Mangrove Endophytic Fungus Research Articles

Four Tremulanes and Two Pyroglutamate-Containing Dipeptides from the Mangrove Endophytic Fungus Phaeosphaeriopsis sp. P11.

Four new tremulane sesquiterpenes, named phaeosphaerienols A-D (1-4), and two new pyroglutamate-containing dipeptides, named phaeosphaeratides A-B (5-6), were isolated from the mangrove endophytic fungus Phaeosphaeriopsis sp. P11, together with a new 2-furancarboxylic acid derivative (7). Structurally, pheaosphaerienols A-C (1-3) are rare tremulanes containing a 1,10-epoxide moiety. The structures of these compounds were established by extensive NMR spectroscopic data, single-crystal X-ray diffraction analysis, and Marfey's derivatization method. All the isolates were evaluated for their cytotoxic, antibacterial, and DPPH free radical scavenging effects. However, none of the compounds exhibited obvious activities.

Two new polyketone derivatives from the mangrove endophytic fungus Aspergillus sp. GXNU TH4b

Two new polyketones, exserone B (1) and cytosporone F (2), along with three known metabolites, were isolated from the mangrove endophytic fungus Aspergillus TH4b. The structures of 1 and 2 were determined by detailed NMR, and MS spectroscopic data. The absolute configurations of 1 and 2 were determined by single crystal X-ray diffraction analysis and the combination of experimental ECD and computational ECD, respectively. Compounds 1–2 have strong inhibitory activity against citrus Psyllid (Diaphorina citri) with 95.4% and 93.7% lethal at 1000 mg/kg.

The Cytochalasins and Polyketides from a Mangrove Endophytic Fungus Xylaria arbuscula QYF.

Twelve compounds, including four undescribed cytochalasins, xylariachalasins A-D (1-4), four undescribed polyketides (5-8), and four known cytochalasins (9-12), were isolated from the mangrove endophytic fungus Xylaria arbuscula QYF. Their structures and absolute configurations were established by extensive spectroscopic analyses (1D and 2D NMR, HRESIMS), electronic circular dichroism (ECD) calculations, 13C NMR calculation and DP4+ analysis, single-crystal X-ray diffraction, and the modified Mosher ester method. Compounds 1 and 2 are rare cytochalasin hydroperoxides. In bioactivity assays, Compound 2 exhibited moderate antimicrobial activities against Staphylococcus aureus and Candida albicans with MIC values of 12.5 μM for both Compound 10 exhibited significant cytotoxic activity against MDA-MB-435 with an IC50 value of 3.61 ± 1.60 μM.

SZ-685C inhibits the growth of non-functioning pituitary adenoma by down-regulating miR-340-3p and inducing autophagy

BackgroundSZ-685C, an anthracycline compound derived from the mangrove endophytic fungus Halorosellinia sp. (No. 1403) collected from the South China Sea, has shown strong anticancer activities. Non-functioning pituitary adenomas (NFPAs) are a type of tumor that can be challenging to manage clinically and have a significant unmet medical need. Our research has found that SZ-685C showed an inhibitory effect on the viability, migration ability, and proliferation ability of a human non-functioning pituitary tumor-derived folliculostellate (PDFS) cell line. MethodsSZ-685C was prepared and purified from the mangrove endophytic fungus No. 1403. PDFS cells were exposed to SZ-685C, and the effect of SZ-685C on PDFS cells was evaluated. RNA sequencing was used to analyze the miRNA expression profile in PDFS cells of the control group and SZ-685C-treated group. Quantitative polymerase chain reaction (qPCR) was performed to verify the expression of selected miR-340-3p. The effects of SZ-685C on PDFS cells after overexpression of miR-340-3p were evaluated. Dual-luciferase reporter assays showed PPP1CB is a direct target of miR-340-3p. Finally, the action pathway of the selected miR-340-3p was predicted and evaluated through bioinformatics analysis. ResultsSZ-685C reduced cell viability in PDFS cells, accompanied by inhibition of migration ability and proliferation ability. The IC50 value for 24 h is 9.144 ± 0.991 μM, and for 48 h is 4.635 ± 0.551 μM. SZ-685C increased the protein levels of Beclin 1, the ratio of LC3-II to LC3-I, and LAMP-1, and down-regulated p62. MiRNA sequencing and further validation showed that miR-340-3p significantly decreased in PDFS cells treated with SZ-685C. After overexpression of miR-340-3p, the inhibition of viability, migration ability, proliferation ability, and autophagy-promoting effect of SZ-685C on PDFS cells were weakened. SZ-685C caused a decrease in PPP1CB expression and activation of the ERK pathway in PDFS cells, and this trend was reversed after overexpression of miR-340-3p. ConclusionsSZ-685C downregulates the expression of miR-340-3p in PDFS cells, thereby reducing the expression of PPP1CB and activating the ERK pathway to promote autophagic cell death, leading to inhibition of PDFS cell growth.

