CL-1957A antibiotic compound

Abstract

A purified isolate of an actinomycete identified as ATCC 39366 is capable of producing the anti-microbial compound CL-1957A which also exhibits antitumor properties.The antimicrobial compound CL-1957A is produced by cultivating isolate ATCC 39366 under aerobic conditions in a culture medium containing assimilable sources of carbon and nitrogen until a substantial quantity of the CL-1957A compound is produced, and subsequently isolating the CL-1957A compound.The antibiotic compound CL-1957A and pharmaceutical compositions comprising this substance together with a pharmaceutically acceptable carrier is also disclosed, as are methods of treating microbial infections and tumors in mammals, employing these pharmaceutical compositions.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an antibiotic compound demonstrating antitumor activity, designated CL-1957A, to pharmaceutically acceptable salts thereof, to a process for the production of said compound, and to a purified isolate of an actinomycete capable of producing this compound.

More particularly, the process of producing the CL-1957A antibiotic compound relates to an aerobic fermentation process using a purified isolate of an actinomycete, identified as isolate ATCC 39366.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is provided a purified isolate of an actinomycete having the identifying characteristics of ATCC 39366 which is capable of producing the antibiotic compound CL-1957A.

In another aspect of the invention, there is provided a process for producing CL-1957A by cultivating the isolate of actinomycete identified as ATCC 39366 under aerobic conditions in a medium containing assimilable sources of carbon and nitrogen until a substantial quantity of CL-1957A is produced, and subsequently isolating the CL-1957A compound.

In accordance with another aspect of the invention, there are provided the antibiotic compound CL-1957A and its pharmaceutically acceptable salts, which compounds exhibit antibiotic and antitumor properties.

In another aspect of the present invention, there are provided pharmaceutical compositions comprising the CL-1957A compound, its pharmaceutically acceptable salts and, optionally, additional antibiotic and/or antitumor compounds together with a pharmaceutically acceptable carrier.

In a further aspect of the present invention, a method of treating microbial infections in a mammal comprises administering an effective amount of the compound CL-1957A or a pharmaceutically acceptable salt thereof in combination with a pharmaceutically acceptable carrier.

In another aspect of the present invention, a method of treating tumors in mammals comprises administering an effective amount of the compound CL-1957A or a pharmceutically acceptable salt thereof in combination with a pharmaceutically acceptable carrier.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1a, 1b, 1c, and 1d are the ultraviolet, infrared, 360 MHz proton magnetic resonance, and 90.5 MHz .sup.13 C nuclear magnetic resonance spectra, respectively, of the compound designated CL-195A.

DETAILED DESCRIPTION

In accordance with the present invention, the CL-1957A antibiotic compound is produced by cultivating a selected isolate of actinomycete, isolate ATCC 39366, under artificial conditions until a substantial quantity of CL-1957A is formed, and subsequently isolating the compound.

The strain of actinomycete suitable for the purpose of this invention was found in a soil sample collected in Pennsylvania, USA. This microorganism was isolated from the soil sample using a suitable agar plating medium, one containing salts such as potassium phosphate, magnesium sulfate, and ferrous sulfate, and carbon sources such as glycerol and asparagine. The strain of microorganism was plated onto the agar medium and, once plated, was incubated at a favorable temperature, particularly 45.degree. C., to allow for the development of the soil microorganisms.

The CL-1957A producing organism that was isolated from the soil sample by the agar plating technique is an unidentified isolate of actinomycete and has been deposited with the American Type Culture Collection, Rockville, Maryland 20852, where it is being maintained in their permanent culture collection as ATCC 39366. This organism, which produces CL-1957A, is also being maintained as a dormant culture in lyophile tubes, cryogenic vials, and in soil tubes in the Warner-Lambert/Parke-Davis Culture Collection, 2800 Plymouth Road, Ann Arbor, Michigan 48105, where it is designated as culture WP-2053.

The compound CL-1957A, which demonstrates both antibiotic and antitumor properties, is produced by isolate ATCC 39366 during aerobic fermentation under controlled conditions. The fermentation medium consists of sources of carbon, nitrogen, minerals, and growth factors. Examples of carbon sources are glycerol and various simple sugars, such as glucose, mannose, fructose, xylose, ribose, or other carbohydrate-containing compounds such as dextrin, starch, cornmeal, and whey. The normal quantity of carbon source materials in the fermentation medium varies from about 0.1 to about 10 weight percent.

Nitrogen sources in the fermentation medium are organic, inorganic, or mixed organic-inorganic material. Examples of such materials are cottonseed meal, soybean meal, corn germ flour, corn steep liquor, distillers dried solubles, peanut meal, peptonized milk, and various ammonium salts.

The addition of minerals and growth factors are also helpful in the production of the CL-1957A compound. Examples of fermentation medium mineral additives include potassium chloride, sodium chloride, ferrous sulfate, calcium carbonate, cobalt chloride, and zinc sulfate. Sources of growth factors include various yeast and milk products.

The preferred method for producing the CL-1957A compound is by submerged culture fermentation. According to this embodiment of the invention, the fermentation ingredients are prepared in solution or suspension and the mixture subsequently sterilized by autoclaving or steam heating. The pH of the aqueous medium is adjusted to preferably between about pH 4 and about pH 8 and the mixture cooled following sterilization to a temperature between about 16.degree. C. to about 45.degree. C. The cooled, sterile fermentation medium is inoculated with the organism and thereafter fermentation is carried out with aeration and agitation.

