Antibiotic BU-1880
United States Patent Kawaguchi et al.  
 [ Apr. 29, 1975 l l ANTIBIOTIC BU-1880 221 Filed: Dec. 6, 1972 [2l] Appl. No.: 312,451  
 [52] U.S. Cl 424/119: l95/8() R [51] Int. Cl. H6lk 21/00 [58] Field of Search .4 424/119; l95/8() [56] References Cited OTHER PUBLICATIONS Miller The Pfizer Handbook of Microbial Metabolites, McGraw-Hill Book Co., lnc., N.Y., N.Y., 196l, pp. 371 &amp; 372.  
 Primary E.\uminer lerome D. Goldberg Attorney Agent, or FirmRobert E. Havranek [57 ABSTRACT Antibiotic Bu-l880 is a basic peptide of unknown structure which is fermented from a strain of Bacillus circ&#39;uluns, herein designated 8255-86 and deposited in the American Type Culture Collection as A.T.CiC. No. 2l 828.  
 2 Claims, 1 Drawing Figure ANTIBIOTIC BU-1880 BACKGROUND OF THE INVENTION 1. Field of the Invention:  
  The antibiotic Bu-1880 is a new and novel basic peptide of unknown structure.  
 2. Description of the Prior Art:  
  A. Suzuki, T.; lnouye, K. Fujikawa and Y. Suketa: Studies on the chemical structure of colistin. 1. Fractionation, molecular weight determination, amino acid and fatty acid composition. J. Biochem. 54: 25-33 (1963).  
  B. Stansly, P. G.; R. G. Shepard and H. J. White: Polymyxin, a new chemotherapeutic agent. Bull. Johns Hopkins Hospital 81: 43 (1947).  
  C. Murray, F. J.; P. A. Tetrault, O. W. Kaufmann, H. Koffler, D. H. Peterson and D. R. Collingsworth: Circulin, an antibiotic from an organism resembling Bacillus circulans. J. Bacteriol. 57: 305 (1949).  
  D. Vogler, K. and P. O. Studer: The chemistry of the polymyxin antibiotics. Experientia 22: 345-416 (1966).  
 SUMMARY OF THE INVENTION Antibiotic Bu-1880, a basic peptide of unknown structure, is fermented from a strain of Bacillus circu- Ians designated herein as B255-B6 and deposited in the American Type Culture Collection as A.T.C.C. No. 21828. Chemically the antibiotic is known to contain phenylalanine, leucine and oz, &#39;y-diaminobutyric acid in an approximate molar ratio of about 1:2:5 and 3- hydroxy-S-methyldecanoic acid. The antibiotic is active against gram-positive and gram-negative bacteria both in vitro and in vivo.  
 COMPLETE DISCLOSURE This invention relates to a new and novel antibiotic called Bu-l880. The basic peptide antibiotic has been isolated from the fermentation broth of a new strain of Bacillus circulans, herein designated B255-B6, which was isolated from a soil sample collected in Indore, lndia. The producing organism elaborated several active components in the broth, among which the major and the most active component was isolated first, characterized and designated as Bu-l880. Bu-l880 is a basic peptide antibiotic and extractable into n-butanol from the fermentation broth. Chemically, it contains phenylalanine, leucine and a, &#39;y-diaminobutyric acid with an approximate molar ratio of 1:2:5, along with 3- hydroxy-8-methyldecanoic acid which is a novel fatty acid moiety never before found as a constituent of an antibiotic. Antibiotic Bu-1880 is active against grampositive and gram-negative bacteria both in vitro and in vivo. Compared with the bacterial peptide antibioticcolistin, Bu-ISSO is more active than colistin against gram-positive bacteria but less active against gramnegative organisms. Bu-188O is several times less toxic than colistin in terms of the acute LD The Bu-l880-producing organism, designated strain No. B255-B6 in the Bristol-Banyu culture collection, appears to belong to Genus Bacillus and has the characteristics described below:  
 Morphology Vegetative cell: Rod, 0.5 to 0.7 by 2.5 to 6.0 microns.  
 Motile. Gram-variable, generally negative.  
  Spores: Oval to ellipsoidal, 0.8 to 1.0 by 1.2 to 1.5 microns. Central to terminal. Spore wall thick. Sporangia definitely swollen.  
