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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.

Four polyene macrolactams including the previously reported niizalactam C (4), and three new ones, streptolactams A–C (1–3) with a 26-membered monocyclic, [4,6,20]-fused tricyclic and 11,23-oxygen bridged [14,16]-bicyclic skeletons, respectively, were isolated from the fermentation broth of the deep-sea sediment-derived Streptomyces sp. OUCMDZ-3159. Their structures were determined based on spectroscopic analysis, X-ray diffraction analysis, and chemical methods. The abiotic formation of compounds 2 and 4 from compound 1 were confirmed by a series of chemical reactions under heat and light conditions. Compounds 1 and 3 showed a selective antifungal activity against Candida albicans ATCC 10231.

Caerulomycin A (CRM A) is the first example of natural caerulomycins with a 2,2′-bipyridyl ring core and 6-aldoxime functional group from Streptomyces caeruleus and recently from marine-derived Actinoalloteichus cyanogriseus WH1-2216-6. Our previous study revealed that CRM A showed anti-tumor activity against human colorectal cancer (CRC) both in vitro and in vivo. Because some intestinal flora can affect the occurrence and development of CRC, the influence of CRM A on the intestinal flora is worthy of study in Sprague–Dawley (SD) rats. The high throughput sequencing of the V3-V4 hypervariable region in bacterial 16S rDNA gene results showed that the CRM A affected the diversity of intestinal flora of the SD rats treated with CRM A for 2, 3 and 4 weeks. Further analysis indicated that the abundance of genera Prevotella_1, Prevotellaceae_UCG-001, and Lactobacillus were increased while the that of genera Alloprevotella and Ruminiclostridium_1 were decreased. For the CRC related intestinal flora, the abundance of genera Bacteroides, Fusobacterium, Enterococcus, Escherichia-Shigella, Klebsiella, Streptococcus, Ruminococcus_2, and Peptococcus of SD rats treated with CRM A were decreased, while that of abundance of genera Bifidobacterium, Lactobacillus, Faecalibacterium, Blautia, Oscillibacter, and Clostridium were increased. The results indicated that CRM A could influence the intestinal flora by inhibiting some species of harmful flora and improving the beneficial bacteria in intestinal flora in the SD rats. The results may provide a new idea for revealing the mechanism of the anti-CRC activity of CRM A.

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 GSK3β, and induced down-regulation of cyclin D1. The inverse docking (INVDOCK) analysis indicated that ophiobolin O could bind to GSK3β, and GSK3β knockdown abolished cyclin D1 degradation and G1 phase arrest. Pre-treatment with phosphatase inhibitor sodium or thovanadate halted dephosphorylation of AKT and GSK3β, 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/GSK3β/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.

Two new indole-diterpenoids (1 and 2) and a new isocoumarin (3), along with the known β-aflatrem (4), paspalinine (5), leporin B (6), α-cyclopiazonic acid (7), iso-α-cyclopiazonic acid (8), ditryptophenaline (9), aflatoxin B1 (10), 7-O-acetylkojic acid (11) and kojic acid (12), were isolated from the fermentation broth of the marine-derived fungus, Aspergillus flavus OUCMDZ-2205. The structures of Compounds 1–12 were elucidated by spectroscopic analyses, quantum ECD calculations and the chemical method. New Compound 1 exhibited antibacterial activity against Staphylococcus aureus with a MIC value of 20.5 μM. Both new Compounds 1 and 2 could arrest the A549 cell cycle in the S phase at a concentration of 10 μM. Compound 1 showed PKC-beta inhibition with an IC50 value of 15.6 μM. In addition, the absolute configurations of the known compounds, 4–6 and leporin A (6a), were also determined for the first time.