Treasures in our backyard: unleashing the biotechnological potentials of endophytic fungi from Tanzanian mangroves

Endophytic fungi are useful in a variety of biological processes and may find value in pharmaceutical settings. However, there hasn’t been much research done on the bioactive compounds produced by mangrove fungal endophytes from the East African coast. Our previous research revealed a significant number of mangrove endophytic fungi in Dar es Salaam, Tanzania. This study explores the antimicrobial and cytotoxic properties of these endophytic fungi. Crude extracts of 34 mangrove endophytic fungal isolates were screened, with thirteen showing antimicrobial activity against tested microorganisms. MIC and cytotoxicity tests revealed varying bioactivity. Aspergillus fumigatus (HMD45) was particularly potent against tested organisms (MIC = <0.195 to 0.391 mg/ml) and (LC50 = 36.001). GC-MS evaluation of HMD45 extracts indicated the existence of compounds including dodecanoic acid, n-heptadecanol-1, and n-hexadecanoic acid, which may contribute to its bioactivity. These findings offer insight into the bioactivity of mangrove endophytic fungi and trigger interest for further research.

Cis -decalin tetramic acid metabolite from a mangrove derived endophytic fungus Nigrospora oryzae.

Most of the natural products containing tetramic acid have trans configuration of the decalin moiety. Undana A (1), a new cis decalin-bearing tetramic acid metabolite was isolated from endophytic fungi Nigrospora oryzae associated with Avicennia marina. The structure was determined based on the mass and NMR spectral data together with the comparison of the literature. This is the first report of cis decalin-tetramic acid metabolite from the mangrove endophytic fungus. Compound 1 was tested for cytotoxic against L5178Y mouse cancer cells and antibacterial activity against several gram-positive including MRSA and gram-negative bacteria but was found inactive.

A new isoprenyl-phenol-type meroterpenoid from mangrove endophytic fungus Aspergillus sp. GXNU-Y65

Asperphenol A (1), a new isoprenyl-phenol-type meroterpenoid, was isolated from the mangrove endophytic fungus Aspergillus sp. GXNU-Y65 together with five known compounds (2-6). All structures were assigned using extensive NMR spectroscopic data and electronic circular dichroism (ECD) calculations. Compounds 1-6 were evaluated for their cytotoxic activity against A549 and T24 human cancer cell lines. Among them, compounds 1 and 5 exhibited moderate inhibitory activities against T24 cancer cell lines with the IC50 values of 26.71 and 43.50 μM, respectively.

Induction of Three New Secondary Metabolites by the Co-Culture of Endophytic Fungi Phomopsis asparagi DHS-48 and Phomopsis sp. DHS-11 Isolated from the Chinese Mangrove Plant Rhizophora mangle.

