A novel cyclic dipeptide from deep marine-derived fungus Aspergillus sp. SCSIOW2

A novel cyclic dipeptide, 14-hydroxy-cyclopeptine (1), was purified from a deep sea derived fungal isolate identified as an Aspergillus sp. The structure was elucidated by detailed spectroscopic analyses using 1D and 2D NMR experiments and high resolution mass spectrometry. The absolute configuration of the amino acid was determined by Marfey's method. Two conformational isomers of 1 were established by ROE analyses. 1 inhibited nitric oxide production with IC₅₀ values at 40.3 μg/mL in a lipopolysaccharide and recombinant mouse interferon-γ -activated macrophage-like cell line, RAW 264.7 and showed no cytotoxic effect in the tested dose range up to 100 μg/mL.     

Antimicrobial activity and molecular docking studies of a novel anthraquinone from a marine-derived fungus Aspergillus versicolor

A novel anthraquinone, 2-(dimethoxymethyl)-1-hydroxyanthracene-9,10-dione (1), together with nine known compounds (2–10), were isolated from the fermentation of Aspergillus versicolor derived from deep sea sediment. Their structures were established through spectroscopic methods. Compound 1 exhibited strong inhibitory activities against MRSA ATCC 43300 and MRSA CGMCC 1.12409 (with MIC values of 3.9 and 7.8 μg/mL respectively) and moderate activities against tested strains of Vibrio (with MIC values ranging from 15.6 to 62.5 μg/mL). Compound 1 was subjected to molecular docking studies for inhibition of topoisomerase IV and AmpC β-lactamase enzymes indicating its usefulness as antimicrobial agent.     

Cytotoxic compounds from the marine-derived fungus Aspergillus sp. recovered from the sediments of the Brazilian coast

A fungal strain of Aspergillus sp. (BRF 030) was isolated from the sediments collected in the northeast coast of Brazil, and the cytotoxic activity of its secondary metabolites was investigated against HCT-116 tumour cell line. The cytotoxicity-guided fractionation of the extracts from this fungus cultured in potato-dextrose-sea water for 14 days at room temperature yielded the hetero-spirocyclic γ-lactams pseurotin A (1), pseurotin D (2) and pseurotin FD-838 (7), the alkaloids fumitremorgin C (5), 12,13-dihydroxy fumitremorgin C (6), methylsulochrin (4) and bis(dethio)bis(methylthio)gliotoxin (3). Among them, fumitremorgin C (5) and 12,13-dihydroxy fumitremorgin C (6) were the most active. The cytotoxic activities of the extracts from Aspergillus sp. grown from 7 to 28 days were investigated, and they were associated with the kinetic production of the compounds. The most active extracts (14 and 21 days) were those with the highest relative concentrations of the compounds fumitremorgin C (5) and 12,13-dihydroxy fumitremorgin C (6).     

Antimicrobial secondary metabolites of an endolichenic Aspergillus niger isolated from lichen thallus of Parmotrema ravum

Abstract

A new 6-benzyl-γ-pyrone (1), named aspergyllone was isolated from the culture filtrates of an endolichenic fungus Aspergillus niger Tiegh, obtained from lichen thallus Parmotrema ravum (Krog & Swinscow) Serus, collected in India. 1 was isolated for the first time from an endolichenic fungus together with six other known metabolites identified as aurasperones A (2) and D (3), asperpyrone A (4), fonsecinone A (5), carbonarone A (6) and pyrophen (7). The compounds were tested against a panel of human, plant, food borne and fish pathogens. Aspergyllone showed strong selective antifungal activity against Candida parapsilosis (Ashford) Langeron & Talice, with an IC₅₀ of 52?µg/mL. Aurasperone A and pyrophen showed moderate to strong antimicrobial activity inhibiting seven different test pathogens, being pyrophen active with IC₅₀ ranging from 35 to 97?µg/mL.

     

Discovery of a new biphenyl derivative by epigenetic manipulation of marine-derived fungus Aspergillus versicolor

Cultivation of the marine-derived Aspergillus versicolor MCCC 3A00080 with the addition of a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), significantly enhanced the diversity of secondary metabolites. From the culture treated, a new biphenyl derivative, named versiperol A (1), along with two known compounds, 2,4-dimethoxyphenol (2) and diorcinol (3) were isolated. The structures of 1–3 were established based on spectroscopic analysis and comparison with literature data. Among the isolates, versiperol A (1) exhibited modest inhibition of Staphylococcus aureus growth with MIC value of 8 μg/mL.     