Penicillium sp. WC-29-5 was co-cultured with Streptomyces fradiae 007 to produce five natural products (1–3, 4a and 4b) that were isolated and characterized by spectroscopic analysis. Interestingly, these compounds were found to be different from those produced in discrete fungal and bacterial controls. Among these compounds, the absolute configurations of compounds 4a and 4b were determined for the first time by X-ray single crystal diffraction experiments and electronic circular dichroism (ECD) calculations. An evaluation of the cytotoxic activities of these compounds revealed that 4b was moderately cytotoxic towards HL-60 and H1975 tumor cells with IC50 values of 3.73 and 5.73 µM, respectively, whereas compound 4a was only moderately cytotoxic towards H1975 cells with an IC50 value of 3.97 µM.

A new alkaloid, 2-(furan-2-yl)-6-(2S,3S,4-trihydroxybutyl)pyrazine (1), along with 12 known compounds, 2-(furan-2-yl)-5-(2S,3S,4-trihydroxybutyl)pyrazine (2), (S)-4-isobutyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (3), (S)-4-isopropyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (4), (4S)-4-(2-methylbutyl)-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (5), (S)-4-benzyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (6), flazin (7), perlolyrine (8), 1-hydroxy-β-carboline (9), lumichrome (10), 1H-indole-3-carboxaldehyde (11), 2-hydroxy-1-(1H-indol-3-yl)ethanone (12), and 5-(methoxymethyl)-1H-pyrrole-2-carbaldehyde (13), were isolated and identified from the fermentation broth of an endophytic actinomycetes, Jishengella endophytica 161111. The new structure 1 and the absolute configurations of 2–6 were determined by spectroscopic methods, J-based configuration analysis (JBCA) method, lactone sector rule, and electronic circular dichroism (ECD) calculations. Compounds 8–11 were active against the influenza A virus subtype H1N1 with IC50 and selectivity index (SI) values of 38.3(±1.2)/25.0(±3.6)/ 39.7(±5.6)/45.9(±2.1) μg/mL and 3.0/16.1/3.1/11.4, respectively. The IC50 and SI values of positive control, ribavirin, were 23.1(±1.7) μg/mL and 32.2, respectively. The results showed that compound 9 could be a promising new hit for anti-H1N1 drugs. The absolute configurations of 2–5, 13C nuclear magnetic resonance (NMR) data and the specific rotations of 3–6 were also reported here for the first time.

Ochrazepines A−D (1−4), four new conjugates dimerized from 2-hydroxycircumdatin C (5) and aspyrone (6) by a nucleophilic addition to epoxide, were isolated from the fermentation broth of the coral-associated Aspergillus ochraceus strain LCJ11-102. Their structures including absolute configurations were determined based on spectroscopic analysis and chemical methods. Compounds 1−4 were also obtained by the semisynthesis from a nucleophilic addition of 2-hydroxycircumdatin C (5) to aspyrone (6). New compound 1 exhibited cytotoxic activity against 10 human cancer cell lines while new compounds 2 and 4 selectively inhibited U251 (human glioblastoma cell line) and compound 3 was active against A673 (human rhabdomyoma cell line), U87 (human glioblastoma cell line), and Hep3B (human liver cancer cell line) with IC50 (half maximal inhibitory concentration) values of 2.5−11.3 μM among 26 tested human cancer cell lines.

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.

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.

A chemical-epigenetic method was used to enhance the chemodiversity of a marine algicolous fungus. Apart from thirteen known compounds, (+)-brevianamide R ((+)-3), (‒)-brevianamide R ((‒)-3), (+)-brevianamide Q ((+)-4), (‒)-brevianamide Q ((‒)-4), brevianamide V ((+)-5), brevianamide W ((‒)-5), brevianamide K (6), diorcinol B (7), diorcinol C (8), diorcinol E (9), diorcinol J (10), diorcinol (11), 4-methoxycarbonyldiorcinol (12), two new compounds, (+)- and (‒)-brevianamide X ((+)- and (‒)- 2)), as well as a new naturally occurring one, 3-[6-(2-methylpropyl)-2-oxo-1H-pyrazin-3-yl]propanamide (1), were isolated from chemical-epigenetic cultures of Aspergillus versicolor OUCMDZ-2738 with 10 µM vorinostat (SAHA). Compared to cultures in the same medium without SAHA, compounds 1–4, 8, 9, 11, and 12 were solely observed under SAHA condition. The structures of these compounds were elucidated based on spectroscopic analysis, specific rotation analysis, ECD, and X-ray crystallographic analysis. (±)-3, (±)-4, and (±)-5 were further resolved into the corresponding optically pure enantiomers and their absolute configurations were determined for the first time. Compounds 11 and 12 showed selective antibacterial against Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 17.4 and 13.9 μM, respectively. Compound 10 exhibited better α-glucosidase inhibitory activity than the assay control acarbose with IC50 values of 117.3 and 255.3 μM, respectively.