Co-cultivation is a powerful emerging tool for awakening biosynthetic gene clusters (BGCs) that remain transcriptionally silent under artificial culture conditions. It has recently been used increasingly extensively to study natural interactions and discover new bioactive metabolites. As a part of our project aiming at the discovery of structurally novel and biologically active natural products from mangrove endophytic fungi, an established co-culture of a strain of Phomopsis asparagi DHS-48 with another Phomopsis genus fungus DHS-11, both endophytes in mangrove Rhizophora mangle, proved to be very efficient to induce the production of new metabolites as well as to increase the yields of respective target metabolites. A detailed chemical investigation of the minor metabolites produced by the co-culture of these two titled fungal strains led to the isolation of six alkaloids (1-6), two sterols (7, 8), and six polyketides (9-14). In addition, all the compounds except 8 and 10, as well as three new metabolites phomopyrazine (1), phomosterol C (7), and phomopyrone E (9), were not present in discrete fungal cultures and only detected in the co-cultures. The structures were elucidated on the basis of spectroscopic analysis, and the absolute configurations were assumed by electronic circular dichroism (ECD) calculations. Subsequently, the cytotoxic, immunosuppressive, and acetylcholinesterase inhibitory properties of all the isolated metabolites were determined in vitro. Compound 8 exhibited moderate inhibitory activity against ConA-induced T and LPS-induced B murine splenic lymphocytes, with IC50 values of 35.75 ± 1.09 and 47.65 ± 1.21 µM, respectively.

Activity of Mangrove-Derived Fusarium equiseti 20CB07RF Extract Against Clinical, Antibacterial-Resistant Pseudomonas aeruginosa

Endophytic fungi originating from mangroves are potential sources of secondary metabolites with varying bioactivities. This research explores the bioactive metabolites produced by endophytes derived from mangrove plants. Endophytic fungi were collected from various parts of several mangrove plants (roots, stems, and leaves, as well as the surrounding mud). A total of 17 endophytics fungi were obtained. The isolates were derived from the leaves (1 isolate), stems (8 isolates), roots (5 isolates), and surrounding mud (3 isolates). A single fungal colony was cultured using solid-state fermentation for 14 days. The fermented fungal biomass was extracted using ethyl acetate (EtOAc) and evaluated for its antibacterial activity against clinical pathogenic bacteria. In the preliminary screening, the EtOAc extract of the CB07RF1 isolate exhibited notable growth-inhibitory effects against Pseudomonas aeruginosa. The isolate was verified by molecular identification using a study of the rDNA internal transcribed spacer (ITS) sequence, revealed that isolate CB07RF1 was very similar to Fusarium equiseti (99% similarity). Isolate 20CB07RF1, obtained by solid-state fermentation using a rice medium indicated as peptide compound group, and featured active components that exhibited potent growth inhibitory activity against Pseudomonas aeruginosa at a concentration of 12.5 mg/mL. This study demonstrates, for the first time, that Fusarium equiseti extracts grown in a rice medium contain antimicrobial compounds that can inhibit the growth of P. aeruginosa, an important clinical pathogen known for its antibacterial resistance. These findings accent mangrove endophytic fungi as important sources of bioactive compounds and will advance related research in the fields of biotechnology, pharmacology, and life sciences.

Talaroacids A-D and Talaromarane A, Diterpenoids with Anti-Inflammatory Activities from Mangrove Endophytic Fungus Talaromyces sp. JNQQJ-4.

Five new diterpenes including four diterpenes with 1,2,3,4,4a,5,6,8a-octalin skeleton talaroacids A-D (1-4) and an isopimarane diterpenoid talaromarane A (5) were isolated from the mangrove endophytic fungus Talaromyces sp. JNQQJ-4. Their structures and absolute configurations were determined by analysis of high-resolution electrospray ionization mass spectroscopy (HRESIMS), 1D/2D Nuclear Magnetic Resonance (NMR) spectra, single-crystal X-ray diffraction, quantum chemical calculation, and electronic circular dichroism (ECD). Talaromarane A (5) contains a rare 2-oxabicyclo [3.2.1] octan moiety in isopimarane diterpenoids. In bioassays, compounds 1, 2, 4, and 5 displayed significant anti-inflammatory activities with the IC50 value from 4.59 to 21.60 μM.

