Microbial conversion of milbemycins: oxidation of milbemycin A4 and related compounds at the C-25 ethyl group by Circinella umbellata and Absidia cylindrospora.

Microbial oxidation of milbemycin A4 at the C-25 ethyl group was performed. Milbemycin A4 was converted to 31- and 32-hydroxy derivatives by Circinella umbellata SANK 44272 along with 24- and 30-hydroxy derivatives. Related compounds, 5-ketomilbemycin A4 5-oxime and 13 beta-fluoromilbemycin A4 were similarly converted to the hydroxylated compounds by this microorganism. Absidia cylindrospora SANK 31472 converted milbemycin A4 to the corresponding 32-oic acid, 24-hydroxy derivative and a few oxygenated compounds including at the C-25 ethyl group.

Structural elucidation of aculeximycin. IV. Absolute structure of aculeximycin, belonging to a new class of macrolide antibiotics.

Aculeximycin (1) produced by Streptosporangium albidum possesses a 30-membered polyhydroxy macrocyclic lactone and five sugars including aculexitriose. We have described the determination of the planar structure of N-diacetylated aculeximycin (2) using degradation products, which were obtained by DBU-methanol treatment, ozonolysis and periodative oxidation. In order to determine the relative and absolute configurations of aculeximycin, first, the relative and absolute configurations of the degradation products 10, 11, 12 and 13 were determined. Rychnovsky's method was very useful to determine the relative configurations of these degradation products, and CD exciton chirality and the modified Mosher's methods were applied to determine their absolute configurations. From these results, fourteen out of the twenty asymmetric centers in aculeximycin were determined to be 5S, 17R, 20S, 21R, 23R, 24R, 29S, 30R, 31S, 34R, 35S, 36S and 37R. The absolute configurations at C-14 and C-15 on the hemiketal ring were confirmed using 12 obtained by the partial glycol bond cleavage of 9. Absolute configurations of the remaining asymmetric centers were determined by spectral analysis of 15 and NOE experiment on 1. From these results, the absolute configuration of 1 was determined to be 5S, 7R, 10S, 11R, 14R, 15S, 17R, 19R, 20S, 21R, 23R, 24R, 25S, 29S, 30R, 31S, 34R, 35S, 36S and 37R.

Screening method for colony-stimulating factor inducers using a human bone marrow stromal cell line, KM-102.

A new screening method for inducers of colony-stimulating factors (CSFs) was established using KM-102, a human bone marrow stromal cell line as the producer. In this method, the assay system which uses CSF dependent cell lines is combined with the CSF production system. Interleukin-1 (IL-1), which is known to upregulate CSF production in many cell populations, was used as a positive control for production of granulocyte CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF). Induction in the positive controls was clearly detected within 24 hours. Activators of protein kinase C (PKC), protein phosphatase inhibitors and lipopolysaccharide (LPS) were positive in this assay system, but muramyl dipeptide (MDP) and Bestatin which are known macrophage activators, were negative. Inducers of CSFs were successfully detected using this assay method. Among 1,600 microbial strains tested, 2 actinomycete strains were found to produce active substances. One strain produces teleocidin-A, a strong activator of PKC, and the other strain produces a mixture of active compounds including three novel compounds. These three compounds do not induce terminal differentiation of HL-60 cells, suggesting that they are not teleocidin-like substances and form a new class of CSF inducers.

Novel microbial metabolites of the phoslactomycins family induce production of colony-stimulating factors by bone marrow stromal cells. I. Taxonomy, fermentation and biological properties.

Three metabolites were isolated from the culture broth of an actinomycete strain identified as Streptomyces platensis SANK 60191, that induce the production of colony-stimulating factors (CSFs) by stromal cell line KM-102 at ED50 concentrations from 40 to 200 ng/ml. The compounds induced quantities of granulocyte CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF) comparable to those induced by interleukin-1, a strong CSF inducer. These metabolites were called leustroducsins (A, B and C) and were later found to be structurally related to phoslactomycins. This is the first report of CSF inducing activity by members of the phoslactomycin class.

Biosynthesis of griseolic acids: incorporation of 13C-labeled compounds into griseolic acid A.

Biosynthesis of griseolic acids, competitive inhibitors of cyclic nucleotide phosphodiesterase, was investigated with the culture of a producing strain of Streptomyces griseoaurantiacus. 13C-Labeled and 15N-labeled compounds were added into the culture, and 13C-enriched and 15N-enriched griseolic acid A was isolated from the culture medium and analyzed by 13C NMR and 15N NMR spectroscopy. The compounds added to growth medium were [2-13C]acetate, [1,2-13C]acetate, [1,4-13C]succinate, [1-13C]glucose, [6-13C]glucose, [2-13C]ribose, and [1-13C, 15N]glycine. The results suggest that adenosine, which is formed from amino acids and sugars contributes the adenine and ribose moieties to griseolic acid A. The data also suggest that a dicarboxylic acid from the Krebs tricarboxylic acid cycle contributes to the dicarboxylic part of the compound.

