TMC-171A,B,C and TMC-154, novel polyketide antibiotics produced by Gliocladium sp. TC 1304 and TC 1282

Four new antibiotics, TMC-171A (2), B (3), C (4) and TMC-154 (5) have been isolated from the fermentation of fungal strains Gliocladium sp. TC 1304 and TC 1282, respectively. Spectroscopic and degradation studies have shown that TMC-171s and TMC-154 were new members of the TMC-151 class of antibiotics, unique polyketides modified with a D-mannose and a D-mannitol or a D-arabitol. These compounds showed moderate cytotoxicity to various tumor cell lines.     

Spylidone, a novel inhibitor of lipid droplet accumulation in mouse macrophages produced by Phoma sp. FKI-1840

During our screening for microbial inhibitors of lipid droplet accumulation in macrophages, a new compound designated spylidone was isolated along with two structurally related known compounds, PF1052 and vermisporin, from the fermentation broth of Phoma sp. FKI-1840 by solvent extraction, silica gel column chromatography, ODS column chromatography and preparative HPLC. From the structure elucidation, spylidone has a spiro ring containing 2,4-pyrrolidinedione. Among the three compounds, only spylidone was found to inhibit lipid droplet accumulation in macrophages at 10 to approximately 50 microM without any cytotoxic effect.     

TMC-66, a new endothelin converting enzyme inhibitor produced by Streptomyces sp. A5008.

A new endothelin converting enzyme (ECE) inhibitor, TMC-66 was isolated from the fermentation broth of Streptomyces sp. A5008. The structure of TMC-66 was elucidated by spectroscopic analyses to be a new member of benzo[a]naphthacenequinone class of antibiotics. TMC-66 had a highly selective inhibitory activity for ECE with an IC50 value of 2.9 microM. Taxonomy of the producing strain is also described.     

TAN-1813, a novel Ras-farnesyltransferase inhibitor produced by Phoma sp. taxonomy, fermentation, isolation and biological activities in vitro and in vivo

A novel Ras-farnesyltransferase inhibitor designated TAN-1813 was isolated from the culture broth of a fungus strain, FL-41510, isolated as a plant endophyte. The producer was taxonomically characterized as Phoma sp. FL-41510. TAN-1813 inhibited rat brain farnesyltransferase and geranylgeranyltransferase I activity with IC50 values of 23 microg/ml and 47/microg/ml, respectively. TAN-1813 showed mixed-type inhibition with respect to farnesylpyrophosphate and noncompetitive inhibition with respect to a K-Ras C-terminal peptide. It also inhibited the in situ farnesylation of cellular Ras proteins in a K-ras transformant (NIH3T3/K-ras) of mouse embryonic fibroblast cell line NIH3T3. TAN- 1813 inhibited the proliferation of various human cancer cells, some of which harbor activated ras alleles, with IC50 values of 15 approximately 110 ng/ml as well as that of NIH3T3 and NIH3T3/K-ras cells with IC50S of 540 and 310 ng/ml, respectively. Flow cytometric analysis indicated that TAN-1813 arrests NIH3T3/K-ras cells at both G1 and G2/M phases of the cell cycle. In addition, TAN-1813 was found to induce morphological reversion of NIH3T3/K-ras cells from the transformed phenotype. Antitumor activity of TAN-1813 against human fibrosarcoma HT-1080 and NIH3T3/K-ras tumors in nude mice was also verified.     

The chemical structure of mumbaistatin, a novel glucose-6-phosphate translocase inhibitor produced by Streptomyces sp. DSM 11641.

The characterization of the structure of mumbaistatin (1), an effective inhibitor of the glucose-6-phosphatase system (EC 3.1.3.9), is reported. Isolation of mumbaistatin from cultures of Streptomyces sp. DSM 11641 was achieved by anion-exchange and reversed-phase chromatography. The acid-labile inhibitor was methylated for the structure determination. Single-crystal X-ray structure analysis of a triply methylated dehydration product, C31H24O11, revealed the structure of an aromatic dispirodiketal (2), a compound containing a previously undescribed ring system. Extensive 2D-NMR experiments with mumbaistatin and with the methylation products showed that mumbaistatin itself possesses the hydroxydiketodicarboxylic acid structure 1, C28H20O12, which, in the presence of acid or upon activation through methyl ester formation, undergoes self-condensation with loss of water to the dispirodiketal form (2). Mumbaistatin is an anthraquinone derivative, whose open-chain diketo form acts as a specific and powerful inhibitor of glucose-6-phosphate translocase: IC50=5 nM. The activity towards the same enzyme of the cyclized dispirodiketal derivatives is roughly one thousand times lower.     

