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.

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.

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.

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.

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.

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.

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.

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.

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.

Studies on novel bacterial translocase I inhibitors, A-500359s. IV. Biosynthesis of A-500359s.

This report describes the isolation of novel A-500359 analogues from the culture broth of Streptomyces griseus SANK 60196 and 13C-incorporation studies of A-500359 A to reveal the biosynthetic pathway of A-500359 derivatives. As a result, A-500359 M-3 and J were isolated as novel analogues. The former, isolated from a culture broth fed with unnatural amino acids, was a novel amino acid adduct of A-500359, and the latter was found to be a putative precursor of all A-500359 derivatives, on the basis of the structure. Moreover, 13C-incorporation studies revealed the origin of every carbon atom of A-500359 A. From these results, it was revealed that the core skeleton of A-500359 was biosynthesized from uridine and phosphoenolpyruvate in the same manner as for polyoxin, a nucleoside antibiotic. Moreover, the uronic acid and aminocaprolactam moiety was derived from hexose and lysine, respectively, and two methyl groups of A-500359 A were derived from methionine.

Studies on novel bacterial translocase I inhibitors, A-500359s. I. Taxonomy, fermentation, isolation, physico-chemical properties and structure elucidation of A-500359 A, C, D and G.

In the course of our screening for bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (translocase I: EC 2.7.8.13) inhibitors, we found inhibitory activity in the cultured broth of the strain identified as Streptomyces griseus SANK 60196. The strain produced capuramycin and four novel capuramycin derivatives designated as A-500359 A, C, D and G. Purification and structural analysis were performed, and the structures of A-500359 A, C, D and G were elucidated as 6'''-methylcapuramycin, 3'-demethyl-6'''-methylcapuramycin, 2''-deoxy-6'''-methylcapuramycin and 3'-demethylcapuramycin, respectively.

Studies on novel bacterial translocase I inhibitors, A-500359s. III. Deaminocaprolactam derivatives of capuramycin: A-500359 E, F, H; M-1 and M-2.

Novel derivatives of capuramycin were obtained when 10 mM of 2-aminoethyl-L-cysteine (AEC), an inhibitor of aspartokinase, was added to the culture of Streptomyces griseus SANK 60196, the producer of A-500359. They were purified from the culture filtrate and their chemical structures were elucidated as a deaminocaprolactam derivative of capuramycin designated as A-500359 F, A-500359 E, a methyl ester of A-500359 F, and A-500359 H, a 3'-demethyl derivative of A-500359 F. Two other compounds, A-500359 M-1 and A-500359 M-2, were purified from the same medium and their structures were elucidated. A-500359 E, F, H, M-1 and M-2 inhibited bacterial translocase I with an IC50 of 0.027 microM, 1.1 microM, 0.008 microM, 0.058 microM and 0.010 microM, respectively. A-500359 E, M-1 and M-2 inhibited the growth of mycobacteria as well.

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.

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, 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.