Microbial conversion of milbemycins: hydroxylation of milbemycin A4 and related compounds by Cunninghamella echinulata ATCC 9244.

Many strains of zygomycetes and actinomycetes were found to convert milbemycin A4 (1a) to 13 beta-hydroxymilbemycin A4 (1b). Among these strains, Cunninghamella echinulata ATCC 9244 had the most efficient 13 beta-hydroxylation ability on milbemycins. In the conversion of milbemycin A3 (2a), 29-hydroxymilbemycin A4 (4a), and 30-hydroxymilbemycin A4 (5a) with this strain, only 13 beta-hydroxylated products were obtained. On the other hand, starting from milbemycin A4 (1a) and 5-ketomilbemycin A4 5-oxime (6a), 13 beta,24- and 13 beta,30-dihydroxy derivatives were also isolated along with 13 beta-hydroxylated products. Similarly, conversion of milbemycin D (3a) and LL-F28249 alpha (8a) gave 13 beta- and 28-hydroxy derivatives (8b and 8c).

Microbial conversion of milbemycins: 30-oxidation of milbemycin A4 and related compounds by Amycolata autotrophica and Amycolatopsis mediterranei.

Microorganisms were screened for their ability to modify milbemycin A4 (1a). Many strains, mostly actinomycetes and zygomycetes, were found to convert milbemycin A4 (1a) to one or more new products. Among these products, M-1, M-2, and M-3 were obtained using Amycolata autotrophica subsp. amethystina ATCC 35204, and were identified as 30-hydroxymilbemycin A4 (1b), 26,30-dihydroxymilbemycin A4 (1c), and milbemycin A4 30-oic acid (1d), respectively. Other milbemycins and LL-F28249 alpha (7a) also underwent 30-hydroxylation by the microorganism. 22,23-Dihydroavermectin B1a (8a) was not hydroxylated at any position by A. autotrophica subsp. amethystina ATCC 35204, but a corresponding hydroxyl product at the C-30 position was obtained using Amycolatopsis mediterranei IFO 13415.

Structural elucidation of aculeximycin. I. Further purification and glycosidic bond cleavage of aculeximycin.

A new insecticidal antibiotic, aculeximycin (ACM), was produced by an actinomycete identified as Streptosporangium albidum. ACM has been successfully isolated from culture filtrate by a combination of Diaion HP-20, Amberlite CG-50, reversed phase silica gel and Sephadex LH-20 chromatographies. It was found that ACM is a basic glycosidic antibiotic with a molecular weight of 1,672 including five monosaccharide units, three double bonds and a hemiketal ring by preliminary spectral analyses. Treatment of ACM with 1,8-diazabicyclo[5,4,0]undecene-7 caused a glycosidic bond cleavage to give aculexitriose, pseudoaglycones I and II.

Structural elucidation of aculeximycin. II. Structures of carbohydrate moieties.

Treatment of aculeximycin with 2% 1,8-diazabicyclo[5,4,0]undecene-7 (DBU)-methanol yielded three products, aculexitriose, pseudoaglycones I and II. The structural elucidation of aculexitriose was carried out by spectral analyses (MS, NMR (1H-1H 2D NMR spectroscopy, nuclear Overhauser effect] and chemical degradations of aculexitriose and its derivatives. The structure of aculexitriose was established to be a branched trisaccharide, O-6-deoxy-beta-D-glucopyranosyl-(1----2)-O-[3-amino-2,3,6-trideoxy-beta- D- arabino-hexopyranosyl-(1----3)]-6-deoxy-D-glucopyranose. On the other hand the pseudoaglycones I and II were stereoisomers with respect to a chiral center newly formed by the DBU reaction. The pseudoaglycones contain one neutral sugar and one amino sugar, which turned out to be D-mannose and L-vancosamine, respectively.

Antimycobacterial activities in vitro and in vivo and pharmacokinetics of dihydromycoplanecin A.

