Novel antifouling and antimicrobial compound from a marine-derived fungus Ampelomyces sp.

In this study, using a bioassay-guided isolation and purification procedure, we obtained 3-chloro-2,5-dihydroxybenzyl alcohol from a marine-derived Ampelomyces species that effectively inhibited larval settlement of the tubeworm Hydroides elegans and of cyprids of the barnacle Balanus amphitrite. The inhibitive effect on larval settlement was nontoxic and the EC50 of 3-chloro-2,5-dihydroxybenzyl alcohol ranged from 3.19 mu g ml(-1) to 3.81 mu g ml(-1) while the LC50 was 266.68 lambda g ml(-1) for B. amphitrite cyprids; EC50 ranged from 0.67 mu g ml(-1) to 0.78 mu g ml(-1), and LC50 was 2.64 mu g ml(-1) for competent larvae of H. elegans, indicating that inhibitive effect of this compound was nontoxic. At a concentration of 50 mu g per disc, this compound showed strong inhibitive effects on the growth of 13 out of 15 marine bacterial species tested in disc diffusion bioassay. Overall, the high inhibitory activities against bacteria and larval settlement as well as the non- or low-toxic nature of this compound to the barnacle and polychaete larvae suggest this compound could be a potent antifoulant and/or antibiotic.

Cytoglobosins A-G, Cytochalasans from a Marine-Derived Endophytic Fungus, Chaetomium globosum QEN-14

Financial support from the Ministry of Science and Technology of China (2010CB833802 and 2007AA09Z446) and from the National Science Foundation of China (30910103914) is gratefully acknowledged.

Chemical Constituents of a Marine-Derived Endophytic Fungus Penicillium commune G2M

Cultivation of the endophytic fungus Penicillium commune, which was isolated from the semi-mangrove plant Hibiscus tiliaceus, afforded one new compound 1-O-(2,4-dihydroxy-6-methylbenzoyl)-glycerol (1) along with thirteen known products, including 1-O-acetylglycerol (2), N-acetyltryptophan (3), 3-indolylacetic acid methyl ester (4), 1-(2,4-dihydroxy-3,5-dimethylphenyl)ethanone (5), 2-(2,5-dihydroxyphenyl)acetic acid (6), (4R,5S)-5-hydroxyhexan-4-olide (7), thymidine (8), uracil (9), thymine (10), ergosterol (11), beta-sitosterol (12), beta-daucosterol (13), and ergosta-7,22-dien-3 beta,5 alpha,6 beta-triol (14). The structures of these compounds were established by detailed NMR spectroscopic analysis, as well as by comparison with literature data or with authentic samples.

Benzodiazepine Alkaloids from Marine-Derived Endophytic Fungus Aspergillus ochraceus

A new fungus-derived benzodiazepine analogue, 2-hydroxycircumdatin C (1), and a compound which has been isolated from a natural resource for the first time, but has been previously synthesized, namely (11aS)-2,3-dihydro-7-methoxy-1H-pyrrolo[2,1-c][1,4]benzodiazepine-5,11(10H,11aH)-dione (2), along with five structurally related known alkaloids (3-7), were isolated from Aspergillus ochraceus, an endophytic fungus derived from the marine brown alga Sargassum kjellmanianum. Their structures were established on the basis of spectroscopic methods. The absolute configuration of I was determined through CD evidence. Compound 1 displayed significant DPPH radical-scavenging activity with an IC50 value of 9.9 mu M, which is 8.9-fold more potent than that of butylated hydroxytoluene (BHT), a well-known synthetic positive control.

5,7-Dihydroxy-5,6,7,8-tetrahydro-1H-azocin-2-one from a marine-derived Streptomyces sp.

In the course of a screening program, we have isolated the new natural product, 5,7-dihydroxy-5,6,7,8-tetrahydroazocin-2(IH)-one (1), from the staurosporine producing marine-derived Streptomyces sp. strain QD518. Here we report the isolation and structure elucidation of 1 and the artifacts 3 and 4 resulting from I by acid catalyzed intra- and inter-molecular reactions.

T-Muurolol Sesquiterpenes from the Marine Streptomyces sp M491 and Revision of the Configuration of Previously Reported Amorphanes

Two new sesquiterpenes, 15-hydroxy-T-muurolol (3d) and 11,15-dihydroxy-T-muurolol (3e), along with the plant cadinenes T-muurolol (3f) and 3 alpha-hydroxy-T-muurolol (3g), were isolated from the marine-derived Streptomyces sp. M491. Their absolute configuration was established via NMR spectroscopy and X-ray crystallography of 3-oxo-T-muurolol (3a), which was reisolated from this strain. In addition, the absolute configuration of further sesquiterpenes previously reported from this strain was revised. These products were tested for their cytotoxicity against 37 human tumor cell lines using the MTT method. Only 3d was cytotoxic against a range of human tumor cell lines with a mean IC50 of 6.7 mu g/mL.

