Muraminomicins, novel ester derivatives: in vitro and in vivo antistaphylococcal activity.

Novel muraminomicin derivatives with antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) were synthesized by esterification of the hydroxy group on the diazepanone ring of muraminomicin Z1. Compound 1b (DS14450354) possessed a diheptoxybenzyl-ß-Alanyl-ß-Alanyl group and exhibited minimum inhibitory concentrations (MICs) against MRSA comparable to those against methicillin-susceptible S. aureus (MSSA). The MICs that inhibited 50 and 90% of the strains were 1 and 2 µg/mL, respectively. Compound 1a (DS60182922) possessed an aminoethylbenzoyldodecylglycyl moiety and showed bactericidal activity against MSSA Smith. The bactericidal activity of 1a against MRSA 10925 was comparatively lower, whilst 1b exhibited dose-dependent bactericidal activity against MRSA 10925. The mutation frequency of 1b was lower than that of 1a. An amino acid substitution (F226I) was observed in MraY mutants isolated from culture plates containing 1a or 1b. Subcutaneous 1a and 1b administration showed good therapeutic efficacy in murine systemic infection models with MSSA Smith and MRSA 10925, comparable to that of vancomycin, suggesting that the novel muraminomicin derivatives may be effective therapeutic agents against MRSA that warrant further investigation. A scheme for the formulation of the key ester intermediate, requiring no HPLC preparation, was also established.

Muraminomicins, new lipo-nucleoside antibiotics from Streptosporangium sp. SANK 60501-structure elucidations of muraminomicins and supply of the core component for derivatization.

We screened for bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (MraY: EC 2.7.8.13) inhibitors with the aim of discovering novel antibiotics and observed inhibitory activity in the culture broth of an actinomycete, SANK 60501. The active compounds, muraminomicins A, B, C, D, E1, E2, F, G, H, and I exhibited strong inhibitory activity against MraY with IC50 values of 0.0105, 0.0068, 0.0104, 0.0099, 0.0115, 0.0109, 0.0089, 0.0134, 0.0186, and 0.0094 µg ml-1, respectively. Although muraminomicin F exhibited favorable antibacterial activity against drug-resistant Gram-positive bacteria, this activity was reduced with the addition of serum. To efficiently supply the core component for chemical modification studies, production was carried out in a controlled trial by adding myristic acid to the medium, and a purification method suitable for large-scale production was successfully developed.

Ogipeptins, novel inhibitors of LPS: physicochemical properties and structural elucidation.

In the course of our screening program for inhibitors of lipopolysaccharide binding to cellular receptor CD14, a potent inhibitory activity was detected in the cultured broth of Pseudoalteromonas sp. SANK 71903. Four active compounds, ogipeptins A, B, C and D, were isolated from the cultured broth. The structures of these compounds were elucidated by physicochemical data and spectral analyses, and they were determined to be new cyclic lipopeptides.

Biosynthesis of nectrisine in Thelonectria discophora SANK 18292.

Nectrisine, an iminosugar with a heterocyclic nitrogen-containing 5-membered ring, acts as a glycosidase inhibitor. Thelonectria discophora SANK 18292, a fungus, was identified as a nectrisine producer from its microbial library in our screening for nectrisine producing microorganisms. Biosynthesis of nectrisine produced by the fungus was studied using stable isotope tracer techniques. Incorporation of (13)C-labeled d-ribose and d-xylose into nectrisine was confirmed by mass spectrometry and (13)C NMR spectroscopy, which suggested that these were its precursors. Chromatographic separation of the hot water extract from the culture broth afforded not only nectrisine, but also substantial amounts of 4-amino-4-deoxyarabinitol. Incubation of the latter with the crude enzyme of the fungus at room temp. caused an increase in levels of nectrisine together with a decrease in amounts of the administered potential precursor suggesting that it is a biosynthetic intermediate. From these results, a biosynthetic pathway to nectrisine is proposed via d-xylulose 5-phosphate and 4-amino-4-deoxyarabinitol by the pentose phosphate pathway.

Structure-based gene targeting discovery of sphaerimicin, a bacterial translocase I inhibitor.

Rise and shine: Using a gene-targeting approach aimed at identifying potential L-threonine:uridine-5'-transaldolases that catalyze the formation of (5'S,6'S)-C-glycyluridine, a new bacterial translocase I inhibitor was discovered from an actinomycete following fermentation optimization.

A-90289 A and B, new inhibitors of bacterial translocase I, produced by Streptomyces sp. SANK 60405.

During the course of screening for translocase I inhibitors, the new liposidomycin-related compounds, A-90289 A and B, were isolated from a culture broth of Streptomyces sp. SANK 60405. The structural elucidations were carried out by NMR and high-resolution mass spectral analyses, and they were classified as members of the liponucleoside antibiotics group with a sulfate group at the C-2' position. A-90289 A and B inhibited bacterial translocase I with IC(50) values of 36.5 ng ml(-1) and 33.8 ng ml(-1), respectively.

