6 hexacyclic ring system characterized by an oxaspiro[5.5]undecane architecture. Compound 3 possesses a benzofuran moiety substituted at C-3 in ergosterol. The structures of the new compounds were identified by comprehensive spectroscopic analysis, X-ray diffraction, and electronic circular dichroism (ECD) calculation. Talarergosteroid B (2) showed significant inhibitory activity against the agricultural plant pathogen Fusarium oxysporum f. sp. lycopersici (MIC = 0.78 μg/mL), outperforming the positive control carbendazim (MIC = 1.56 μg/mL). Preliminary research disclosed that compound 2 may inhibit the spore germination progress, malform the fungal mycelium, and damage the organelle. These results indicate that compound 2 could be a potential fungicidal lead compound against Fusarium oxysporum f. sp. lycopersici.

Anti-inflammatory potential of aspergillus unguis SP51-EGY: TLR4-dependent effects & chemical diversity via Q-TOF LC-HRMS

Inflammation serves as an intricate defense mechanism for tissue repair. However, overactivation of TLR4-mediated inflammation by lipopolysaccharide (LPS) can lead to detrimental outcomes such as sepsis, acute lung injury, and chronic inflammation, often associated with cancer and autoimmune diseases. This study delves into the anti-inflammatory properties of "Aspergillus unguis isolate SP51-EGY" on LPS-stimulated RAW 264.7 macrophages. Through real-time qPCR, we assessed the expression levels of pivotal inflammatory genes, including iNOS, COX-2, TNF-α, and IL-6. Remarkably, our fungal extracts significantly diminished NO production and showed noteworthy reductions in the mRNA expression levels of the aforementioned genes. Furthermore, while Nrf2 is typically associated with modulating inflammatory responses, our findings indicate that the anti-inflammatory effects of our extracts are not Nrf2-dependent. Moreover, the chemical diversity of the potent extract (B Sh F) was elucidated using Q-TOF LC-HRMS, identifying 54 compounds, some of which played vital roles in suppressing inflammation. Most notably, compounds like granisetron, fenofibrate, and umbelliprenin were found to downregulate TNF-α, IL-1β, and IL-6 through the NF-κB signaling pathway. In conclusion, "Aspergillus unguis isolate SP51-EGY", isolated from the Red Sea, Egypt, has been unveiled as a promising TLR4 inhibitor with significant anti-inflammatory potentials, presenting novel insights for their potential therapeutic use in inflammation.

Recent Advances in Anti-Inflammatory Compounds from Marine Microorganisms

Marine microbial secondary metabolites with diversified structures have been found as promising sources of anti-inflammatory lead compounds. This review summarizes the sources, chemical structures, and pharmacological properties of anti-inflammatory natural products reported from marine microorganisms in the past three years (2021-2023). Approximately 252 anti-inflammatory compounds, including 129 new ones, were predominantly obtained from marine fungi and they are structurally divided into polyketides (51.2%), terpenoids (21.0%), alkaloids (18.7%), amides or peptides (4.8%), and steroids (4.3%). This review will shed light on the development of marine microbial secondary metabolites as potential anti-inflammatory lead compounds with promising clinical applications in human health.

Ergone Derivatives from the Deep-Sea-Derived Fungus Aspergillus terreus YPGA10 and 25,28-Dihydroxyergone-Induced Apoptosis in Human Colon Cancer SW620 Cells

Ten new ergone derivatives (1-10) and five known analogues (11-15) were isolated from the deep-sea-derived fungus Aspergillus terreus YPGA10. The structures including the absolute configurations were established by detailed analysis of the NMR spectroscopic data, HRESIMS, ECD calculation, and coupling constant calculation. All the structures are characterized by a highly conjugated 25-hydroxyergosta-4,6,8(14),22-tetraen-3-one nucleus. Structurally, compound 2 bearing a 15-carbonyl group and compounds 5-7 possessing a 15β-OH/OCH3 group are rarely encountered in ergone derivatives. Bioassay results showed that compounds 1 and 11 demonstrated cytotoxic effects on human colon cancer SW620 cells with IC50 values of 8.4 and 3.1 μM, respectively. Notably, both compounds exhibited negligible cytotoxicity on the human normal lung epithelial cell BEAS-2B. Compound 11 was selected for preliminary mechanistic study and was found to inhibit cell proliferation and induce apoptosis in human colon cancer SW620 cells. In addition, compound 1 displayed cytotoxic activity against five human leukemia cell lines with IC50 values ranging from 5.7 to 8.9 μM. Our study demonstrated that compound 11 may serve as a potential candidate for the development of anticolorectal cancer agents.