In the submerged culture method, fermentation is carried out in shake-flasks or in stationary tank fermentors. In shake-flasks, aeration is achieved by agitation of the flasks to bring about mixing of the medium with air. In stationary tank fermentors, agitation is provided by impellers which may take the form of disc turbines, vaned discs, open turbine or marine propellers. Aeration is accomplished by injecting air or oxygen into the agitated mixture.

Adequate production of the CL-1957A compound is normally achieved under these conditions after a period of about two to ten days.

In an alternative embodiment, the CL-1957A compound may also be produced by solid state fermentation of the microorganism.

The following examples are provided to enable one skilled in the art to practice the present invention and are merely illustrative thereof. They are not to be viewed as limiting the scope of the invention as defined by the appended claims.

Fermentative Production of the CL-1957A Compound

EXAMPLE 1

The culture of actinomycete (ATCC 39366) of the present invention, following its isolation from the agar plate, was transferred to an agar slant employing CIM 23 medium and incubated at 28.degree. C. for 7 to 14 days.

TABLE I______________________________________Formulation of CIM 23 Medium______________________________________Amidex corn starch 10 gN-Z amine, type A 2 gBeef Extract (Difco) 1 gYeast Extract (Difco) 1 gCobalt chloride pentahydrate 20 mgAgar 20 gDistilled water 1000 ml______________________________________

A portion of the microbial growth from the agar slant was used to inoculate an 18-mm .times.150-mm test tube containing 5 ml of SD-05 seed medium. The inoculated seed was shaken at 24.degree. C., 170 rpm, for three to four days.

TABLE II______________________________________Formulation of SD-05 Seed Medium______________________________________Amberex 1003 (Amber Laboratories) 0.5%Glucose monohydrate (Cerelose) 0.1%Dextrin-Amidex B 411 (Corn Products) 2.4%N-Z Case (Humko Sheffield) 0.5%Spray-dried meat solubles (Daylin Labs) 0.3%Calcium carbonate 0.2%______________________________________

EXAMPLE 3

A 1-ml portion of the microbial growth of Example 2 was transferred to a 185-ml shake-tube containing 25 ml of SM-57 screening medium.

TABLE III______________________________________Formulation of SM-57 Screening Medium______________________________________Sucrose 1.5%Lactose 1.0%Peptonized milk 0.65%Fish meal 0.35%Torula yeast 0.25%______________________________________

The inoculated shake-tube was incubated at 24.degree. C. for four days with shaking (170 rpm gyratory shaking, 5 cm throw). Production of the CL-1957A compound was observed for the first time in this broth.

To confirm the fermentation activity of the microorganism, a second 50-ml batch of SM-57 screening medium, contained in a 300-ml baffled shake-flask, was inoculated with 2 ml of microbial seed from Example 2. This mixture was incubated at 24.degree. C. for four days with shaking (170 rpm gyratory shaking, 5 cm throw). After four days, the fermentation beer was granular to mycelial in appearance, and the pH was in the range of pH 5.5-6.0.

The antitumor activity of this fermentation broth was assayed at a dilution of 1:100 versus L1210 mouse leukemia cells grown in tissue culture. The assay technique is fully described in Cancer Chemotherapy Reports, Part 3, Vol. 3, No. 2 (1972), Deran, Greenberg, MacDonald, Schumacher, and Abbott. A broth which gave L1210 leukemia cell growth rates of 0 to 35%, compared with the growth of these cells under control conditions, was considered active, 0%, most active. The observed activities of the fermentation broth of Example 3 are given in Table IV.

TABLE IV______________________________________Antitumor Activity of Fermentation Broth fromExample 3 (As Measured Against L1210 MouseLeukemia Cells)Sample % L1210 Cell Growth______________________________________Broth from shake-tube 11Broth from shake-flask 6______________________________________

The crude fermentation beer from Example 3 was also tested for antimicrobial activity against several microorganisms employing the agar-disc method. The crude beer was found to be active against Agrobacterium tumefaciens, Alcaligenes viscolactis, Bacillus subtilis, Branhamella catarhalis, Escherichia coli, Micrococcus luteus, and Micrococcus lysodeikticus.

EXAMPLE 4

Two 2-liter shake-flasks, each containing 300 ml of SM-57 screening medium, were inoculated with 12 ml of microbial seed. The flasks were incubated for four days at 24.degree. C. with shaking (170 rpm gyratory shaking, 5 cm throw).

The fermentation beer from the two flasks was pooled and tested for antitumor activity against both L1210 mouse leukemia cells grown in tissue culture and P388 murine lymphocytic leukemia in vivo. Both tests were conducted in accordance with the methods detailed in Cancer Chemotherapy Reports, Part 3, Vol. 3, No. 2 (1972) referenced above.

The crude beer was observed to limit L1210 cell growth to 6% in vitro. The results of the P388 in vivo tests appear in Table V. The data are given there in terms of % T/C values where: ##EQU1##

TABLE V______________________________________Antitumor Activity of Fermentation Broth fromExample 4 (As Measured Against P388 MurineLymphocytic Leukemia In Vivo)Dilution of Fermentation % T/CBeer Test 1 Test 2______________________________________undiluted Toxic --1:2 66 (Toxic) 59 (Toxic)1:4 146 1261:8 -- 140 1:16 -- 117______________________________________

EXAMPLE 5

Culture suspension (1 ml) from a cryogenic vial was thawed and aseptically transferred to a 2liter baffled flask containing 600 ml of SD-05 seed medium. The inoculated flask contents were incubated for 72 hours at 34.degree. C. with shaking (130 rpm gyratory shaking, 5 cm throw).

