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.

JBIR-56 and JBIR-57, 2(1H)-pyrazinones from a marine sponge-derived Streptomyces sp. SpD081030SC-03.

Strain SpD081030SC-03, representing a novel species of Streptomyces, was isolated from a marine sponge. Two 3,5,6-trisubstituted 2(1H)-pyrazinones, JBIR-56 (1) and JBIR-57 (2), were isolated from a culture of SpD081030SC-03. The planar structures of 1 and 2 were assigned on the basis of extensive NMR and MS analyses. In addition, analyses of the methylated derivative of 1 confirmed a 3,5,6-trisubstituted 2(1H)-pyrazinone moiety. The absolute configurations of the amino acid residues were determined by application of Marfey's method. Because 1 did not appear to comprise the normal connection of amino acid units, we confirmed its structure by the total synthesis of 1. Biosynthetically, 1 consists of a unique skeleton connected to the peptide chain at C-5 of the pyrazinone ring.

Streptomyces associated with a marine sponge Haliclona sp.; biosynthetic genes for secondary metabolites and products.

Terrestrial actinobacteria have served as a primary source of bioactive compounds; however, a rapid decrease in the discovery of new compounds strongly necessitates new investigational approaches. One approach is the screening of actinobacteria from marine habitats, especially the members of the genus Streptomyces. Presence of this genus in a marine sponge, Haliclona sp., was investigated using culture-dependent and -independent techniques. 16S rRNA gene clone library analysis showed the presence of diverse Streptomyces in the sponge sample. In addition to the dominant genus Streptomyces, members of six different genera were isolated using four different media. Five phylogenetically new strains, each representing a novel species in the genus Streptomyces were also isolated. Polyphasic study suggesting the classification of two of these strains as novel species is presented. Searching the strains for the production of novel compounds and the presence of biosynthetic genes for secondary metabolites revealed seven novel compounds and biosynthetic genes with unique sequences. In these compounds, JBIR-43 exhibited cytotoxic activity against cancer cell lines. JBIR-34 and -35 were particularly interesting because of their unique chemical skeleton. To our knowledge, this is the first comprehensive study detailing the isolation of actinobacteria from a marine sponge and novel secondary metabolites from these strains.

JBIR-66, a new metabolite isolated from tunicate-derived Saccharopolyspora sp. SS081219JE-28.

In the course of our chemical screening program for new secondary metabolites, we isolated a new compound JBIR-66 (1) from the culture broth of the tunicate-derived actinomycete, Saccharopolyspora sp. SS081219JE-28. The structure of 1 was determined to be (3Z,6E,8E)-N-(4-acetamido-3-hydroxybutyl)-2-hydroxy-4,8-dimethylundeca-3,6,8-trienamide on the basis of extensive NMR and MS spectroscopic data.

Anti-influenza virus compound from Streptomyces sp. RI18.

Screening for anti-influenza virus activity in compounds isolated from Streptomyces sp. RI18, which was isolated using the membrane filter method, uncovered a novel compound, JBIR-68 (1), which contains a unique skeleton. Its structure was established by extensive NMR and MS analyses. In addition, 1 was synthesized to confirm the configuration of its sugar moiety. Compound 1 inhibited influenza virus growth in plaque assays.

A new angucycline and a new butenolide isolated from lichen-derived Streptomyces spp.

A new 1,1-dichlorocyclopropane-containing angucycline, JBIR-88 (1), and a new butenolide, JBIR-89 (2), respectively, were isolated from the fermentation broths of two lichen-derived actinomycetes identified as a new species of Streptomyces (strains RI104-LiC106 and RI104-LiB101) using phylogenetic methods. The structures of 1 and 2 were elucidated on the basis of 1D and 2D NMR spectroscopy and MS analyses. Compound 1 showed cytotoxic activities against cancer cells and antimicrobial activity against Micrococcus luteus.

Isolation and structure elucidation of tumescenamides A and B, two peptides produced by Streptomyces tumescens YM23-260.

Two peptides, tumescenamides A and B, were isolated from the fermentation broth of a marine bacterium, Streptomyces tumescens YM23-260. The structure of tumescenamide A was determined to be a cyclic depsipeptide consisting of α-amino-2-butenoic acid, tyrosine, valine, leucine and threonine, substituted with a 2,4-dimethylheptanoyl residue at the α-NH(2) position. Tumescenamide B possesses a 2,4,6-trimethylnonanoyl residue in place of the 2,4-dimethylheptanoyl substituent in tumescenamide A. Tumescenamide A induced reporter gene expression under the control of the insulin-degrading enzyme promoter.

Terpenoids produced by actinomycetes: isolation, structural elucidation and biosynthesis of new diterpenes, gifhornenolones A and B from Verrucosispora gifhornensis YM28-088.

