A strain of Bacillus circulans produced a complex of basic peptide antibiotics designated Bu-2470, which was found to contain four active components, A, B1, B2a and B2b. Bu-2470 A specifically inhibited various Pseudomonas species including P. aeruginosa, P. maltophilia and P. putida, but otherwise its antibacterial spectrum was limited to certain Gram-negative organisms. Bu-2470 B1 and B2 (B2a+B2b) showed broad antibiotic activity against Gram-positive and Gram-negative bacteria including Pseudomonas species. The physicochemical and biological properties of Bu-2470 B1 and B2 are very similar to those of the octapeptin group of antibiotics.
The structures of Bu-2470 A, B1, B2a, and B2b have been determined. Bu-2470 A is a simple octapeptide having no fatty acid moiety, while Bu-2470 B1, B2a and B2b are octapeptides that have been acylated with a β-hydroxy C11 or C10 fatty acid. The octapeptide structure of Bu-2470 components was found identical with that of octapeptin C1, hence generic names of octapeptin C0, C2, C3 and C4 are proposed for Bu-2470 A, B1, B2a, and B2b, respectively.
A strain of Streptomyces was found to produce new antifungal antibiotics. The active compounds were purified and separated into two substances named leptomycin A and B by high performance liquid chromatography. The molecular formulae of leptomycins A and B are C32H46O6 and C33H48O6 respectively, and physicochemical and biological properties of them are very similar to each other. Leptomycins A and B exhibit strong inhibitory activity against Schizosaccharomyces and Mucor.
The structures of new antifungal antibiotics, leptomycins A and B produced by Streptomyces sp. ATS1287 were determined as described below (Fig. 1) on the basis of their spectral and chemical character. Leptomycins have unique structures which belong to the unsaturated, branched-chain fatty acids with δ-lactone rings at the end.
A new aminoglycoside antibiotic, saccharocin has been isolated from the fermentation broth of Saccharopolyspora sp. AC-3440 (FERM P-6238) by column chromatography on a cation-exchange resin. Saccharocin is active against Gram-positive and Gram-negative bacteria. The structure was elucidated to be 4"-deamino-4"-hydroxyapramycin by 13C NMR spectral analysis.
Vanoxonin, a new inhibitor of thymidylate synthetase, was found in cultured broths of the strain MG245-CF2 classified as Saccharopolyspora hirsuta. Vanoxonin, C15H25N3O9, was obtained as colorless powder. Vanoxonin forms a vanadium complex which exhibits a strong inhibition against thymidylate synthetase. The concentration for 50%. inhibition of the enzyme (IC50) was 0.7 μg/ml.
Two new antifungal (E)-β-methoxyacrylates, strobilurin C and oudemansin B, were isolated from cultures of Xerula longipes and Xerula melanotricha. Their structures were elucidated by spectroscopic methods. Both antibiotics inhibit the growth of a wide variety of saprophytic and phytopathogenic fungi at very low concentrations. Like strobilurins A, B, and oudemansin A the new metabolites are potent inhibitors of respiration.
An inhibitor of cyclic adenosine 3', 5'-monophosphate (cAMP) phosphodiesterase was isolated from the culture filtrate of Bacillus subtilis C-756 isolated from soil. It was purified and finally separated into three fractions by reverse-phase HPLC. The respective fractions were designated as APD-I, -II and -III in the order eluted and the relative quantities of APD-I, -II and -III were approximately 10%, 40% and 50%, respectively. They were acylpeptides composed of β-hydroxy fatty acid residues and heptapeptide. Though the amino acid compositions of the peptides were the same, the fatty acid residues were all different. APD-I contained a mixture of 3-hydroxy-11-methyldodecanoic acid (i-C13h3) and 3-hydroxy-10-methyldodecanoic acid (α-C13h3). APD-II contained 3-hydroxytetradecanoic acid (n-C14h3). APD-III contained a mixture of 3-hydroxy-13-methyltetradecanoic acid (i-C15h3) and 3-hydroxy-12-methyltetradecanoic acid (α-C15h3).
Bacillus subtilis C-756 produced three kinds of inhibitors of cyclic adenosine 3', 5'-monophosphate (cAMP) phosphodiesterase. Each was an acylpeptide consisting of a β-hydroxy fatty acid residue and heptapeptide. By the application of mass spectrometry, the amino acid sequence of peptide was determined to be β-hydroxy fatty acid-Glu-Leu-Leu-Val-Asp-Leu-Leu in all three cases. Each had a lactone linkage between the carboxyl group of C-terminal leucine and the β-hydroxyl group of the fatty acid moiety. The total structures of these inhibitors were thus established.
Acylpeptides, APD-I, -II and -III, were inhibitors of cyclic adenosine 3', 5'-monophosphate (cAMP) phosphodiesterase, and their inhibition types were non-competitive. The inhibitory activity of APD-II was the most potent among them. Opening of the lactone linkage reduced the inhibitory activity to about half. The activity almost disappeared when an inhibitor or a derivative with opened lactone linkage was methylated with diazomethane. The activity was, however, restored by the addition of metal ions such as Ca2+, Mn2+, Fe2+, and Co2+. This suggests that the inhibition may be caused by a chelating action of the free carboxyl groups of glutamic acid and aspartic acid in the peptide.