After 72 hours, the contents of the seed flask were transferred aseptically to a 30-liter jar fermentor containing 16 liters of SD-05 seed medium. The inoculated jar contents were incubated for 24 hours at 24.degree. C. while being stirred at 300 rpm and sparged with air at a rate of 1 vol/vol/min.

EXAMPLE 6

Three 30-liter stirred-jars, each containing 16 liters of PM-10 production medium, were sterilized by autoclaving for 40 minutes at 121.degree. C. The fermentors and contents were cooled and each was inoculated with about 800 ml of the microbial growth from Example 5. The inoculated production jars were incubated for six days at 24.degree. C. while being stirred at 300 rpm and sparged with air at a rate of 1 vol/vol/min. Dow Corning "C" antifoam agent was used to control foaming.

TABLE VI______________________________________Formulation of PM-10 Production Medium______________________________________Maltose 1.5%Glucose monohydrate 1.0%Cotton seed meal (Pharmamedia) 0.75%Corn meal 0.4%Torula yeast 0.25%______________________________________ Note: pH adjusted to 6.5 with NaOH

The production of the Cl-1957A compound was monitored throughout the fermentation cycle by assay against L1210 mouse leukemia in vitro, and by measuring antimicrobial activity against several microorganisms. In addition, such fermentation parameters as pH and percent sedimentation were recorded throughout the fermentation cycle. The data are presesnted in Table VII.

TABLE VII__________________________________________________________________________ Observed Bioactivity Inhibition of Growth of Microorganism Percent Growth of L1210 Mouse Inhibition Zone Diameter Leukemia Cells atFermentation Time % Sedimentation (Using 12.7 mm discs) Given Dilution(Hours) pH (Growth) E. coli B. subtilis M. luteus 1:100 1:500 1:1000 1:2500 1:5000__________________________________________________________________________ 0 6.3 -- -- -- -- -- -- -- -- --24 6.4 4.7 -- -- -- NA* -- -- -- --48 5.9 7.4 21 23 15 5.7 1.6 -- -- --69 5.2 8.0 19 23 16 6.2 0.4 -- -- --96 5.15 8.7 19 20 16 5.7 0 -- -- --120 6.0 12.0 19 19 17 -- 0 1.5 2.8 2.9144 6.1 15.3 21 19 17 -- 0 1.3 2.9 3.2__________________________________________________________________________ *NA = Not active.

EXAMPLE 7

A 1-ml portion of a cryogenically preserved culture of isolate ATCC 39366 was used to inoculate 600 ml of SD-05 seed medium contained in a 2-liter baffled shake-flask. The inoculated shake-flask contents were incubated for 71 hours at 24.degree. C. with shaking (130 rpm gyratory shaking, 5 cm throw).

The microbial growth from the 2-liter flask was used to inoculate 16 liters of SD-05 seed medium contained in a 30-liter stirred jar fermentor. The inoculated fermentor contents were incubated at 24.degree. C. for 24 hours while being stirred at 300 rpm and sparged with air at a rate of 1 vol/vol/min.

A 200-gallon (757-liter) fermentor containing 160 gallons (606 liters) of PM-10 production medium was sterilized by heating with steam for 40 minutes at 121.degree. C. The fermentor and its contents were cooled to 24.degree. C. and inoculated with about 15 liters of the microbial growth from the 30-liter stirred jar fermentor. The inoculated production medium was incubated at 24.degree. C. for five days with stirring at 155 rpm while being sparged with air at a rate of 0.75 vol/vol/min. Dow Corning "C" antifoam agent was added as needed to control foaming of the fermentation medium.

The production of the CL-1957A compound was monitored throughout the fermentation cycle using the L1210 mouse leukemia cell assay, by measuring the antimicrobial activity of the fermentation beer against Micrococcus luteus and Bacillus subtilis, and by such fermentation parameters as pH and percent sedimentation. The data appear in Table VIII.

TABLE VIII__________________________________________________________________________ Observed Bioactivity Percent Growth of L1210 Mouse Inhibition Zone Diameter (mm) Leukemia Cells atFermentation Time % Sedimentation (Using 12.7 mm Discs) Given Dilution(Hours) pH (Growth) Micrococcus luteus Bacillus Subtilis 1:100 1:500 1:2500 1:5000__________________________________________________________________________ 0 6.35 -- -- -- -- -- -- --26 6.65 4.7 0 0 NA* -- -- --52 6.10 7.4 14.0 20.5 5.0 4.5 -- --72 6.0 8.7 16.5 21.5 6.8 3.8 -- --96 5.9 11.3 16.5 23.5 -- 5.5 5.0 16.4116 6.0 14.7 18.0 20.0 -- 0 3.8 3.1__________________________________________________________________________ *NA = Not active

The crude beer was harvested, and the CL-1957A compound isolated as described below.

