Izumiphenazines A-C: isolation and structure elucidation of phenazine derivatives from Streptomyces sp. IFM 11204

Three new phenazine derivatives, named izumiphenazines A-C (1-3), and the known phenazine-1,6-dicarboxylic acid (4) were isolated from Streptomyces sp. IFM 11204. The structures of the isolated compounds were elucidated by means of spectroscopic methods including UV, IR, HRESIMS, and 1D and 2D NMR. Compounds 1-3 were evaluated for their activity in overcoming TRAIL (TNF-related apoptosis-inducing ligand) resistance in human gastric adenocarcinoma cells. Compounds 2 (30 μM) and 3 (20 μM) in combination with TRAIL showed synergistic activity in sensitizing TRAIL-resistant AGS cells.     

Cycloartane triterpenes isolated from Combretum quadrangulare in a screening program for death-receptor expression enhancing activity

In our screening program for natural products that increase DR5 (death-receptor 5) expression, nine new cycloartane triterpenes, combretanones A-G (1-7), combretic acid A (8), and combretic acid B (9), were isolated from a MeOH extract of Combretum quadrangulare leaves. The known oleanane triterpenes (10, 11) and six known flavonols (12-17) were also isolated. The structures of 1-9 were elucidated by spectroscopic studies. Compounds 7, 9, 12, 16, and 17 enhanced DR5 expression, and 16 showed TRAIL-resistance abrogating activity.     

Streptothricin derivatives from Streptomyces sp. I08A 1776

Five new streptothricin derivatives with a carbamoyl group substituted at C-12 (1-5) and three known analogues have been isolated from the culture broth of Streptomyces sp. I08A 1776 by ion exchange and hydrophilic interaction chromatographic techniques. Their structures were determined by spectroscopic and chemical methods. Compound 3 was a streptothricin derivative possessing a cis-streptolidine moiety. Its absolute configuration was defined by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. Compound 5 and streptothricin E (6) displayed antibacterial and antifungal activity with MIC values in the range 1-64 μg/mL.     

Brandisianins A-F, isoflavonoids isolated from Millettia brandisiana in a screening program for death-receptor expression enhancement activity

In a screening study for natural products with tumor-selective apoptosis-inducing properties, six new isoflavonoids (1- 6), named brandisianins A-F, respectively, have been isolated from a MeOH extract of the dried leaves of Millettia brandisiana, together with five known compounds. The structures of the new compounds were elucidated by spectroscopic data interpretation. Among these compounds, brandisianin D (4) exhibited death-receptor 5 expression enhancement activity in a luciferase assay based in DLD-1/ SacI cells. The results suggest that brandisianin D (4) might overcome TRAIL-resistance by an increase in DR5 expression.     

Bohemamines from a marine-derived Streptomyces sp

Investigation of the culture extracts of a marine-derived Streptomyces sp. led to the isolation of three new bohemamine-type pyrrolizidine alkaloids, bohemamine B (1), bohemamine C (2), and 5-chlorobohemamine C (3). The structures were elucidated using NMR methods, and the relative stereochemistry was determined using double-pulsed-field-gradient spin echo (DPFGSE) NOE studies.     

Naphthoquinone-like polyketide isolated from Streptomyces sp. RI-77 and its predicted biosynthetic pathway

A novel naphthoquinone-like polyketide, JBIR-85 (1), with a unique skeleton and antioxidative activity was isolated from a culture of Streptomyces sp. RI-77. The planar structure of 1 was established on the basis of extensive NMR and MS analyses. The structure of 1 including the absolute configuration was established via X-ray crystallographic analysis. Since 1 exhibits a unique skeleton, we performed feeding experiments to reconfirm the structure and predict the biosynthetic pathway.     

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, 10alpha,11-dihydroxyamorph-4-ene (4), 10alpha,15-dihydroxyamorph-4-en-3-one (6), and 5alpha,10alpha,11-trihydroxyamorphan-3-one (7). In addition, the known compounds 10alpha-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.     

