Anti-inflammatory effect of berkeleyacetal C through the inhibition of interleukin-1 receptor-associated kinase-4 activity

Target Discovery of Dhilirane-Type Meroterpenoids by Biosynthesis Guidance and Tailoring Enzyme Catalysis

Dhilirane-type meroterpenoids (DMs) featuring a 6/6/6/5/5 ring system represent a rare group of fungal meroterpenoids. To date, merely 11 DMs have been isolated or derived, leaving their chemical diversity predominantly unexplored. Herein, we leverage an understanding of biosynthesis to develop a workflow for discovery of DMs by genome mining, metabolite analysis, and tailoring enzyme catalysis. Twenty-three new DMs, including seven unprecedented scaffolds, were consequently identified. An α-ketoglutarate (α-KG)-dependent oxygenase DhiD was found to catalyze the stereodivergent ring contraction of dhilirolide D to form the dhilirane skeleton; while the cytochrome P450 DhiH reshaped the structural diversity by establishing diverse C-C bonds and oxidation. Crystallographic and mutagenesis experiments provide a molecular basis for the DhiD reaction and its stereodivergent products. Notably, DhiD exhibits substrate-controlled catalytic versatility in the chemical expansion of DMs through ring contraction, hydroxylation, dehydrogenation, epoxidation, isomerization, epimerization, and α-ketol cleavage. Bioassay results demonstrated that the obtained meroterpenoids exhibited anti-inflammatory and insecticidal activities. Our work provides insight into nature's arsenal for DM biosynthesis and the functional versatility of α-KG-dependent oxygenase and P450, which can be applied for target discovery and diversification of DM-type natural products.

Peniandranoids A-E: Meroterpenoids with Antiviral and Immunosuppressive Activity from a Penicillium sp

Peniandranoids A-E (1-5), five new meroterpenoids, together with three known analogues (6-8), were isolated from the fermentation of a soil-derived fungus, Penicillium sp.sb62. Their structures including absolute configurations were determined by extensive spectroscopic analysis, and the absolute configurations of compounds 1 and 5 were further elucidated by single-crystal X-ray diffraction. Peniandranoids A-E belong to a rare class of andrastin-type meroterpenoids incorporating an extra polyketide unit (a C₁₀ polyketide unit for 1 and 2, a C₉ polyketide unit for 3 and 4, and a furancarboxylic acid unit for 5). Compounds 1 and 6 exhibited favorable inhibitory activities against influenza virus A (H1N1) with EC₅₀ values of 19 and 14 μg/mL, respectively. Compounds 3-8 exhibited potent immunosuppressive activities against concanavalin A-induced T cell proliferation with EC₅₀ values ranging from 4.3 to 27 μM and lipopolysaccharide-induced B cell proliferation with EC₅₀ values ranging from 7.5 to 23 μM, respectively.

Seco and Nor-seco Isodhilarane-Type Meroterpenoids from Penicillium purpurogenum and the Configuration Revisions of Related Compounds

Seco and nor-seco isodhilarane-type meroterpenoids (SIMs and NSIMs) are mainly found in Penicillium fungi and have been characterized by highly congested polycyclic skeletons and a broad range of bioactivities. However, the literature reports inconsistent configuration assignments for some SIMs and NSIMs, due to their complex polycyclic systems and multichiral centers. Herein, we described eight SIMs and NSIMs isolated from the EtOAc extract of Penicillium purpurogenum, which led to the configuration revisions of purpurogenolide C (1a), berkeleyacetal B (2a), chrysogenolide F (3a), and berkeleyacetal C (4a) as compounds 1-4, respectively. Furthermore, extensive re-evaluation of the experimental and computational ¹³C NMR chemical shifts of the reported 39 SIMs and NSIMs provided an empirical approach for determining the C-9 relative configuration, according to the ¹³C NMR chemical shifts of C-9, which contributed to the configuration revisions of another three SIMs (5a and 6a) and NSIMs (7a), denoted as compounds 5-7, respectively. Biological assays indicated that compound 3 exhibited cytotoxic activity against HepG2 and A549 cell lines with IC₅₀ values of 5.58 and 6.80 μM, respectively. Compounds 2-4, 8, 9, and 32 showed moderate hepatoprotective activity at 10 μM in the APAP-induced HepG2 cell injury model.