Chemical Isolation of the CL-1957A Compound

EXAMPLE 8

Fermentation beer as prepared above in Example 7 was adjusted to pH 3.5 with sulfuric acid and mixed for one hour with ethyl acetate (227 liters). Celite 545 (11.4 kg) was added and the mixture filtered through a 46-cm plate-and-frame filter press. The filtrate was allowed to stand to let the lower aqueous phase separate from the ethyl acetate extract. The filter cake was washed with ethyl acetate (132 liters) and the wash, after dilution with 76 liters of fresh ethyl acetate, was used to extract the separated aqueous layer from above. After allowing the mixture to settle, the aqueous and organic layers from the second extract were separated and the aqueous layer extracted a third time with fresh ethyl acetate (189 liters). The three organic layers were combined and washed with deionized water (95 liters). The mixture was allowed to settle and the water wash separated. The upper ethyl acetate layer (529 liters) was concentrated in vacuo to 31 liters and then concentrated further with the displacement of ethyl acetate by methanol to yield 4.5 liters of a methanolic concentrate. This concentrate, diluted with one-tenth volume of water, was extracted two times with four-liter portions of petroleum ether (bp 30.degree.-60.degree. C.) and then concentrated to approximately 500 ml. Continued concentration with displacement of methanol by water yielded approximately 400 ml of an aqueous suspension which was extracted three times with 400 ml portions of ethyl acetate. The ethyl acetate extracts were combined, dried over anhydrous sodium sulfate, filtered, concentrated to a small volume, and then mixed with 250 grams of a mixture of silicic acid and Celite 545 (1:1). The resulting slurry was evaporated in vacuo to a dry solid which was slurried with dichloromethane (300 ml), and added to the top of a column containing 4 kg of a mixture of silicic acid and Celite 545 (1:1) packed in dichloromethane. The column was washed with dichloromethane (16 liters) and then eluted with dichloromethane-methanol (99:1, 14 liters), dichloromethane-methanol (98:2, 20 liters) and dichloromethane-methanol (96:4, 20.5 liters). The fractions eluting with dichloromethane-methanol (99:1) and dichloromethane-methanol (98:2) were combined and concentrated in vacuo to a viscous oil containing crude CL-1957A.

Purification of CL 1957-A

EXAMPLE 9

The crude CL-1957A fraction from above was triturated two times with 750-ml portions of n-heptane. The heptane insoluble material was dissolved in methanol (250 ml) and the resulting methanolic solution filtered and concentrated to dryness in vacuo to afford 22 g of a solid residue containing CL-1957A. The solid was redissolved in methanol (20 ml) and chromatographed over two liters of Sephadex LH-20 packed in methanol. After the appearance of color in the effluent, one 100 ml fraction and five 200 ml fractions were collected. Fractions five and six, which contained most of the CL-1957A (based upon HPLC assay), were combined and concentrated to dryness to afford 13.6 g of crude CL-1957A. This material was then further purified by chromatography over 1.9 kg of C.sub.18 -silica gel (Sepralyte C-18, 40 .mu.m particle size, Analytichem International, Harbor City, California) contained in a stainless steel column (7 cm [i.d.].times.85 cm), using methanol-water (80:20) as the eluent. A total of eighteen 500 ml fractions and seven one liter fractions were collected. Fractions nine through seventeen contained all of the CL-1957A (by HPLC assay), and were combined according to the estimated purity of CL-1957A present in the individual fractions. Thus, fractions nine through twelve, thirteen through fifteen, and sixteen through seventeen yielded 5.75 g, 12.5 g, and 0.7 g of solids, respectively. Each lot of solids was subsequently chromatographed over separate columns containing silica gel 60 (40-60 .mu.m, E. Merck Reagents) deactivated by the addition of 1% water. After sample application, each column was washed with dichloro-methane-methanol (98:2) and eluted with dichloro-methane-methanol (95:5). For example, the 12.5 g product from C.sub.18 -silica gel fractions thirteen through fifteen was chromatographed over 200 g of deactivated silica gel contained in a 2.5 cm [i.d.].times.85 cm glass column. After five 150-ml fractions of dichloromethane-methanol (98:2) were collected, the column was eluted with dichloromethane-methanol (95:5) collected in three 150-ml fractions, eight 50-ml fractions, and one 150-ml fraction. Fractions eight through twelve of the 5% methanol eluates, contained most of the CL-1957A (based upon HPLC and TLC assay) and were combined and concentrated to dryness to yield 1.03 g of purified CL-1957A as a pale yellow solid foam. Similar silica gel chromatographic purification of C18-silica gel fractions nine through twelve and sixteen through seventeen afforded 1.6 g and 0.4 g of purified CL-1957A, respectively. The chemical and physical properties of CL-1957A appear in Table IX and the ultraviolet, infrared, 360 MHz proton magnetic resonance, and 90.5 MHz .sup.13 C nuclear magnetic resonance spectra of the compound appear as FIGS. 1a, 1b, 1c, and 1d, respectively.