Biotransformation of (+)-isofraxinellone by Aspergillus niger and insect antifeedant activity

The biotransformation of (+)-isofraxinellone (1) by Aspergillus niger was investigated. Compound 1 was transformed to only one new compound 2. The structure of 2 was identified as (-)-(4S)-4-hydroxyisofraxinellone which was regio- and stereo-selective hydroxylated at the C-4 position by IR, EI-MS 1D and 2D NMR. Absolute configuration of hydroxyl group at the C-4 position was detected by modified Mosher’s method. Antifeedant activity of compounds 1 and 2 against larvae of Spodoptera litura was assayed. These compounds showed potent antifeedant activity and ED₅₀ (50% of effective dose) values were 3.91 and 4.43 μg/cm², respectively.     

Antifungal activity of Bignoniaceae plants on Aspergillus carbonarius and Aspergillus niger

Abstract

Twenty four extracts from Bignoniaceae plants of northwest Argentina were tested for antifungal activity against Aspergillus species responsible of the grape black rot. Stems and leaves of Amphilophium cynanchoides, Macfadyena cynanchoides, Tecoma stans and Jacaranda mimosifolia were separately extracted with solvents of increasing polarity to obtain the dichloromethane (fCH₂Cl₂), ethyl acetate (fEtOAc) and methanol extracts (fMeOH). The fCH₂Cl₂ from stem of M. cynanchoides had the lowest IC₅₀ (1.0–1.2?mg/mL) and MID values (0.6–1.2?mg) and the highest ID values (5.0–6.8?mm) on A. niger and A. carbonarius. The main contributors of the antifungal activity of fCH₂Cl₂ were identified as lapachol (MIC?=?0.25–1.00?mg/ml) and 1-hydroxy-4-methylanthraquinone (MIC?=?0.0625–0.125?mg/mL). These compounds synergized the antifungal activity of sodium metabisulfite and showed an additive effect in mixtures with propiconazol. They might be used as additives of commercial antifungals to protect grapes against A. niger and A. carbonarius.     

A new naphthoquinoneimine derivative from the marine algal-derived endophytic fungus Aspergillus niger EN-13

Cultivation of an endophytic fungus Aspergillus niger EN-13 that was isolated from the inner tissue of the marine brown alga Colpomenia sinuosa resulted in the characterization of a new naphthoquinoneimine derivative,namely,5,7-dihydroxy-2-[1-(4- methoxy-6-oxo-6H-pyran-2-yl)-2-phenylethylamino]-[1,4]naphthoquinone.The structure of the new compound was established on the basis of various NMR spectroscopic analyses including 2D NMR techniques,EI-MS,and HR-ESI-MS.This compound displayed moderate antifungal activity.     

Effect of Chitosan and Temperature on Spore Germination of Aspergillus niger

Inhibition of radial growth and spore germination of Aspergillus niger in media with added chitosan were detected. The highest radial growth inhibition (73%) was determined at 24 h with 3 g · L^?1 of chitosan, and the percent inhibition of spore germination was 40% after 13 h of inoculation. Further, the CC₅₀, that is, the concentration at which spore germination is inhibited by 50%, was estimated by probit analysis (3.5 g · L^?1). The activation energies, E_A were estimated by an Arrhenius model in control and amended chitosan media, obtaining 35.6 and 36.6 kcal · mol^?1, respectively. These values were in the same order of magnitude because chitosan as inhibitor was more effective at low temperature (≤ 18 °C). Hence synergism of temperature and chitosan were only observed at 12 and 18 °C. Therefore, the maximal percentage of germinated spores, S_max was also affected by low temperatures in chitosan‐amended media with estimated values lower than 70% at temperatures < 37 °C whereas in control media S_max reached values close to 100%. Scanning electron micrographs showed that chitosan produced spore aggregation and morphological anomalies affecting swelling, germ tube emergence, and polarization.

Germinated spores percentages of Aspergillus niger in Czapeck media at several chitosan concentrations and 30 °C.     