Synthetic Studies toward the Berkeleyacetal Core Architecture

Berkeleyacetals are structurally complex natural products that have shown potent anti-inflammatory activity. The presence of a highly dense oxygen functionality and a polycyclic ring system presents significant synthetic challenges. Herein, we report an efficient strategy for the construction of the tetracyclic core system of berkeleyacetal. Our synthetic strategy features two cycloadditions ([4+2] and [5+2]) to forge the tetracyclic core and Achmatowicz rearrangement for the preparation of the cyclization substrates containing B and E rings.

Secondary metabolites of endophytic fungi isolated from Huperzia serrata

The natural product Huperzine A isolated from Huperzia serrata is a targeted inhibitor of acetylcholinesterase that has been approved for clinical use in the treatment of Alzheimer's disease. Given the large demand for natural sources of Huperzine A  (Hup. A), efforts have been made to explore whether it is also produced by endophytic fungi from H. serrata and, if so, identify its biosynthetic pathway. These studies have indicated that endophytic fungi from H. serrata represent a huge and largely untapped resource for natural products (including Hup. A) with chemical structures that have been optimized by evolution for biological and ecological relevance. To date, more than three hundred endophytic fungi have been isolated from H. serrata, of which 9 strains can produce Hup. A, whilst more than 20 strains produce other important metabolites, such as polyketones, xanthones, alkaloids, steroids, triterpenoids, furanone derivatives, tremulane sesquitepenes and diterpenoids. In total, 200 secondary metabolites have been characterized in endophytic fungi from H. serrata to date. Functionally, some have cholinesterase-inhibitory or antibacterial activity. This review also considers the different classes of secondary metabolites produced by endophytic fungi, along with their possible applications. We systematically describe the taxonomy, biology, and chemistry of these secondary metabolites. It also summarizes the biosynthetic synthesis of metabolites, including that of Hup. A. The review will aid researchers in obtaining a clearer understanding of this plant-endophyte relationship to better exploit the excellent resources it offers that may be utilized by pharmaceutical industries.

Marine-Derived Penicillium purpurogenum Reduces Tumor Size and Ameliorates Inflammation in an Erlich Mice Model

Background: This study addresses the antitumoral properties of Penicillium purpurogenum isolated from a polluted lagoon in Northeastern Brazil. Methods: Ethyl Acetate Extracellular Extract (EAE) was used. The metabolites were studied using direct infusion mass spectrometry. The solid Ehrlich tumor model was used for antitumor activity. Female Swiss mice were divided into groups (n = 10/group) as follows: The negative control (CTL−), treated with a phosphate buffered solution; the positive control (CTL+), treated with cyclophosphamide (25 mg/kg); extract treatments at doses of 4, 20, and 100 mg/kg; animals without tumors or treatments (Sham); and animals without tumors treated with an intermediate dose (EAE20). All treatments were performed intraperitoneally, daily, for 15 days. Subsequently, the animals were euthanized, and the tumor, lymphoid organs, and serum were used for immunological, histological, and biochemical parameter evaluations. Results: The extract was rich in meroterpenoids. All doses significantly reduced tumor size, and the 20 and 100 mg/kg doses reduced tumor-associated inflammation and tumor necrosis. The extract also reduced the cellular infiltration of lymphoid organs and circulating TNF-α levels. The extract did not induce weight loss or renal and hepatic toxic changes. Conclusions: These results indicate that P. purpurogenum exhibits immunomodulatory and antitumor properties in vivo. Thus, fungal fermentation is a valid biotechnological approach to the production of antitumor agents.