Glaciapyrroles A, B, and C, pyrrolosesquiterpenes from a Streptomyces sp. isolated from an Alaskan marine sediment

A Streptomyces sp. (NPS008187) isolated from a marine sediment collected in Alaska was found to produce three new pyrrolosesquiterpenes, glyciapyrroles A (1), B (2), and C (3), along with the known diketopiperazines cyclo(leucyl-prolyl) (4), cyclo(isoleucyl-prolyl) (5), and cyclo(phenylalanyl-prolyl) (6). The structures of 1, 2, and 3 were established using spectroscopic methods.     

Phthalide and isocoumarin derivatives produced by an Acremonium sp. isolated from a mangrove Rhizophora apiculata

Nine new fungal metabolites, one phthalide derivative, acremonide (1), and eight isocoumarin derivatives, acremonones A-H (2-9), were isolated from the mangrove-derived fungus Acremonium sp. PSU-MA70 together with 10 known compounds. Their structures were determined by NMR analysis. The known 8-deoxytrichothecin and trichodermol exhibited moderate antifungal activity against Candida albicans and Cryptococcus neoformanns, respectively.     

A phenylacetylated peptide, JBIR-96, isolated from Streptomyces sp. RI051-SDHV6

Searching for metabolites from Streptomyces sp. RI051-SDHV6 resulted in the discovery of a novel peptide, JBIR-96 (1). The structure of 1 was established as an N-phenylacetylated pentapeptide involving a cysteic acid and a peptide lactone structure by extensive NMR and MS analyses. In addition, the absolute configuration of 1 was established by Marfey's and modified Mosher's methods.     

Chromophenazines from the terrestrial Streptomyces sp. Ank 315

The new chromophenazines A-F [9-methyl-5-(3'-methylbut-2'-enyl)-5H-benzo[a]phenazin-7-one (1a), 9-methyl-5-(3'-methylbut-2'-enyl)-7-oxo-5,7-dihydrobenzo[a]phenazine-1-carboxylic acid (1b), 5-(3'-methylbut-2'-enyl)-7-oxo-5,7-dihydrophenazine-1-carboxamide (2), 3-benzoyl-5-(3'-methylbut-2'-enyl)-5,10-dihydrophenazine-1-carboxylic acid (5a), 3,7-dibenzoyl-5-(3'-methylbut-2'-enyl)-5,10-dihydrophenazine-1-carboxylic acid (5b), and 3,7-dibenzoyl-5-(3'-methylbut-2'-enyl)-5,10-dihydrophenazine-1-carboxamide (5c)], together with phenazine-1-carboxylic acid, 1-phenazinecarboxamide, 1-phenazinol, tryptophol, and anthranilic acid, were isolated from Streptomyces sp. Ank 315. The structures of the new compounds were established on the basis of spectroscopic data, 1D NOE, 2D NMR, and ESIMS measurements and comparison with literature values.     

Abyssomicin I, a modified polycyclic polyketide from Streptomyces sp. CHI39

Abyssomicin I (1), a new modified polycyclic polyketide, was isolated from the culture extract of a soil-derived Streptomyces sp. The structure of 1 was elucidated by interpretation of NMR and other spectroscopic data. The stereochemistry of the new compound was assigned by NOE analysis, chemical derivatization, and application of the modified Mosher method. While 1 was inactive against bacteria and yeasts, the oxidized derivative 7 showed weak activities against gram-positive bacteria. Compounds 1 and 7 exhibited inhibitory effects on tumor cell invasion with IC(50) values of 11 and 0.21 μM, respectively.     

BI-32169, a bicyclic 19-peptide with strong glucagon receptor antagonist activity from Streptomyces sp

A new bicyclic 19-peptide, BI-32169, has been isolated from the culture broth of Streptomyces sp. (DSM 14996). Its structure has been established by amino acid analysis, mass spectrometry, and 2D NMR analysis. BI-32169 consists exclusively of protein amino acids and is cyclized from the side chain of Asp(9) to the N-terminus of Gly(1). One disulfide bond between Cys(6) and Cys(19) forms a bicyclic structure. BI-32169 and its methyl ester derivative showed potent inhibitory activity against the human glucagon receptor (IC(50) 440 and 320 nM, respectively) in a functional cell-based assay.     

