Characterization of a Newly Isolated Marine Fungus Aspergillus dimorphicus for Optimized Production of the Anti-Tumor Agent Wentilactones.

The potential anti-tumor agent wentilactones were produced by a newly isolated marine fungus Aspergillus dimorphicus. This fungus was derived from deep-sea sediment and identified by polyphasic approach, combining phenotypic, molecular, and extrolite profiles. However, wentilactone production was detected only under static cultures with very low yields. In order to improve wentilactone production, culture conditions were optimized using the response surface methodology. Under the optimal static fermentation conditions, the experimental values were closely consistent with the prediction model. The yields of wentilactone A and B were increased about 11-fold to 13.4 and 6.5 mg/L, respectively. The result was further verified by fermentation scale-up for wentilactone production. Moreover, some small-molecule elicitors were found to have capacity of stimulating wentilactone production. To our knowledge, this is first report of optimized production of tetranorlabdane diterpenoids by a deep-sea derived marine fungus. The present study might be valuable for efficient production of wentilactones and fundamental investigation of the anti-tumor mechanism of norditerpenoids.

Cyclohexadepsipeptides of the isaridin class from the marine-derived fungus Beauveria felina EN-135.

Three new cyclohexadepsipeptides of the isaridin class including isaridin G (1), desmethylisaridin G (2), and desmethylisaridin C1 (3), along with three related known metabolites (4-6), were isolated and identified from the marine bryozoan-derived fungus Beauveria felina EN-135. The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis, and the structures and absolute configurations of compounds 1-3 were confirmed by single-crystal X-ray diffraction analysis. The crystal structures showed the presence of ß-turns for the Tyr(3)/N-Me-Val(4) and Phe(3)/N-Me-Val(4) amide bonds in compounds 2 and 3, respectively, in the cis conformations, which were opposite other reported isaridins. The conformations of the HMPA(1)-Pro(2) amide bond in compound 2 are different in the solution and in the crystal structures, which showed trans and cis geometries, respectively, while compounds 1 and 3 do not exhibit this phenomenon. Each of the isolated compounds was evaluated for antimicrobial activity and brine shrimp lethality. Compound 3 exhibited antibacterial activity against E. coli with an MIC value of 8 µg/mL.

Cyclodepsipeptides and other O-containing heterocyclic metabolites from Beauveria felina EN-135, a marine-derived entomopathogenic fungus.

Bioassay-guided fractionation of a culture extract of Beauveria felina EN-135, an entomopathogenic fungus isolated from a marine bryozoan, led to the isolation of a new cyclodepsipeptide, iso-isariin D (1); two new O-containing heterocyclic compounds that we have named felinones A and B (2 and 3); and four known cyclodepsipeptides (4-7). The structures were elucidated via spectroscopic analysis, and the absolute configurations of 1 and 2 were determined using single-crystal X-ray diffraction and CD, respectively. All isolated compounds were evaluated for antimicrobial activity and brine-shrimp (Artemia salina) lethality.

Prenylated indolediketopiperazine peroxides and related homologues from the marine sediment-derived fungus Penicillium brefeldianum SD-273.

Three new indolediketopiperazine peroxides, namely, 24-hydroxyverruculogen (1), 26-hydroxyverruculogen (2), and 13-O-prenyl-26-hydroxyverruculogen (3), along with four known homologues (4-7), were isolated and identified from the culture extract of the marine sediment-derived fungus Penicillium brefeldianum SD-273. Their structures were determined based on the extensive spectroscopic analysis and compound 1 was confirmed by X-ray crystallographic analysis. The absolute configuration of compounds 1-3 was determined using chiral HPLC analysis of their acidic hydrolysates. Each of the isolated compounds was evaluated for antibacterial and cytotoxic activity as well as brine shrimp (Artemia salina) lethality.

4-Phenyl-3,4-dihydroquinolone derivatives from Aspergillus nidulans MA-143, an endophytic fungus isolated from the mangrove plant Rhizophora stylosa.

Six new 4-phenyl-3,4-dihydroquinolone derivatives (1-6) along with the related aflaquinolone A (7) were isolated and identified from the cultures of Aspergillus nidulans MA-143, an endophytic fungus obtained from the fresh leaves of the marine mangrove plant Rhizophora stylosa. Their structures including absolute configurations were determined by spectroscopic analysis and electronic circular dichroism experiments, and the structure of compound 1 was confirmed by single-crystal X-ray crystallographic analysis. In bioscreening experiments, none of the isolated compounds showed potent antibacterial or cytotoxic activity. However, compounds 2, 3, and 7 exhibited lethality against brine shrimp (Artemia salina), with LD50 values of 7.1, 4.5, and 5.5 µM, respectively.