  Cultural characteristics 1. Nutrient broth: Pellicle and surface ring formed.  
 Turbid. Pellicle and sediment viscous.  
  2. Glucose broth: pH 5.4. Very viscous sediment formed.  
 3. Colony on nutrient agar: Opaque, convex, entire,  
 10 later crenated edge, smooth, later becoming wrinkled, viscous. Mediate size, 2 to 5 mm. in diameter. No or scant motile micro-colony.  
 4. Gelatin-stab: Pellicle and surface ring growth.  
 5. Milk: pH invariable. Viscous surface ring growth.  
  Viscous.  
  6. Growth-temperature: Abundant growth at 28 C. and 42 C. Restricted growth at C. and 45 C. No. growth at 15 C. and 52 C. No growth at pH 6.0, 50 C.  
 20 7. Oxygen demand: Aerobic.  
  8. NaCl broth: Abundant growth at 2%NaCl. Restricted growth at 3 percent-NaCl. No growth at 4%- NaCl.  
 9. Growth factor: None.  
 Physiological characteristics 1. Gas production from sugars: Negative 2. Starch hydrolysis: Positive 3. Acetylmethylcarbinol: Negative 4. lndole: Negative 5. Liquefaction of gelatin: Positive 6. Milk: Coagulated without peptonization 7. Reduction of nitrate to nitrite: Positive 8. Utilization of citrate: Negative 9. Utilization of ammonium-salts: Positive 10. Catalase: Positive 1 1. Urease: Negative 40 12. Acid production from carbohydrates (with ammonium salt as sole nitrogen source): Glycerol L- Arabinose D-Xylose Rhamnose D-Fructose D-Galactose D-Glucose D-Mannose Sucrose Lactose Maltose Raffinose -i, lnositol D- Mannitol D-Sorbitol Dulcitol Starch Cellulose lnuline Salicine In view of the morphological, cultural and physiological characteristics described above, strain B255-B6 was concluded to be classified to a species of Bacillus 0 circulans. The determinative characteristics of strain B255-B6 for this taxonomic identification are summarized below.  
  1. Cell: Rod, Gram-variable. mostly negative.  
  2. Spores: Oval to ellipsoidal. 3. Sporangia: Definitely swollen. 4. No growth under anaerobic conditions. 5. Catalase: Positive. 6. No gas formation from carbohydrate. 7. Starch: hydrolyzed. 8. Acetylmethylcarbionol: Not produced.  
  9. lndole: Not produced. 10. No growth at 52 C. l 1. No growth in 4%-NaCl broth.  
  A culture of the living organism has been deposited in the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Maryland 20852 and has been assigned the following name and catalog number:  
 Antibiotic Production Bacillus circulans strain B255-B6 grows well at 28- 42 C. on agar slant. The well-sporulated agar slant was used to inoculate the germination medium having the following composition: 7.5 percent soybean meal, 2.0 percent corn starch, 0.33% MgSO -7 H and 1.0% CaCO The seed culture was incubated at 28C. for 2 days on a rotary shaker (250 rpm), and 2 ml. of the growth was transferred to 100 ml. of the fermentation medium (same composition as the seed medium) in a SOO-ml. Erlenmeyer flask.  
  The progress of the fermentation was followed by the paper disc-agar plate assay using Bacillus subtilis PCI 219 as the test organism. In one of the shaking flask experiments, the antibiotic production was 250 mcg./ml. on the second day (pH 8.0) and reached the maximum of 1000 mcg./ml. on the third day (pH 8.5). The pilot tank fermentations gave a peak potency of 100-200 mcg./ml.  
 Isolation and Purification The fermentation broth (ca. 300L, 100 meg/ml.) was extracted at pH 8 with about one-half volume of n-b utanol (15OL). The extract was washed with water, concentrated in vacuo and then stirred with 5L of N/5 HCl to transfer the activity. The aqueous acidic extract was again backextracted at pH 8 with 10L of n-butanol. The solvent extract was evaporated in vacuo to a small volume and the concentrate was added with 10 volumes of ethyl acetate-acetone mixture (2:1 to precipitate inactive impurities. The mother liquor was evaporated in vacuo to give about 60 g. of crude Bu-l 880 as a yellowish brown solid.  
