Marine-derived Fungus Aspergillus Terreus Research Articles

Four sulfur-containing compounds with anti-colon cancer effect from marine-derived fungus Aspergillus terreus

Sulfur-containing natural products possess a variety of biological functions including antitumor, antibacterial, anti-inflammatory and antiviral activities. In this study, four previously undescribed sulfur-containing compounds asperteretals L and M, terreins A and B, together with 17 known compounds were obtained from a culture of marine fungus A. terreus supplemented with inorganic sulfur source Na2SO4. Their planar structures and absolute configurations were elucidated by NMR, HRESIMS, and ECD experiments. The in vitro cytotoxicities of compounds 1–21 against HCT-116 and Caco-2 were evaluated by SRB assay. Asperteretal M (2) exhibited activity against HCT-116 with the IC50 value at 30μM. The antiproliferative effect of asperteretal M was confirmed by colony formation assay and cell death staining. Furthermore, the preliminary study on the anti-colon cancer mechanism of asperteretal M was performed by RNA-seq analysis. Western blotting validated that asperteretal M significantly decreased the expression of cell-cycle regulatory proteins CDK1, CDK4, and PCNA in a concentration-dependent manner.

Meroterpenoids from the marine-derived fungus Aspergillus terreus GZU-31-1 exerts anti-liver fibrosis effects by targeting the Nrf2 signaling in vitro

Six undescribed meroterpenoids aspertermeroterpenes A−F and four known analogues were isolated from the marine-derived fungus Aspergillus terreus GZU-31-1. Their structures were elucidated based on spectroscopic methods and electronic circular dichroism calculations. All meroterpenoids possessed the unique acetyl group at C-11, and also aspertermeroterpene A featured the rare C-14 decarboxylated in DMOA meroterpenoids. In the bioassays, aspermeroterpene B exhibited a potent inhibitory effect on the activation of hepatic stellate cells at the concentration of 5 μM via targeting the Nrf2 signaling. This is the first time reported that aspermeroterpene B as a previously undescribed carbon skeleton of meroterpenoid possessed anti-liver fibrosis effect.

New butanolide derivatives from the marine derived fungus Aspergillus terreus GZU-31-1 by chemical epigenetic manipulation

Chemical epigenetic manipulation of Aspergillus terreus GZU-31-1 led to the discovery of five butanolide derivatives (1–5), including two new ones (1 and 2), and four known diphenyl ether derivatives (6−9). Compound 1 featured a Z-configuration double bond in the isoprenyl group was a potential anti-inflammatory bioactive group. Compound 2 was a new natural product. Moreover, compound 3 with a deacetylated group at C-4 was rarely reported as a butanolide analogue, which was isolated from the liquid culture treated with polyketide pathway inhibitor sodium citrate dihydrate. All of the isolates (1−9) were tested for their anti-inflammatory effects on the production of nitric oxide in lipopolysaccharide-induced microglial cells (RAW 264.7 cells). Compounds 1, 7, 8 and 9 exhibited more potent anti-inflammatory activity with IC50 values of 16.31, 20.16, 9.53 and 21.64 μM than the positive control (indomethacin, IC50, 24.0 μM).

Induction of Secondary Metabolite Biosynthesis by Deleting the Histone Deacetylase HdaA in the Marine-Derived Fungus Aspergillus terreus RA2905.

Aspergillus terreus is well-known for its ability to biosynthesize valuable pharmaceuticals as well as structurally unique secondary metabolites. However, numerous promising cryptic secondary metabolites in this strain regulated by silent gene clusters remain unidentified. In this study, to further explore the secondary metabolite potential of A. terreus, the essential histone deacetylase hdaA gene was deleted in the marine-derived A. terreus RA2905. The results showed that HdaA plays a vital and negative regulatory role in both conidiation and secondary metabolism. Loss of HdaA in A. terreus RA2905 not only resulted in the improvement in butyrolactone production, but also activated the biosynthesis of new azaphilone derivatives. After scaled fermentation, two new azaphilones, asperterilones A and B (1 and 2), were isolated from ΔhdaA mutant. The planar structures of compounds 1 and 2 were undoubtedly characterized by NMR spectroscopy and mass spectrometry analysis. Their absolute configurations were assigned by circular dichroism spectra analysis and proposed biosynthesis pathway. Compounds 1 and 2 displayed moderate anti-Candida activities with the MIC values ranging from 18.0 to 47.9 μM, and compound 1 exhibited significant cytotoxic activity against human breast cancer cell line MDA-MB-231. This study provides novel evidence that hdaA plays essential and global roles in repressing secondary metabolite gene expression in fungi, and its deletion represents an efficient strategy to mine new compounds from A. terreus and other available marine-derived fungi.