TABLE IX__________________________________________________________________________Chemical and Physical Properties of CL-1957AProperty Cl-1957A__________________________________________________________________________Molecular weight 540 atomic mass unitsElemental analysis* Calculated for C.sub.33 R.sub.48 O.sub.6.C.28 CHCl.sub.3 : 69.64% C, 8.41% H, 5.20% Cl. Found: 69.85% C, 8.52% H, 5.02% Cl.Melting point 41.degree.-44.degree. C. (with prior softening)Optical rotation [.alpha.] .sub.D.sup.23 = -157.degree. (0.7% in chloroform)Ultraviolet absorption spectra Free acid form (in methanol): No maxima; inflection at 290 nm; end absorption below 260 nm. Carboxylate form (in methanol): Maxima at 240 nm (a = 61.1), 287 nm (a = 6.6), and 378 nm (a = 3.5).Infrared absorption spectrum Principal absorption peaks at 2975, 2940,(in chloroform) 1715, 1700 (shoulder), 1645, 1455, 1375, 1255, 1105, and 965 reciprocal centimeters.360 MHz proton magnetic Principal signals at 0.77 (doublet, 3 protons),resonance spectrum 0.97 (doublet, 3 protons), 1.03 (triplet,(deuterochloroform 3 protons), 1.05 (doublet, 3 protons), 1.10solution) (doublet, 3 protons), 1.13 (doublet, 3 protons), 1.73 (multiplet, 1 proton), 1.80 (singlet, 3 protons), 1.88 (doublet of doublets, 1 proton), 2.06 (triplet, 2 protons), 2.11 (singlet, 3 protons), 2.17 (multiplet, 1 proton), 2.17 (quartet, 2 protons), 2.51 (multiplet, 1 proton), 2.65 (multiplet, 1 proton), 2.80 (multiplet, 1 proton), 3.56 (triplet, 1 proton), 3.64 (multiplet, 1 proton), 4.97 (doublet of doublets, 1 proton), 5.06 (doublet, 1 proton), 5.21 (doublet, 1 proton), 5.57 (multiplet, 1 proton), 5.66 (singlet, 1 proton), 5.70 (doublet of doublets, 1 proton), 5.97 (doublet, 1 proton), 5.98 (doublet, 1 proton), 6.62 (doublet, 1 proton), and 6.93 (doublet of doublets, 1 proton) parts per million downfield from tetra- methylsilane.90.5 MHz .sup.13 C nuclear magnetic Principal signals at 215.08, 171.01,resonance spectrum 164.30, 161.06, 151.47, 137.90, 136.44(deuterochloroform solution) 135.53, 135.18, 130.18, 128.14, 128.01 122.76, 120.05, 116.85, 81.49, 74.32, 46.74, 45.70, 45.65, 40.84, 33.58, 32.21, 26.61, 20.85, 18.65, 16.08, 13.68, 13.62, 13.08, 12.61, and 12.38 parts per million downfield from tetramethylsilane.Retention time (high pressure 5.45 minuteschromatography, .mu.Bondpak .TM.C18-silica gel column, 3.9 mmi.d. .times. 30 cm, WatersAssociates, Milford, MA,solvent: 45:55 0.05 Mammonium acetate buffer(pH 6.5)-acetonitrile,flow rate 1.5 ml/min)R.sub.f (thin-layer chromatography 0.50on silica gel 60 F254, E.Merck, solvent 90:10chloroform-methanol)__________________________________________________________________________ *Elemental analysis calculated on the basis of included chloroform solven of crystallization

While not holding to particular structures to the exclusion of others, the chemical structure of CL-1957A is believed to correspond to that indicated by structure I below, which is consistent with the spectral data presented in Table IX. ##STR1##

The exact cis-trans configuration of the groups attached to the lactone ring and the exact E-Z configurations about the carbon-carbon double bonds are not known with certainty at the time of filing of the present application. The present invention is therefore contemplated as encompassing all possible cis-trans and E-Z isomers of structure I given above. The name of the compound designated above (while not specifying cis-trans or E-Z configuration) is 19-(3,6-dihydro-3-methyl-6-oxo-2H-pyran-2-yl)-17-ethyl-6-hydroxy-3,5,7,9, 11,15-hexamethyl-8-oxo 2,10,12 16,18-nonadecapentaenoic acid.

Biological Activity of CL-1957A

EXAMPLE 10

The antimicrobial activity of CL-1957A was evaluated by saturating 12.7 mm paper discs with solutions of CL-1957A prepared at concentrations of 10, 100, and 500 .mu.g/ml and placing each saturated paper disc on a bioassay tray containing an agar medium seeded with a particular organism. The disc and inoculated medium were incubated for 16 hours at 37.degree. C. and the diameter of the resulting growth inhibition zone, if any, was measured. The data from these tests appear in Table X.

TABLE X__________________________________________________________________________ Diameter of Inhibition Zone (mm) CL-1957AMicroorganism Culture Number* Medium 500 .mu.g/ml 100 .mu.g/ml 10 .mu.g/ml__________________________________________________________________________Alcaligenes viscolactis ATCC 21698 Mycin 19 0 0Bacillus subtilis ATCC 6633 #169 26 16 0Bacillus subtilis PD 04969 #169 19 14 0Bacillus subtilis ATCC 6633 Mycin 18 0 0Escherichia coli ATCC 10536 GAA 0 0 0Kloeckera brevis PD M1378 #69 0 0 0Branhamella catarrahalis PD 03596 CAP 30 20 0Penicillium avellaneum PD M2988 H & B 0 0 0Proteus vulgaris PD 05062 PAS 0 0 0Micrococcus luteus PD 05064 PAS 15 0 0Staphylococcus aureus PD 02482 PAS 16 14 0Staphylococcus aureus PD 5045 AM-10 22 19 0Staphylococcus aureus PD 5045 AM-9 22 17 0Xanthomonas phaseoli PD 06002 CMA 0 0 0__________________________________________________________________________ *ATCC = American Type Culture Collection, Rockville, Maryland 20852 PD = WarnerLambert/Parke-Davis Culture Collection, 2800 Plymouth Road, An Arbor, Michigan 48105

EXAMPLE 11

The in vivo activity of CL-1957A against P388 leukemia in mice was assayed using the protocol established in Cancer Chemotherapy Reports, Vol. 3, Part 3, 1-87 (1972). The mice were infected intraperitoneally on Day 0 and then given the dose of CL-1957A indicated in Table XI on Days 1-5. The results of these tests are presented in Table XI in terms of % T/C valued as defined above.

