Structural elucidation of aculeximycin. III. Planar structure of aculeximycin, belonging to a new class of macrolide antibiotics.

The planar structure of aculeximycin (1) produced by Streptosporangium albidum has been determined by spectral methods and chemical degradations such as 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU)-methanol reaction, ozonolysis, and periodative oxidation. The antibiotic consists of a 30-membered polyhydroxy lactone ring, an alpha, beta-unsaturated ester group, an intramolecular hemiketal, an oligosaccharide (aculexitriose), a neutral sugar and an amino sugar. The structure of aculeximycin is closely related to those of sporaviridins produced by Streptosporangium viridogriseum. We consider that aculeximycin and sporaviridins belong to a new class of macrolide antibiotics, which is different from the polyol macrolides produced by Streptomyces.

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.

Cornexistin: a new fungal metabolite with herbicidal activity.

Cornexistin, a new compound demonstrating promising herbicidal activity, was purified from the culture filtrate of a newly-isolated fungus identified as Paecilomyces variotii SANK 21086. The compound was extracted with organic solvents from the culture filtrate, purified using column chromatography on Sephadex LH-20 and finally crystallized from methylene chloride. Following analysis of its physico-chemical properties it was identified to be a new compound belonging to the nonadride group. Chemical structure elucidation was conducted by analyses of various spectral data and the structure was finally confirmed by means of X-ray crystallographic analysis. Based on its herbicidal characteristics cornexistin may be classified as a postemergence herbicide active against certain young annual and perennial monocotyledonous and dicotyledonous plants with selective protection for corn.

Synerazol, a new antifungal antibiotic.

Synerazol, a new antifungal antibiotic, was isolated from cultured broth of Aspergillus fumigatus SANK 10588. The structure was determined based on NMR and mass spectral evidences. Synerazol was found to be a related substance to pseurotin A. Synerazol was active against Candida albicans and other fungi, and showed marked synergistic activity with azole-type antifungal agents.

Hydantocidin: a new compound with herbicidal activity from Streptomyces hygroscopicus.

Hydantocidin, a new compound with potent non-selective herbicidal activity, was found in a submerged culture of Streptomyces hygroscopicus SANK 63584. It was isolated from the culture filtrate by the following successive treatments comprised of activated carbon, Diaion HP-20, Dowex 50WX4, and Avicel column chromatographies. Finally it was crystallized as colorless needles from acetone. The molecular formula, C7H10N2O6, was determined by analyses of HRFAB mass spectrum in conjunction with 13C NMR spectrometry. The structural elucidation revealed that it has a unique structure with a spiro-bond between ribose and hydantoin moieties in the molecule. The characteristic herbicidal activities against annuals as well as perennials, including monocotyledonous and dicotyledonous weeds, were observed.

New diterpenoid antibiotics, spirocardins A and B.

New antibiotics spirocardins A and B were isolated from the culture broth of an actinomycete isolated from a soil sample collected near Lake Hibara, Fukushima Prefecture, Japan. The producing strain was classified as Nocardia sp. SANK 64282. The antibiotics were isolated from the culture filtrate by solvent extraction and purified further by silica gel and preparative reverse phase column chromatography. They were primarily active against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus and limited species of Gram-negative bacteria such as Bacteroides fragilis and Klebsiella pneumoniae. They were also moderately active against several species of Mycoplasma. The molecular formulae of spirocardins A and B were C20H30O6 and C20H32O6, respectively. From their physico-chemical characteristics they were revealed to be diterpenoid antibiotics with closely related structures and the former was easily converted to the latter by the reduction with NaBH4.

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. I. Taxonomy, fermentation, isolation and physico-chemical properties.

A strain of actinomycetes identified as Streptomyces flavidovirens produced new antibiotics, mureidomycins (MRD's) A approximately D, specifically active against Pseudomonas aeruginosa. They were isolated from the culture filtrate by successive column chromatographies such as Amberlite XAD-2 and CG-50, Whatman DE-52 and Toyopearl HW-40. They were amphoteric white powders and soluble in methanol and water. Their molecular weights and molecular formulae in parentheses were 840 (C38H48N8O12S), 842 (C38H50N12S), 897 (C40H51N9O13S) and 899 (C40H53N9O13S), respectively. m-Tyrosine and two unknown substances were detected by amino acid analyses as their common constituents. MRD's A and C contained uracil but MRD's B and D dihydrouracil instead of uracil.

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. II. Structural elucidation.

Structures of new antibiotics, mureidomycins (MRD's) A approximately D, were deduced from spectroscopic analyses and degradation studies. Two residues of m-tyrosine, one residue of 2-amino-3-N-methylaminobutyric acid (AMBA) and methionine are present in all components of the complex. Uracil is contained in MRD's A and C, while dihydrouracil in MRD's B and D. Methionine and m-tyrosine are connected through an ureido bond, and uracil or dihydrouracil is linked to AMBA via enamine sugar moiety. In addition, MRD's C and D contain a glycine residue at the N-terminal.

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. III. Biological properties.

Mureidomycins (MRD's) A-D were specifically active against Pseudomonas aeruginosa. Among them, MRD C was most active, with MICs of 0.1 to 3.13 micrograms/ml against many strains of the target organism. Its activity was comparable to that of cefoperazone, ceftazidime and cefsulodin. MRD C-resistant mutants of P. aeruginosa appeared spontaneously at a high frequency when cultured in the presence of the antibiotic. No cross-resistance was observed with beta-lactam antibiotics. A rapid decrease of turbidity along with spheroplast formation and cell lysis was observed when cells of P. aeruginosa were grown in the presence of MRD C. The compounds exhibited low toxicity and protected mice from experimental infection with P. aeruginosa. The urinary and fecal recoveries of MRD C given subcutaneously were 5 and 18%, respectively.

