Sesquiterpenoids from the Mangrove-Derived Aspergillus ustus 094102.

Four new drimane sesquiterpenoids (1-4) and three known ones (5-7) were isolated from the fermentation broth of the mangrove-derived Aspergillus ustus 094102. Compound 5 was further resolved as four purified compounds 5a-5d. By means of extensive spectroscopic and ECD analysis as well as the chemical transformation, their structures were identified as (2R,3R,5S,9R,10S)-2,3,9,11-tetrahydroxydrim-7-en-6-one (ustusol F, 1), (2R,3R,5R,9S,10R)-2,3,11-trihydroxydrim-7-en-6-one (9-deoxyustusol F, 2), (3S,5R,9R,10R)-3,11,12-trihydroxydrim-7-en-6-one (ustusol G, 3), (5S,6R,9S,10S, 11R,2'E,4'E)-(11-dideoxy-11-hydroxystrobilactone A-6-yl)-5-carboxypenta-2,4-dienoate (ustusolate H, 4), ((5S,6R,9S,10S)-strobilactone A-6-yl) (2E,4E)-6,7-dihydroxyocta-2,4-dienoate (ustusolate I, 5), (2'E,4'E;6',7'-erythro)-ustusolate I (5a) and (2'E,4'E;ent-6',7'-erythro)-ustusolate I (5b), (2'E,4'E,6'R,7'R)-ustusolate I (5c) and (2'E,4'E,6'S,7'S)-ustusolate I (5d), (5S,6R,9S,10S,2'E,4'E)-(strobilactone A-6-yl)-5-carboxypenta-2,4-dienoate (ustusolate J, 6), and (2S,5S,9R,10S)-2,9,11-trihydroxydrim-7-en-6-one (ustusol B, 7), respectively. Compound 5 showed antiproliferation against the human tumor cells CAL-62 and MG-63 with the IC50 values of 16.3 and 10.1 µM, respectively.

Azaphilones from the Marine Sponge-Derived Fungus Penicillium sclerotiorum OUCMDZ-3839.

Four new azaphilones, sclerotiorins A-D (1-4), as well as the dimeric sclerotiorin E (5) of which we first determined its absolute configuration, and 12 known analogues (5-16) were isolated from the fermentation broth of Penicillium sclerotiorum OUCMDZ-3839 associated with a marine sponge Paratetilla sp.. The new structures, including absolute configurations, were elucidated by spectroscopic analyses, optical rotation, ECD spectra, X-ray single-crystal diffraction, and chemical transformations. Compounds 11 and 14 displayed significant inhibitory activity against α-glycosidase, with IC50 values of 17.3 and 166.1 µM, respectively. In addition, compounds 5, 7, 10, 12-14, and 16 showed moderate bioactivity against H1N1 virus.

Pyrazinone derivatives from the coral-derived Aspergillus ochraceus LCJ11-102 under high iodide salt.

Five new pyrazin-2(1H)-one derivatives, ochramides A-D (1-4) and ochralate A (5), as well as three known analogues (6-8) were isolated from the fermentation broth of the marine coral-derived halotolerant Aspergillus ochraceus LCJ11-102 in a nutrient-limited medium containing 10% NaI. Their chemical structures were determined by analyzing NMR and X-ray diffraction data. Compounds 2, 5 and 6 showed antimicrobial activities against Enterobacter aerogenes with the MIC values of 40.0, 18.9, and 20.1 µM, respectively.

Ophiobolins from the Mangrove Fungus Aspergillus ustus.

Seven new ophiobolins (1-5, 12, and 14) along with the 11 known analogues (6-11, 13, 15-18) were isolated from the ethyl acetate extracts of the liquid and solid cultures of the mangrove fungus Aspergillus ustus 094102. The structures including the absolute configurations of the seven new compounds were elucidated by spectroscopic analysis, chemical methods, and quantum ECD calculations. Compounds 4-8 and 11-15 showed cytotoxicities against the G3K, MCF-7, MD-MBA-231, MCF/Adr, A549, and HL-60 human cancer cell lines with the IC50 values ranging from 0.6 to 9.5 µM.