TABLE XI______________________________________In Vivo Activity of CL-1957AAgainst P388 Leukemia in MiceCL-1957ADose (.mu.g/kg/ % T/Cinjection) Test 1 Test 2______________________________________100 Toxic Toxic50 148 14625 127 14112.5 118 137______________________________________

EXAMPLE 12

The cytotoxicity of CL-1957A against L1210 mouse leukemia cells and against human colon adenocarcinoma cells was measured in vitro. The ID.sub.50 values appear in Table XII.

TABLE XII______________________________________ ID.sub.50 L1210 Mouse Human ColonCompound Leukemia Cells Adenocarcinoma Cells______________________________________CL-1957A 0.118 ng/ml 0.02 ng/ml______________________________________

EXAMPLE 13

In this Example, the in vivo activity of CL-1957A was tested against Ridgeway Osteogenic Sarcoma in mice as follows. Male AKR mice were pooled, inoculated subcutaneously by trocar with 30-60 mg fragments of Ridgeway Osteogenic Sarcoma, repooled, and randomly distributed to treatment groups on Day 0.

Appropriate mice received intrapertioneal injections of the test compound dissolved in 0.9% sodium chloride solution on Days 2, 6, and 10, and then weekly thereafter. Tumors were measured on Days 24 and 35. The results are presented in Table XIII as % T/C (as defined below). % T/C values of less than 40 on Day 35 are considered active. ##EQU2##

TABLE XIII______________________________________Activity of CL-1957A Against Ridgeway OsteogenicSarcoma in MiceDose % T/C(mg/kg of body weight/injection) Day 24 Day 35______________________________________0.50 0 00.25 15 9 0.125 14 22______________________________________

EXAMPLE 14

The in vivo activity of CL-1957A against B16 Melanoma in mice was tested using the protocol established in Cancer Chemotherapy Reports, Vol 3, Part 3, 1-87 (1972). Mice were inoculated by trochar with B16 melanoma on Day 0 and then given intraperitoneal injections of CL1957A on Days 1, 5, 9. The activity of the compound against B16 melanoma is presented in Table XIV in terms of % T/C values which represents the ratio of median life span in days of treated mice to untreated mice, expressed as a percentage.

TABLE XIV______________________________________Activity of CL-1957A Against B16 Melanomain MiceDosemg/kg of body weight/injection % T/C______________________________________0.60 Toxic0.30 1410.15 145 0.075 201______________________________________

The compound of the present invention forms pharmaceutically acceptable salts with organic and inorganic bases. Examples of suitable inorganic bases are ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, calcium hydroxide, sodium bicarbonate, and the like. Pharmaceutically acceptable salts are also formed with amine cations derived from organic nitrogenous bases strong enough to form cations.

The pharmaceutically acceptable salts of the acid are prepared, for example, by suspending the acid in water and adjusting the pH with the pharmaceutically acceptable base, or by reacting the compounds with one equivalent of the pharmaceutically acceptable base in a solvent and removing the solvent under reduced pressure.

The term, pharmaceutically acceptable metal cation contemplates the positively charged ions derived from such metals as sodium, potassium, calcium, magnesium, aluminum, zinc, iron, and the like. The salts are prepared by contacting the free acid form of the compound with an equivalent amount of the desired base in the conventional manner. The free forms may be regenerated by treating the salt form with an acid. For example, dilute aqueous acid solutions may be utilized to regenerate the free acid form from a respective salt. Dilute aqueous hydrochloric acid is suitable for this purpose. The free acid form differs from its respective salt forms somewhat in certain physical properties such as solubility in polar solvents, but the salts are otherwise equivalent to the respective free acid form for purposes of the invention.

The term pharmaceutically acceptable amine cation contemplates the positively charged ammonium ion and analogous ions derived from organic nitrogenous bases strong enough to form such cations. Bases useful for the purpose of forming pharmacologically acceptable nontoxic addition salts of such compounds containing free carboxyl groups form a class whose limits are readily understood by those skilled in the art. Merely for illustration, they can be said to comprise, in cationic form, those of the formula: ##STR2## wherein R.sub.a, R.sub.b, and R.sub.c, independently, are hydrogen, alkyl of from about one to about six carbon atoms, cycloalkyl of from about three to about six carbon atoms, aryl of about six carbon atoms, aralkyl of from about 7 to about 11 carbon atoms, hydroxyalkyl of from about 2 to about 4 carbon atoms, or monoarylhydroxyalkyl of from about 8 to about 15 carbon atoms, or, when taken together with the nitrogen atom to which they are attached, any two of R.sub.a, R.sub.b, and R.sub.c may form part of a 5- to 6-membered heterocyclic ring containing carbon, hydrogen, oxygen, or nitrogen, said heterocyclic rings and said aryl groups being unsubstituted or mono- or dialkyl substituted said alkyl groups containing from about one to about six carbon atoms. Illustrative therefore of R.sub.a, R.sub.b, and R.sub.c groups comprising pharmaceutically acceptable cations derived from ammonia or a basic amine are ammonium, mono-, di-, and trimethylammonium, mono, di- and triethylammonium, mono-, di-, and tripropylammonium (iso and normal), ethyldimethylammonium, benzyldimethylammonium, cyclohexylammonium, benzylammonium, dibenzylammonium, piperidinium, morpholinium, pyrrolidinium, piperazinium, pyridinium, 1-methylpiperidinium, 4-ethylmorpholinium, 1-isopropylpyrrolidinium, 1,4-dimethylpiperazinium, 1-n-butylpiperidinium, 2-methylpiperidinium, 1-ethyl-2-methylpiperidinium, mono-, di-, and triethanolammonium, ethyldiethanolammonium, n-butylmonoethanolammonium, tris(hydroxymethyl)methylammonium, phenylmonoethanolammonium, and the like.