Two new bioactive steroids from a mangrove-derived fungus Aspergillus sp

Two unusual naturally Diels-Alder additive steroids, ergosterdiacids A and B (1 and 2), constructing a 6/6/6/6/5 pentacyclic steroidal system, together with three known compounds (3-5) were obtained from the mangrove-derived fungus Aspergillus sp. Their structures were elucidated based on the comprehensive spectroscopic analysis, including 1D, 2D NMR and HRESIMS, as well as the quantum chemical ECD calculations. The plausible biosynthetic pathways of 1 and 2 were discussed. In the bioactivity assays, 1 and 2 exhibited potential in vitro inhibition activity against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with an IC₅₀ value of 15.1 and 30.1 μM, respectively. The inhibitory kinetic experiments indicated that both of them acted via a noncompetitive inhibition mechanism. Moreover, 1 and 2 showed strong in vitro anti-inflammatory effects by suppressing the NO production at 4.5 and 3.6 μM, respectively.

Anti-inflammatory meroterpenoids from the mangrove endophytic fungus Talaromyces amestolkiae YX1

Four previously undescribed meroterpenoids, amestolkolides A-D, along with three known compounds were isolated from the mangrove endophytic fungus Talaromyces amestolkiae YX1 cultured on wheat solid-substrate medium culture. Their structures were elucidated by a combination of spectroscopic analyses. The absolute configurations of amestolkolides B and C, and purpurogenolide E were determined by single-crystal X-ray diffraction using Cu Kα radiation, and those of amestolkolides A and D were elucidated on the basis of experimental and calculated electronic circular dichroism spectra. The absolute configuration of amestolkolides A-D, and purpurogenolide E (9R) at C-9 was different from that of analogues (9S) in references, so that their plausible and distinct biosynthetic pathways were proposed. Amestolkolide B showed strong anti-inflammatory activity in vitro by inhibiting nitric oxide (NO) production in lipopolysaccharide activated in RAW264.7 cells with IC₅₀ value of 1.6 ± 0.1 μM.

Two new sesquiterpenes derivatives from marine fungus Leptosphaerulina Chartarum sp. 3608

Two new sesquiterpenes, leptoterpenes A (1) and B (2) were isolated from the fungus Leptosphaerulina Chartarum sp. 3608, derived from a crinoid. It was the first chemical study on this species. The structures of these compounds were elucidated by spectroscopic methods including NMR and MS spectrometry. The absolute configurations of the new compounds were determined on the basis of the single-crystal X-ray diffraction and electronic circular dichroism data analysis. All compounds were tested for their anti-inflammatory activity and the inhibitory effects on Tyrosyl DNA phosphodiesterase II (TDP2).

3,5-Dimethylorsellinic Acid Derived Meroterpenoids from Penicillium chrysogenum MT-12, an Endophytic Fungus Isolated from Huperzia serrata

Eight new chrysogenolides (A-H (1-8)) and seven known (9-15) 3,5-dimethylorsellinic acid derived meroterpenoids were isolated from the solid substrate fermentation cultures of a Huperzia serrata endophytic fungus, Penicillium chrysogenum MT-12. The structures of the new compounds were elucidated by interpretation of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of 1-4 were determined by single-crystal X-ray crystallographic analysis, and those of 5-8 were assigned on the basis of experimental and calculated electronic circular dichroism spectra. Compounds 3, 4, 6, 11, and 12 showed inhibition of nitric oxide production in lipopolysaccharide-activated RAW 264.7 macrophage cells with IC₅₀ values in the range of 4.3-78.2 μM (positive control, indomethacin, IC₅₀ = 33.6 ± 1.4 μM).

Berkeleyacetal C, a meroterpenoid isolated from the fungus Penicillium purpurogenum MHZ 111, exerts anti-inflammatory effects via inhibiting NF-κB, ERK1/2 and IRF3 signaling pathways