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.

Fosfonochlorin, a new antibiotic with spheroplast forming activity.

A new antibiotic, fosfonochlorin, was found in the culture filtrate of four strains of fungi freshly isolated from soil samples. These strains were identified as Fusarium avenaceum, Fusarium oxysporum, Fusarium tricinctum and Talaromyces flavus. Fosfonochlorin was a low molecular weight antibiotic (MW 158), soluble in water and methanol, but insoluble in acetone, ethyl acetate and chloroform. It was named after its possession of phosphorus and chlorine atoms, each one molar in its structure. The structure was determined as chloroacetylphosphonic acid mainly by the 1H NMR and mass spectrometric analyses. It was moderately active against some species of Gram-negative bacteria and its synergistic effect with glucose-6-phosphate was observed on Staphylococcus aureus and Escherichia coli. Spheroplast formation of the susceptible organisms with this antibiotic suggested that it might inhibit their cell wall synthesis.

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. II. Fermentation, isolation and physico-chemical characterization.

New antibiotics, chloropolysporins A, B and C, were found in the culture broth of an actinomycete identified as Faenia interjecta sp. nov. They were isolated from the culture filtrate by column chromatography on various resinous adsorbents, followed by preparative reverse phase HPLC. Chloropolysporins A, B and C possessed all the same new aglycone composed of actinoidic acid, 3-chloro-4-hydroxyphenylglycine, N-methyl-p-hydroxyphenylglycine and vancomycinic acid. From elementary analyses and mass spectroscopic measurements, the molecular formulae of chloropolysporins A, B and C appear to be C89H99O39N8Cl3 (MW 2,008), C83H89O34N8Cl3 (MW 1,846) and C77H79O30N8Cl3 (MW 1,700), respectively. Their physico-chemical characterizations including molecular formulae revealed that chloropolysporins A, B and C were new members of glycopeptide antibiotics.

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. III. Structure elucidation of chloropolysporins.

Structure elucidations of chloropolysporins A, B and C were achieved mainly by chemical degradation studies. These components possessed the same pseudoaglycone in common and their structures were closely related to that of beta-avoparcin. The structures of chloropolysporins differ from that of beta-avoparcin in the presence of vancomycinic acid moiety instead of monodechlorovancomycinic acid moiety and glucose, not ristosaminylglucose, in its side chain. Chloropolysporin C was identified as derhamnosylchloropolysporin B based on its 1H NMR and mass spectral analysis and degradation studies. Two minor components, chloropolysporins D and E, were identified as the epimers of each of chloropolysporins B and C, respectively, based on their Cotton effects and retention times on reverse phase HPLC.

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. V. Comparative studies of the biological properties.

Chloropolysporins A, B and C, as well as derivatives prepared from this group and alpha- and beta-avoparcins by enzymatic and mild acid hydrolysis, were active against Gram-positive bacteria including clinically isolated methicillin-resistant Staphylococci (MIC 0.39-6.25 micrograms/ml) and anaerobic enterobacteria (MIC 0.10-1.56 micrograms/ml). Derhamnosyl and demannosyl derivatives from both groups of antibiotics showed stronger activities than the parent compounds. The MIC and MBC values against Staphylococci were similar and were not effected by the presence of serum. Moreover, chloropolysporin C exhibited very strong synergistic effects with various beta-lactam antibiotics against methicillin-resistant strains of Staphylococcus aureus. Some of these compounds also protected mice from experimental infection with S. aureus. Acute toxicities of chloropolysporin by intravenous administration ranged from 215-290 mg/kg in mice. Chloropolysporin B as well as other glycopeptide antibiotics, showed distinctive growth promoting activity in broiler chickens.

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. IV. Partially deglycosylated derivatives.

Chloropolysporins A, B and C, new members of the glycopeptide antibiotic family, were enzymatically and chemically converted to their partially deglycosylated derivatives. The alpha- and beta-avoparcins were also deglycosylated by the same method. The conversions were achieved by treatments with rhamnosidase (Naringinase) and alpha-mannosidase, and by mild acid hydrolysis.

Effects of a new antibiotic, isohematinic acid, on the resistance of mice to experimental infections.

Isohematinic acid, an antibiotic newly isolated from the culture broth of Actinoplanes philippinensis SANK 61681, was assessed for its ability to enhance nonspecific resistance to bacterial infections against Escherichia coli and Pseudomonas aeruginosa in mice. This agent, as well as BM 12,531 (Azimexon), was found to prolong the survival of normal mice infected with E. coli and also of compromised mice infected with either E. coli or P. aeruginosa, whose defense system had been deteriorated by treatment with carboquone, an alkylating agent. Like BM 12,531, isohematinic acid administered to normal mice significantly increased the nitroblue tetrazolium reducing potency of polymorphonuclear leucocytes (PMN), indicating that the microbicidal activity of PMN was enhanced by these agents. In addition, in the compromised mice these agents were able to restore the number of peripheral blood leucocytes, which had been reduced to about 30% of the normal level by carboquone. These results suggest that isohematinic acid, like BM 12,531, enhances nonspecific resistance to these bacterial infections by stimulating the microbicidal activity of PMN and inducing leucocytosis.