New polyketides and cytotoxic alkaloids from the mangrove endophytic fungus Talaromyces sp. SAF14

Investigation of secondary metabolites from the mangrove endophytic fungus Talaromyces sp. SAF14 led to the isolation of two new polyketides, methyl (R)-3-(6,8-dihydroxy-7-methoxy-1-oxoisochroman-3-yl)propanoate (1), (R)-3-(5,8- dihydroxy-1-oxoisochroman-3-yl)propanoic acid (2), together with four known alkaloids (3–6). The planar structures of new compounds were elucidated by comprehensive analysis of HR-ESI-MS and NMR data. The absolute configurations were determined by comparison of the calculated ECD spectrum with the measured one. All the isolated compounds were tested for cytotoxic activities against three human cancer cell lines. The known beauvericin (3) exhibited strong cytotoxic activity against A549, MCF-7, and KB cell lines with IC50 values of 5.36 ± 2.49, 1.96 ± 1.09 and 4.46 ± 0.68 μM, respectively.

Mangrove endophytic fungi: Biocontrol potential against Rhizoctonia solani and biofertilizers for fragrant rice cultivation

The mangrove ecosystem has emerged as a fascinating source for exploring novel bioresources which have multiple applications in modern agriculture. This study evaluates the potential applications of mangrove endophytic fungi (MEF), such as biocontrol agents against Rhizoctonia solani and as biofertilizers for improving the yield of fragrant rice variety Malaysian Rice Quality 76 (MRQ76). Through the antagonism assays, it is observed that among the 14 MEF studied, 4 fungal isolates (Colletotrichum sp. MEFN02, Aspergillus sp. MEFN06, Annulohypoxylon sp. MEFX02 and Aspergillus sp. MEFX10) exhibited promising antagonistic effect against the pathogen R. solani compared to the chemical fungicide (Benomyl). These isolates also revealed significant production of enzymes, phytochemicals, indoleacetic acid (40.96 mg/mL) and ammonia (32.54 mg/mL) and displayed tolerance to salt and temperature stress up to 2000 mM and >40 °C respectively. Furthermore, employing the germination and pathogenicity test, inoculation of these endophytes showed lower percentage of disease severity index (DSI%) against R. solani, ranging from (24 %–46 %) in MRQ76 rice seedlings. The in-vivo experiments of soil and seed inoculation methods conducted under greenhouse conditions revealed that these endophytes enhanced plant growth (8–15 % increase) and increased crop yield (≥50 %) in comparison to control treatments. The current findings provide valuable insights into eco-friendly, cost-effective and sustainable alternatives for addressing R. solani infection and improving the agronomic performance of the fragrant rice cultivar MRQ76, contributing to food security.

A New Diphenylethylene Derivative from a Mangrove Endophytic Fungus Alternaria sp. R6

A New Diphenylethylene Derivative from a Mangrove Endophytic Fungus Alternaria sp. R6

A copper(II)-based complex from mangrove endophytic fungus Fusarium proliferatum inhibits ovarian cancer in vitro via VEGF/VEGFR2 pathways and apoptosis factors

From a mangrove endophytic fungus, Fusarium proliferatum, four compounds were isolated. These compounds include a copper(II)-based complex (1), its ligand fusaric acid (2), and two fusaric acid derivatives (3, 4). Among them, compounds 1 and 4 are undescribed natural compounds. The elucidation of their structures, including absolute configurations, was accomplished through a combination of analytical techniques, including nuclear magnetic resonance (NMR), mass spectrometry (MS), and single-crystal X-ray analysis. Compound 1 has exhibited inhibitory effects on the growth of ovarian cancer SKOV3 in vitro, primarily through its induction of mitochondrial membrane potential collapse in SKOV3 cells. Additionally, it has demonstrated the ability to activate key signaling molecules within the vascular endothelial growth factor (VEGF) pathway, particularly focal adhesion kinase (FAK) and its phosphorylated form (p-FAK), as well as protein kinase B (AKT) and its phosphorylated form (p-AKT), and extracellular signal-regulated kinases 1/2 (ERK1/2) and their phosphorylated forms (p-ERK1/2). As a result of these findings, compound 1 is now considered a promising copper-based candidate for both anticancer and antiangiogenic therapeutic applications.