Haplofungins, novel inositol phosphorylceramide synthase inhibitors, from Lauriomyces bellulus SANK 26899 I. Taxonomy, fermentation, isolation and biological activities.

In the course of screening for antifungal agents, we have discovered eight novel compounds, haplofungin A, B, C, D, E, F, G and H, from a culture broth of the fungus strain Lauriomyces bellulus SANK 26899. Haplofungins are composed of an arabinonic acid moiety linked through an ester to a modified long alkyl chain and show potent inhibitory activities against fungal inositol phosphorylceramide (IPC) synthase. Haplofungin A inhibited the activity of IPC synthase from Saccharomyces cerevisiae with an IC(50) value of 0.0015 microg ml(-1). This inhibitor also suppressed the growth of Candida glabrata at the MIC value of 0.5 microg ml(-1).

Haplofungins, new inositol phosphorylceramide synthase inhibitors, from Lauriomyces bellulus SANK 26899 II. Structure elucidation.

Eight new inositol phosphorylceramide synthase inhibitors: haplofungin A, B, C, D, E, F, G and H, were discovered in a culture broth of the fungus Lauriomyces bellulus SANK 26899. The planar structures for these haplofungins were elucidated by various spectroscopic analyses and a GC/MS analysis of their degradation products. All eight compounds were found to comprise an arabinonic acid moiety linked through an ester bond to a modified long alkyl chain.

Haplofungins, novel inositol phosphorylceramide synthase inhibitors, from Lauriomyces bellulus SANK 26899 III. Absolute structure of haplofungin A.

The absolute structure of haplofungin A, a potent fungal inositol phosphoceramide (IPC) synthase inhibitor from Lauriomyces bellulus SANK 26899, was determined by chiral GC/MS analysis, NMR and X-ray crystallographic analysis of the derivatives of degradation products.

Ascotricins A and B, novel antagonists of sphingosine-1-phosphate receptor 1 from Ascotricha chartarum Berk. SANK 14186.

Ascotricins A and B were isolated as novel sphingosine-1-phosphate receptor 1 (S1P(1)) antagonists from a cultured broth of a fungus identified as Ascotricha chartarum Berk. SANK 14186. The two compounds were purified by solvent extraction, reversed-phase (RP) column chromatography and a preparative RP-HPLC. The structures were determined by various NMR experiments and by LC/MS and GC/MS analyses. The S1P(1) antagonist activities were measured by a cyclic AMP assay using S1P(1)-expressing cells and the IC(50) values were 8.2 and 1.8 microM, respectively. In a [(33)P]sphingosine-1-phosphate/S1P(1)-binding assay, those values were 120 and 39 microM, and in a migration assay using human umbilical vein endothelial cells (HUVECs), they were 94 and 28 microM, respectively. Thus, ascotricins A and B are novel S1P(1) antagonists showing an inhibition activity toward HUVEC migration.

A novel assay of bacterial peptidoglycan synthesis for natural product screening.

Although a large number of microbial metabolites have been discovered as inhibitors of bacterial peptidoglycan biosynthesis, only a few inhibitors were reported for the pathway of UDP-MurNAc-pentapeptide formation, partly because of the lack of assays appropriate for natural product screening. Among the pathway enzymes, D-Ala racemase (Alr), D-Ala:D-Ala ligase (Ddl) and UDP-MurNAc-tripeptide:D-Ala-D-Ala transferase (MurF) are particularly attractive as antibacterial targets, because these enzymes are essential for growth and utilize low-molecular-weight substrates. Using dansylated UDP-MurNAc-tripeptide and L-Ala as the substrates, we established a cell-free assay to measure the sequential reactions of Alr, Ddl and MurF coupled with translocase I. This assay is sensitive and robust enough to screen mixtures of microbial metabolites, and enables us to distinguish the inhibitors for D-Ala-D-Ala formation, MurF and translocase I. D-cycloserine, the D-Ala-D-Ala pathway inhibitor, was successfully detected by this assay (IC(50)=1.7 microg ml(-1)). In a large-scale screening of natural products, we have identified inhibitors for D-Ala-D-Ala synthesis pathway, MurF and translocase I.

Sterenin A, B, C and D, novel 11beta-hydroxysteroid dehydrogenase type 1 inhibitors from Stereum sp. SANK 21205.

The novel 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) inhibitors known as sterenin A, B, C and D were found in a solid-state culture of the producing basidiomycetes identified as Stereum sp. SANK 21205. Purification of the 50% aq Me(2)CO extract of the culture was performed by EtOAc extraction, reversed phase open-column chromatography and successive ODS HPLC preparation. These compounds, whose structures were determined by several spectroscopic methods, were found to be novel isoindolinone alkaloids which exhibited potent selective inhibitory activities against 11beta-HSD1.

Colletoic acid, a novel 11beta-hydroxysteroid dehydrogenase type 1 inhibitor from Colletotrichum gloeosporioides SANK 21404.

Colletoic acid, a novel 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) inhibitor, was found and isolated from the cultured broth of the producing fungus Colletotrichum gloeosporioides SANK 21404. Its structure was determined to be a novel acorene-type sesquiterpene by several spectroscopic methods. The absolute structure of colletoic acid was established using a modified Mosher's method and single-crystal X-ray diffraction analysis.