The in vitro activity of dihydromycoplanecin A (DHMP A), a new cyclic peptide antibiotic, was compared with those of antimycobacterial drugs such as streptomycin, isoniazid (INH), rifampin, and ofloxacin against several clinically isolated species of mycobacteria, including Mycobacterium tuberculosis, M. intracellulare, and M. kansasii. DHMP A demonstrated stronger activities than other drugs against all species of mycobacteria tested at concentrations of less than 0.0125 to 25 microgram/ml. A marked synergism between DHMP A and INH was demonstrated by the checkerboard technique against M. tuberculosis, M. intracellulare, and M. smegmatis, and the synergistic effect was observed by treatment of the culture of M. smegmatis with DHMP A for at least 3 h prior to treatment with INH. It was also shown that both absorption and excretion of INH in mice were faster than those of DHMP A. On the basis of these results, combination therapy with DHMP A and INH was successfully carried out in experimental tuberculosis in mice infected with M. bovis Ravenel. After a single intravenous administration of 10 mg of DHMP A per kg, its half-life in serum in mice was about 0.5 h and in dogs it was 5.5 h. A single oral administration to dogs of 12.5 mg/kg gave a peak of 5.0 micrograms/ml at 3 h. In these experiments, urinary recoveries within 48 h were 21.0% in mice and 25.2% in dogs. The tissue distribution level of DHMP A in mice after oral administration was in the order of liver greater than kidney greater than serum greater than spleen = lung. The 50% lethal doses of DHMP A for mice were more than 6,000 mg/kg orally and 1,840 mg/kg intraperitoneally.

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. I. Taxonomy of producing organism.

Strain SANK 60983, an actinomycete isolated from a soil sample, was found to produce the new glycopeptide antibiotics, chloropolysporins A, B and C. Short chains of spores occur in the both aerial and substrate hyphae. meso-Diaminopimelic acid is present in the cell wall and galactose and arabinose in the whole-cell hydrolysate. Mycolic acid is absent. On the basis of the morphological, cultural and physiological characteristics, this strain was determined to be a new species of Faenia designated Faenia interjecta sp. nov. The type strain of F. interjecta Okazaki and Enokita is SANK 60983.

Aculeximycin, a new antibiotic from Streptosporangium albidum. I. Taxonomy of producing organism and fermentation.

A soil isolate of actinomycete, strain TI-1, was found to produce a new antibiotic aculeximycin which killed insects as well as inhibited the growth of bacteria, yeasts and molds in vitro. Yellowish gray colonies on agar media, formation of spherical to oval sporangia at the tip of aerial mycelium and the presence of meso-diaminopimelic acid and madurose in the cell wall ascribed this strain to genus Streptosporangium. From its morphological, cultural and physiological characteristics, the strain was determined to be S. albidum. Production of aculeximycin was carried out by conventional submerged culture: the highest antibiotic titer obtained was 1,250 micrograms/ml.

Taxonomy of actinomycetes capable of hydroxylation of ML-236B (compactin).

Three actinomycetes having capability of 3 beta-hydroxylation of ML-236B were isolated from soil samples collected in Australia. Strain SANK 62781 was identified as Nocardia autotrophica. Strain SANK 62881 and strain SANK 62981 were identified as new subspecies of N. autotrophica for which the name N. autotrophica subsp. canberrica and N. autotrophica subsp. amethystina are proposed, respectively. The type strains of N. autotrophica subsp. canberrica and N. autotrophica subsp. amethystina are ATCC 35203 and ATCC 35204.

Mycoplanecins, novel antimycobacterial antibiotics from Actinoplanes awajinensis subsp. mycoplanecinus subsp. nov. I. Taxonomy of producing organism and fermentation.

Strain No. 41042, an actinomycete isolated from a soil sample, was found to produce 5-azacytidine and new antibiotics, mycoplanecins. Yellowish brown to yellowish orange color of colonies on agar media, formation of globose to subglobose sporangia bearing motile spores and presence of meso- and hydroxy-diaminopimelic acid and glycine in the cell wall ascribed this strain to genus Actinoplanes. From its morphological, cultural and physiological characteristics, this strain was determined to be a new subspecies of Actinoplanes awajinensis and designated as A. awajinensis subsp. mycoplanecinus subsp. nov. Production of mycoplanecins was carried out by conventional submerged culture: the highest antibiotic titer obtained was 145 micrograms/ml.

Mycoplanecins, novel antimycobacterial antibiotics from Actinoplanes awajinensis subsp. mycoplanecinus subsp. nov. II. Isolation, physico-chemical characterization and biological activities of mycoplanecin A.

New antibiotics, mycoplanecins, were found in the culture broth of an actinomycete identified as Actinoplanes awajinensis subsp. mycoplanecinus subsp. nov. Mycoplanecin complex was extracted with organic solvents both from the culture filtrate and mycelium and purified by column chromatography on silica gel and Florisil. Mycoplanecin A, a major component, was separated by high performance liquid chromatography on Prep PAK-500/C18 column. The physico-chemical characterization revealed that mycoplanecin A was a new cyclic peptide antibiotic. Mycoplanecins exhibited strong activities primarily against mycobacteria and related microorganisms.