Sulfur-containing cytotoxic curvularin macrolides from Penicillium sumatrense MA-92, a fungus obtained from the rhizosphere of the mangrove Lumnitzera racemosa.

Sumalarins A-C (1-3), the new and rare examples of sulfur-containing curvularin derivatives, along with three known analogues (4-6), were isolated and identified from the cytotoxic extract of Penicillium sumatrense MA-92, a fungus obtained from the rhizosphere of the mangrove Lumnitzera racemosa . Their structures were established by detailed interpretation of NMR and MS data, and compound 1 was confirmed by X-ray crystallographic analysis. Compounds 1-3 and 5 showed potent cytotoxicity against some of the tested tumor cell lines. Sulfur substitution at C-11 or a double bond at C-10 significantly increased the cytotoxic activities of the curvularin analogues.

Secondary metabolites from Penicillium pinophilum SD-272, a marine sediment-derived fungus.

Two new secondary metabolites, namely, pinodiketopiperazine A (1) and 6,7-dihydroxy-3-methoxy-3-methylphthalide (2), along with alternariol 2,4-dimethyl ether (3) and L-5-oxoproline methyl ester (4), which were isolated from a natural source for the first time but have been previously synthesized, were characterized from the marine sediment-derived fungus Penicillium pinophilum SD-272. In addition, six known metabolites (5-10) were also identified. Their structures were elucidated by analysis of the NMR and mass spectroscopic data. The absolute configuration of compound 1 was determined by experimental and calculated ECD spectra. Compound 2 displayed potent brine shrimp (Artemia salina) lethality with LD50 11.2 µM.

Cytotoxic anthranilic acid derivatives from deep sea sediment-derived fungus Penicillium paneum SD-44.

Five new anthranilic acid derivatives, penipacids A-E (1-5), together with one known analogue (6), which was previously synthesized, were characterized from the ethyl acetate extract of the marine sediment-derived fungus Penicillium paneum SD-44. Their structures were elucidated mainly by extensive NMR spectroscopic and mass spectrometric analysis. The cytotoxicity and antimicrobial activity of the isolated compounds were evaluated. Compounds 1, and 5 exhibited inhibitory activity against human colon cancer RKO cell line, while compound 6 displayed cytotoxic activity against Hela cell line.

Aniquinazolines A-D, four new quinazolinone alkaloids from marine-derived endophytic fungus Aspergillus nidulans.

Four new quinazolinone alkaloids, namely, aniquinazolines A-D (1-4), were isolated and identified from the culture of Aspergillus nidulans MA-143, an endophytic fungus obtained from the leaves of marine mangrove plant Rhizophora stylosa. The structures of the new compounds were elucidated by spectroscopic analysis, and their absolute configurations were determined on the basis of chiral HPLC analysis of the acidic hydrolysates. The structure for 1 was confirmed by single-crystal X-ray diffraction analysis. All these compounds were examined for antibacterial and cytotoxic activity as well as brine shrimp (Artemia salina) lethality.

Cristatumins A-D, new indole alkaloids from the marine-derived endophytic fungus Eurotium cristatum EN-220.

Four new indole alkaloids, namely, cristatumins A-D (1-4), along with six known congeners (5-10) were identified from the culture extract of Eurotium cristatum EN-220, an endophytic fungus isolated from the marine alga Sargassum thunbergii. The structures of these compounds were established on the basis of extensive spectroscopic analysis. Each of these compounds was evaluated for antimicrobial and insecticidal activity. Compounds 1 and 9 showed antibacterial activity against Escherichia coli and Staphyloccocus aureus, respectively, while compounds 2, 6, and 7 exhibited moderate lethal activity against brine shrimp. Preliminary structure-activity relationships were also discussed.

Meroterpenoid and diphenyl ether derivatives from Penicillium sp. MA-37, a fungus isolated from marine mangrove rhizospheric soil.