Four new meroterpenoids 1–4 and four new isocoumarinoids 5–8, along with five known isocoumarinoids (9–13), were isolated from the fungus Myrothecium sp. OUCMDZ-2784 associated with the salt-resistant medicinal plant, Apocynum venetum (Apocynaceae). Their structures were elucidated by means of spectroscopic analysis, X-ray crystallography, ECD spectra and quantum chemical calculations. Compounds 1–5, 7, 9 and 10 showed weak α-glucosidase inhibition with the IC50 values of 0.50, 0.66, 0.058, 0.20, 0.32, 0.036, 0.026 and 0.37 mM, respectively.

Five new diketopiperazine derivatives, (3Z,6E)-1-N-methyl-3-benzy lidene-6-(2S-methyl-3-hydroxypropylidene)piperazine-2,5-dione (1), (3Z,6E)-1-N-methyl-3-benzylidene-6-(2R-methyl-3-hydroxypropylidene)piperazine-2,5-dione (2), (3Z,6Z)-3- (4-hydroxybenzylidene)-6-isobutylidenepiperazine-2,5-dione (3), (3Z,6Z)-3-((1H-imidazol-5-yl)-methylene)-6-isobutylidenepiperazine-2,5-dione (4), and (3Z,6S)-3-benzylidene-6-(2S-but-2-yl)piperazine-2,5-dione (5), were isolated from the marine-derived actinomycete Streptomyces sp. FXJ7.328. The structures of 1–5 were determined by spectroscopic analysis, CD exciton chirality, the modified Mosher’s, Marfey’s and the C3 Marfey’s methods. Compound 3 showed modest antivirus activity against influenza A (H1N1) virus with an IC50 value of 41.5 ± 4.5 μM. In addition, compound 6 and 7 displayed potent anti-H1N1 activity with IC50 value of 28.9 ± 2.2 and 6.8 ± 1.5 μM, respectively. Due to the lack of corresponding data in the literature, the 13C NMR data of (3Z,6S)-3-benzylidene-6-isobutylpiperazine-2,5-dione (6) were also reported here for the first time.

The indolocarbazole (ICZ) alkaloids have attracted much attention due to their unique structures and potential therapeutic applications. A series of ICZs were recently isolated and identified from a marine-derived actinomycete strain, Streptomyces sanyensis FMA. To elucidate the biosynthetic machinery associated with ICZs production in S. sanyensis FMA, PCR using degenerate primers was carried out to clone the FAD-dependent monooxygenase gene fragment for ICZ ring formation, which was used as a probe to isolate the 34.6-kb DNA region containing the spc gene cluster. Sequence analysis revealed genes for ICZ ring formation (spcO, D, P, C), sugar unit formation (spcA, B, E, K, J, I), glycosylation (spcN, G), methylation (spcMA, MB), as well as regulation (spcR). Their involvement in ICZ biosynthesis was confirmed by gene inactivation and heterologous expression in Streptomyces coelicolor M1152. This work represents the first cloning and characterization of an ICZ gene cluster isolated from a marine-derived actinomycete strain and would be helpful for thoroughly understanding the biosynthetic mechanism of ICZ glycosides.