YM-254890, a novel platelet aggregation inhibitor produced by Chromobacterium sp. QS3666

A novel platelet aggregation inhibitor, YM-254890, was isolated from the culture broth of strain QS3666. This strain was isolated from a soil sample collected at Okutama, Tokyo, Japan, and was identified as Chromobacterium sp. by morphological and physiological criteria. YM-254890 was purified from the culture supernatant by solvent extraction, ODS and silica gel flash chromatography, followed by preparative HPLC. YM-254890 inhibited ADP-induced platelet aggregation in human platelet-rich plasma with an IC50 value below 0.6 microM by blocking the P2Y1 receptor-signal transduction pathway.     

Phellinsin A, a novel chitin synthases inhibitor produced by Phellinus sp. PL3

Phellinsin A, a novel chitin synthases inhibitor was isolated from the cultured broth of fungus PL3, which was identified as Phellinus sp. PL3. Phellinsin A was purified by solvent partition, silica gel, ODS column chromatographies, and preparative HPLC, consecutively. The structure of phellinsin A was assigned as a phenolic compound on the basis of various spectroscopic analyses including UV, IR, Mass, and NMR. Its molecular weight and formula were found to be 358 and C18H14O8, respectively. Phellinsin A selectively inhibited chitin synthase I and II of Saccharomyces cerevisiae with an IC50 value of 76 and 28 microg/ml, respectively, in our cell free assay system. This compound showed antifungal activity against Colletotrichum lagenarium, Pyricularia oryzae, Rhizoctonia solani, Aspergillus fumigatus, and Trichophyton mentagrophytes.     

Byelyankacin: a novel melanogenesis inhibitor produced by Enterobacter sp. B20

A novel melanogenesis inhibitor, byelyankacin (1), was isolated from the fermentation broth of a bacterial strain. The producing organism, designated B20, was identified as a member of the genus Enterobacter based on taxonomic characteristics. 1 was obtained as a white powder from the culture medium by solvent extraction and serial chromatographic purification. The structure of 1 was determined as (E)-4-(2-isocyanovinyl)phenyl alpha-L-rhamnopyranoside on the basis of spectroscopic data. 1 potently inhibited mushroom tyrosinase and melanogenesis of B16-2D2 melanoma cells with IC50 value of 2.1 nM and 30 nM, respectively.     

TMC-69, a new antitumor antibiotic with Cdc25A inhibitory activity, produced by Chrysosporium sp. TC1068. Taxonomy, fermentation and biological activities

A new antibiotic designated TMC-69 has been isolated from the fermentation broth of a fungal strain Chrysosporium sp. TC 1068. TMC-69 exhibited moderate in vitro cytotoxic activity. TMC-69-6H, a derivative of TMC-69 prepared by hydrogenation, possessed more potent in vitro cytotoxicity than TMC-69, and exhibited in vivo antitumor activity against murine P388 leukemia and B16 melanoma. TMC-69-6H was found to specifically inhibit Cdc25A and B phosphatases.     

TMC-86A, B and TMC-96, new proteasome inhibitors from Streptomyces sp. TC 1084 and Saccharothrix sp. TC 1094. I. Taxonomy, fermentation, isolation, and biological activities

TMC-86A, B and TMC-96, new 20S proteasome inhibitors with an epoxy-beta-aminoketone moiety, were isolated from the fermentation broth of Streptomyces sp. TC 1084 and Saccharothrix sp. TC 1094, respectively. TMC-86A, B and TMC-96 inhibited the chymotrypsin-like and peptidylglutamyl-peptide hydrolyzing activities of 20S proteasome with the following IC50 values: TMC-86A, 5.1 microM and 3.7microM; TMC-86B, 1.1 microM and 31 microM; TMC-96, 2.9 microM and 3.5 microM, respectively. TMC-86A, B and TMC-96 exhibited the weak inhibitory activity against the trypsin-like activity of 20S proteasome with IC50 values of 51 microM, 250 microM, and 36 microM, respectively. They did not inhibit m-calpain, cathepsin L, and trypsin at 100 microM, suggesting their high specificity for proteasome. Taxonomy of the producing strains is also described.     