Amorphane sesquiterpenes from a marine Streptomyces sp.

The chemical investigation of the crude extract of the marine-derived Streptomyces sp. M491 yielded three new sesquiterpenes, namely, 10 alpha,11-dihydroxyamorph-4-ene (4), 10 alpha,15-dihydroxyamorph-4-en-3-one (6), and 5 alpha,10 alpha,11-trihydroxyamorphan-3-one (7). In addition, the known compounds 10 alpha-hydroxyamorph-4-en-3-one (2), o-hydroxyacetanilide, genistein, prunetin, and indole-3-carbaldehyde and the macrolide antibiotic chalcomycin A were identified. The structures were determined on the basis of spectroscopic analysis, especially 1D and 2D NMR data. This is the first report of these sesquiterpenes from bacteria.

Sources and transport of dissolved and particulate organic carbon in the Mississippi River estuary and adjacent coastal waters of the northern Gulf of Mexico

Dissolved organic carbon (DOC), stable carbon isotopic (delta(13)C) compositions of DOC and particulate organic carbon (POC), and elemental C/N ratios of POC were measured for samples collected from the lower Mississippi and Atchafalaya rivers and adjacent coastal waters in the northern Gulf of Mexico during the low flow season in June 2000 and high flow season in April 2001. These isotopic and C/N results combined with DOC measurements were used to assess the sources and transport of terrestrial organic matter from the Mississippi and Atchafalaya rivers to the coastal region in the northern Gulf of Mexico. delta(13)C values of both POC (-23.8parts per thousand to -26.8parts per thousand) and DOC (-25.0parts per thousand to -29.0parts per thousand) carried by the two rivers were more depleted than the values measured for the samples collected in the offshore waters. Strong seasonal variations in delta(13)C distributions were observed for both POC and DOC in the surface waters of the region. Fresh water discharge and horizontal mixing played important roles in the distribution and transport of terrestrial POC and DOC offshore. Our results indicate that both POC and DOC exhibited non-conservative behavior during the mixing especially in the mid-salinity range. Based on a simple two end-member mixing model, the comparison of the measured DOC-delta(13)C with the calculated conservative isotopic mixing curve indicated that there was a significant in situ production of marine-derived DOC in the mid- to high-salinity waters consistent with our in situ chlorophyll-a measurements. Our DOC-delta(13)C data suggest that a removal of terrestrial DOC mainly occurred in the high-salinity (>25) waters during the mixing. Our study indicates that the mid- to high- (10-30) salinity range was the most dynamic zone for organic carbon transport and cycling in the Mississippi River estuary. Variability in isotopic and elemental compositions along with variability in DOC and POC concentrations suggest that autochthonous production, bacterial utilization, and photo-oxidation could all play important roles in regulating and removing terrestrial DOC in the northern Gulf of Mexico and further study of these individual processes is warranted. (C) 2004 Elsevier B.V. All rights reserved.

Chaetopyranin, a benzaldehyde derivative, and other related metabolites from Chaetomium globosum, an endophytic fungus derived from the marine red alga Polysiphonia urceolata

Cultivation of the endophytic fungus Chaetomium globosum, which was isolated from the inner tissue of the marine red alga Polysiphonia urceolata, resulted in the isolation of chaetopyranin (1), a new benzaldehyde secondary metabolite. Ten known compounds were also isolated, including two benzaldehyde congeners, 2-(2 ',3-epoxy-1 ',3 '-heptadienyl)-6-hydroxy- 5-(3-methyl-2-butenyl) benzaldehyde (2) and isotetrahydroauroglaucin (3), two anthraquinone derivatives, erythroglaucin (4) and parietin (5), five asperentin derivatives including asperentin ( 6, also known as cladosporin), 5 '-hydroxy-asperentin-8-methylether (7), asperentin-8-methyl ether (8), 4 '-hydroxyasperentin (9), and 5 '-hydroxyasperentin (10), and the prenylated diketopiperazine congener neoechinulin A (11). The structures of these compounds were determined on the basis of their spectroscopic data analysis (H-1, C-13, H-1-H-1 COSY, HMQC, and HMBC NMR, as well as low- and high-resolution mass experiments). To our knowledge, compound 1 represents the first example of a 2H-benzopyran derivative of marine algal-derived fungi as well as of the fungal genus Chaetomium. Each isolate was tested for its DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging property. Compounds 1-4 were found to have moderate activity. Chaetopyranin (1) also exhibited moderate to weak cytotoxic activity toward several tumor cell lines.