To investigate the structurally novel and bioactive natural compounds from marine-derived microorganisms under high salinity, the fungus Aspergillus terreus PT06-2 was isolated from the sediment of the Putian Sea Saltern, Fujian, China. Three new compounds, terremides A (1) and B (2) and terrelactone A (3), along with twelve known compounds (4–15) were isolated and identified from the fermentation broth of A. terreus PT06-2 at 10% salinity. Among these metabolites, compounds 4 and 15 only produced in the 10% salinity culture, were identified as methyl 3,4,5-trimethoxy-2-(2-(nicotinamido) benzamido) benzoate, and (+)-terrein, respectively. The new compounds 1 and 2 exhibited antibacterial activity against Pseudomonas aeruginosa and Enterobacter aerogenes with MIC values of 63.9 and 33.5 μM, respectively. Compounds 5 showed moderate anti-H1N1 activity and lower cytotoxicity with IC50 and CC50 values of and 143.1 and 976.4 μM, respectively.

To obtain structurally novel and bioactive natural compounds from marine-derived microorganisms, the effect of high salt stress on secondary metabolite production in the marine-derived fungal strain, Spicaria elegans KLA-03, was investigated. The organism, which was isolated from marine sediment, produced different secondary metabolites when cultured in 3% and 10% saline conditions. Four characteristic metabolites, only produced in the 10% salinity culture, were isolated, and their structures were identified as (2E,2'Z)-3,3'-(6,6'-dihydroxybiphenyl-3,3'-diyl)diacrylic acid (1), aspulvinone E (2), aspochalasin E (3) and trichodermamide B (6), according to their 1D and 2D NMR spectra. Compound 1 is a new compound. High salt stress may therefore be a promising means to induce the production of new and chlorinated compounds in halotolerant fungi. Compound 1 showed moderate antibacterial activity against Pseudomonas aeruginosa and Escherichia coli with minimum inhibitory concentration (MIC) values of 0.038 and 0.767 mM, respectively.

Two new ansamycins, trienomycins H (1) and I (2), together with the known trienomycinol (3), were isolated from the fermentation broth of the deep-sea-derived bacterium Ochrobactrum sp. OUCMDZ-2164. Their structures, including their absolute configurations, were elucidated based on spectroscopic analyses, ECD spectra, and Marfey’s method. Compound 1 exhibited cytotoxic effects on A549 and K562 cell lines with IC50 values of 15 and 23 μM, respectively.

One new indolocarbazole, 3-hydroxy-K252d (3), together with the recently reported 3-hydroxyholyrine A (1) and 3′-N-acetyl-3-hydroxyholyrine A (2), were obtained by feeding a culture of the marine-derived Streptomyces strain OUCMDZ-3118 with 5-hydroxy-l-tryptophan. Their structures were elucidated on the basis of spectroscopic analysis. Compound 1 potently induced apoptosis of gastric cancer cells by inhibiting topoisomerase IIα enzyme activity and reducing the expression of antiapoptosis protein level. Compound 3 displayed moderate cytotoxicity against the A549 and MCF-7 cell lines with IC50 values of 1.2 ± 0.05 μM, 1.6 ± 0.09 μM, respectively.