YM-202204, a new antifungal antibiotic produced by marine fungus Phoma sp

A new antifungal antibiotic, YM-202204 (1), was found in the culture broth of marine fungus Phoma sp. Q60596. The structure of 1 was determined by several spectroscopic experiments as a new lactone compound. This antibiotic exhibited potent antifungal activities against Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus, and also inhibited glycosyl-phosphatidyl-inositol (GPI)-anchoring in yeast cells.     

Acaterin, a novel inhibitor of acyl-CoA: cholesterol acyltransferase produced by Pseudomonas sp. A92.

Acaterin, a novel inhibitor of acyl-CoA: cholesterol acyltransferase (ACAT), was isolated from a culture broth of Pseudomonas sp. A92 by Diaion HP-20 column chromatography, solvent extraction and reverse phase HPLC. Spectroscopic analyses of the compound yielded 3-(1-hydroxyoctyl)-5-methyl-2(5H)-furanone as the proposed structure. In the presence of oxidized low density lipoprotein, acaterin inhibited the synthesis of cholesteryl ester in macrophage J774 by 50% at a concentration of 45 microM. Acaterin also inhibited ACAT activity in the rat liver microsomes by 50% at a concentration of 120 microM. Kinetic studies suggested that inhibition of ACAT by acaterin was noncompetitive with respect to oleoyl-CoA.     

YM-215343, a novel antifungal compound from Phoma sp. QN04621

Through our screening for novel antifungal compounds, YM-215343 was found in the culture extract of Phoma sp. QN04621. The structure of YM-215343 was determined by several spectroscopic experiments as a novel compound closely related to apiosporamide and fischerin. YM-215343 exhibited antifungal activity against the pathogenic fungi, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus with MIC values of 2 to approximately 16 microg/ml. It also showed cytotoxicity against HeLa S3 cells with an IC50 of 3.4 microg/ml.     

YCM1008A, a novel Ca2+-signaling inhibitor, produced by Fusarium sp. YCM1008

In the course of screening for drugs that suppress the Ca(2+)-mediated growth inhibition in a yeast mutant, we found that the metabolite of Fusarium sp. strain YCM1008 inhibited Ca(2+)-signaling. A novel pyrano-pyridone, YCM1008A was isolated from the fermentation broth using HLB column chromatography followed by HPLC, and the structure was elucidated by spectral analysis. YCM1008A suppressed Ca(2+)-induced growth inhibition of the Saccharomyces cerevisiae (Deltazds1Deltasyr1) mutant.     

CJ-21,164, a new D-glucose-6-phosphate phosphohydrolase inhibitor produced by a fungus Chloridium sp

A new D-glucose-6-phosphate phosphohydrolase (G6Pase) inhibitor, CJ-21,164 (1) was isolated from the fermentation broth of the fungus Chloridium sp. CL48903. The structure was elucidated to be a novel tetramer of the salicylic acid derivatives by spectroscopic analyses. Compound I inhibited G6Pase in rat liver microsomes with an IC50 of 1.6 microM. Glucose output from hepatocytes isolated from rat liver was inhibited when I was present in the incubation medium, consistent with the role of I as a G6Pase inhibitor.     

The squalestatins, novel inhibitors of squalene synthase produced by a species of Phoma. III. Biosynthesis.

The biosynthetic origin of the carbon and oxygen atoms of the novel fungal secondary metabolite 1 was studied. Incorporation studies with single and multiple labelled 13C precursors indicated that the major portion of the molecule was derived from two polyketide chains made up of acetate units. One of the chains had benzoic acid (which can be derived from phenylalanine) as a starter unit. The remaining carbons were derived from a four-carbon unit related to succinate and from methionine. Studies with [1-(13)C,18O2]acetate and 18O2 indicated that five of the oxygens, including both of the heterocyclic oxygens, were derived from atmospheric oxygen. The oxygens at the two ester carbonyls were derived from acetate.