Natural Anthraquinone Derivatives from a Marine Mangrove Plant-Derived Endophytic Fungus Eurotium rubrum: Structural Elucidation and DPPH Radical Scavenging Activity

There is considerable interest in the isolation of potent radical scavenging compounds from natural resources to treat diseases involving oxidative stress. In this report, four new fungal metabolites including one new bisdihydroanthracenone derivative (1, eurorubrin), two new seco-anthraquinone derivatives [3, 2-O-methyl-9-dehydroxyeurotinone and 4, 2-O-methyl4-O-(alpha-D-ribofuranosyl)-9-dehydroxyeurotinone], and one new anthraquinone glycoside [6,3-O-(alpha-D-ribofuranosyl)questin], were isolated and identified from Eurotium rubrum, an endophytic fungal strain that was isolated from the inner tissue of the stem of the marine mangrove plant Hibiscus tiliaceus. In addition, three known compounds including asperflavin (2), 2-O-methyleurotinone (5), and questin (7) were also isolated and identified. Their structures were elucidated on the basis of spectroscopic analysis. All of the isolated compounds were evaluated for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity.

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-(4methoxy-6-oxo-6H-pyran-2-yl)-2-phenylethylaniino]-[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. (c) 2007 Bin Gui Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Dioxopiperazine Alkaloids Produced by the Marine Mangrove Derived Endophytic Fungus Eurotium rubrum

Cultivation of the fungal strain Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus, resulted in the isolation of two new dioxopiperazine derivatives, namely, dehydrovariecolorin L (1) and dehydroechinulin (2), together with eight known dioxopiperazine compounds including variecolorin L (3), echinulin (4), isoechinulin A (5), dihydroxyisoechinulin A (6), preechinulin (7), neoechinulin A (8), neoechinulin E (9), and cryptoechinuline D (10). The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. Compounds 1, 2, 9, and 10 were investigated for their a,a-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity. In addition, the new compounds, 1 and 2, were evaluated for their cytotoxic activity against the P-388, HL-60, and A549 cell lines.

Benzaldehyde derivatives from Eurotium rubrum, an endophytic fungus derived from the mangrove plant Hibiscus tiliaceus

Four new (1-4) and seven known (5-11) benzaldehyde derivatives were characterized from the liquid fermentation cultures of Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus. The structures of these compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compound 1, which was named as eurotirumin, possesses a new carbon skeleton with a cyclopentabenzopyran ring system.

Evaluation of 28 marine algae from the Qingdao coast for antioxidative capacity and determination of antioxidant efficiency and total phenolic content of fractions and subfractions derived from Symphyocladia latiuscula (Rhodomelaceae)

The extracts obtained from 28 species of marine algae were evaluated for their antioxidant activity (AA) versus the positive controls butylated hydroxytoluene (BHT), gallic acid (GA), and ascorbic acid (AscA). Most of the tested samples displayed antioxidant activity to various degrees. Among them, the extract of Symphyocladia latiuscula exhibited the strongest AA, which was comparable to BHT, GA, and AscA in radical scavenging activity, as shown in the DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) assay, and higher than those of the positive controls in beta-carotene-linoleate assay system. In addition, the ethyl acetate-soluble fraction isolated from the crude extract of S. latiuscula exhibited the highest antioxidant activity in both assay systems. This fraction was further fractionated into seven subfractions (F1-F7) by vacuum liquid chromatography (VLC). F1 and F4 were found to be the most effective subfractions in scavenging DPPH radical assay and in the beta-carotene-linoleate assay, respectively. The total phenolic content (TPC) and reducing power (RP) for all of the extracts, fractions, and subfractions (F1-F7) were also determined. The TPC of the 28 extracts ranged from 0.10 to 8.00 gallic acid equivalents (mg/g seaweed dry weight) while the RP ranged from 0.07 to 11.60 ascorbic acid equivalents (mg center dot g(-1) seaweed dry weight). Highly positive relationships between AA and TPC as well as between AA and RP were found for the extracts and fractions, while for the subfractions F1-F7 only weak or no such relations were found. The results obtained from this study indicate that further analysis is needed of those marine algal species that contain the most antioxidant activity in order to identify the active principles.

New sphingolipids with a previously unreported 9-Methyl-C-20-sphingosine moiety from a marine algous endophytic fungus Aspergillus niger EN-13

Asperamides A (1) and B (2), a sphingolipid and their corresponding glycosphingolipid possessing a hitherto unreported 9-methyl-C-20-sphingosine moiety, were characterized from the culture extract of Aspergillus niger EN-13, an endophytic fungus isolated from marine brown alga Colpomenia sinuosa. The structures were elucidated by spectroscopic and chemical methods as (2S,2'R,3R,3'E,4E,8E)-N-(2'-hydroxy-3'-hexadecenoyl)-9-methyl-4,8-icosadien-1,3-diol (1) and 1-O-beta-D-glucopyranosyl-(2S,2'R,3R,3'E,4E,8E)-N-(2'-hydroxy-3'-hexadecenoyl)-9-methyl-4,8-icosadien-1,3-diol (2). In the antifungal assay, asperamide A (1) displayed moderate activity against Candida albicans.