  A part of the solid g.) was purified by silica gel chromatography using a column of silica gel (Wakogel C-200, 3.5 cm. diameter X 70 cm.) which was developed by ethanol14 percent ammonia (4:1) solution collecting 10-ml. fractions. Tube Nos. 286 through 470 were combined, concentrated in vacuo and then lyophilized to give 3.4 g. of white powder. A trace amount of impurity in the solid was eliminated by repeating the silica gel chromatography.  
 Physico-chemical Properties Bu-1880 is a white amorphous solid with basic nature (pKa 8.83 in aqueous ethanol) and melts at 239242 C. with decomposition. The specific rotation is: [(11 18 (c. 1.0, N/lO HCl). It has only end absorption in monomer. The theoretical molecular weight for this molecule would be 1058.36.  
  Bu-l88O is soluble in acidic water, aqueous ethanol, aqueous butanol and aqueous dioxane, slightly soluble 5 .in distilled water, methanol, ethanol and n-butanol, and  
 UV (ultraviolet) regions and shows a peptide-type IR 4 (infrared) spectrum (FIG. 1). The NMR (nuclear magnetic resonance) spectrum indicates a presence of aromatic protons at 87.14 ppm. Analytical data are:  
 C, 56.34; H, 8.51; N, 15.92; no halogen, no sulfur. It gives positive reactions with ninhydrin and Ehrlich reagents, and decolorized permanganate. The Sakaguchi reaction is negative.  
  The molecular weight was determined by the ultracentrifugation technique and was determined to be in the range of about 1050i50. This would appear to support a structure comprised of one part phenylalanine, two parts leucine, five parts a, &#39;y-diaminobutyric acid and one part 3-hydroxy-S-methyldecanoic acid as a practically insoluble in alkaline water, acetone and ethyl acetate. The hydrochloride salt is soluble in water and aqueous methanol.  
 The paper and thin-layer chromatographic data are as follows:  
 Paper Chromatography System (ascending) RF n-butanol saturated with water 035 aqueous 3% NH Cl 0.70 acetone-water (1:1) 0.00 n-butanol-methanol-water (4: 1:2) 0.60 above 1.5% methyl orange 0.75 benzene-methanol (4:1) 0.00 water 0.00  
  TLC (Thin Layer TLC plate Chromatography) System RF silica gel n-pr0panol-l77r aqueous NH OH 0.10 do. n-butanol-acetic acid water 0.40  
  (3:1:l) do. n-propanol-pyridine acetic acid- 0.70  
  water (15:10:32) do. chloroform-pyridine-28% NH OH- 0.85  
  water (1:4:211) cellulose n-butanol-ethanol-acetic acid- 0.85  
 water (25:25:3:47)  
  Bu-1880 was hydrolyzed with 6N HCl in a sealed tube for 16 hours. The amino acid analysis of the hydrolysate indicated three amino acids, phenylalanine, leucine and a, y-diaminobutyric acid with an approximate molar ratio of 1:2:5. Extraction of the hydrolysate with ether afforded an acidic substance which was identified with 3-hydroxy-8-methyldecanoic acid.  
  CH OH Biological Activities Antibiotic preparations used in this section were the hydrochloride salt of Bu-1880 and colistin sulfate. The latter was a commercial product supplied by Banyu Pharmaceutical Company Ltd., containing colistins A and B in an approximate ratio of 3:1.  
 Antibacterial spectrum The minimum inhibitory concentrations (MIC) of Bu-1880 against a wide variety of bacteria were deter mined by the serial agar dilution method on nutrient agar plates of pH 7.0. The results are shown in Table 1 along with those of colistin which was used as a reference antibiotic. Bu-1880 inhibits growth of both grampositive and gram-negative bacteria including Pseudomonas species. When compared with colistin, Bu-l880 is less active than colistin against gram-negative bacteria but more active against staphylococci and other gram-positive bacilli. Serratia marcescens and Proteus species are mostly resistant to the both antibiotics.  
 Table I Test Organisms Antibacterial Spectra of Bu-l880 MIC (meg/ml.)  