New terpenoids named gifhornenolones A (1) and B (2) were isolated from the culture broth of Verrucosispora gifhornensis YM28-088, and their structures were established as hydroxylated isopimaradiene derivatives on the basis of extensive NMR and MS spectral analyses. In addition, a known sesquiterpene compound cyperusol C (3) was isolated. The absolute configuration of 1 was determined by nuclear Overhauser effect spectroscopy (NOESY) and CD spectra as 4R, 5S, 9R, 10S, 13R, and that of 2 was determined by NOESY experiments as 3R, 4R, 5R, 9R, 10S, 13R. Labeling experiments with [1-(13)C]glucose and [U-(13)C(6)]glucose confirmed that the MEP (2-C-methyl-D-erythritol-4-phosphate) pathway was used for the biosynthesis of terpenoids in this organism. 1 showed potent inhibitory activity to the androgen receptor with an IC(50) of 2.8 microg ml(-1).

Tetracenoquinocin and 5-iminoaranciamycin from a sponge-derived Streptomyces sp. Sp080513GE-26.

Two new anthracyclines, tetracenoquinocin (1) and 5-iminoaranciamycin (2), together with the known compounds aranciamycin (3) and antibiotic SM 173B were isolated from the culture of Streptomyces sp. Sp080513GE-26 associated with a marine sponge, Haliclona sp. The structures of 1 and 2 were established on the basis of extensive NMR and MS analyses along with (13)C-labeling experiments. The compounds 1-3 were evaluated for cytotoxicity against two cancer cell lines.

Tetrapeptides possessing a unique skeleton, JBIR-34 and JBIR-35, isolated from a sponge-derived actinomycete, Streptomyces sp. Sp080513GE-23.

Two new modified indole-containing peptides, JBIR-34 (1) and JBIR-35 (2), were isolated from the fermentation broth of a sponge-derived actinomycete identified by phylogenetic methods as a Streptomyces sp. (strain Sp080513GE-23). The planar structures of 1 and 2 were assigned on the basis of 1D and 2D NMR spectroscopy and MS analyses. Further, the absolute configurations of the amino acid residues were determined using Marfey's method.

Distribution of the 3-hydroxyl-3-methylglutaryl coenzyme A reductase gene and isoprenoid production in marine-derived Actinobacteria.

During the course of our screening program to isolate isoprenoids from marine Actinobacteria, 523 actinobacterial strains were isolated from 18 marine sponges, a tunicate, and two marine sediments. These strains belonged to 21 different genera, but most were members of Streptomyces, Nocardia, Rhodococcus, and Micromonospora. Some Actinobacteria have been reported to use the mevalonate pathway for the production of isoprenoids as secondary metabolites. Therefore, we investigated whether these strains possessed the 3-hydroxyl-3-methylglutaryl coenzyme A reductase (hmgr) gene, which indicates the presence of the mevalonate pathway. As a result, six strains belonging to the genera Streptomyces (SpC080624SC-11, SpA080624GE-02, and Sp080513GE-23), Nocardia (Sp080513SC-18), and Micromonospora (Se080624GE-07 and SpC080624GE-05) were found to possess the hmgr gene, and these genes were highly similar to hmgr genes in isoprenoid biosynthetic gene clusters. Among the six strains, the two strains SpC080624SC-11 and SpA080624GE-02 produced the novel isoprenoids, JBIR-46, -47, and -48, which consisted of phenazine chromophores, and Sp080513GE-23 produced a known isoprenoid, fumaquinone. Furthermore, these compounds showed cytotoxic activity against human acute myelogenous leukemia HL-60 cells.

Screening and evaluation of new inhibitors of hepatic glucose production.

In the course of our screening program for inhibitors of hepatic glucose production in rat hepatoma H4IIE-C3 cells, which were used as model liver cells, five naphtoquinone derivatives-javanicin, solaniol, 9-O-methylfusarubin, 5,10-dihydroxy-1,7-dimethoxy-3-methyl-1H-naphtho[2,3-c]pyran-6,9-dione, 9-O-methylbostrycoidin-and vanillin were selected from our natural product library. These naphtoquinone derivatives inhibited hepatic glucose production at IC(50) values of 3.8-29 microM, but showed cytotoxicity against hepatic cells after incubation for 48 h. However, vanillin showed an IC(50) value of 32 microM without exhibiting cytotoxicity at 50 microM. Therefore, we examined 12 vanillin derivatives to investigate their inhibitory activities against glucose production. Among these analogs, 4-hydro-3-methoxyacetophenone and 5-nitrosalicylaldehyde exhibited stronger inhibition than the other compounds at IC(50) values of 25 and 24 microM, respectively, with no cytotoxicity at a concentration of 50 microM. Hence, 4-hydro-3-methoxyacetophenone and 5-nitrosalicylaldehyde may be useful as a lead compound of anti-type 2 diabetic drugs.