Four New Chloro-Eremophilane Sesquiterpenes from an Antarctic Deep-Sea Derived Fungus,Penicillium sp. PR19N-1

A new chloro-trinoreremophilane sesquiterpene 1, three new chlorinated eremophilane sesquiterpenes 2–4, together with a known compound, eremofortine C (5), were isolated from an Antarctic deep-sea derived fungus, Penicillium sp. PR19N-1. Structures were established using IR, HRMS, 1D and 2D NMR techniques. In addition, the plausible metabolic network of these isolated products is proposed. Compound 1 showed moderate cytotoxic activity against HL-60 and A549 cancer cell lines.     

MDN-0170, a New Napyradiomycin from Streptomyces sp. Strain CA-271078

A new napyradiomycin, MDN-0170 (1), was isolated from the culture broth of the marine-derived actinomycete strain CA-271078, together with three known related compounds identified as 4-dehydro-4a-dechloronapyradiomycin A1 (2), napyradiomycin A1 (3) and 3-chloro-6,8-dihydroxy-8-α-lapachone (4). The structure of the new compound was determined using a combination of spectroscopic techniques, including 1D and 2D NMR and electrospray-time of flight mass spectrometry (ESI-TOF MS). The relative configuration of compound 1, which contains two independent stereoclusters, has been established by molecular modelling in combination with nOe and coupling constant analyses. Biosynthetic arguments also allowed us to propose its absolute stereochemistry. The antimicrobial properties of the compounds isolated were evaluated against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Aspergillus fumigatus, and Candida albicans. The potent bioactivity previously reported for compounds 2 and 3 against methicillin-sensitive S. aureus has been extended to methicillin-resistant strains in this report.     

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.     

Luteophanol D,New Polyhydroxyl Metabolite from Marine Dinoflagellate Amphidinium sp

Luteophanol D (1), a new polyhydroxyl linear carbon-chain metabolite, has been isolated from the cultured marine dinoflagellate Amphidinium sp., which was isolated from Okinawan marine acoel flatworm Pseudaphanostoma luteocoloris. The structure of 1 was elucidated by detailed analyses of 2D NMR spectra. Luteophanol D (1) possesses two tetrahydropyran rings and twenty-three hydroxyl groups on C₆₃-linear aliphatic chain with one exo-methylene and two methyl branches.     

Anthraquinones,Diphenyl Ethers,and Their Derivatives from the Culture of the Marine Sponge-Associated Fungus Neosartorya spinosa KUFA 1047

Previously unreported anthraquinone, acetylpenipurdin A (4), biphenyl ether, neospinosic acid (6), dibenzodioxepinone, and spinolactone (7) were isolated, together with (R)-6-hydroxymellein (1), penipurdin A (2), acetylquestinol (3), tenellic acid C (5), and vermixocin A (8) from the culture of a marine sponge-associated fungus Neosartorya spinosa KUFA1047. The structures of the previously unreported compounds were established based on an extensive analysis of 1D and 2D NMR spectra as well as HRMS data. The absolute configurations of the stereogenic centers of 5 and 7 were established unambiguously by comparing their calculated and experimental electronic circular dichroism (ECD) spectra. Compounds 2 and 5–8 were tested for their in vitro acetylcholinesterase and tyrosinase inhibitory activities as well as their antibacterial activity against Gram-positive and Gram-negative reference, and multidrug-resistant strains isolated from the environment. The tested compounds were also evaluated for their capacity to inhibit biofilm formation in the reference strains.     

Structure and Absolute Configuration of Phenanthro-perylene Quinone Pigments from the Deep-Sea Crinoid Hypalocrinus naresianus

Two new water-soluble phenanthroperylene quinones, gymnochrome H (2) and monosulfated gymnochrome A (3), as well as the known compounds gymnochrome A (4) and monosulfated gymnochrome D (5) were isolated from the deep-sea crinoid Hypalocrinus naresianus, which had been collected in the deep sea of Japan. The structures of the compounds were elucidated by spectroscopic analysis including HRMS, 1D ¹H and ¹³C NMR, and 2D NMR. The absolute configuration was determined by ECD spectroscopy, analysis of J-couplings and ROE contacts, and DFT calculations. The configuration of the axial chirality of all isolated phenanthroperylene quinones (2–5) was determined to be (P). For gymnochrome H (2) and monosulfated gymnochrome A (3), a (2′S,2″R) configuration was determined, whereas for monosulfated gymnochrome D (5) a (2′R,2″R), configuration was determined. Acetylated quinones are unusual among natural products from an echinoderm and gymnochrome H (2) together with the recently reported gymnochrome G (1) represent the first isolated acetylated phenanthroperylene quinones.     