Development of versatile and efficient genetic tools for the marine-derived fungus Aspergillus terreus RA2905.

Marine-derived Aspergillus terreus produces a variety of structurally novel secondary metabolites, most of which show unique biological activities. However, the lack of efficient genetic tools limits the discovery of new compounds, the elucidation of involved biosynthesis mechanism, as well as the strain engineering efforts. Therefore, in this study, we first established both an effective PEG-mediated chemical transformation system of protoplasts and an electroporation system of conidia in a marine-derived fungus A. terreus RA2905. To overcome the insensitivity of RA2905 to fungicides, the uracil auxotrophy strain (pyrG gene deletion mutant, ΔpyrG) was constructed using PEG-mediated transformation system, and using ΔpyrG as the genetic background, the methyltransferase gene laeA-overexpression transformants were further constructed through both PEG- and electroporation-mediated transformations, which showed enhanced terrein production. Besides, in this study, an efficient CRISPR/Cas9 genome-editing system was established for the first time in A. terreus, and a higher gene deletion efficiency of 71% for APSES transcription factor gene stuA could be achieved when using short homologous arms compared with conventional long homologous ones. In addition, using a non-integrative Cas9 plasmid, another efficient and marker-free genome-editing system was established, which allowing repeatable and unlimited genetic manipulation in A. terreus. Using the marker-free genome-editing system, we successfully developed the ΔpyrGΔku70 double-deletion mutant in RA2905, which could further improve gene deletion efficiency. In conclusion, efficient genetic manipulation systems along with a variety of functional mutants were developed in this study, which would significantly expedite both theoretical and applied researches in not only A. terreus but also other marine-derived filamentous fungi.

Furanaspermeroterpenes A and B, two unusual meroterpenoids with a unique 6/6/6/5/5 pentacyclic skeleton from the Marine-derived fungus Aspergillus terreus GZU-31-1

Furanaspermeroterpenes A (1) and B (2), with a unique 6/6/6/5/5 pentacyclic skeleton, and five new congeners aspermeroterpenes D–H (3–7) were co-isolated from the marine-derived fungus Aspergillus terreus GZU-31-1. Among them, compounds 1 and 2 with rare five-membered D/E coupling rings were the first example of DMOA-derived meroterpenoids. Moreover, compound 3 was the first reported 6/6/6/6/5 pentacyclic meroterpenoid featuring an unusual cis-fused A/B ring. In the bioassays, all of the isolates were evaluated on the inhibitory activities against lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells, and compounds 3–7 exhibited significant anti-inflammatory activity with IC50 values ranging from 6.74 to 29.59 μM than positive control (Indomethacin, IC50 30.98 μM).

Anti-Inflammatory, Antiallergic, and COVID-19 Main Protease (Mpro) Inhibitory Activities of Butenolides from a Marine-Derived Fungus Aspergillus terreus.

In December 2020, the U.K. authorities reported to the World Health Organization (WHO) that a new COVID-19 variant, considered to be a variant under investigation from December 2020 (VUI-202012/01), was identified through viral genomic sequencing. Although several other mutants were previously reported, VUI-202012/01 proved to be about 70% more transmissible. Hence, the usefulness and effectiveness of the newly U.S. Food and Drug Administration (FDA)-approved COVID-19 vaccines against these new variants are doubtfully questioned. As a result of these unexpected mutants from COVID-19 and due to lack of time, much research interest is directed toward assessing secondary metabolites as potential candidates for developing lead pharmaceuticals. In this study, a marine-derived fungus Aspergillus terreus was investigated, affording two butenolide derivatives, butyrolactones I (1) and III (2), a meroterpenoid, terretonin (3), and 4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde (4). Chemical structures were unambiguously determined based on mass spectrometry and extensive 1D/2D NMR analyses experiments. Compounds (1–4) were assessed for their in vitro anti-inflammatory, antiallergic, and in silico COVID-19 main protease (Mpro) and elastase inhibitory activities. Among the tested compounds, only 1 revealed significant activities comparable to or even more potent than respective standard drugs, which makes butyrolactone I (1) a potential lead entity for developing a new remedy to treat and/or control the currently devastating and deadly effects of COVID-19 pandemic and elastase-related inflammatory complications.

