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Four novel proteasome inhibitors, TMC-95A-D (1-4) have been isolated from the fermentation broth of Apiospora montagnei Sacc. TC 1093, isolated from a soil sample. All of the molecular formulas of 1-4 were established as C(33)H(38)N(6)O(10) by high-resolution FAB-MS. Their planar structures were determined on the basis of extensive analyses of 1D and 2D NMR, and degradation studies. Compounds 1-4 have the same planar structures to each other, and are unique highly modified cyclic peptides containing L-tyrosine, L-aspargine, highly oxidized L-tryptophan, (Z)-1-propenylamine, and 3-methyl-2-oxopentanoic acid units. The absolute configuration at C-11 and C-36 of 1-4 was determined based on chiral TLC and HPLC analyses of their chemical degradation products. The ROESY analysis along with (1)H-(1)H coupling constants clarified the absolute stereochemistry at C-6, -7, -8, and -14 of the cyclic moieties. These studies revealed the relationships of 1-4 to be diastereomers at C-7 and C-36.
In the course of screening for new antibiotics active against fungi, an actinomycete strain No. PI57-2 that had been isolated from a soil sample collected in Fiji Island was found to produce novel antibiotics, pradimicins A and B1*^. Pradimicin A, the major component showed moderate in vitro activity against a wide variety of fungi and yeasts including clinically important pathogens. More interestingly, it exhibited marked in vivo therapeutic activity against systemic fungal infections caused by Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans strains in mice. Degradation studies revealed that pradimicin A has a unique structure containing the following moieties : D-Alanine, D-xylose, 4 ,6-dideoxy-4-methylamino-D-galactose and a substituted 5,6-dihydrobenzo[a]naphthacenequinone. This communicationpresents production, isolation, chemical and biological properties and structures of pradimicins A and B. Based on the taxonomic studies performed, strain PI57-2 is classified as a heretofore undescribed species of the genus Actinomaduraand named Actinomadurahibisca sp. nov. (ATCC 53557), and the details will be reported in a separate pap er. Pradimicin was produced in a 200-liter tank fermentor using a mediumconsisting of glucose 3%, soybean meal 3%, Pharmamedia 0.5%, yeast extract 0.1 % and CaCO3 0.3%. The tank was operated at 28°C with agitation of 250 rpm and aeration of 120 liters/minute. Antibiotic production was monitored by bioassay using C, albicans A9540 as a test organism and visible absorption at 500 nm in 0.01 n NaOH-MeOH (1 :1). After 5~6 days of fermentation, antibiotic potency reached the maximum of 500~700 /*g/ml.
In a systematic search for microbial products active in the syncytia inhibition assay (SIA)1}, two streptomycetes strains AA6532 (ATCC 55290) and AA3891 (ATCC 55286) were found to produce new antiviral antibiotics, named siamycins I and II, respectively. They are peptide group antibiotics structurally related to each other, and both show good inhibitory activity against HIV and HSV viruses. This paper describes the fermentation, isolation, physico-chemical properties and biological activities of siamycins I and II. Streptomyces sp. AA3891and AA6532were isolated from soil samples collected in Madhya Pradesh, India and Tokyo, Japan, respectively. Siamycin I was produced by the strain AA6532 in 500-ml Erlenmeyer flasks using medium composed of lactose 2%, dextrin (Nichiden Kagaku Co.) 2%, glucose 0.5%, corn steep liquor (Oji Corn Starch Co.) 1%, rice bran 1.5%, K2HPO4 0.05% and CoCl2-6H2O 0.0002%, pH 7.0. The flasks were shaken on a rotary shaker (200 rpm) at 28°C for 88 hours. Antibiotic production in the fermentation broth was estimated by the SIA. The medium for siamycin II herpes simplex viruses to antiviral agents. Antiviral Research 3: 223-234, 1986
A newantibiotic, cispentacin, was isolated from the culture broth of a Bacillus cereus strain, L450-B2. The antibiotic is water-soluble and amphoteric; its structure was determined by spectroscopic analysis and chemical synthesis to be (ljR,25)-2-aminocyclopentane-l-carboxylic acid. Cispentacin demonstrated only weak in vitro activity against certain fungi but strong protection of mice from lethal infection of Candida albicans A9540.1 749In our search of the microbial metabolites effective against systemic Candida infection in mice, a bacterial strain L450-B2was discovered to produce a new active substance named cispentacin. The producing strain was identified as Bacillus cereus by our taxonomical studies. The antibiotic was extracted from the culture broth and purified by ion exchange chromatographies. The structure of cispentacin was determined to be (li?,2£)-2-aminocyclopentane-l-carboxylic acid by spectral analysis. It showed weak inhibitory activity against Candida albicans A9540and Cryptococcus neoformans IAM4514 only in certain media and no activity against other fungi and bacteria. In a murine systemic infection model with C. albicans, the antibiotic exhibited strong protection of the mice from the lethal infection by intravenous, intramuscular, or oral administration.This report describes the taxonomy of the producing organism and the production, isolation, physico-chemical properties and structure of cispentacin. The biological activities of the antibiotic are reported in a companion paper1}. TaxonomyStrain L450-B2 was isolated from a soil sample collected around Berberis (barbering) tree at Cuenca, Providence Azuay, Ecuador. The strain is an endospore-forming, Gram-positive rod bacterium. As shown in Table 1 , the cultural and physiological characteristics of strain L450-B2 correspond to the genus Bacillus2). The characteristics of strain L450-B2are similar to those of Bacillus megaterium or B. cereus. It was, however, differentiated from B. megaterium in the colonial morphology, V-P reaction, growth in anaerobic agar, acid production of V-P reaction and resistance to lysozyme, while it could not be differentiated from B. cereus in any way. Thus, strain L450-B2is assigned to B. cereus.Antibiotic Production A loopful of the slant culture of B. cereus strain L450-B2, was inoculated into a 500-ml Erlenmeyer flask containing 100 ml of vegetative medium composed of glycerol 3%, distiller's solubles (Sungrowth)Cispentacin was originally cited as BU-3201 or BMY-28795.
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