Nigerasterols A and B,Antiproliferative Sterols from the Mangrove‐Derived Endophytic Fungus Aspergillus niger MA‐132

Two new 6,8(14),22‐hexadehydro‐5α,9α‐epidioxy‐3,15‐dihydroxy sterols, nigerasterols A and B ( 1 and 2 , resp.), together with two known cyclopentapeptides, malformins A₁ and C ( 3 and 4 , resp.), were identified in the culture extract of Aspergillus niger MA‐132, an endophytic fungus isolated from a fresh healthy sample of the mangrove plant Avicennia marina. The structures and relative configurations of these compounds were established on the basis of extensive spectroscopic analyses. The absolute configuration of compound 1 was determined by application of a modified version of Mosher's method. Nigerasterols A and B ( 1 and 2 , resp.) represent the first 5,9‐epidioxy‐sterol compounds of marine origin, and they displayed potent activity against tumor cell lines HL60 and A549 in a preliminary bioassay.     

Antioxidant coumarin and pyrone derivatives from the insect-associated fungus Aspergillus Versicolor

Abstract

Two new compounds, versicolones A and B (1 and 2), and three known pyrone derivatives (3?5) were isolated from the insect-associated fungus Aspergillus versicolor. Their structures were elucidated through a combination of HRESIMS and NMR spectroscopic analysis. Versicolone A (1) was revealed as a coumarin derivative with the rare 5-alkyl side chain substitution. Compound 5 exhibited significant antioxidant activity with EC₅₀ value of 8.0?μM in the ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) assay, which was more than 2-fold potency of the positive control trolox.     

Isolation and structure determination of a new diketopiperazine dimer from marine-derived fungus Aspergillus sp. SF-5280

A new diketopiperazine dimer designated as SF5280-415 (1) was isolated from an EtOAc extract of the marine-derived fungus Aspergillus sp. SF-5280 by various chromatographic methods. The structure of 1 was mainly determined by analysis of the NMR spectroscopic data and MS data, along with Marfey’s method. This compound is a new diastereoisomer of known bispyrrolidinoindoline diketopiperazine alkaloid WIN 64745, which possesses unique architecture biosynthetically derived from an indole oxidation reaction of tryptophan.     

Isolation and antiproliferative activity of chemical constituents from Asystasia buettneri Lindau

N-hexane and methanol extracts of Asystasia buettneri Lindau aerial parts exhibited antiproliferative activity on leukaemia blood carcinoma, K-562. Hexadecane (1), 1,3-propan-2-ol (9Z,12′Z,15″Z)-bis(doeicos-9,12,15-trienoate) (2), hydrocarbon, 2,3,3,10,23-pentamethyl tetraeicos-10,13,16-trien-1-ol (3), hexadecanoic acid (4) and taraxerol (5) were isolated from n-hexane extract; stigmasterol (6) and (Z)-9-octadecenoic acid (7) were isolated from ethyl acetate extract; while unsaturated hydrocarbons, octadecene (8), 8-methyl tetradec-6-ene (9) and 19-methyl eicos-1-ene (10), fatty acids, (Z)-5-hexadecenoic acid (11), 11,22-dimethyl ethyltrieicos-11-enoate (12) and taraxasterol (13) were isolated from methanol extract of the plant. Compounds 4, 5, 7, 11, 12 and 13 exhibited antiproliferative activity against K-562, while compounds 5, 6, 7 and 9 revealed antiproliferative activity by inhibiting hepatic liver (WRL68) cell lines.     

Microbial carbonylation and hydroxylation of 20(R)-panaxadiol by Aspergillus niger

20(R)-panaxadiol (PD) was metabolised by the fungus Aspergillus niger AS 3.3926 to its C-3 carbonylated metabolite and five other hydroxylated metabolites (1–6). Their structures were elucidated as 3-oxo-20(R)-panaxadiol (1), 3-oxo-7β-hydroxyl- 20(R)-panaxadiol (2), 3-oxo-7β,23α-dihydroxyl-20(R)-panaxadiol (3), 3,12-dioxo- 7β,23β-dihydroxyl-20(R)-panaxadiol (4), 3-oxo-1α,7β-dihydroxyl-20(R)-panaxadiol (5) and 3-oxo-7β,15β-dihydroxyl-20(R)-panaxadiol (6) by spectroscopic analysis. Among them, compounds 2–6 were new compounds. Pharmacological studies revealed that compound 6 exhibited significant anti-hepatic fibrosis activity.     

High production of β-glucosidase from a marine Aspergillus niger immobilized on towel gourd vegetable sponges

To produce β-glucosidase by consecutive batch fermentation, a marine Aspergillus niger was immobilized on a natural carrier, towel gourd vegetable sponges. The immobilized mycelia were 0.15 g/g carrier with the immobilized biomass percentage of over 95%. The immobilized mycelia possessed the long durability(22.5 days). The maximum production occurred 1.5 day earlier by the immobilized mycelia than by the free mycelia. β-Glucosidase production of five consecutive batches was over 110 U/m L. At high salinity,the activity and stability of β-glucosidase from the marine A. niger increased remarkable. Immobilizing the marine A. niger on the novel natural carrier achieved the efficient production of β-glucosidase.     