Benzyl Furanones and Pyrones from the Marine-Derived Fungus Aspergillus terreus Induced by Chemical Epigenetic Modification.

Chemical epigenetic modification on a marine-derived fungus Aspergillus terreus RA2905 using a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), resulted in a significantly changed metabolic profile. A chemical investigation of its ethyl acetate (EtOAc) extract led to the isolation of a racemate of benzyl furanone racemate (±)-1, which further separated chirally as a pair of new enantiomers, (+)- and (−)-asperfuranone (1), together with two new benzyl pyrones, asperpyranones A (2) and B (3). Their structures were elucidated by analysis of the comprehensive spectroscopic data, including one-dimensional (1D) and two-dimensional (2D) NMR, and HRESIMS. The absolute configurations were determined by electronic circular dichroism (ECD) calculation and single-crystal X-ray crystallographic experiment. The structures with benzyl furanone or benzyl pyrone skeletons were discovered from natural products for the first time. Compounds (±)-1, (+)-1, (−)-1, and 2 displayed the antifungal activities against Candida albicans with MIC values of 32, 16, 64, and 64 μg/mL and PTP1B inhibitory activities with the IC50 values of 45.79, 17.32, 35.50, and 42.32 μM, respectively. Compound 2 exhibited antibacterial activity against Pseudomonas aeruginosa with the MIC value of 32 μg/mL.

Antimicrobial, antimalarial and anticholinesterase substances from the marine-derived fungus Aspergillus terreus BCC51799

Five new natural products [asperteramide, aspulvinones R and S, astalluminoxide and astepyrazinol B] and five naturally new ones (aspernolide C, astepyrazinoxide, astepyrazinol A, 4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde and methyl 2-[4-hydroxy-3-(3-methylbut-2-en-1-yl)phenyl]acetate), together with twenty-one previously described compounds were isolated from marine-derived Aspergillus terreus BCC51799. Chemical structures were determined on the basis of spectroscopic evidence (NMR, UV, IR spectral data) and their physical properties. The isolated compounds were tested for their antimalarial, antimicrobial and anticholinesterase activities. Asperteramide exhibited antimicrobial activity against Bacillus cereus and Colletrichum acutatum with MIC values of 25 and 50 μg/mL, respectively. Astechrome showed strong antimalarial activity with an IC50 value of 0.94 μM, while territrem B had significant anticholinesterase activity with an IC50 value of 0.071 μM. All tested compounds, except for astepyrazinoxide and lavastatin, had moderate to weak cytotoxicity against both cancerous and non-cancerous cells.

Asperbutenolide A, an unusual aromatic butenolide dimer with diverse bioactivities from a marine-derived fungus Aspergillus terreus SCAU011

Two new aromatic butenolides (1 and 2), along with a known analogue (3), were isolated and structurally identified from the fermentation extract of a mangrove sediment derived fungus Aspergillus terreus SCAU011. Structures of the new compounds were established mainly by spectroscopic data analyses, and the absolute configurations were determined by a combination of various strategies including electronic circular dichroism (ECD) comparison, induced circular dichroism (ICD) experiments and chemical derivation and degradation. Compound 2, with an unusual dimeric scaffold linked via an ether bridge, exhibited a wide range of biological properties including strong cyclooxygenase-2 (COX-2) and α-glucosidase inhibitory activities, as well as moderate antiradical and antibacterial effects.

Furanasperterpenes A and B, two meroterpenoids with a novel 6/6/6/6/5 ring system from the marine-derived fungus Aspergillus terreus GZU-31-1.

Furanasperterpenes A (1) and B (2) with a novel 6/6/6/6/5 pentacyclic skeleton and a new 11-acetoxy-terretonin E (3), were isolated from the marine-derived Aspergillus terreus GZU-31-1. Their structures were elucidated based on spectroscopic methods, and the absolute configurations were determined by X-ray diffraction and electronic circular dichroism (ECD) calculations. A possible biogenetic pathway was proposed. These compounds were evaluated for their lipid-lowering effects in 3T3-L1 adipocytes. Furanasperterpene A (1) showed the equivalent activity in reducing TG levels to positive control (berberine) at the concentration of 5μM.

New Thiodiketopiperazine and 3,4-Dihydroisocoumarin Derivatives from the Marine-Derived Fungus Aspergillus terreus.