A new biologically active substance, M-9337, was obtained from Streptomyces strain M-9337, a soil isolate. The producing organism was subsequently determined to be a new strain and named Streptomyces antihaemolyticus M-9337. The active substance was prepared as white yellow powder from culture broth by solvent extraction and silica gel thin-layer chromatography. It showed no antimicrobial activity and potent inhibitory activity against streptolysin, a type of hemolysin.
Cultures of actinomycete strain WRAT-210 produced a dark red crystalline metabolite which was named texazone. Spectroscopic evidence suggested that the structure of texazone is 2-(N-methylamino)-3 H-phenoxazin-3-one-8-carboxylic acid. The structure was confirmed by chemical synthesis through oxidative dimerization of ethyl 3-amino-4-hydroxybenzoate with 2-(N-methylamino)phenol and subsequent hydrolysis of the resultant phenoxazinone ester.
Bestatin, an immunomodulator useful in cancer treatment with the structure: N-[(2S, 3R)-3-amino-2-hydroxy-4-phenylbutanoyl]-L-leucine, has been synthesized from N-acyl-α-aminoacetophenone. This novel method using readily available reagents and mild conditions can be applied to a large scale production of this useful agent. The overall yield of bestatin was 10.5% from N-acetyl-α-aminoacetophenone and 7.8%. from N-benzoyl-α-aminoacetophenone. Bestatin(1) is an aminopeptidase B inhibitor discovered in a culture filtrate of Streptomyces1-3 ).
Cephalosporin C biosynthesis by Cephalosporium acremonium was delayed until most glucose in the medium was used. Addition of increasing concentrations of glucose up to 55 g/liter decreased cephalosporin C biosynthesis but stimulated growth. Sequential formation of penicillin N (an intermediate in the cephalosporin C biosynthetic pathway) and cephalosporin C was found when the culture was developed synchronously. Little cephalosporin C formation was observed until most penicillin N had already been formed. The sequential formation of penicillin N and cephalosporin C was due to the sequential formation of the "penicillin N synthetase system" and the "gcephalosporin C synthetase system" Cells grown in the presence of glucose showed an increased accumulation of penicillin N and clear reduction of the conversion of penicillin N to cephalosporin C. Resting cell studies indicated that the glucose effect was due to the repression of one or more of the enzymes converting penicillin N into cephalosporin C. Little inhibition by glucose of the activity of these enzymes, once formed, was observed. Glucose did not effect significantly the pool sizes of either precursor amino acids of cephalosporin (α-aminoadipic acid and valine) or methionine (an inducer of penicillin N and cephalosporin C biosynthesis). On the basis of these data it is suggested that glucose catabolism specifically represses the enzyme system converting penicillin N into cephalosporin C.
The preparation of α-D-benzylpenicilloyl-n-propylamine and octa-ε-(α-D-benzylpenicilloyl)-octa-α-L-lysine are described. Their structures were established by chemical and spectroscopic evidence. Proton and carbon-13 nuclear magnetic resonance spectra of these two penicillin derivatives and some related compounds are provided. These compounds are useful in skin testing for penicillin allergy.
With the use of three human lung cultured cell lines : normal diploid fibroblasts (WI38), their SV40-transformants (VA13) and carcinoma cells (A549), whose doubling times were similar, the cytotoxicity of the protein antitumor antibiotics, auromomycin (AUR) and macromomycin (MCR), was studied by colony formation method. The susceptibilities of the three cell lines to these antibiotics were in the order: WI38
The free chromophores isolated from the antitumor protein antibiotics, auromomycin (AUR) and macromomycin (MCR), were rapidly inactivated by incubation in serum-containing medium at 37°C in the dark with respect to cytocidal activity to human lung carcinoma A549 cells. Under the same conditions, the intact antibiotics, their pronase-hydrolysates and reconstituents from the Chromophores and apo-proteins were stable. IntaCt and reconstituted AUR and MCR were more resistant to pronase digestion than the apo-proteins. The analyses of the pronase-hydrolysates of AUR and MCR by SDS-polyacrylamide gel electrophoresis and ultrafiltration showed that the antibiotics (13 kilodaltons (kDa)) were degraded to produce peptide fragments (1-3 kDa) in which most cytotoxicity of the pronase-hydrolysates resided. The pronase-hydrolysates exhibited a differential cytocidal activity to normal diploid fibroblasts (WI38), their SV40-transformants (VA13) and carcinoma cells (A549) of human lung origin as was observed for the intact antibiotics. These results indicate that specificinteraction between the chromophores and the pronaseresistant peptide segments (1-3 kDa) of the protein moiety stabilizes the cytocidal activity of the chromophores and also protects the peptide segments from pronase digestion.
The microbial product bestatin is known to inhibit soluble microsomal- and cytosolic leucine aminopeptidase (Leu-APm and Leu-APc) as well as aminopeptidase B (AP-B). To clarify which of these enzymes is the target for bestatin on the cell surface, indirect immunofluorescence studies with antisera raised against purified Leu-APm and AP-B were performed. These antibodies (anti-Leu-APm and anti-AP-B) were found to react with intracellularly localized Leu-APm and AP-B of ethanol-treated L5178y cells. Using non-treated L5178y cells fluorescence was detected only on the cell surface after incubation with anti-Leu-APm. To confirm the supposition that only Leu-APm is present on the cell surface, the AP from the cell membrane was solubilized and analyzed electrophoretically. Based on relative migration data it could be shown, that the cell surface is charged with Leu-APm and not with detectable amounts of Leu-APc or AP-B. Moreover, it could be demonstrated that the solubilized Leu-APm binds to [3H]bestatin.