EXAMPLE 15

Preparation of the Sodium Salt of CL-1957A

Cooled sodium hydroxide solution (10 mg, 0.0176 M) was added dropwise to a cooled solution of 100 mg (0.176 mmol) of CL-1957A in 2.5 ml of methanol. During the addition, a white precipitate formed which redissolved by the end of the addition of base solution. The resulting solution was concentrated in vacuo and diluted to 40 ml with water. Two-milliliter aliquots of this solution were added to each of several 6-ml vials. Lyophilization of the contents of each vial afforded a white solid corresponding, in each vial, to 5 mg of CL-1957A sodium salt.

EXAMPLE 16

Preparation of the Calcium Salt of CL-1957A

Cooled calcium hydroxide solution (10 ml, 0.0088 M) was added dropwise to a cooled solution of 100 mg (0.176 mmol) of CL-1957A in 2.5 ml of methanol. After addition of the base solution, a white suspension formed, and some material coagulated on the walls of the solution container. The methanol was removed by evaporation, and sufficient 1,1-dimethylethanol was added to dissolve the water-insoluble calcium salt of CL-1957A. The resulting solution was lyophilized to yield the solid calcium salt, which was found to be insoluble in water, but soluble in ethanol.

EXAMPLE 17

Preparation of the Potassium Salt of CL-1957A

Cooled potassium hydroxide solution (10 ml, 0.0176 M) was added dropwise with stirring to a cooled solution of 100 mg (0.176 mmol) of CL-1957A in 2.5 ml of methanol. The resulting solution was concentrated in vacuo and then diluted with 40 ml of water. Two-milliliter aliquots of this solution were added to each of several 6-ml vials. Lyophilization of the contents of each vial afforded a white solid corresponding, in each vial, to 5 mg of CL-1957A potassium salt.

EXAMPLE 18

Preparation of the Triethylammonium Salt of CL-1957A

A cooled solution of triethylamine (2.45 ml, 0.176 mmol) in 7.55 ml of water was added dropwise with stirring to a solution of 100 mg (0.176 mmol) of CL-1957A in 2.5 ml of methanol. The resulting solution was concentrated to a final volume of about 2 ml on a rotary evaporator and then diluted to 40 ml with water. Two-milliliter aliquots of this solution were added to each of several 6-ml vials. Lyophilization of the contents of each vial afforded a white solid corresponding, in each vial, to 5 mg of CL-1957A triethylammonium salt, which was found to be soluble in water.

EXAMPLE 19

Preparation of the Sodium Salt of CL-1957A with Mannitol

Cooled sodium hydroxide solution (10 ml, 0.0176 M) was added dropwise to a cooled solution of 100 mg (0.176 mmol) of CL-1957A in 2.5 ml of methanol. The resulting solution was concentrated in vacuo to remove the methanol, and then 500 mg of mannitol contained in 10 ml of water was added to the concentrate. This mixture was diluted to 40 ml with water. Two-milliliter aliquots of this solution were added to each of several 6-ml vials. Lyophilization of the contents of each vial afforded a white solid corresponding, in each vial, to 5 mg of CL-1957A sodium salt with mannitol as a bulking agent.

EXAMPLE 20

Preparation of the Sodium Salt of CL-1957A with Ascorbic Acid and Mannitol

Cooled sodium hydroxide solution (10 ml, 0.0176 M) was added dropwise to a cooled solution of 100 mg (0.176 mmol) of CL-1957A in 2.5 ml of methanol. The resulting solution was concentrated in vacuo to remove the methanol, and then 500 mg of mannitol and 73.3 mg of ascorbic acid, both contained in 10 ml of water, were added to the concentrate. The resulting mixture was diluted to 40 ml with water. Two-milliliter aliquots of this solution were added to each of the several 6-ml vials. Lyophilization of the contents of each vial afforded a white solid corresponding, in each vial, to 5 mg of CL-1957A sodium salt and 2.48 mg of ascorbic acid, with mannitol as a bulking agent.

EXAMPLE 21

Preparation of the N-methyl-D-glucamine Salt of CL-1957A

A 5-ml solution of 11 mg N-methyl-D-glucamine in water was added dropwise with stirring to 32 mg of CL-1957A in 2-ml methanol, cooled in an ice bath. The solution was concentrated in vacuo to remove methanol and diluted to 10 ml for lyophilization. The lyophilized solid is white and powdery. The N-methyl-D-glucamine salt is soluble in water.