Penicillium sp. MA-37, which was obtained from the rhizospheric soil of the mangrove plant Bruguiera gymnorrhiza, exhibited different chemical profiles in static and shaken fermentation modes. Three new meroterpenoid derivatives, 4,25-dehydrominiolutelide B (1), 4,25-dehydro-22-deoxyminiolutelide B (2), and isominiolutelide A (3), together with three known ones were characterized from its static fermentation, while three new diphenyl ether derivatives, namely, Δ(1('),3('))-1'-dehydroxypenicillide (4), 7-O-acetylsecopenicillide C (5), and hydroxytenellic acid B (6), along with five related metabolites were isolated from the shaken culture. The structures of these compounds were elucidated on the basis of spectroscopic analysis, and the structure of compound 2 was confirmed by X-ray crystallographic analysis. The absolute configurations of 1-3 and 6 were determined by ECD and modified Mosher's method, respectively. All isolated compounds were evaluated for brine shrimp lethality and antibacterial activity.

Asperolides A-C, tetranorlabdane diterpenoids from the marine alga-derived endophytic fungus Aspergillus wentii EN-48.

Bioassay-guided fractionation of the culture extract of Aspergillus wentii EN-48, an endophytic fungus isolated from an unidentified marine brown algal species of the genus Sargassum, led to the isolation of three new tetranorlabdane diterpenoids, asperolides A-C (1-3), and five related derivatives (4-8). The structures of these compounds were established on the basis of spectroscopic interpretation, and compound 1 was confirmed by X-ray crystallographic analysis. The absolute configuration of 1 was determined by application of the modified Mosher's method. An X-ray structure for wentilactone B (6) is also reported. Compounds 1-8 were evaluated for cytotoxic and antibacterial activities.

Secondary metabolites produced by solid fermentation of the marine-derived fungus Penicillium commune QSD-17.

The marine sediment-derived fungus Penicillium commune QSD-17 was re-investigated and cultured on rice solid medium. Two new compounds, isophomenone (1) and 3-deacetylcitreohybridonol (2), together with seven known derivatives (3-9), were identified. Their structures were determined by spectroscopic analysis.

Sesquiterpene and acetogenin derivatives from the marine red alga Laurencia okamurai.

In addition to 13 known compounds, four new bisabolane sesquiterpenes, okamurenes A-D (1-4), a new chamigrane derivative, okamurene E (5), and a new C12-acetogenin, okamuragenin (6), were isolated from the marine red alga Laurencia okamurai. The structures of these compounds were determined through detailed spectroscopic analyses. Of these, okamurenes A and B (1 and 2) are the first examples of bromobisabolane sesquiterpenes possessing a phenyl moiety among Laurencia-derived sesquiterpenes, while okamuragenin (6) was the first acetogenin aldehyde possessing a C12-carbon skeleton. Each of the isolated compounds was evaluated for the brine shrimp (Artemia salina) lethal assay and 7-hydroxylaurene displayed potent lethality with LD50 1.8 µM.

Diverse secondary metabolites produced by marine-derived fungus Nigrospora sp. MA75 on various culture media.

Bioassay-guided isolation of a fungal strain Nigrospora sp. MA75, an endophytic fungus obtained from the marine semi-mangrove plant Pongamia pinnata, which was fermented on three different culture media, resulted in the isolation and identification of seven known compounds, 2, 3, and 5-9, from a medium containing 3.5% NaCl, while a new compound, 2,3-didehydro-19α-hydroxy-14-epicochlioquinone B (10) was obtained from the medium containing 3.5% NaI. In addition, two new griseofulvin derivatives, 6-O-desmethyldechlorogriseofulvin (1) and 6'-hydroxygriseofulvin (4), were isolated and identified from the rice solid medium. Dechlorogriseofulvin (2) and griseofulvin (3) were the major components in fermentation extracts of all these culture media, while compounds 1 and 4, 5 and 6, and 10 were only present in the extract of respective culture medium. The structures of these compounds were elucidated by detailed spectroscopic analysis, and the absolute configuration of 1 was determined by CD measurement. Compounds 9 and 10 exhibited antibacterial activities toward five tested bacterial strains, while compounds 5, 6, and 8 selectively inhibited MRSA, E. coli, and S. epidermidis, and compound 3 showed moderate activity against V. mali and S. solani. Moreover, compound 10 potently inhibited the growth of MCF-7, SW1990, and SMMC7721 tumor cell lines with IC(50) values of 4, 5, and 7 µg/ml, respectively.

Penicisteroids A and B, antifungal and cytotoxic polyoxygenated steroids from the marine alga-derived endophytic fungus Penicillium chrysogenum QEN-24S.