 Escherichia do. do. do. Klebsiella do.  
  do. Pxeudomzmar Serratia do do. Salmonella do. do.  
  do Shigella do. Shigella Proteus Sarcina M icrocvccus Bacillus do. do  
 Bu- 1 800 Colistin coli NIl-IJ 3.1 0.4 do. J uhl 3. 1 0.4 do. A20363 3.1 0.4 do. K 12 3. 1 0.4 pneumoniae D1 1 3.1 0.4 do. A9678 3. 1 0.8 do. A9977 3. 1 0.4 do. A20680 12.5 12.5 aeruginusa D 1 5 6.3 3. 1 do. A9923 12.5 6.3 do. A9930 3. 1 0.8 do. D1 1 3 1 2.5 6.3 do. Yale 6.3 I .6 multophilia A20620 3.1 3.1 sp. A20355 6.3 1.6 do. A20358 12.5 3.1 do. A20368 100 100 marcescens A200 19 1 00 100 do. A20335 100 100 do. A20442 100 100 enleriridis A935 1 3. 1 0.8 typhosa Yale 3. 1 0.8 do. NIHJ 3. 1 0.4 paralyphi A 3.1 0.4 flexneri A9634 3. 1 0.4 dysenteriae 3. 1 0.4 .i&#39;onnei Yale 3.1 0.4 t&#39;ulgaris A9436 100 100 do. A9699 6.3 12.5 do. ATCC9920 100 100 morganii A9553 100 100 do. A20455 100 100 do. A9900 6.3 100 do. A20454 100 100 aureus Smith 6.3 50 o. No. 193 6.3 50 do. BX-1633 6.3 25 do. Terajima 3.1 12.5 do. Russell 6.3 50 [men PC] 1001 12.5 50 flavus 3. 1 6. 3 mycoides 25 100 cereus ATCC 1 0702 6.3 100 anthracis No.1 15 6.3 100 Table 2 40 Effect of inoculum size Effect of Media pH on MIC (mcg.lm1.)  
 Test Organism Bu-1880 Colistin pH6 pI-l7 pI-18 pH6 pI-I7 pI-I8 E. coli NIHJ 6.3 3.1 3.1 0.8 0.8 0.2 Ps. aeruginosa 3.1 3.1 3.1 3.1 3.1 1.6  
 S. aureus Smith 25 6.3 3.1 100 100 12.5 B. sublilis PCI 1.6 1.6 0.4 25 3.1 0.2  
 Effect of inoculum Size (cell/ml.) on MIC (mcg./m1.)  
 Table 3 The effect of inoculum size of test organisms on the MIC of Bu- 1 880 was tested in Nutrient Broth at pH 7.0, the organisms being inoculated at 10 10 and 10 cell/ml. of the medium. As shown in Table 3, increase of the inoculum size resulted in greated MIC value of Bu-l880 in a like fashion as with colistin.  
 Test Organism E. coli NIHJ 25 3.1 3.1 1.6 0.2  
 Ps. aeruginosa 12.5 3.1 1.6 12.5 0.4  
 S. aureus Smith 6.3 3.1 1.6 50 6.3  
 B. subtilis PCI 1.6 0.8 0.2 3.1 0.2  
 Effect of serum Increasing concentrations of human serum were added to Nutrient Broth to give final serum concentrations of 25 percent, 50 percent and 75 percent. The MICs were determined against four test organisms and colistin was used as a reference. The results are shown in Table 4.  
 Table 4 Effect of Serum on MIC (meg/ml.)  
 Bu-l880 Test Organism Colistin E. culi NIHJ Ps. aeruginosa S. aureus Smith B. sublilis PCI Gun but  
 Table In vivo Activity Test Organism CD (mg/kg.)  
 Bu-1880 Colistin E. coli .luhl 165 3.4 Ps. ueruginosa D 100 15 S. aureus Smith 80 No protection at non-toxic dose mg./kg.).  
 Toxicity The acute toxicity of Bu-1880 (hydrochloride salt) was determined in mice. The subcutaneous and intravenous LD were 300 mg./kg. and 37 mg./kg., respectively. In a comparative test, colistin hydrochloride showed the subcutaneous and intravenous LD of 56 mg./kg. and 11 mg./kg., respectively.  