Trikoramides B–D,Bioactive Cyanobactins from the Marine Cyanobacterium Symploca hydnoides

Three new cyanobactins, trikoramides B (1)–D (3), have been isolated from the marine cyanobacterium, Symploca hydnoides, following a preliminary bioassay-guided isolation of the two most active polar fractions based on the brine shrimp toxicity assay. These new cyanobactins are new analogues of the previously reported cytotoxic trikoramide A (4) with differences mainly in the C-prenylated cyclotryptophan unit. Their planar structures were elucidated from their 1D and 2D NMR spectral data in combination with the HRMS/MS data. Marfey’s method, 2D NOESY NMR spectroscopic and ECD spectra analyses were used to determine the absolute stereochemistry of trikoramides B (1)–D (3). Trikoramides B (1) and D (3) exhibited cytotoxicity against MOLT-4 acute lymphoblastic leukemia cell line with IC₅₀ values of 5.2 µM and 4.7 µM, respectively. Compounds 1 and 3 were also evaluated for their quorum-sensing inhibitory assay based on the Pseudomonas aeruginosa PAO1 lasB-gfp and rhlA-gfp bioreporter strains. Although trikoramide B (1) exhibited weak quorum-sensing inhibitory activity, the Br-containing trikoramide D (3) exhibited moderate to significant dose-dependent quorum-sensing inhibitory activities against PAO1 lasB-gpf and rhlA-gfp bioreporter strains with IC₅₀ values of 19.6 µM and 7.3 µM, respectively.     

Cembrane Derivatives from the Soft Corals,Sinularia gaweli and Sinularia flexibilis

A new norcembranoidal diterpene, 1-epi-sinulanorcembranolide A (1), and a new cembranoidal diterpene, flexibilin D (2), were isolated from the soft corals, Sinularia gaweli and Sinularia flexibilis, respectively. The structures of new metabolites 1 and 2 were elucidated by spectroscopic methods, and compound 2 was found to significantly inhibit the accumulation of the pro-inflammatory iNOS and COX-2 proteins of the lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. In addition, S. flexibilis yielded a known cembrane, 5-dehydrosinulariolide (3); the structure, including its absolute stereochemistry, was further confirmed by single-crystal X-ray diffraction analysis.     

A New Dibenz[b,e]oxepine Derivative, 1-Hydroxy-10-methoxy-dibenz[b,e]oxepin-6,11-dione,from a Marine-Derived Fungus,Beauveria bassiana TPU942

1-Hydroxy-10-methoxy-dibenz[b, e]oxepin-6,11-dione (1) was obtained from the culture broth of a marine-derived fungus, Beauveria bassiana TPU942, isolated from a marine sponge collected at Iriomote Island in Okinawa, together with two known compounds, chrysazin (2) and globosuxanthone A (3). The structure of 1 was elucidated on the basis of its spectroscopic data (HREIMS, 1D and 2D NMR experiments including ¹H–¹H COSY, HMQC and HMBC spectra). Dibenz[b, e]oxepines are rare in nature, and only six natural products have been reported. Therefore, compound 1 is the seventh natural product in this class. Compounds 2 and 3 showed an antifungal activity against Candida albicans, and 3 inhibited the cell growth against two human cancer cell lines, HCT-15 (colon) and Jurkat (T-cell lymphoma). Compound 1 did not show an apparent activity in the same bioassays.     

Alterporriol-Type Dimers from the Mangrove Endophytic Fungus,Alternaria sp. (SK11), and Their MptpB Inhibitions

A new alterporriol-type anthranoid dimer, alterporriol S (1), along with seven known anthraquinone derivatives, (+)-aS-alterporriol C (2), hydroxybostrycin (3), halorosellinia A (4), tetrahydrobostrycin (5), 9α-hydroxydihydrodesoxybostrycin (6), austrocortinin (7) and 6-methylquinizarin (8), were isolated from the culture broth of the mangrove fungus, Alternaria sp. (SK11), from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra. The absolute configurations of 1 and the axial configuration of 2 were defined by experimental and theoretical ECD spectroscopy. 1 was identified as the first member of alterporriols consisting of a unique C-10−C-2′ linkage. Atropisomer 2 exhibited strong inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with an IC₅₀ value 8.70 μM.     

Neuroprotective Metabolites from Vietnamese Marine Derived Fungi of Aspergillus and Penicillium Genera

Low molecular weight secondary metabolites of marine fungi Aspergillus flocculosus, Aspergillus terreus and Penicillium sp. from Van Phong and Nha Trang Bays (Vietnam) were studied and a number of polyketides, bis-indole quinones and terpenoids were isolated. The structures of the isolated compounds were determined by 1D and 2D NMR and HR-ESI-MS techniques. Stereochemistry of some compounds was established based on ECD data. A chemical structure of asterriquinone F (6) was thoroughly described for the first time. Anthraquinone (13) was firstly obtained from a natural source. Neuroprotective influences of the isolated compounds against 6-OHDA, paraquat and rotenone toxicity were investigated. 4-Hydroxyscytalone (1), 4-hydroxy-6-dehydroxyscytalone (2) and demethylcitreoviranol (3) have shown significant increasing of paraquat- and rotenone-treated Neuro-2a cell viability and anti-ROS activity.     