Berkeleyacetal C (BAC), a meroterpenoid compound, was isolated from the fungus Penicillium purpurogenum MHZ 111 and showed favorable activity of inhibiting nitrogen oxide (NO) production of macrophages stimulated by lipopolysaccharide (LPS) in our preliminary screening. In order to develop novel therapeutic drug for acute and chronic inflammatory diseases, the anti-inflammatory activity and underlying mechanisms of BAC were investigated in macrophages and neutrophils. The results showed that BAC significantly inhibited the expression of inducible nitric oxide synthase (iNOS) and the following NO production by macrophages. The expression and secretion of key pro-inflammatory factors and chemokines, including tumor necrosis factor-α (TNF-α)，interleukin-6 (IL-6), interleukin-1β (IL-1β), macrophage inflammatory protein-1α (MIP-1α), and monocyte chemotactic protein-1 (MCP-1) were also intensively suppressed by BAC. Furthermore, BAC also markedly inhibited activation of neutrophils and reactive oxygen species production. In mechanism study, BAC selectively suppressed phosphorylation of nuclear factor-κB (NF-κB), extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), and interferon regulatory transcription factor 3 (IRF3) during the activation of NF-κB, mitogen-activated protein kinase (MAPK), signal transducer and activator of transcription 1 and 3 (STAT1/3), and IRF3 signaling pathways induced by LPS. In summary, BAC exerts strong anti-inflammatory effects by inhibiting NF-κB, ERK1/2 and IRF3 signaling pathways and thereby shows great potential to be developed into therapeutic agent for inflammatory disorders.

Antiviral and anti-inflammatory meroterpenoids: stachybonoids A–F from the crinoid-derived fungus Stachybotrys chartarum 952

Six new meroterpenoids, which have been named as stachybonoids A–F (1–3 and 5–7), and three known phenylspirodrimanes (4, 8 and 9) were isolated from the crinoid-derived fungus Stachybotrys chartarum 952.

Nitric Oxide Inhibitory Meroterpenoids from the Fungus Penicillium purpurogenum MHZ 111

Five new meroterpenoids, purpurogenolides A-E (1-5), and four known metabolites (6-9) were isolated from the solid substrate fermentation cultures of the fungus Penicillium purpurogenum MHz 111. The structures of the new meroterpenoids were elucidated by analysis of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of 1 and 5 were determined by single-crystal X-ray crystallographic analysis, and those of 2-4 were elucidated on the basis of experimental and calculated electronic circular dichroism spectra. Compounds 2-4 and 6 showed inhibition of nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 0.8-30.0 μM.

Biosynthesis of fungal meroterpenoids

Covering: up to September 2015. Meroterpenoids are hybrid natural products that partially originate from the terpenoid pathway. The meroterpenoids derived from fungi display quite diverse structures, with a wide range of biological properties. This review summarizes the molecular bases for their biosyntheses, which were recently elucidated with modern techniques, and also discusses the plausible biosynthetic pathways of other related natural products lacking genetic information. (Complementary to the coverage of literature by Geris and Simpson in Nat. Prod. Rep., 2009, 26, 1063-1094.).

Inhibitory Effects of Chemical Compounds Isolated from the Rhizome of Smilax glabra on Nitric Oxide and Tumor Necrosis Factor- α Production in Lipopolysaccharide-Induced RAW264.7 Cell

The rhizome of Smilax glabra has been used for a long time as both food and folk medicine in many countries. The present study focused on the active constituents from the rhizome of S. glabra, which possess potential anti-inflammatory activities. As a result, nine known compounds were isolated from the rhizome of S. glabra with the bioassay-guiding, and were identified as syringaresinol (1), lasiodiplodin (2), de-O-methyllasiodiplodin (3), syringic acid (4), 1,4-bis(4-hydroxy-3,5-dimethoxyphenyl)-2,3-bis(hydroxymethyl)-1,4-butanediol (5), lyoniresinol (6), trans-resveratrol (7), trans-caffeic acid methyl ester (8), and dihydrokaempferol (9). Among these compounds, 2 and 3 were isolated for the first time from S. glabra. In addition, the potential anti-inflammatory activities of the isolated compounds were evaluated in vitro in lipopolysaccharide- (LPS-) induced RAW264.7 cells. Results indicated that 4 and 7 showed significant inhibitory effects on NO production of RAW264.7 cells, and 1, 2, 3, and 5 showed moderate suppression effects on induced NO production. 1, 7, and 5 exhibited high inhibitory effects on TNF-α production, with the IC₅₀ values less than 2.3, 4.4, and 16.6 μM, respectively. These findings strongly suggest that compounds 1, 2, 3, 4, 5, 7, and 9 were the potential anti-inflammatory active compositions of S. glabra.