  Antibiotic Bu-l880 resembles to colistins&#34;, polymyxins and circulins in that they are all bacterial peptide antibiotics containing in the structure a fatty acid moiety and 5 to 6 moles of a, &#39;y-diaminobutyric acid I&#39;Iowever, Bu-l880 is different from the others in the. lack of threonine in the molecule and the presence of new fatty acid moiety, 3-hydroxy-8-methyldecanoic acid, which to our knowledge is the first occurrence innatural products.  
  The antibacterial spectra of the bacterial peptide antibiotics are generally limited to either gram-negative or gram-positive. The colistin-polymyxin-circulin group of antibiotics are mainly active against gramnegative bacteria, and gramicidin-bacitracin groups are primarily active against gram-positive organisms. Bu- 1880 is therefore different from these known antibiotics in its broader antibacterial spectrum.  
 the bowel. Both aerobic and anaerobic flora which are suseptible to Bu-1880 is reduced in the large intestine. When accompanied by adequate mechanical cleansing, they are useful in preparing for colonic surgery.  
  Bu-l880 is effective in the treatment of systemic bacterial infections when administered parenterally in the dosage range of about 250 mg. to about 3000 mg. per day in divided doses three or four times a day. Generally it is effective when administered at a dosage of about 5.0 to 7.5 mg./kg. of body weight every 12 hours.  
  A preferred embodiment of the present invention is the process for the preparation of the antibiotic Bu- 1880, a basic peptide comprised of phenylalanine, leucine and a, y-diaminobutyric acid in an approximate molar ratio of 1:2:5 and 3-hydroxy-8-methyldecanoic acid, having the infrared spectrum of FIG. 1 and the following physical characteristics: pKa of 8.83 in aqueous ethanol, m.p. of 239-242 C. with decomposition, [a] =18(c. 1.0, N/lO HCl) and an elemental analysis of C, 56.34; H, 8.51; N, 15.92, and a molecular weight of about 1050:50; which process comprises aerobically fermenting Bacillus circulans A.T.C.C. 21828 and recovering the antibiotic by extraction.  
  A most preferred embodiment is the antibiotic Bu- 1880, a basic peptide comprised of phenylalanine, leucine and a, &#39;y-diaminobutyric acid in an approximate molar ratio of 1:225 and 3-hydroxy-8-methyldecanoic acid, having the infrared spectrum of FIG. 1 and the following physical characteristics: pKa of 8.83 in aqueous ethanol, m.p. of 239242 C. with decomposition, [a] &#39;-18 (c. 1.0, N/lO I-ICl), an elemental analysis of C, 56.34; H, 8.51; N, 15.92; and a molecular weight of l050i50.  
 We claim:  
  1. The antibiotic Bu-1880, a basic peptide comprised of phenylalanine, leucine, a, &#39;y-diaminobutyric acid and 3-hydroxy-8-methyldecanoic acid in an approximate molar ratio of l:2:5:1, having the infrared spectrum of FIG. 1 and the following physical characteristics: pKa of 8.83 in aqueous ethanol, m.p. of 239-242 C. with decomposition, [a] =18(c. 1.0, N/lO I-lCl), an elemental analysis of C, 56.34; H, 8.51; N, 15.92, and a molecular weight of about 1050fi0.  
  2. The process for the preparation of the antibiotic Bu-1880, a basic peptide comprised of phenylalanine, leucine, a, &#39;y-diaminobutyric acid and 3-hydroxy-8- methyldecanoic acid in an approximate molar ratio of 1:2:5: l having the infrared spectrum of FIG. 1 and the following physical characteristics: pKa of 8.83 in aqueous ethanol, m.p. of 239242 C. with decomposition, [a] =l8 (c. 1.0, N/lO HCl), an elemental analysis cally fermenting Bacillus circulans A.T.C.C. 21828 in a carbohydrate-proteinrich media for a period of about two to about three days, at a pH of about 8 to about 8.5, at a temperature of about 28 C., and then recoverof 56.34; -9 and a m l l r gh 5 ing the antibiotic by extraction with n-butanol.  
 of about 1050-50; which process comprises aerobi-