Four New Antibacterial Xanthones from the Marine-Derived Actinomycetes Streptomyces caelestis

Four new polycyclic antibiotics, citreamicin θ A (1), citreamicin θ B (2), citreaglycon A (3), and dehydrocitreaglycon A (4), were isolated from marine-derived Streptomyces caelestis. The structures of these compounds were elucidated by 1D and 2D NMR spectra. All four compounds displayed antibacterial activity against Staphylococcus haemolyticus, Staphylococcus aureus, and Bacillus subtillis. Citreamicin θ A (1), citreamicin θ B (2) and citreaglycon A (3) also exhibited low MIC values of 0.25, 0.25, and 8.0 μg/mL, respectively, against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300.     

Cytoskyrins and cytosporones produced by Cytospora sp. CR200: taxonomy, fermentation and biological activities

In screening endophytic fungi from Costa Rica for bioactivity, fungal culture CR200, isolated from a buttonwood tree, was found to contain compounds that initiate DNA damage in a test strain of E. coli (Biochemical Induction Assay, BIA) and inhibit growth of Gram-positive bacteria, including antibiotic-resistant strains. Two new bisanthraquinones (cytoskyrins A and B) and five new related octaketides (cytosporones A-E) were isolated from fermentation broths of this fungus. Cytoskyrin A exhibited potent in-vitro antibacterial (MICs against Gram-positive bacteria, 0.03 – 0.25 μg/mL) and DNA-damaging activities (10 ng/spot), whereas cytoskyrin B was inactive in these assays. Among the cytosporones, only D and E exhibited Gram-positive activity, but they were inactive in the BIA. Mechanistically, cytoskyrin A specifically inhibited DNA synthesis in E. coli imp at its MIC; however, it also moderately inhibited protein synthesis at 2x its MIC. Cytoskyrin A exhibited poor cytotoxicity against tumor cell lines (IC₅₀ > 5 μg/mL) compared to known antitumor agents. The nuclear ribosomal internal transcribed spacer region of CR200 was found to share highest similarity (94–96%) with Cytospora spp. Micro- and macroscopic morphological observations of the conidia and conidiomata, respectively, also suggested this fungus to be a Cytospora sp.     

Kurilosides A1, A2, C1, D,E and F—Triterpene Glycosides from the Far Eastern Sea Cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin): Structures with Unusual Non-Holostane Aglycones and Cytotoxicities

Six new monosulfated triterpene tetra-, penta- and hexaosides, namely, the kurilosides A₁ (1), A₂ (2), C₁ (3), D (4), E (5) and F (6), as well as the known earlier kuriloside A (7), having unusual non-holostane aglycones without lactone, have been isolated from the sea cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin) (Cucumariidae, Dendrochirotida), collected in the Sea of Okhotsk near Onekotan Island from a depth of 100 m. Structures of the glycosides were established by 2D NMR spectroscopy and HR-ESI mass spectrometry. Kurilosides of the groups A and E contain carbohydrate moieties with a rare architecture (a pentasaccharide branched by C(4) Xyl1), differing from each other in the second monosaccharide residue (quinovose or glucose, correspondingly); kurilosides of the group C are characterized by a unique tetrasaccharide branched by a C(4) Xyl1 sugar chain; and kurilosides of the groups D and F are hexaosides differing from each other in the presence of an O-methyl group in the fourth (terminal) sugar unit. All these glycosides contain a sulfate group at C-6 of the glucose residue attached to C-4 Xyl1 and the non-holostane aglycones have a 9(11) double bond and lack γ-lactone. The cytotoxic activities of compounds 1–7 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells and erythrocytes were studied. Kuriloside A₁ (1) was the most active compound in the series, demonstrating strong cytotoxicity against the erythrocytes and JB-6 cells and a moderate effect against Neuro 2a cells.     

1,5-Diazacyclohenicosane,a New Cytotoxic Metabolite from the Marine Sponge Mycale sp

A new cyclic diamine, 1,5-diazacyclohenicosane (1), was isolated from samples of the marine sponge Mycale sp. collected at Lamu Island (Kenya). Its structure was determined by a combination of spectroscopic techniques, including (+)-HRESIMS and 1D and 2D NMR spectroscopy. The compound displayed cytotoxicity at the μM level against three human tumor cell lines.     