Two new polyoxygenated steroids, namely, penicisteroids A and B (1 and 2), were obtained from the culture extract of Penicillium chrysogenum QEN-24S, an endophytic fungus isolated from an unidentified marine red algal species of the genus Laurencia. In addition, seven known steroids (3-9) were also isolated and identified. The structures of these compounds were established on the basis of extensive spectroscopic analysis. The absolute configuration for compound 1 was determined by application of the modified Mosher's method. Penicisteroid A (1), which is a structurally unique steroid having tetrahydroxy and C-16-acetoxy groups, displayed potent antifungal and cytotoxic activity in the preliminary bioassays. Preliminary structure-activity relationships are discussed.

Comazaphilones A-F, azaphilone derivatives from the marine sediment-derived fungus Penicillium commune QSD-17.

Chemical investigation of Penicillium commune QSD-17, a fungus isolated from a marine sediment sample collected in the southern China Sea, yielded six new azaphilone derivatives, namely, comazaphilones A-F (1-6). The structures of these compounds were established on the basis of spectroscopic analysis. Attempts to define the absolute configuration of these azaphilones through investigation of Mosher's esters failed, possibly due to steric crowding at C-6 and C-7 and due to the degradation of these azaphilone derivatives under the reaction conditions. The inhibitory activities of the six azaphilones against four bacteria, one pathogenic fungus, and seven tumor cell lines were evaluated. Compounds 3-5 displayed potent inhibitory activity against several of these bacteria, while compounds 4-6 showed cytotoxic activity against human pancreatic tumor cell line SW1990. The preliminary SAR results indicated that the double bond at C-10 and the location of the orsellinic acid unit at C-6 in these azaphilones are important for the antibacterial activity and cytotoxicity, respectively. This is the first report of the isolation of azaphilone derivatives from a marine sediment-derived fungus.

Triazole and dihydroimidazole alkaloids from the marine sediment-derived fungus Penicillium paneum SD-44.

A novel triazole carboxylic acid, penipanoid A (1), two new quinazolinone alkaloids, penipanoids B (2) and C (3), and a very recently reported quinazolinone derivative (4) were isolated from the marine sediment-derived fungus Penicillium paneum SD-44. Their structures were elucidated by spectroscopic analysis, and the structure for 1 was confirmed by X-ray crystallographic analysis. Compound 1 represents the first example of a triazole derivative from marine sediment-derived fungi, and compound 2 is a rare quinazolinone derivative having a dihydroimidazole ring system. The cytotoxicity of compounds 1 and 4 and the antimicrobial activity of 1-4 were evaluated.

Nigerapyrones A-H, α-pyrone derivatives from the marine mangrove-derived endophytic fungus Aspergillus niger MA-132.

Eight new α-pyrone derivatives, namely, nigerapyrones A-E (1-5) and nigerapyrones F-H (8-10), along with two known congeners, asnipyrones B (6) and A (7), were isolated from Aspergillus niger MA-132, an endophytic fungus obtained from the fresh tissue of the marine mangrove plant Avicennia marina. The structures of these compounds were elucidated on the basis of spectroscopic analysis. The undescribed geometries of the trisubstituted double bonds (C-9 and C-11) for asnipyrone B (6) have now been explicitly determined, while the incorrect placement of the methyl group at C-5 of asnipyrone A (7) has now been revised at C-3. The cytotoxic activities of the isolated α-pyrone derivatives against eight tumor cell lines as well as antimicrobial activities against two bacteria and four plant-pathogenic fungi of these compounds were evaluated. Compounds 2, 4, 5, and 7 showed weak cytotoxicity against some of the tested tumor cell lines.

Conidiogenones H and I, two new diterpenes of Cyclopiane class from a marine-derived endophytic fungus Penicillium chrysogenum QEN-24S.

Two new tetracyclic diterpenes of the rarely reported cyclopiane class, conidiogenones H and I (1 and 2, resp.), along with five related congeners, conidiogenones B - D and F (3-5 and 6, resp.) and conidiogenol (7), were characterized from the culture extracts of Penicillium chrysogenum QEN-24S, an endophytic fungus derived from an unidentified marine red algal species of the genus Laurencia. The structures of these compounds were established on the basis of extensive spectroscopic analysis. The inhibitory activity of theses diterpenes against four bacteria and one pathogen fungus was evaluated. Conidiogenone B (3) showed potent activity against Methicillin resistant Staphylococcus aureus (MRSA), Pseudomonas fluorescens, P. aeruginosa, and Staphylococcus epidermidis (each with a MIC value of 8 µg/ml), while conidiogenol (7) showed obvious activity against P. fluorescens and S. epidermidis (each with a MIC value of 16 µg/ml). This is the first report on antimicrobial activity of cyclopiane diterpenes.