Penifuranone A: A Novel Alkaloid from the Mangrove Endophytic Fungus Penicillium crustosum SCNU-F0006.

One previously undescribed alkaloid, named penifuranone A (1), and three known compounds (2-4) were isolated from the mangrove endophytic fungus Penicillium crustosum SCNU-F0006. The structure of the new alkaloid (1) was elucidated based on extensive spectroscopic data analysis and single-crystal X-ray diffraction analysis. Four natural isolates and one new synthetic derivative of penifuranone A, compound 1a, were screened for their antimicrobial, antioxidant, and anti-inflammatory activities. Bioassays revealed that penifuranone A (1) exhibited strong anti-inflammatory activity in vitro by inhibiting nitric oxide (NO) production in lipopolysaccharide-activated RAW264.7 cells with an IC50 value of 42.2 μM. The docking study revealed that compound 1 exhibited an ideal fit within the active site of the murine inducible nitric oxide synthase (iNOS), establishing characteristic hydrogen bonds.

Isolation of two peptaibols with potent antimicrobial and cytotoxic activities from the mangrove endophytic fungus Trichoderma lentiforme ML-P8-2

Trichorzin PA is a family of 18-residue peptaibols with linear and flexible peptide chains. The three-dimensional structures and biological activities of trichorzin PA peptaibols are largely uncharacterised. In this work, two previously identified peptaibols, trichorzin PA VI (1) and II (2), were isolated from Trichoderma lentiforme ML-P8-2. While for the first time, we report here the X-ray crystallographic structure of 1, antimicrobial activities against a panel of common pathogenic bacteria and fungi, and cytotoxicities of 1 and 2. In bioassays, 1 and 2 exhibited strong antimicrobial activities against the seven tested microbes, with MIC values in the range of 0.19–6.25 μM. Additionally, 1 and 2 displayed potent cytotoxicities against five human cancer cell lines, with IC50 values in the range of 0.01 ± 0.02–2.75 ± 0.17 μM. The bioassay results were generally better than those reported for other 18-residue peptaibols, including other trichorzin PA members.

4-Hydroxy-2-pyridone derivatives with antitumor activity produced by mangrove endophytic fungus Talaromyces sp. CY-3

OSMAC strategy is a useful tool for discovering series of metabolites from microorganism. Five new sambutoxin derivatives (1–2, 4, 8–9), together with seven known compounds (3, 5–7, 10–12), were isolated from Talaromyces sp. CY-3 under OSMAC strategy and guidance of molecular networking. Their planar structures and absolute configurations were determined by NMR, HRESIMS, ECD spectra and common biosynthetic pathway. In bioassay, compounds 1–12 showed cytotoxicity to tumor cell lines with IC50 values in the range of 1.76–49.13 μM. The antitumor molecular mechanism of 10 was also explored. In vitro compound 10 significantly inhibited the growth and proliferation of two lung cancer cell lines (A549 and H1703). Furthermore, colony formation, EdU analysis, flow cytometry and Western blot analysis showed that 10 could induce cell cycle arrest in G0/G1 phase by promoting the expression of p53 and p21. The molecular mechanism of its antitumor effects in vitro is that 10 arrests the cell cycle by activating the p21/CyclinD1/Rb signaling pathway and the p53 pathway. Our results identified a lead small molecule compound with efficient antitumor growth and proliferation activity.