Aspergillus terreus has been reported to produce many secondary metabolites that exhibit potential bioactivities, such as antibiotic, hypoglycemic, and lipid-lowering activities. In the present study, two new thiodiketopiperazines, emestrins L (1) and M (2), together with five known analogues (3–7), and five known dihydroisocoumarins (8–12), were obtained from the marine-derived fungus Aspergillus terreus RA2905. The structures of the new compounds were elucidated by analysis of the comprehensive spectroscopic data, including high-resolution electrospray ionization mass spectrometry (HRESIMS), one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), and electronic circular dichroism (ECD) data. This is the first time that the spectroscopic data of compounds 3, 8, and 9 have been reported. Compound 3 displayed antibacterial activity against Pseudomonas aeruginosa (minimum inhibitory concentration (MIC) = 32 μg/mL) and antifungal activity against Candida albicans (MIC = 32 μg/mL). In addition, compound 3 exhibited an inhibitory effect on protein tyrosine phosphatase 1 B (PTP1B), an important hypoglycemic target, with an inhibitory concentration (IC)50 value of 12.25 μM.

Aspermeroterpenes A-C: Three Meroterpenoids from the Marine-Derived Fungus Aspergillus terreus GZU-31-1.

Aspermeroterpene A (1) with an unprecedented and highly congested 5/3/6/6/6/5 hexacyclic skeleton, together with two precursors aspermeroterpenes B (2) and C (3), were isolated from the marine-derived fungus Aspergillus terreus GZU-31-1. Their structures were elucidated by quantum chemical calculations, X-ray diffraction, and spectroscopic methods. The biogenetic pathway for 1-3 is proposed. Aspermeroterpenes A-C (1-3) showed significant inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells compared to positive control.

Terretonin D1, a new meroterpenoid from marine-derived Aspergillus terreus ML-44

A new meroterpenoid, named terretonin D1 (1), and three known ones, terretonin (2), terretonin A (3), and terretonin D (4), were isolated from marine-derived fungus Aspergillus terreus ML-44. The structure of 1 was elucidated by extensive spectroscopic methods, including 1D and 2D NMR, HR-ESI-MS, and the absolute configuration was determined by X-ray crystallographic analysis. The anti-inflammation activity of 1–4 was preliminarily tested, and all of them weakly inhibited the nitric oxide (NO) production of RAW264.7 macrophages stimulated by lipopolysaccharide (LPS), with inhibitory rates of 22–34% at 50 μg/mL.

Butenolides from a marine-derived fungus Aspergillus terreus with antitumor activities against pancreatic ductal adenocarcinoma cells.

Chemical study on the extract of a marine-derived fungus Aspergillus terreus yielded twelve butenolide derivatives, including three new compounds, namely asperlides A-C (1-3) and nine known butenolides (4-12). The structures of 1-3 were confirmed by comprehensive spectroscopic analysis, including HRESIMS, NMR spectroscopy, and calculated electronic circular dichroism (ECD). The cytotoxicity of the compounds was evaluated using PANC-1, HCC1806, HepG2, BEAS-2B and HT-29 cancer cells. The results showed that (+)-3',3'-di-(dimethylallyl)-butyrolactone II (4) and versicolactone B (6) exhibited the most potent cytotoxin of PANC-1 cell line, with the IC50 values of 5.3 and 9.4 μM, respectively. Morphological features of apoptosis were observed in 4 and 6-treated PANC-1 cells, including apoptotic body formation, membrane blebbing, cell shrinkage and nuclear condensation. Cell cycle analysis with propidium iodide staining exhibited that 4 inhibits proliferation of PANC-1 cells via the induction of G2/M and S phase arrest, while 6 could retard the PANC-1 cells via the induction of S phase arrest. Flow cytometric analysis suggested that treatment with 4 and 6 significantly induced PANC-1 cells apoptosis. These findings indicated that 4 and 6 might serve as a starting point for the development of an anticancer drug for the treatment of pancreatic ductal adenocarcinoma.