Sesterterpene ophiobolin biosynthesis involving multiple gene clusters in Aspergillus ustus.

Terpenoids are the most diverse and abundant natural products among which sesterterpenes account for less than 2%, with very few reports on their biosynthesis. Ophiobolins are tricyclic 5-8-5 ring sesterterpenes with potential pharmaceutical application. Aspergillus ustus 094102 from mangrove rizhosphere produces ophiobolin and other terpenes. We obtained five gene cluster knockout mutants, with altered ophiobolin yield using genome sequencing and in silico analysis, combined with in vivo genetic manipulation. Involvement of the five gene clusters in ophiobolin synthesis was confirmed by investigation of the five key terpene synthesis relevant enzymes in each gene cluster, either by gene deletion and complementation or in vitro verification of protein function. The results demonstrate that ophiobolin skeleton biosynthesis involves five gene clusters, which are responsible for C15, C20, C25, and C30 terpenoid biosynthesis.

Ophiobolin O isolated from Aspergillus ustus induces G1 arrest of MCF-7 cells through interaction with AKT/GSK3ß/cyclin D1 signaling.

Ophiobolin O is a member of ophiobolin family, which has been proved to be a potent anti-tumor drug candidate for human breast cancer. However, the anti-tumor effect and the mechanism of ophiobolin O remain unclear. In this study, we further verified ophiobolin O-induced G1 phase arrest in human breast cancer MCF-7 cells, and found that ophiobolin O reduced the phosphorylation level of AKT and GSK3ß, and induced down-regulation of cyclin D1. The inverse docking (INVDOCK) analysis indicated that ophiobolin O could bind to GSK3ß, and GSK3ß knockdown abolished cyclin D1 degradation and G1 phase arrest. Pre-treatment with phosphatase inhibitor sodium or thovanadate halted dephosphorylation of AKT and GSK3ß, and blocked ophiobolin O-induced G1 phase arrest. These data suggest that ophiobolin O may induce G1 arrest in MCF-7 cells through interaction with AKT/GSK3ß/cyclin D1 signaling. In vivo, ophiobolin O suppressed tumor growth and showed little toxicity in mouse xenograft models. Overall, these findings provide theoretical basis for the therapeutic use of ophiobolin O.

New Isochromane Derivatives from the Mangrove Fungus Aspergillus ustus 094102.

Four new isochromane derivatives (1-4) along with the known peniciphenol (5) and (R)-2-(hydroxymethyl)-3-(2-hydroxypropyl)pheno (6) were isolated from the EtOAc extract of the fermentation broth of the mangrove fungus, Aspergillus ustus 094102. The structures of the new compounds including the absolute configuration were elucidated on the basis of spectroscopic analysis, CD and ECD calculation. Compounds 1 and 2 exhibited α-glucosidase inhibition and anti-oxidation against DPPH radical with IC50 values of 1.4 mM and 25.7 µM, respectively.

New rubrolides from the marine-derived fungus Aspergillus terreus OUCMDZ-1925.

Two new rubrolides, rubrolides R (1) and S (2), were isolated from the fermentation broth of the marine-derived fungus Aspergillus terreus OUCMDZ-1925. Their structures were elucidated on the basis of spectroscopic analysis and X-ray single crystal diffraction. Compound 1 showed comparable or superior antioxidation against 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radicals to those of trolox and ascorbic acid with an IC50 value of 1.33 mM. Compound 2 showed comparable or superior anti-influenza A (H1N1) virus activity to that of ribavirin with an IC50 value of 87.1 µM. Both compounds 1 and 2 showed weak cytotoxicity against the K562 cell line with IC50 values of 12.8 and 10.9 µM, respectively.

