Abundant respirable ergot alkaloids from the common airborne fungus Aspergillus fumigatus

Ergot alkaloids are mycotoxins that interact with several monoamine receptors, negatively affecting cardiovascular, nervous, reproductive, and immune systems of exposed humans and animals. Aspergillus fumigatus, a common airborne fungus and opportunistic human pathogen, can produce ergot alkaloids in broth culture. The objectives of this study were to determine if A. fumigatus accumulates ergot alkaloids in a respirable form in or on its conidia, to quantify ergot alkaloids associated with conidia produced on several different substrates, and to measure relevant physical properties of the conidia. We found at least four ergot alkaloids, fumigaclavine C, festuclavine, fumigaclavine A, and fumigaclavine B (in order of abundance), associated with conidia of A. fumigatus. Under environmentally relevant conditions, the total mass of ergot alkaloids often constituted >1% of the mass of the conidium. Ergot alkaloids were extracted from conidia produced on all media tested, and the greatest quantities were observed when the fungus was cultured on latex paint or cultured maize seedlings. The values for physical properties of conidia likely to affect their respirability (i.e., diameter, mass, and specific gravity) were significantly lower for A. fumigatus than for Aspergillus nidulans, Aspergillus niger, and Stachybotrys chartarum. The demonstration of relatively high concentrations of ergot alkaloids associated with conidia of A. fumigatus presents opportunities for investigations of potential contributions of the toxins to adverse health effects associated with the fungus and to aspects of the biology of the fungus that contribute to its success.     

New indole-diterpenoids from the algal-associated fungus Aspergillus nidulans

Two new compounds, including a chlorinated indole-diterpenoid 19-hydroxypenitrem A (1) and its dechlorinated derivative 19-hydroxypenitrem E (2), along with two known congeners (3 and 4), were isolated and identified from the cultures of Aspergillus nidulans EN-330, an endophytic fungus obtained from the marine red alga Polysiphonia scopulorum var. villum. Their structures and absolute configurations were assigned on the basis of 1D and 2D NMR and CD experiments. Compounds 1–4 exhibited cytotoxic activity against brine shrimp with LD₅₀ values of 3.2, 4.6, 1.7, and 8.7 μM, respectively. Besides, the chlorinated 19-hydroxypenitrem A (1) showed antimicrobial activity against four human- and aqua-pathogens. Preliminary SAR study revealed that the Cl-substitution at C-6 enhanced the cytotoxic activity against brine shrimp and antimicrobial activity, while the 19-OH substitution suppressed the activity.     

New paralytic alkaloids, asperparalines A, B and C, from Aspergillus japonicus JV-23

New paralytic alkaloids, asperparalines A (1), B (2) and C (3), were isolated from okara (the insoluble residue of whole soybean) that had been fermented with Aspergillus japonicus JV-23. Their structures were elucidated by spectroscopic methods and X-ray crystallography. These asperparalines showed paralytic activity against silk worms.     

3-Anhydro-6-hydroxy-ophiobolin A,a new sesterterpene inhibiting the growth of methicillin-resistant Staphylococcus aureus and inducing the cell death by apoptosis on K562, from the phytopathogenic fungus Bipolaris oryzae

A new ophiobolin derivative, 3-anhydro-6-hydroxy-ophiobolin A (1), as well as two known ophiobolin derivatives 3-anhydro-ophiobolin A (2) and 3-anhydro-6-epi-ophiobolin A (3) were isolated from the PDB culture of a phytopathogenic fungus Bipolaris oryzae. The structure of 1 was elucidated through 2D NMR and other spectroscopic techniques. Compound 1 exhibited strong antimicrobial activity against Bacille Calmette–Guerin, Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus with MIC value of 12.5 μg/mL, and potent antiproliferative activity against cell lines HepG2 and K562 with IC₅₀ of 6.49 μM and 4.06 μM, respectively. Further studies on the cytotoxicity of compound 1 against K562 cells demonstrated that it induced apoptosis, observed by flow cytometric method. Preliminary structure–activity relationships of these ophiobolins and the mechanism of apoptosis induced by 1 were analyzed.     

Tropane and pyrrolidine alkaloids from Convolvulus lanatus Vahl

The alkaloid composition of Convolvulus lanatus was investigated by GLC and GLC-MS. Altogether, thirteen tropane and pyrrolidine alkaloids were identified on the basis of mass spectral data and/or Kovats retention indices. Twelve of them have been recorded for the first time in this plant and some of these alkaloids were identified for the first time in the genus Convolvulus. Cuscohygrine is the major constituent. Qualitative and quantitative differences of root and aerial parts are discussed.     