Naphthomycins L-N, ansamycin antibiotics from Streptomyces sp. CS

Previous analyses of the naphthomycin biosynthetic gene cluster and a comparison with known naphthomycin-type products from Streptomyces sp. CS have suggested that new products can be found from this strain. In this study, screening by LC-MS of Streptomyces sp. CS products formed under different culture conditions revealed several unknown peaks in the product spectra of extracts derived from oatmeal medium cultures. Three new naphthomycins, naphthomycins L (1), M (2), and N (3), and the known naphthomycins A (4), E (5), and D (6) were obtained. The structures were elucidated using spectroscopic data from 1D and 2D NMR and HRESIMS experiments.     

Blanchaquinone: a new anthraquinone from an Australian Streptomyces sp

Chemical analysis of an Australian Streptomyces species yielded a range of known anthracyclines and biosynthetically related metabolites, including daunomycin (1), epsilon-rhodomycinone (2), 11-hydroxyauramycinone (3), 11-hydroxysulfurmycinone (4), aklavinone (5), bisanhydro-gamma-rhodomycinone (6), and the anthraquinone 7, as well as the hitherto unreported blanchaquinone (8). The structure assigned to 8 was secured by detailed spectroscopic analysis and correlation to known analogues, such as the anthraquinone 7. This account also represents the first natural occurrence of 3, 4, and 7 and the first spectroscopic characterization of 11-hydroxysulfurmycinone (4).     

Streptobactin, a tricatechol-type siderophore from marine-derived Streptomyces sp. YM5-799

A new catechol-type siderophore, streptobactin (1), was isolated from a culture broth of the marine-derived actinomycete Streptomyces sp. YM5-799. The structure of streptobactin was determined by NMR and MS analyses and ESIMS/MS experiments to be a cyclic trimer of benarthin. A dibenarthin (2), a tribenarthin (3), and benarthin (4) were also obtained. The production of 1 was regulated by an iron concentration in the culture. The iron-chelating activity of the compounds was evaluated by the chrome azurol sulfonate assay.     

Novel cytotoxic thiodiketopiperazine derivatives from a Tilachlidium sp

Three novel thiodiketopiperazine derivatives, T988 A, B, and C (1-3), were isolated from a Tilachlidium sp. Their structures were elucidated by spectroscopic analyses using various 1D and 2D NMR techniques. All the compounds showed potent cytotoxicity against cultured P388 leukemia cells.     

海洋真菌Aspergillus sp.中的苯甲醛衍生物研究

目的 研究海洋真菌Aspergillus sp.的化学成分及其抗氧化活性.方法 采用硅胶柱色谱、高效液相色谱等方法进行分离纯化,以现代波谱技术和理化性质鉴定化合物的结构,并测定了所得化合物清除DPPH自由基的活性.结果 分离得到6个苯甲醛衍生物,分别鉴定为2-(E-3-庚烯基)-5-异戊烯基-3,6二羟基苯甲醛(1)、二氢金(色)灰绿曲霉素(2)、异二氢金(色)灰绿曲霉素(3)、曲霉素(4)、灰绿曲霉黄色素(5)和毛壳菌吡喃宁(6).结论 化合物1为新化合物,命名为异曲霉素,化合物1～6具有很强的清除DPPH自由基的活性.     

Methylsulfomycin I, a new cyclic peptide antibiotic from a Streptomyces sp. HIL Y-9420704

Methylsulfomycin I (1) is a new cyclic peptide antibiotic isolated from the fermentation broth of a Streptomyces sp. HIL Y-9420704. Its structure was elucidated by NMR and GC-MS. The in vitro activity (MIC) against a wide range of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-, and teicoplanin-resistant strains, is described.     

Totopotensamides, polyketide-cyclic peptide hybrids from a mollusk-associated bacterium Streptomyces sp

Two new compounds, the peptide-polyketide glycoside totopotensamide A (1) and its aglycone totopotensamide B (2), were isolated from a Streptomyces sp. cultivated from the gastropod mollusk Lienardia totopotens collected in the Philippines. The compounds contain a previously undescribed polyketide component, a novel 2,3-diaminobutyric acid-containing macrolactam, and a new amino acid, 4-chloro-5,7-dihydroxy-6-methylphenylglycine. The application of Marfey's method to phenylglycine derivatives was explored using quantum mechanical calculations and NMR.