Isolation of a new antibiotic oligomycin G produced by Streptomyces sp. WK-6150.
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Biomedical subjects
Publications and source records attributed to H B Woodruff.
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Streptomyces sp. WK-5344, a soil isolate, was found to produce structurally related inhibitors of cholesteryl ester transfer protein (CETP). New active compounds, designated ferroverdins B and C, were isolated along with known ferroverdin A from the fermentation broth by solvent extraction, ODS column chromatography and silica gel column chromatography. All ferroverdins showed a dose-dependent inhibitory activity against human CETP. The IC50 values were 21, 0.62 and 2.2 microM for ferroverdins A, B and C, respectively, indicating that ferroverdin B is one of the most potent CETP inhibitors of microbial origin.
Chloropeptins I and II, which are gp120-CD4 binding inhibitors, were isolated as pale yellow-brown powders from the mycelia of a soil actinomycete, Streptomyces sp, WK-3419. Their physico-chemical properties showed that they are chlorinated peptides. Chloropeptin I (C61H45N7O15Cl6) is a novel compound, but chloropeptin II was identified as complestatin. Both compounds inhibited gp120-CD4 binding (IC50: 1.3 and 2.0 microM, respectively), the cytopathic effect of HIV in MT-4 cells (EC50: 1.6 and 1.7 microM, respectively) and syncytium formation in co-cultured HIV-1-infected and uninfected MOLT-4 cells (IC50. 0.5 and 1.1 microM, respectively). Chloropeptin I was synergistic in the inhibition of the cytopathic effect when combined with other anti-HIV drugs such as zidovudine (AZT), didanosine (ddI), zalcitabine (ddC) and nevirapine.
In the course of screening for non-steroidal growth inhibitors of testosterone-responsive Shionogi carcinoma 115 cells, louisianins A, B, C and D, were isolated from fermentation broth of Streptomyces sp. WK-4028. Louisianin A remarkably inhibited the growth of SC 115 cells in the presence of 10(-7) M testosterone at an IC50 value of 0.6 microgram/ml, whereas, no inhibition was observed on the other cell lines. Furthermore, inhibitory activity of testosterone 5 alpha-reductase and antimicrobial activity have not been observed at a concentration of 50 micrograms/ml and 1,000 micrograms/ml, respectively.
New non-steroidal growth inhibitors of testosterone-responsive SC 115 cells, louisianins A (MW: 189; C11H11NO2), B (MW: 191; C11H13NO2), C (MW: 173; C11H11NO) and D (MW: 173; C11H11NO) were isolated from the cultured broth of Streptomyces sp. WK-4028. Their structures were determined on the basis of spectroscopic data. The structure of louisianin A in particular was confirmed by X-ray crystallographic analysis. The four compounds commonly possess a unique pyrindine skeleton in the molecule.
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Streptomyces sp. WK-2955, a soil isolate, was found to produce a series of new anticoccidial compounds. Four active compounds, designated diolmycins A1, A2, B1 and B2, were isolated from the fermentation broth of the producing strain by solvent extraction, silica gel column chromatography, gel filtration on Sephadex LH-20, and preparative HPLC. Diolmycins inhibited the growth of Eimeria tenella in an in vitro assay system using BHK-21 cells as a host. No schizont in the cells was observed at concentrations of 0.02-2.0 micrograms/ml for diolmycin A1, at 0.2-2.0 micrograms/ml for diolmycin A2, and at 20 micrograms/ml for diolmycins B1 and B2.
A new antibiotic, phenazinomycin (C27H32N2O, MW 400), was isolated from the cultural mycelium of Streptomyces sp. WK-2057. This antibiotic possesses antibacterial activities against Gram-positive bacteria in vitro, direct cytotoxic activities against HeLa S3, P388 and P388 doxorubicin-resistant cells in vitro and antitumor activities against experimental murine tumors in vivo.
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A soil isolate, Streptomyces sp. WK-142, was found to produce new acid protease inhibitors, ahpatinins A, B, D, E, F and G active against pepsin and renin. Ahpatinin C was found to be identical with pepstatin A. The structure determinations were based on mass spectral data. Four of the compounds contain the unusual amino acid, 4-amino-3-hydroxy-5-phenylpentanoic acid as a building component.
A computer program has been prepared for grouping soil actinomycetes into cluster groups based on the presence or absence of aerial mycelium, the color of soluble pigment, and the shade of color of surface and reverse mycelium. The program automatically condenses cultures with wide ranges of characteristics into a limited number of groups and provides a permanent record so that comparisons can be made among experiments performed over a span of time. The program permits the grouping of large numbers of cultures with minimal laboratory effort and has proven useful in defining some of the ecological factors that lead to changed actinomycete populations in soils.
Many new technologies arrived at through basic research have practical applications. Two recent breakthroughs in microbiology, recombinant DNA techniques and hybridoma techniques, will permit designing cells for specific practical purposes resulting in new products or functions of commercial significance. The unique cell or its usefulness, or both, may satisfy the requirements of a patentable invention, i.e. an inventive act having utility and novelty. Ownership of such patents permits recovery of expenses incurred in the invention process and investment for all concerned in additional research. An integral part of the patenting process is submission of the new cell to an official repository, an outstanding example of which is The American Type Culture Collection.
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Microorganisms are capable of producing natural products with widely divergent chemical structures. Greatest attention in the past has been paid to natural products that have antibiotic properties. Natural products accumulate in fermentation broths during secondary metabolism, a characteristic of the incomplete metabolic control operative in growth-inhibited microorganisms. With this general mechanism of biosynthesis, the natural products synthesized by microorganisms would be expected to have a broad range of pharmacological activities. The directed screening for non-antibiotic natural products has been of limited scope. The expectation that new compounds of interest would be found has been validated. The pharmacologically active natural products provide previously unrecognized structures as tools for fundamental research programs, as well as offering the possibility of direct use in medicine or in industrial processes.
A new beta-lactam antibiotic, named thienamycin, was discovered in culture broths of Streptomyces MA4297. The producing organism, subsequently determined to be a hitherto unrecognized species, is designated Streptomyces cattleya (NRRL 8057). The antibiotic was isolated by adsorption on Dowex 50, passage through Dowex 1, further chromatography on Dowex 50 and Bio-Gel P2, and final purification and desalting on XAD-2. Thienamycin is zwitterionic, has the elemental composition C11H16N2O4S (M.W. = 272.18) and possesses a distinctive UV absorption (lambda max = 297 nm, epsilon = 7,900). Its beta-lactam is unusually sensitive to hydrolysis above pH8 and to reaction with nucleophiles such as hydroxylamine, cysteine and, to a lesser degree, the primary amine of the antibiotic itself. The latter reaction results in accelerated inactivation at high antibiotic concentrations.
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Fosfomycin, a nontoxic broad-spectrum antibiotic, different in structure from all previously described antibiotics, acts selectively by inhibiting cell wall formation. It was overlooked during many years of screening because of antagonism by culture medium ingredients and frequent occurrence of resistant mutants. It is effective in many because the neutralizing substances are not present and resistant mutants of most species are avirulent. Fosfomycin has favorable pharmacologic characteristics. It is not cross resistant, does not show antagonism, and has been used successfully in combinations. An insoluble calcium salt is used in oral formulation and a sodium salt for parenteral administration. Overall success rates of 86% were reported with 1,000 patients in Spain and 79% in Japan.