Characterisation and expression of phospholipases B from the opportunistic fungus Aspergillus fumigatus

The phospholipase B family (PLB) are enzymes sharing phospholipase (PL), lysophospholipase (LPL) and lysophospholipase-transacylase (LPTA) activities. They have been shown to be important virulence factors in several human fungal pathogens including Candida albicans and Cryptococcus neoformans. Aspergillus fumigatus, a human opportunistic fungal pathogen leading to a high rate of mortality in immunosuppressed patients is known to possess an extracellular phospholipase B activity. In this paper, we report the molecular characterisation of three PLB genes from A. fumigatus (afplb) using degenerate primers in PCR amplification and data from the A. fumigatus genome project. They are expressed at 37 degrees C, and two of them (afplb1 and afplb3) are induced by lecithin. They encode proteins of 633, 588 and 630 amino acids, respectively, presenting together a T-Coffee score of 81. They also possess the amino acid triad responsible for enzymatic activity in the mammalian cytosolic PLA2 and other fungal PLBs. AfPLB1 and afPLB3 are secreted with a cleaved signal peptide. The complete cDNA sequences were obtained by RACE-PCR for the two secreted afPLBs and probably account for the extracellular phospholipase activity previously reported in the culture media of A. fumigatus.     

Analysis of sesterterpenoids from Aspergillus terreus using ESI‐QTOF and ESI‐IT

Introduction – Biosynthesis of terretonin was studied due to the interesting skeleton of this series of sesterterpenoids. Very recently, López‐Gresa reported two new sesterterpenoids (terretonins E and F) which are inhibitors of the mammalian mitochondrial respiratory chain. Mass spectrometry (MS), especially tandem mass spectrometry, has been one of the most important physicochemical methods for the identification of trace natural products due to it rapidity, sensitivity and low levels of sample consumption. The potential application prospect and unique skeleton prompted us to study structural characterisation using MS. Objective – To obtain sufficient information for rapid structural elucidation of this class of compounds using MS. Methodology – The elemental composition of the product ions was confirmed by low‐energy ESI‐CID‐QTOF‐MS/MS analyses. The fragmentation pathways were postulated on the basis of ESI‐QTOF‐MS/MS/MS and ESI‐IT‐MSⁿ spectra. Common features and major differences between ESI‐QTOF‐MS/MS and IT‐MSⁿ spectra were compared. For ESI‐QTOF‐MS/MS/MS experiments, capillary exit voltage was raised to induce in‐source dissociation. Ammonium acetate or acetic acid were added into solutions to improve the intensity of [M + H]⁺. The collision energy was optimised to achieve sufficient fragmentation. Some fragmentation pathways were unambiguously proposed by the variety of abundance of fragment ions at different collision energies even without MSⁿ spectra. Results – Fragmentation pathways of five representative sesterterpenoids were elucidated using ESI‐QTOF‐MS/MS/MS and ESI‐IT‐MSⁿ in both positive‐ and negative‐ion mode. The key group of characterising fragmentation profiles was ring B, and these fragmentation patterns are helpful to identify different types of sestertepenoids. Conclusion – Complementary information obtained from fragmentation experiments of [M + H]⁺ (or [M + NH₄]⁺) and [M ? H]^? precursor ions is especially valuable for rapid identification of this kind of sesterterpenoid.     

New p-terphenyls from the endophytic fungus Aspergillus sp. YXf3

Five new p-terphenyls named prenylterphenyllin D (1), prenylterphenyllin E (2), 2′-O-methylprenylterphenyllin (3), 4-O-methylprenylterphenyllin (4) and 3′-O-methylterphenyllin (5) together with seven known compounds (6–12), were isolated from cultures of Aspergillus sp. YXf3. The structures of the new compounds were elucidated by extensive MS and NMR analyses. The NMR and MS data of 5 is reported for the first time, as its structure was listed in SciFinder Scholar with no associated reference. Compounds 6 and 7 were distinguished from each other on the basis of 2D NMR experiments. Compounds 1, 2, 3 and 8 showed antibacterial activities against X. oryzae pv. oryzicola Swings and E. amylovora with the same MIC values of 20 μg/mL while 10 exhibited activities against E. amylovora with an MIC value of 10 μg/mL.     

New secondary metabolites from the mangrove-derived fungus Aspergillus sp. AV-2

Chemical investigation of the mangrove-derived fungus Aspergillus sp. AV-2 following fermentation on solid rice medium led to the isolation of a new phenyl pyridazine derivative (1) and a new prenylated benzaldehyde derivative, dioxoauroglaucin (2), together with fourteen known compounds (3-16). Chemical structures of the new compounds were unambiguously determined based on HRESIMS and extensive 1D and 2D NMR spectroscopic analyses. Compounds 2-7, 8 and 13 were assessed for their antiproliferative activity against Caco-2 cell lines, where flavoglaucin (6) revealed the most potent cytotoxicity with IC₅₀ of 2.87 μM.     

