Novel triterpene sulfates from Fusarium compactum using a rhinovirus 3C protease inhibitor screen.

Two novel triterpene sulfates have been isolated from Fusarium compactum by bioactivity-directed fractionation using an assay which measures the inhibition of proteolytic activity of rhinovirus 3C protease on a fluorogenic peptide substrate. The compounds were purified by countercurrent and reverse phase chromatographies. NMR, MS, UV and IR studies revealed two triterpene sulfates, uncommon metabolites of terrestrial fungi.

A method for the selective isolation of Myxococcus directly from soil.

A new method is described for the selective isolation of species of Myxococcus directly from soil by dilution plating. The method involves suppression of competing microorganisms with antibiotics combined with air drying and wet heat treatment of soils. Fungi were eliminated by supplementing the plating medium with cycloheximide and nystatin. Non-sporulating bacteria were controlled by air drying soils and then heating aqueous soil dilutions for 10 min at 56 degrees C. The predominant sporulating bacteria in soil, Streptomyces and Bacillus, were suppressed by adding either tiacumicin B, ristocetin or vancomycin to the medium. Swarming of Myxococcus colonies was controlled with a casein digest-yeast extract plating medium (CY-C10 agar). Ultrasound treatment of soil suspensions gave the highest number of Myxococcus colonies in the soils studied, but these cultures could be recovered without ultrasound. Strains of Myxococcus fulvus, M. xanthus, M. coralloides, M. stipitatus and M. virescens were isolated from soil using this technique. Soils examined yielded one or two Myxococcus species per sample.

Dibefurin, a novel fungal metabolite inhibiting calcineurin phosphatase activity.

The novel calcineurin inhibitor, dibefurin, has been isolated from the fungal culture AB 1650I-759. The isolation was bioactivity-directed fractionation using an assay which measures the phosphatase activity of calcineurin. The compound was purified by countercurrent, reverse phase and gel filtration chromatographies. Several studies, including crystallographic, NMR and MS, revealed that dibefurin is a novel dimeric compound of a unique structural type.

Fusacandins A and B; novel antifungal antibiotics of the papulacandin class from Fusarium sambucinum. I. Identity of the producing organism, fermentation and biological activity.

The fuscandins, antifungal agents of the papulacandin class, are produced by a strain of Fusarium sambucinum. Fermentation yielded 60 mg/liter of fusacandin A and minor amounts of fusacandin B. As expected, the fusacandins inhibit (1,3)-beta-glucan synthesis. Fusacandin A is slightly less active than papulacandin B against Candida albicans and, like papulacandin, loses activity in the presence of serum.

Macquarimicins, microbial metabolites from Micromonospora. I. Discovery, taxonomy, fermentation and biological properties.

A novel series of microbial metabolites were discovered in fermentation broths of two soil isolates. Both cultures were identified as strains of Micromonospora chalcea. Production of the metabolites, named macquarimicins, was monitored by an HPLC assay. A seven-day fermentation yielded 27 mg/liter of macquarimicin A. With MICs of 50 to 100 micrograms/ml, macquarimicin A has only very low activity against strains of Bacteroides and other anaerobes. Macquarimicin B has inhibitory activity against the leukemia cell line P-388.

Simple aromatics identified with a NFAT-lacZ transcription assay for the detection of immunosuppressants.

Determination of the mechanism of action of FK506 and cyclosporin A has yielded new molecular targets involved in signal transduction during T cell activation. A common target of FK506 and cyclosporin A is inhibition of activation of the NFAT transcription factor, for which a specific binding region is present in the promoter of the IL-2 gene. A reporter gene assay has been used to screen for agents that interfere with this early step in T cell activation. Simple aromatic compounds that block NFAT-dependent transcription and show in vitro immunosuppressive activity were isolated from the broth and mycelia of two Streptomyces sp. fermentations. The compounds were active at concentrations that were not directly cytotoxic.

Dorrigocins: novel antifungal antibiotics that change the morphology of ras-transformed NIH/3T3 cells to that of normal cells. I. Taxonomy of the producing organism, fermentation and biological activity.

The dorrigocins are new secondary metabolites produced by submerged fermentation of a streptomycete which was isolated from a soil sample collected in Australia. The dorrigocins show moderate antifungal activity and reverse the morphology of ras-transformed NIH/3T3 cells from a transformed phenotype to a normal one. The producing culture was identified as Streptomyces platensis subsp. rosaceus strain AB1981F-75.

Aselacins, novel compounds that inhibit binding of endothelin to its receptor. I. The producing organism, fermentation and biological activity.

A radioligand test to detect inhibitors of endothelin-1 binding to its receptors in bovine atrial and porcine cerebral membranes was used to screen fungal metabolites from stationary fermentations. Inhibitory activity, observed in culture extracts of two Acremonium species, led to the discovery of aselacins A, B and C. Aselacin A inhibits binding to both membrane fractions with IC50s of approximately 20 micrograms/ml.

MLR-52, (4'-demethylamino-4',5'-dihydroxystaurosporine), a new inhibitor of protein kinase C with immunosuppressive activity.