Asperlones A and B,Dinaphthalenone Derivatives from a Mangrove Endophytic Fungus Aspergillus sp. 16-5C

Racemic dinaphthalenone derivatives, (±)-asperlone A (1) and (±)-asperlone B (2), and two new azaphilones, 6″-hydroxy-(R)-mitorubrinic acid (3) and purpurquinone D (4), along with four known compounds, (−)-mitorubrinic acid (5), (−)-mitorubrin (6), purpurquinone A (7) and orsellinic acid (8), were isolated from the cultures of Aspergillus sp. 16-5C. The structures were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra and the structures of 1 further confirmed by single-crystal X-ray diffraction analysis, while the absolute configuration of 3 and 4 were determined by comparing their optical rotation and CD with those of the literature, respectively. Compounds 1, 2 and 6 exhibited potent inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with IC₅₀ values of 4.24 ± 0.41, 4.32 ± 0.60 and 3.99 ± 0.34 μM, respectively.     

Tanjungides A and B: New Antitumoral Bromoindole Derived Compounds from Diazona cf formosa. Isolation and Total Synthesis

Tanjungides A (1) (Z isomer) and B (2) (E isomer), two novel dibrominated indole enamides, have been isolated from the tunicate Diazona cf formosa. Their structures were determined by spectroscopic methods including HRMS, and extensive 1D and 2D NMR. The stereochemistry of the cyclised cystine present in both compounds was determined by Marfey’s analysis after chemical degradation and hydrolysis. We also report the first total synthesis of these compounds using methyl 1H-indole-3-carboxylate as starting material and a linear sequence of 11 chemical steps. Tanjungides A and B exhibit significant cytotoxicity against human tumor cell lines.     

Bioactive indole derivatives from the South Pacific marine sponges Rhopaloeides odorabile and Hyrtios sp

Indole derivatives including bromoindoles have been isolated from the South Pacific marine sponges Rhopaloeides odorabile and Hyrtios sp. Their structures were established through analysis of mass spectra and 1D and 2D NMR spectroscopic data. Their potential inhibitory phospholipase A₂ (PLA₂), antioxidant and cytotoxic activities were evaluated. The new derivative 5,6-dibromo-l-hypaphorine (9) isolated from Hyrtios sp. revealed a weak bee venom PLA₂ inhibition (IC₅₀ 0.2 mM) and a significant antioxidant activity with an Oxygen Radical Absorbance Capacity (ORAC) value of 0.22. The sesquiterpene aureol (4), also isolated from Hyrtios sp., showed the most potent antioxidant activity with an ORAC value of 0.29.     

Structural and Immunochemical Studies of the Lipopolysaccharide from the Fish Pathogen,Aeromonas bestiarum Strain K296, Serotype O18

Chemical analyses and mass spectrometry were used to study the structure of the lipopolysaccharide (LPS) isolated from Aeromonas bestiarum strain K296, serotype O18. ESI-MS revealed that the most abundant A. bestiarum LPS glycoforms have a hexa-acylated or tetra-acylated lipid A with conserved architecture of the backbone, consisting of a 1,4′-bisphosphorylated β-(1→6)-linked d-GlcN disaccharide with an AraN residue as a non-stoichiometric substituent and a core oligosaccharide composed of Kdo₁Hep₆Hex₁HexN₁P₁. 1D and 2D NMR spectroscopy revealed that the O-specific polysaccharide (OPS) of A. bestiarum K296 consists of a branched tetrasaccharide repeating unit containing two 6-deoxy-l-talose (6dTalp), one Manp and one GalpNAc residues; thus, it is similar to that of the OPS of A. hydrophila AH-3 (serotype O34) in both the sugar composition and the glycosylation pattern. Moreover, 3-substituted 6dTalp was 2-O-acetylated and additional O-acetyl groups were identified at O-2 and O-4 (or O-3) positions of the terminal 6dTalp. Western blots with polyclonal rabbit sera showed that serotypes O18 and O34 share some epitopes in the LPS. The very weak reaction of the anti-O34 serum with the O-deacylated LPS of A. bestiarum K296 might have been due to the different O-acetylation pattern of the terminal 6dTalp. The latter suggestion was further confirmed by NMR.     

A New Spatane Diterpenoid from the Cultured Soft Coral Sinularia leptoclados

A new spatane diterpenoid, leptoclalin A (1), along with two previously reported known norcembranoid diterpenes (2 and 3), were isolated from a cultured soft coral Sinularia leptoclados. The structures were determined by extensive spectroscopic analyses and by comparison with the spectral data of related known compounds. Metabolite 1 is rarely found in spatane skeletons reported from soft corals. In addition, compound 1 exhibited weak cytotoxicity towards human tumor cell lines T-47 D and K-562.