Aspergilones A and B, two benzylazaphilones with an unprecedented carbon skeleton from the gorgonian-derived fungus Aspergillus sp

Two novel benzylazaphilone derivatives with an unprecedented carbon skeleton, aspergilone A (1), and its symmetrical dimer with a unique methylene bridge, aspergilone B (2), have been isolated from the culture broth of a marine-derived fungus Aspergillus sp. from a gorgonian Dichotella gemmacea. Their structures and relative stereochemistries of 1 and 2 were elucidated using a combination of NMR spectroscopy and X-ray crystallography. Compound 1 not only exhibited in vitro selective cytotoxicity but also showed potent antifouling activity.     

Diketopiperazine alkaloids from the fungus Penicillium piscarium Westling

Fungi of the species Penicillium piscarium produced diketopiperazine alkaloids (isorugulosuvine, puberuline, verrucosine, prolyltryptophanyldiketopiperazine, 12,13-dehydroprolyltryptophanyldiketopiperazine, fellutanine A, phenylalanylphenylalanyldiketopiperazine, as well as roquefortine and 3,12-dihydroroquefortine whose precursors are tryptophan, phenylalanine, leucine, proline, and histidine.     

Steroids and anthraquinones from the deep-sea-derived fungus Aspergillus nidulans MCCC 3A00050

Aspergillus nidulans MCCC 3A00050 was isolated from a deep-sea sediment sample of the western Pacific Ocean. A systematic investigation on its chemical constituents led to the isolation of 19 compounds, including 13 steroids (1–13), four anthraquinones (14–17), one phenolics (18), and one chromanone (19). For the first time, three diosgenins (1–3) were isolated from fungi, three ergosterols (4–6) from the genus of Aspergillus, while other 11 miscellaneous compounds (7–11 and 14–19) from the species of Aspergillus nidulans. The isolation of diosgenins (1–3) and ergosterols (4–6) might be used as chemotaxonomic markers for the genus of Aspergillus and the species of Aspergillus nidulans, respectively.     

Minor alkaloids from the fungus Penicillium roquefortii Thom 1906

New spatial of clavine alkaloids, distinguished by low chromatographical mobility, have been isolated from the collection and mutant strain of Penicillium roquefortii, in addition to alkaloids roquefortine, 3,12-dihydroroquefortine, isofumigaclavines A and B, festuclavine, and chanoclavine-I, characteristic of this fungal species. In has been shown that the collection strain produces isomers of agroclavine and epoxyagroclavine, and the mutant strain produces isomers of fumigaclavines A and B, festuclavine, and chanoclavine.     

Isolation and properties of pectinases from the fungus Aspergillus japonicus

Using anion-exchange chromatography on different carriers and phenyl-Sepharose hydrophobic chromatography, five pectolytic enzymes were isolated from the culture liquid of a mutant strain of Aspergillus japonicus: two endo-polygalacturonases (I and II, 38 and 65 kD, pI5.6 and 3.3), pectin lyase (50 kD, pI3.8), and two pectinesterases (I and II) with similar molecular weights (46 and 47 kD) and the same pI(3.8). The pectinesterases apparently represent two isoforms of the same enzyme. All purified enzymes were homogenous according to SDS-PAGE and polyacrylamide gel-IEF, except for endo-polygalacturonase II that gave two bands on isoelectric focusing, but one band on electrophoresis. All enzymes had maximal activity in an acid medium (at pH 4.0-5.5). The pectin lyase and pectinesterase were stable at 40-50°C. The thermal stability of both endo-polygalacturonases was much lower (after 3 h of incubation at 30°C, endo-polygalacturonases I and II lost 40 and 10% of the activity, respectively). The activity of endo-polygalacturonases I and II towards polygalacturonic acid strongly depended on NaCl concentration (optimal concentration of the salt was 0.1-0.2 M); the enzymes were also capable of reducing the viscosity of pectin solution, but rather slowly. The pectin lyase had no activity towards polygalacturonic acid. The activity of the pectin lyase increased with increasing degree of methylation of pectins. Both endo-polygalacturonases demonstrated synergism with the pectinesterase during the hydrolysis of highly methylated pectin. On the contrary, in the mixture of pectin lyase and pectinesterase an antagonism between the two enzymes was observed.     