A-94964, a novel inhibitor of bacterial translocase I, produced by Streptomyces sp. SANK 60404. I. Taxonomy, isolation and biological activity.

Bacterial phospho-N-acetylmuramyl-pentapeptide translocase (translocase I: EC 2.7.8.13) is a key enzyme in peptidoglycan biosynthesis, and a known target of antibiotics. Here we report a novel nucleoside inhibitor against translocase I, A-94964, isolated from the culture broth of the strain Streptomyces sp. SANK 60404. A-94964 inhibited bacterial translocase I with IC50 value of 1.1 microg/ml, and showed antimicrobial activities against Staphylococcus aureus and Enterococcus faecalis with MIC of 100 and 50 microg/ml, respectively. A-94964 did not show cytotoxicity against mammalian cell lines.

A-94964, novel inhibitor of bacterial translocase I, produced by Streptomyces sp. SANK 60404. II. Physico-chemical properties and structure elucidation.

In our screening for translocase I inhibitors, we found the novel nucleoside antibiotic, A-94964 in the culture broth of Streptomyces sp. SANK 60404. The structure of A-94964 was elucidated primarily by various NMR studies, including a 1H-31P HMBC experiment. A-94964 has a unique structure which possesses a nucleoside moiety and an N-acylglucosamine moiety connected via a phosphate.

A-102395, a new inhibitor of bacterial translocase I, produced by Amycolatopsis sp. SANK 60206.

Bacterial phospho-N-acetylmuramyl-pentapeptide translocase (translocase I: EC 2.7.8.13) is a key enzyme in peptidoglycan biosynthesis, and a known target of antibiotics. Here we report a new nucleoside inhibitor for translocase I, A-102395, isolated from the culture broth of the strain Amycolatopsis sp. SANK 60206. A-102395 is a new derivative of capuramycin that has the benzene with a uniquely substituted chain instead of an aminocaprolactam. A-102395 is a potent inhibitor of bacterial translocase I with IC50 value of 11 nM, but possesses no antimicrobial activity against various strains tested.

Pleofungins, novel inositol phosphorylceramide synthase inhibitors, from Phoma sp. SANK 13899. I. Taxonomy, fermentation, isolation, and biological activities.

In the course of a screening for inositol phosphorylceramide (IPC) synthase inhibitors, the novel inhibitors pleofungins A, B, C, and D were found in a mycelial extract of a fungus, Phoma sp. SANK13899. Purification was performed by 50% methanol and ethyl acetate extraction, reversed phase open-column chromatography, and HPLC separations. Pleofungin A inhibited the IPC synthase of Saccharomyces cerevisiae and Aspergillus fumigatus at IC(50) values of 16 and 1.0 ng/ml, respectively. The inhibitor also suppressed the growth of Candida albicans, Cryptococcus neoformans, and A. fumigatus at MIC values of 2.0, 0.3, and 0.5 mug/ml, respectively. These biological properties indicate that pleofungins belong to a novel class of IPC synthase inhibitors efficacious against A. fumigatus.

Pleofungins, novel inositol phosphorylceramide synthase inhibitors, from Phoma sp. SANK 13899. II. Structural elucidation.

Pleofungins (formerly called F-15078) A, B, C and D, novel depsipeptide antifungal antibiotics, were found in a mycelium extract of the producing fungus, Phoma sp. SANK 13899. The structures of pleofungins A, B, C and D were elucidated mainly by various NMR studies. The absolute configurations of the amino acids and N-methyl amino acids of pleofungin A constituents in the hydrolysate were determined by the application of advanced Marfey's method in combination with gas chromatography/mass spectrometry analysis of their silylation products with N-methyl-N-(tert-butylsilyl)trifluoroacetamide. Two alpha-hydroxy acid constituents, alpha-hydroxyisocaproic acid and alpha-hydroxyisovaleric acid, were isolated from the hydrolysate and their stereochemistries were determined by their specific rotations.

A-503083 A, B, E and F, novel inhibitors of bacterial translocase I, produced by Streptomyces sp. SANK 62799.

Novel nucleoside antibiotics were isolated from the cultured broth of the strain classified as Streptomyces sp. SANK 62799. The strain produced four novel capuramycin derivatives designated as A-503083 A, B, E and F. Their structures were elucidated as 2'-O-carbamoyl derivatives of A-500359 A, B (capuramycin), E and F, respectively. A-503083 A, B, E and F inhibited bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (translocase I: EC 2.7.8.13) with IC50 values of 0.024, 0.038, 0.135 and 17.9 microM, respectively.

Synthesis and antimycobacterial activity of capuramycin analogues. Part 1: substitution of the azepan-2-one moiety of capuramycin.

Capuramycin analogues with a variety of substituents in place of the azepan-2-one moiety were synthesized from A-500359E and were tested for their translocase I inhibitory activity and in vitro antimycobacterial activity. Phenyl-type moieties were found to be effective substituents for capuramycin analogues.