Five new diketopiperazine derivatives, (3Z,6E)-1-N-methyl-3-benzy lidene-6-(2S-methyl-3-hydroxypropylidene)piperazine-2,5-dione (1), (3Z,6E)-1-N-methyl- 3-benzylidene-6-(2R-methyl-3-hydroxypropylidene)piperazine-2,5-dione (2), (3Z,6Z)-3- (4-hydroxybenzylidene)-6-isobutylidenepiperazine-2,5-dione (3), (3Z,6Z)-3-((1H-imidazol- 5-yl)-methylene)-6-isobutylidenepiperazine-2,5-dione (4), and (3Z,6S)-3-benzylidene-6- (2S-but-2-yl)piperazine-2,5-dione (5), were isolated from the marine-derived actinomycete Streptomyces sp. FXJ7.328. The structures of 1-5 were determined by spectroscopic analysis, CD exciton chirality, the modified Mosher's, Marfey's and the C3 Marfey's methods. Compound 3 showed modest antivirus activity against influenza A (H1N1) virus with an IC50 value of 41.5 ± 4.5 µM. In addition, compound 6 and 7 displayed potent anti-H1N1 activity with IC50 value of 28.9 ± 2.2 and 6.8 ± 1.5 µM, respectively. Due to the lack of corresponding data in the literature, the 13C NMR data of (3Z,6S)-3-benzylidene-6- isobutylpiperazine-2,5-dione (6) were also reported here for the first time. [ABSTRACT FROM AUTHOR]

The indolocarbazole (ICZ) alkaloids have attracted much attention due to their unique structures and potential therapeutic applications. A series of ICZs were recently isolated and identified from a marine-derived actinomycete strain, Streptomyces sanyensis FMA. To elucidate the biosynthetic machinery associated with ICZs production in S. sanyensis FMA, PCR using degenerate primers was carried out to clone the FAD-dependent monooxygenase gene fragment for ICZ ring formation, which was used as a probe to isolate the 34.6-kb DNA region containing the spc gene cluster. Sequence analysis revealed genes for ICZ ring formation (spcO, D, P, C), sugar unit formation (spcA, B, E, K, J, I), glycosylation (spcN, G), methylation (spcMA, MB), as well as regulation (spcR). Their involvement in ICZ biosynthesis was confirmed by gene inactivation and heterologous expression in Streptomyces coelicolor M1152. This work represents the first cloning and characterization of an ICZ gene cluster isolated from a marine-derived actinomycete strain and would be helpful for thoroughly understanding the biosynthetic mechanism of ICZ glycosides. [ABSTRACT FROM AUTHOR]

To investigate the structurally novel and bioactive natural compounds from marine-derived microorganisms under high salinity, the fungus Aspergillus terreus PT06-2 was isolated from the sediment of the Putian Sea Saltern, Fujian, China. Three new compounds, terremides A (1) and B (2) and terrelactone A (3), along with twelve known compounds (4-15) were isolated and identified from the fermentation broth of A. terreus PT06-2 at 10% salinity. Among these metabolites, compounds 4 and 15 only produced in the 10% salinity culture, were identified as methyl 3,4,5-trimethoxy-2-(2-(nicotinamido) benzamido) benzoate, and (+)-terrein, respectively. The new compounds 1 and 2 exhibited antibacterial activity against Pseudomonas aeruginosa and Enterobacter aerogenes with MIC values of 63.9 and 33.5 μM, respectively. Compounds 5 showed moderate anti-H1N1 activity and lower cytotoxicity with IC50 and CC50 values of and 143.1 and 976.4 μM, respectively. [ABSTRACT FROM AUTHOR]

To obtain structurally novel and bioactive natural compounds from marine-derived microorganisms, the effect of high salt stress on secondary metabolite production in the marine-derived fungal strain, Spicaria elegans KLA-03, was investigated. The organism, which was isolated from marine sediment, produced different secondary metabolites when cultured in 3% and 10% saline conditions. Four characteristic metabolites, only produced in the 10% salinity culture, were isolated, and their structures were identified as (2E,2'Z)-3,3′-(6,6′-dihydroxybiphenyl-3,3′-diyl)diacrylic acid (1), aspulvinone E (2), aspochalasin E (3) and trichodermamide B (6), according to their 1D and 2D NMR spectra. Compound 1 is a new compound. High salt stress may therefore be a promising means to induce the production of new and chlorinated compounds in halotolerant fungi. Compound 1 showed moderate antibacterial activity against Pseudomonas aeruginosa and Escherichia coli with minimum inhibitory concentration (MIC) values of 0.038 and 0.767 mM, respectively. [ABSTRACT FROM AUTHOR]