In the course of screening with the mixed lymphocyte reaction, a new inhibitor of protein kinase C with immunosuppressive activity was isolated from the fermentation broth and mycelia of Streptomyces sp. AB 1869R-359. Although certain similarities exist, this strain is morphologically and physiologically distinct from other reported producers of staurosporine-related compounds. We have found that this strain produces relatively high levels of staurosporine and the new minor compound MLR-52, which possesses the indolo[2,3-a]carbazole chromophore of staurosporine, but differs in the substitution pattern of the sugar moiety. Their structures have been elucidated by mass and NMR spectra. MLR-52 has been shown to inhibit the enzymatic activity of protein kinase C and the murine mixed lymphocyte reaction.

5-N-acetylardeemin, a novel heterocyclic compound which reverses multiple drug resistance in tumor cells. I. Taxonomy and fermentation of the producing organism and biological activity.

The ardeemins are a new family of secondary metabolites produced by submerged fermentation of a fungus which was isolated from a soil sample collected in Brazil. Based on taxonomic studies, the producing culture was identified as Aspergillus fischeri var. brasiliensis strain AB 1826M-35. 5-N-Acetylardeemin potentiated the cytotoxicity of the anticancer agent vinblastine in multidrug resistant human tumor cells.

Calbistrins, novel antifungal agents produced by Penicillium restrictum. I. Production, taxonomy of the producing organism and biological activity.

A novel antibiotic complex, named the calbistrins, has been discovered in the culture broth of a soil fungus. The producing organism, designated AB 1875C-28, was identified as a strain of Penicillium restrictum. Calbistrin A, the most potent of the 4-membered complex, has MICs of 0.78 micrograms/ml against Candida albicans. Only poor activity is observed against non-candida yeasts, filamentous fungi and bacteria.

Tirandalydigin, a novel tetramic acid of the tirandamycin-streptolydigin type. I. Taxonomy of the producing organism, fermentation and biological activity.

Tirandalydigin is a new tetramic acid antibiotic which was discovered in a screen designed to find compounds with activity against pathogenic anaerobic bacteria. It was named tirandalydigin because it possesses structural features that are common to both tirandamycin and streptolydigin. The producing culture, strain AB 1006A-9, is a Streptomyces and was compared to the streptomycetes that synthesize tirandamycin and streptolydigin. It is closely related to the former culture and was named Streptomyces tirandis subsp. umidus. Tirandalydigin has MICs in the range of 0.5 to 32 micrograms/ml against many pathogenic anaerobes, streptococci, enterococci and legionellae.

Dunaimycins, a new complex of spiroketal 24-membered macrolides with immunosuppressive activity. I. Taxonomy of the producing organisms, fermentation and antimicrobial activity.

The dunaimycins are a new complex of spiroketal 24-membered macrolides discovered in the fermentation broth of two actinomycetes. Based on taxonomic studies these two cultures, which were isolated from soil, were identified as Streptomyces diastatochromogenes strains AB 1691Q-321 and AB 1711J-452. The dunaimycins possess both immunosuppressive and antimicrobial activity.

Altromycins, novel pluramycin-like antibiotics. I. Taxonomy of the producing organism, fermentation and antibacterial activity.

The altromycins are novel anthraquinone-derived antibiotics related to the pluramycins. They are produced by an actinomycete, AB 1246E-26, which was isolated from a South African bushveld soil. The altromycins have Gram-positive antibacterial activity with MICs of 0.2 to 3.12 micrograms/ml against Streptococci and Staphylococci.

Pacidamycins, a novel series of antibiotics with anti-Pseudomonas aeruginosa activity. I. Taxonomy of the producing organism and fermentation.

The pacidamycins are a new complex of nucleosidyl-peptide antibiotics with highly specific activity against Pseudomonas aeruginosa. They are produced by Streptomyces coeruleorubidus AB 1183F-64 which was isolated from a soil sample collected at Offenburg in the FRG. The mature spore masses of the producing organism are greenish gray to blue, and the spore chains are arranged in spirals. After the structures of the pacidamycins were determined, the fermentation medium was supplemented with component amino acids. This resulted in the directed biosynthesis of several members of the complex. The overall antibiotic recovered was increased from 1 approximately 2 mg/liter to more than 100 mg/liter through a combination of strain selection, medium manipulation and amino acid feeding experiments.

Coumamidines, new broad spectrum antibiotics of the cinodine type. I. Discovery, taxonomy of the producing organism and fermentation.

Coumamidines are water-soluble basic antibiotics related to the glycocinnamoylspermidines. They are produced by a soil isolate designated Saccharopolyspora sp. AB 1167L-65. The coumamidines have broad spectrum activity and were selected in a screen for substances which inhibit Pseudomonas aeruginosa.

Phenelfamycins, a novel complex of elfamycin-type antibiotics. I. Discovery, taxonomy and fermentation.

Phenelfamycins A, B, C, E, F and unphenelfamycin have been discovered in the fermentation broth of two soil isolates, designated AB 999F-80 and AB 1047T-33. These isolates were identified as strains of Streptomyces violaceoniger. The antibiotics were selected for their activity against anaerobic bacteria.

Arizonins, a new complex of antibiotics related to kalafungin. I. Taxonomy of the producing culture, fermentation and biological activity.

The arizonins, a novel complex of antibiotics related to kalafungin, were discovered in the fermentation broth of Actinoplanes sp. AB660D-122. Comparative taxonomic studies indicated that the culture is a new species and therefore has been designated Actinoplanes arizonaensis sp. nov. Two members of the complex, arizonins A1 and B1, exhibit moderate to potent in vitro antimicrobial activity against pathogenic strains of Gram-positive bacteria.