Immunosuppressive steroids quadrilisteroids A-C and derivatives from the terrestrial fungus Aspergillus quadrilineatus

Seven undescribed compounds (1-7) along with six known compounds (8-13) were isolated from Eurotiaceae Aspergillus quadrilineatus. Their structures and absolute configurations were elucidated by NMR, HRESIMS, and ECD calculations. Quadrilisteroids A (1) and B (2) possessed an unprecedented 6/5/6/6/6/5 hexacyclic ring system in conjugation with a highly fused benzene ring, while quadrilisteroid C (3) featured a surprising 6/6/6/5/5-fused carbocyclic skeleton. Quadrilisteroid C (3) exhibited potent inhibitory activity against LPS-induced proliferation of B lymphocyte cells with an IC50 value of 1.03 μM. Compound 4, demonstrated inhibitory activity against Con A-induced proliferation of T lymphocyte cells with IC50 values of 6.42 μM.

Survey of natural products reported by Asian research groups in 2022

The new natural products reported in 2022 in peer-reviewed articles in journals with good reputations were reviewed and analyzed. The advances made by Asian research groups in the field of natural products chemistry in 2022 were summarized. Compounds with unique structural features and/or promising bioactivities originating from Asian natural sources were discussed based on their structural classification.

Marine natural products

Covering: January to the end of December 2022This review covers the literature published in 2022 for marine natural products (MNPs), with 645 citations (633 for the period January to December 2022) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1417 in 384 papers for 2022), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of NP structure class diversity in relation to biota source and biome is discussed.

Genus Litophyton: A Hidden Treasure Trove of Structurally Unique and Diversely Bioactive Secondary Metabolites

Marine soft corals are prolific sources of various natural products that have served as a wealthy reservoir of diverse chemical scaffolds with potential as new drug leads. The genus Litophyton contains almost 100 species but only a small proportion of them has been chemically investigated, which calls for more attentions from global researchers. In the current work, 175 secondary metabolites have been discussed, drawing from published data spanning almost five decades, up to July 2023. The studied species of the genus Litophyton resided in various tropical and temperate regions and encompassed a broad range of biologically active natural products including terpenes, steroids, nitrogen-containing metabolites, lipids, and other metabolites. A wide spectrum of pharmacological effects of these compounds had been evaluated, such as cytotoxic, antiviral, antibacterial, antifungal, anti-malarial, antifeedant, anti-inflammatory, molluscicidal, PTP1B inhibitory, insect growth inhibitory, and neuroprotective activities. This review aims to offer an up-to-date survey of the literature and provide a comprehensive understanding of the chemical structures, taxonomical distributions, and biological activities of the reported metabolites from the title genus whenever available.

Endophytic Microbes from Medicinal Plants in Fenghuang Mountain as a Source of Antibiotics