Brasilane sesquiterpenoids and dihydrobenzofuran derivatives from Aspergillus terreus [CFCC 81836

Brasilanones A–F and asperterreusines A–C, undescribed brasilane sesquiterpenoids and dihydrobenzofuran derivatives, were isolated from the marine-derived fungus Aspergillus terreus [CFCC 81836]. Their structures with absolute configurations were elucidated on the basis of spectroscopic data, X-ray crystallographic analyses, and electronic circular dichroism (ECD) calculations. Brasilanones A–F are unusual brasilane sesquiterpenoids with an α,β-unsaturated ketone unit, interestingly, brasilanones B–D are stereo isomers. All of the isolates were evaluated for their inhibitory activities against NO production and cytotoxic activities against five human cancer cell lines (HL-60, SW-480, A-549, MCF-7, and SMMC-7721). Brasilanones A and E showed moderate inhibitory effect with NO inhibition rates of 47.7% (p < 0.001) and 37.3% (p < 0.001) at the concentration of 40 μM. Asperterreusines A showed cytotoxicity against HL-60 and SW-480 cell lines with IC50 values of 15.3 and 25.7 μM, respectively.

A novel alginate–CMC gel beads for efficient covalent inulinase immobilization

Covalent immobilization of inulinase, produced by the marine-derived fungus Aspergillus terreus, on novel gel beads was made by the combination of alginate and carboxymethyl cellulose. Optimization of the loading time and loading units was done by response surface methodology. The bound enzyme displayed a change in optimum operating pH from 5.0 to 5.5 while the optimum operating temperature increased from 50 to 55 °C. K m value has been increased (from 3.6 to 7.1 mg/ml) in comparison with the free enzyme. However, the V max was lowered (from 145 to 77.5 U/g carrier) after immobilization. The immobilized inulinase showed enhancement in thermal stability against high temperature. There was an observed increase in half-lives and D values which revealed the improvement in the enzyme thermal stability. Thermodynamically, after immobilization, a remarkable increase in enthalpy and free energy was observed due to the enhancement of enzyme stability. Immobilized inulinase showed retention of 60% of its original activity after 10 successive cycles. Stability and reusability of immobilized inulinase on alginate–CMC enable the enzyme to be more convenient for industrial application.

Antifouling Compounds from the Marine-Derived Fungus Aspergillus terreus SCSGAF0162

A new cyclic tetrapeptide, asperterrestide B (1), and 11 known compounds (2-12) were isolated from a marine-derived fungus Aspergillus terreus SCSGAF0162. The structure of 1 was elucidated by spectroscopic analysis, and the absolute configuration of 1 was determined by Mosher ester and Marfey's methods. Compounds 4, 6, and 8 had potent antifouling activity against larvae of the barnacle Balanus amphitrite, with EC50 values of 17.1 ± 1.2, 11.6 ± 0.6, and 17.1 ± 0.8 μg x mL(-1), respectively.

Lumazine peptides from the marine-derived fungus Aspergillus terreus.

Terrelumamides A (1) and B (2), two new lumazine-containing peptides, were isolated from the culture broth of the marine-derived fungus Aspergillus terreus. From the results of combined spectroscopic and chemical analyses, the structures of these compounds were determined to be linear assemblies of 1-methyllumazine-6-carboxylic acid, an amino acid residue and anthranilic acid methyl ester connected by peptide bonds. These new compounds exhibited pharmacological activity by improving insulin sensitivity, which was evaluated in an adipogenesis model using human bone marrow mesenchymal stem cells. In addition, the compounds exhibited fluorescence changes upon binding to DNA, demonstrating their potential applications to DNA sequence recognition.

Territrem and butyrolactone derivatives from a marine-derived fungus Aspergillus terreus.

Seventeen lactones including eight territrem derivatives (1–8) and nine butyrolactone derivatives (9–17) were isolated from a marine-derived fungus Aspergillus terreus SCSGAF0162 under solid-state fermentation of rice. Compounds 1–3 and 9–10 were new, and their structures were elucidated by spectroscopic analysis. The acetylcholinesterase inhibitory activity and antiviral activity of compounds 1–17 were evaluated. Among them, compounds 1 and 2 showed strong inhibitory activity against acetylcholinesterase with IC50 values of 4.2 ± 0.6, 4.5 ± 0.6 nM, respectively. This is the first time it has been reported that 3, 6, 10, 12 had evident antiviral activity towards HSV-1 with IC50 values of 16.4 ± 0.6, 6.34 ± 0.4, 21.8 ± 0.8 and 28.9 ± 0.8 μg·mL−1, respectively. Antifouling bioassay tests showed that compounds 1, 11, 12, 15 had potent antifouling activity with EC50 values of 12.9 ± 0.5, 22.1 ± 0.8, 7.4 ± 0.6, 16.1 ± 0.6 μg·mL−1 toward barnacle Balanus amphitrite larvae, respectively.