New bisabolane sesquiterpenoids from a marine-derived fungus Aspergillus sp. isolated from the sponge Xestospongia testudinaria

Three new phenolic bisabolane sesquiterpenoid dimers, disydonols A-C (1-3), and one known compound (S)-(+)-sydonol (4) were isolated from the fermentation broth of a marine-derived fungus Aspergillus sp., which was isolated from the sponge Xestospongia testudinaria collected from the South China Sea. Their structures were elucidated on the basis of comprehensive spectral analysis including 1D and 2D NMR spectra and HR-ESI-MS. These compounds were evaluated for cytotoxic activity against HepG-2 and Caski human tumour cell lines. Among them, compounds 1 and 3 exhibited cytotoxicity against the two cell lines.     

Bioactive secondary metabolites from the marine-associated fungus Aspergillus terreus

Three new compounds, including a prenylated tryptophan derivative, luteoride E (1), a butenolide derivative, versicolactone G (2), and a linear aliphatic alcohol, (3E,7E)-4,8-dimethyl-undecane-3,7-diene-1,11-diol (3), together with nine known compounds (4–12), were isolated and identified from a coral-associated fungus Aspergillus terreus. Their structures were elucidated by HRESIMS, one- and two-dimensional NMR analysis, and the absolute configuration of 2 was determined by comparison of its electronic circular dichroism (ECD) spectrum with the literature. Structurally, compound 1 featured an unusual (E)-oxime group, which occurred rarely in natural products. Compounds 1–3 were evaluated for the α-glucosidase inhibitory activity, and compound 2 showed potent inhibitory potency with IC₅₀ value of 104.8 ± 9.5 μM, which was lower than the positive control acarbose (IC₅₀ = 154.7 ± 8.1 µM). Additionally, all the isolated compounds were evaluated for the anti-inflammatory activity against NO production, and compounds 1–3, 5–7, and 10 showed significant inhibitory potency with IC₅₀ values ranging from 5.48 to 29.34 μM.     

Indole alkaloids from a culture of the fungus Aporpium caryae

In a screening for antifungal metabolites, two indole compounds of mixed biogenesis, 1H-indole-3-carboxylic acid, 1-(1,1-dimethyl-2-propenyl) methyl ester and 1H-indole-3-carboxylic acid, 1-(2,3-dihydroxy-1,1-dimethylpropyl) methyl ester were isolated from a culture of the basidiomycete Aporpiums caryae. The structural elucidation of these compounds was accomplished by spectroscopic methods.     

A New Metabolite from Aspergillus nidulans

Among the bacteria isolated from polluted water and viscid sludges in the factories manufacturing sweet potato starch, a group of strains was ascertained to be capable of producing slimy materials keeping fairly stable viscosity through the alterations in pH. Representative strain A-1 of the group was assigned to Agrobacterium radiobacter. The polysaccharide produced by culturing the strain in the medium containing glucose, yeast extracts and CaCO₃ was estimated to be Gal: Glc: succinic acid: pyruvic acid = 1: 7.2~7.3: 1: 0.85 in a molar ratio. The IR spectra, basicity and other determinations indicated that the one of the moieties showing acidic function was succinic acid linking in ester bond, and another one was pyruvic acid linking to glucose in ketal.     

A New Metabolite from Aspergillus versicolor

Neurospora sitophila produced extracellular and cell wall-associated lectins. The addition of l-sorbose to a culture resulted in a decrease in the production of the former lectin and complete abolition of the latter. The lectin in the culture filtrate was purified by bovine submaxillary mucin-conjugated Sepharose chromatography. The molecular weight of the lectin was calculated to be approx. 40,000 by Sephacryl S-200 gel filtration, and that of the subunit to be approx. 22,000 by SDS/polyacrylamide- gel electrophoresis. The lectin was not inhibited by simple sugars or their homopolymers. It was inhibited strongly by glycoproteins from human erythrocyte membrane and bovine submaxillary mucin, and moderately by α1-acid glycoprotein from human plasma, human IgA and IgM, and fetal calf fetuin. The lectin agglutinated human type A, B and O erythrocytes to the same degree. Erythrocytes from chick, horse, rabbit and sheep were more efficiently agglutinated.     

泰国红树内生真菌土曲霉xy03菌株中新杂萜类成分

采用硅胶柱层析、SephadexLH-20凝胶柱层析和高效液相色谱(HPLC)等技术,从一株红树马六甲木果楝来源的土曲霉Aspergillus terreusxy03的发酵物中分离得到了7个杂萜类化合物:asptercin A(1)、(1R,4aR,6aR,12aR,12bS)-1,3,4,4a,5,6,6a,12,1...