Size-Dependent Impact of Magnetic Nanoparticles on Growth and Sporulation of Aspergillus niger

Magnetic nanoparticles (MNPs) are becoming important DNA nanocarriers for genetic engineering of industrial fungi. However, the biological effect of MNPs on industrial fungi remains unknown. In this study, we prepared three kinds of magnetic nanoparticles with different sizes (i.e., 10 nm, 20 nm, and 200 nm) to investigate their impact on the growth and sporulation of the important industrial fungus Aspergillus niger. Transmission electron microscopy, X-ray diffraction analysis and Zeta potential analysis revealed that the three kinds of MNPs, including MNP10, MNP20 and MNP200, had uniform size distribution, regular Fe₃O₄ X-ray diffraction (XRD) patterns and similar Zeta potentials. Interestingly, although the three kinds of MNPs did not obviously inhibit growth of the fungus, the MNP20 at 500 mg/L strongly attenuated sporulation, leading to a remarkable decrease in spore numbers on culturing plates. Further investigation showed that MNP20 at the high concentration led to drastic chitin accumulation in the cell wall, indicating cell wall disruption of the MNP20-treated fungal cells. Moreover, the MNPs did not cause unusual iron dissolution and reactive oxygen species (ROS) accumulation, and the addition of ferrous ion, ferric ion or the reactive oxygen species scavenger N-acetyl-L-cysteine (NAC) had no impact on the sporulation of the fungus, suggesting that both iron dissolution and ROS accumulation did not contribute to attenuated sporulation by MNP20. This study revealed the size-dependent effect of MNPs on fungal sporulation, which was associated with MNP-induced cell wall disruption.     

Characterisation and antiproliferative activity of irinotecan and sulphonatocalixarene inclusion complex

The interaction between water-soluble sulphonatocalix[4]arene (SC4A) and irinotecan (CPT-11) was investigated by using UV spectrophotometry. Inclusion complex of SC4A with CPT-11 was confirmed by ¹H NMR and DSC analysis. Water solubility study showed that SC4A has remarkable solubilisation on CPT-11 and the complex has good water solubility. The antiproliferative activity of the complex was evaluated. The results showed that the complexation of CPT-11 with SC4A increases the antiproliferative activity of CPT-11.     

Antioxidant and antiproliferative activity of Stachys glutinosa L. ethanol extract

Ethanol extracts of Stachys glutinosa L. (Lamiaceae) were investigated for antioxidative properties, as well as antiproliferative action on various cell lines. The antioxidant activities were investigated by ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulphonic acid) assay, DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, β-carotene/linoleic acid assay, scavenging of hydrogen peroxide (horseradish peroxidase test), superoxide anion scavenging, and hypochlorous acid scavenging (taurine test). The antioxidant activity was reported as IC₅₀ and reveals antioxidant effects. Antiproliferative effects were measured in vitro on three cell lines: HepG2 (human hepatocarcinoma), MCF7 (breast human adenocarcinoma) and C2C12 (mouse myoblast) cell lines by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The ethanol extract induced variations in cell viability on all cell lines tested. At 200 μg/mL, the effects on cell viability were ? 23%, ? 27% and ? 37%, respectively, for C2C12, MCF7 and HepG2.     

A new triterpenoid saponin from Gleditsia sinensis and its antiproliferative activity

Chemical investigation of the anomalous fruits of Gleditsia sinensis led to the isolation and identification of a new triterpenoid saponin, 3-O-β-D-xylopyranosyl-(1 → 2)-α-L-arabinopyranosyl-(1 → 6)-β-D-glucopyranosyl oleanolic acid 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyrano--syl-(1 → 4)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 3)-β-D-glucopyranosyl ester (1), along with other nine known compounds (2–10). All the isolates from this species were reported for the first time. The structure of Compound 1 was determined by a detailed analysis using various analytical techniques, including 1D and 2D NMR. In vitro antiproliferative activities of Compound 1 on MCF-7 and Hep-G2 tumor cell lines were evaluated. IC₅₀ values against the two cell lines were 9.5 and 11.6 μM, respectively.