Metabolomics-Guided Discovery of New Dimeric Xanthones from Co-Cultures of Mangrove Endophytic Fungi Phomopsis asparagi DHS-48 and Phomopsis sp. DHS-11.

The co-culture strategy, which mimics natural ecology by constructing an artificial microbial community, is a useful tool for the activation of biosynthetic gene clusters (BGCs) to generate new metabolites, as well as to increase the yield of respective target metabolites. As part of our project aiming at the discovery of structurally novel and biologically active natural products from mangrove endophytic fungi, we selected the co-culture of a strain of Phomopsis asparagi DHS-48 with another Phomopsis genus fungus DHS-11, both endophyted in mangrove Rhizophora mangle considering the impart of the taxonomic criteria and ecological data. The competition interaction of the two strains was investigated through morphology observation and scanning electron microscopy (SEM), and it was found that the mycelia of the DHS-48 and DHS-11 compacted and tangled with each other with an interwoven pattern in the co-culture system. A new approach that integrates HPLC chromatogram, 1HNMR spectroscopy, UPLC-MS-PCA, and molecular networking enabled the targeted isolation of the induced metabolites, including three new dimeric xanthones phomoxanthones L-N (1-3), along with six known analogs (4-9). Their planar structures were elucidated by an analysis of their HRMS, MS/MS, and NMR spectroscopic data and the absolute configurations based on ECD calculations. These metabolites showed broad cytotoxic activity against the cancer cells assessed, of which compounds 7-9 displayed significant cytotoxicity towards human liver cells HepG-2 with IC50 values ranging from 4.83 μM to 12.06 μM. Compounds 1-6 exhibited weak immunosuppressive activity against the proliferation of ConA-induced (T-cell) and LPS-induced (B-cell) murine splenic lymphocytes. Therefore, combining co-cultivation with a metabolomics-guided strategy as a discovery tool will be implemented as a systematic strategy for the quick discovery of target bioactive compounds.

Pleosmaranes A-R, Isopimarane and 20-nor Isopimarane Diterpenoids with Anti-inflammatory Activities from the Mangrove Endophytic Fungus Pleosporales sp. HNQQJ-1.

Pleosmaranes A-R (1-18), 18 new isopimarane-type diterpenoids, together with four known analogs (19-22), were isolated from the mangrove endophytic fungus Pleosporales sp. HNQQJ-1. Their structures and absolute configurations were established by analysis of their spectroscopic data and electronic circular dichroism (ECD) calculations. Compounds 1-9 possess an unusual aromatic B ring and a 20-nor-isopimarane skeleton. Compounds 15-17 contain a unique 2-oxabicyclo[2.2.2]octane moiety. Compound 18 features an unexpected 2-oxabicyclo[3.2.1]octane moiety. Compounds 8 and 12 exhibited a moderate inhibitory effect against LPS-induced NO production, with IC50 values of 19 and 25 μM, respectively.

Oxygen-bridged cyclooctadienes and other polyketides from the mangrove endophytic fungus Diaporthe sp. ZJHJYZ-1

Nine oxygen-bridged cyclooctadienes (1 – 9), including four undescribed previously (1, 2, 5, and 6), together with a new cyclohexanone derivative (10) and a new oxaspiroundecanone derivative (11), were isolated from the mangrove endophytic fungus Diaporthe sp. ZJHJYZ-1. The structures of compounds were elucidated via detailed NMR, HR-ESI-MS analyses, ECD spectra calculation, 1H - 1H coupling constants comparison and X-ray single-crystal diffraction analysis. In bioassays, compound 8 significantly suppressed six human cancer cell lines, MDA-MB-231, MDA-MB-435, HCT116, A549, SNB19, and PC3, with IC50 values in the range of 1.97 ± 0.01 – 19.17 ± 1.02 μM. And compound 10 promisingly inhibited MDA-MB-231 and PC3 with IC50 values of 2.54 ± 1.23 and 22.07 ± 0.64 μM, respectively.