Ophiobolin-O reverses adriamycin resistance via cell cycle arrest and apoptosis sensitization in adriamycin-resistant human breast carcinoma (MCF-7/ADR) cells.

Multidrug-resistance is a major obstacle facing cancer chemotherapy. This paper demonstrates that novel compound Ophiobolin-O reverses MCF-7/ADR resistance to adriamycin (ADM). The IC50 of ADM treated MCF-7 cells was 2.02 ± 0.05 µM and 74.00 ± 0.18 µM treated MCF-7/ADR cells, about 37-fold, compared to the former. However, 0.1 µM Ophiobolin-O (less than 20% inhibition concentration) combined with ADM caused the decreased IC50 of ADM to 6.67 ± 0.98 µM, indicating it reversed ADM resistance of MCF-7/ADR cells (11-fold). Furthermore, Ophiobolin-O increased ADM-induced mitochondrial pathway apoptosis and G2/M phase arrest, which is partly due to the elevation level of ROS in MCF-7/ADR cells. As we described in this paper, the reversal effect of Ophiobolin-O may be due to the reduction of resistance-related protein P-Glycoprotein (P-gp, also known as MDR1) through inhibiting the activity of the multidrug resistance 1 (MDR1) gene promoter, which makes MCF-7/ADR cells more sensitive to ADM treatment. Assays in nude mice also showed that the combination of ADM and Ophiobolin-O significantly improved the effect of ADM.

Indole-diterpenoids with anti-H1N1 activity from the aciduric fungus Penicillium camemberti OUCMDZ-1492.

An aciduric fungal strain, Penicillium camemberti OUCMDZ-1492, was isolated from an acidic marine niche, mangrove soil and mud, around the roots of Rhizophora apiculata. Six new indole-diterpenoids (1-6), along with five known analogues, emindole SB (7), 21-isopentenylpaxilline (8), paspaline (9), paxilline (10), and dehydroxypaxilline (11), were isolated from the fermentation broth of P. camemberti OUCMDZ-1492 grown at pH 5.0. On the basis of spectroscopic analyses, CD spectra, quantum ECD calculations, and chemical methods, new structures 1-6 were established as 3-deoxo-4b-deoxypaxilline, 4a-demethylpaspaline-4a-carboxylic acid, 4a-demethylpaspaline-3,4,4a-triol, 2'-hydroxypaxilline, 9,10-diisopentenylpaxilline, and (6S,7R,10E,14E)-16-(1H-indol-3-yl)-2,6,10,14-tetramethylhexadeca-2,10,14-triene-6,7-diol, respectively. Compounds 1-3 and 5-10 exhibited significant activity against the H1N1 virus with IC50 values of 28.3, 38.9, 32.2, 73.3, 34.1, 26.2, 6.6, 77.9, and 17.7 µM, respectively. The results showed that 3-oxo, 4b-hydroxy, and 9-isopentenyl substitutions tend to increase the anti-H1N1 activity of hexacyclic indole-diterpenoids.

Antimicrobial aflatoxins from the marine-derived fungus Aspergillus flavus 092008.

A new aflatoxin, aflatoxin B(2b) (1), together with six known compounds, were isolated from the marine-derived fungus Aspergillus flavus 092008 endogenous with the mangrove plant Hibiscus tiliaceus (Malvaceae). The structure of 1 was determined by the spectroscopic and chemical methods. Compound 1 exhibited a moderate antimicrobial activity against Escherichia coli, Bacillus subtilis and Enterobacter aerogenes, with MIC values of 22.5, 1.7 and 1.1 M, respectively. Compound 1 also showed a weak cytotoxicity against A549, K562 and L-02 cell lines, with IC(50) values of 8.1, 2.0 and 4.2 M, respectively. The results showed that hydration and hydrogenation of (8)-double bond significantly reduces the cytotoxicity of aflatoxins, while the esterification at C-8 increases the cytotoxicity.