One of the largest concerns with world health today is still antibiotic resistance, which is making it imperative to find efficient alternatives as soon as possible. It has been demonstrated that microbes are reliable sources for the creation of therapeutic antibiotics. This research intends to investigate the endophytic microorganisms from several medicinal plants in Fenghuang Mountain (Jiangsu Province, China) and to discover new antibiotics from their secondary metabolites. A total of 269 endophytic strains were isolated from nine distinct medicinal plants. Taxonomic analysis revealed that there were 20 distinct species among these endophytes, with Streptomyces being the most common genus. Three of the target strains were chosen for scale-up fermentation after preliminary screening of antibacterial activities and the metabolomics investigation using LC-MS. These strains were Penicillium sp. NX-S-6, Streptomyces sp. YHLB-L-2 and Streptomyces sp. ZLBB-S-6. Twenty-three secondary metabolites (1-23), including a new sorbicillin analogue (1), were produced as a result of antibacterial activity-guided isolation. Through spectroscopic analysis using MS and NMR, the structures of yield compounds were clarified. According to antibacterial data, S. aureus or B. subtilis were inhibited to varying degrees by sorrentanone (3), emodic acid (8), GKK1032 B (10), linoleic acid (14), toyocamycin (17) and quinomycin A (21). The most effective antimicrobial agent against S. aureus, B. subtilis, E. coli and A. baumannii was quinomycin A (21). In addition, quinomycin A showed strong antifungal activity against Aspergillus fumigatus, Cryptococcus neoformans, and two clinical isolated strains Aspergillus fumigatus #176 and #339, with MIC as 16, 4, 16 and 16 µg/mL, respectively. This is the first time that bioprospecting of actinobacteria and their secondary metabolites from medicinal plants in Fenghuang Mountain was reported. The finding demonstrates the potential of endophytic microbes in medical plants to produce a variety of natural products. Endophytic microbes will be an important source for new antibiotics.

Thiolactones and Δ8,9-Pregnene Steroids from the Marine-Derived Fungus Meira sp. 1210CH-42 and Their α-Glucosidase Inhibitory Activity

The fungal genus Meira was first reported in 2003 and has mostly been found on land. This is the first report of second metabolites from the marine-derived yeast-like fungus Meira sp. One new thiolactone (1), along with one revised thiolactone (2), two new Δ^8,9-steroids (4, 5), and one known Δ^8,9-steroid (3), were isolated from the Meira sp. 1210CH-42. Their structures were elucidated based on the comprehensive spectroscopic data analysis of 1D, 2D NMR, HR-ESIMS, ECD calculations, and the pyridine-induced deshielding effect. The structure of 5 was confirmed by oxidation of 4 to semisynthetic 5. In the α-glucosidase inhibition assay, compounds 2-4 showed potent in vitro inhibitory activity with IC₅₀ values of 148.4, 279.7, and 86.0 μM, respectively. Compounds 2-4 exhibited superior activity as compared to acarbose (IC₅₀ = 418.9 μM).

Chemical Emulation of the Biosynthetic Route to Anthrasteroids: Synthesis of Asperfloketal A

The anthrasteroid rearrangement has been discussed for the formation of the eponymous substance class since its discovery. We here report its chemical emulation from a plausible biogenetic precursor and show how it accounts for the formation of asperfloketals A and B through a mechanistic bifurcation event. As a result, these natural products arise from double Wagner-Meerwein rearrangements and, thus, are 1(10→5),1(5→6)- and 1(10→5),4(5→6)diabeo-14,15-secosteroids, respectively. To establish an efficient route to a bioinspired precursor, we devised a sequence of orchestrated oxidative activation and rearrangement from ergosterol.

Secondary Metabolites Diversity of Aspergillus unguis and Their Bioactivities: A Potential Target to Be Explored

Aspergillus unguis belongs to the Aspergillus section Nidulantes. This species is found in soils and organisms from marine environments, such as jellyfishes and sponges. The first chemical study reported in the literature dates from 1970, with depsidones nidulin (1), nornidulin (2), and unguinol (3) being the first isolated compounds. Fifty-two years since this first study, the isolation and characterization of ninety-seven (97) compounds have been reported. These compounds are from different classes, such as depsides, depsidones, phthalides, cyclopeptides, indanones, diarylethers, pyrones, benzoic acid derivatives, orcinol/orsenillate derivatives, and sesterpenoids. In terms of biological activities, the first studies on isolated compounds from A. unguis came only in the 1990s. Considering the tendency for antiparasitic and antibiotics to become ineffective against resistant microorganisms and larvae, A. unguis compounds have also been extensively investigated and some compounds are considered very promising. In addition to these larvicidal and antimicrobial activities, these compounds also show activity against cancer cell lines, animal growth promotion, antimalarial and antioxidant activities. Despite the diversity of these compounds and reported biological activities, A. unguis remains an interesting target for studies on metabolic induction to produce new compounds, the determination of new biological activities, medicinal chemistry, structural modification, biotechnological approaches, and molecular modeling, which have yet to be extensively explored.