The antibiotic compound CL-1957A, either in its free acid form, or in the form of one or more of its pharmaceutically acceptable salts, are useful for their antimicrobial and antitumor activity as pharmaceutical compositions in combination with a compatible pharmaceutically acceptable carrier. These compositions may also contain other antimicrobial and/or antitumor agents. The compositions may be made up in any pharmaceutically appropriate form for the desired route of administration. Examples of such forms include solid forms for oral administration as tablets, capsules, pills, powders and granules, liquid forms for topical or oral administration as solutions, suspensions, syrups, and elixirs, and forms suitable for parenteral administration such as sterile solutions, suspensions, or emulsions.

For preparing pharmaceutical compositions from the compounds described by this invention, inert, pharmaceutically acceptable carriers can be either solid or liquid. Solid form preparations include powders, tablets, dispersible granules, capsules, cachets, and suppositories. A solid carrier can be one or more substances which may also act as diluents, flavoring agents, solubilizers, lubricants, suspending agents, binders, or tablet disintegrating agents; it can also be an encapsulating material. In powders, the carrier is a finely divided solid which is in admixture with the finely divided active compound. In the tablet the active compound is mixed with carrier having the necessary binding properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain from 5 or 10 to about 70 percent of the active ingredient. Suitable solid carriers are magnesium carbonate, magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose, a low melting wax, cocoa butter, and the like. The term "preparation" is intended to include the formulation of the active compound with encapsulating material as carrier providing a capsule in which the active component with encapsulating material as carrier providing a capsule in which the active component (with or without other carriers) is surrounded by carrier, which is thus in association with it. Similarly, cachets are included. Tablets, powders, cachets, and capsules can be used as solid dosage forms suitable for oral administration.

For preparing suppositories, a low melting wax such as a mixture of fatty acid glycerides or cocoa butter is first melted, and the active ingredient is dispersed homogeneously therein as by stirring. The molten homogeneous mixture is then poured into convenient sized molds, allowed to cool and thereby to solidify.

Liquid form preparations include solutions, suspensions, and emulsions. As an example may be mentioned water or water-propylene glycol solutions for parenteral injection. Liquid preparations can also be formulated in solution in aqueous polyethylene glycol solution. Aqueous solutions suitable for oral use can be prepared by dissolving the active component in water and adding suitable colorants, flavors, stabilizing, and thickening agents as desired. Aqueous suspensions suitable for oral use can be made by dispersing the finely divided active component in water with viscous material, i.e., natural or synthetic gums, resins, methylcellulose, sodium carboxymethylcellulose, and other well-known suspending agents.

Also included are solid form preparations which are intended to be converted, shortly before use, to liquid form preparations for either oral or parenteral administration. Such liquid forms include solutions, suspensions, and emulsions. These particular solid form preparations are most conveniently provided in unit dose form and as such are used to provide a single liquid dosage unit. Alternately, sufficient solid may be provided so that after conversion to liquid form, multiple individual liquid doses may be obtained by measuring predetermined volumes of the liquid form preparation as with a syringe, teaspoon, or other volumetric container. When multiple liquid doses are so prepared, it is preferred to maintain the unused portion of said liquid doses at low temperature (i.e., under refrigeration) in order to retard possible decomposition. The solid form preparations intended to be converted to liquid form may contain, in addition to the active material, flavorants, colorants, stabilizers, buffers, artificial and natural sweeteners, dispersants, thickeners, solubilizing agents, and the like. The liquid utilized for preparing the liquid form preparation may be water, isotonic water, ethanol, glycerine, propylene glycol, and the like as well as mixtures thereof. Naturally, the liquid utilized will be chosen with regard to the route of administration, for example, liquid preparations containing large amounts of ethanol are not suitable for parenteral use.

However, the antibiotic compound CL-1957A and its salts have been found to be unexpectedly unstable at room temperature both in the pure, solid form and in combination with many nontoxic, pharmaceutically acceptable liquid solvents normally employed in the formulation of pharmaceutical compositions.

For example, as illustrated by the data in Table XV, solid preparations of the pure compound were found to be insufficiently stable for pharmaceutical use. Solutions of CL-1957A were prepared in various solvents at concentrations of 4 mg/ml and 0.5-ml aliquots of the resulting solution were placed in 6-ml vials and evaporated to dryness in vacuo. The thin-film preparations which resulted were assayed for stability by comparing the purity of the film against a standard sample by HPLC techniques.

The data in Table XV illustrate that the thin-film preparations of CL-1957A were not stable for periods of even one week, with the exception of the ascorbate-containing preparation which began to show some decomposition after about one month.

TABLE XV______________________________________Stability of Solid Preparations of CL-1957A Percent RemainingFormulation Method After One Week______________________________________Thin film from abs. ethanol 60Thin film from 95% ethanol 40Solid cake from 1,1- 56dimethylethanolThin film from 95% ethanol/ 912 mg of polyethylene glycolThin film from 95% ethanol/ 10020 mg of polyethylene glycol 89plus 2.5 mg of ascorbic acid (After one month)______________________________________

Likewise, as illustrated by the data presented in Table XVI, Cl-1957A is not sufficiently stable in solution preparations employing as solvents dimethylacetamide (DMA) or dimethylsulfoxide (DMSO). In Table XVI, solutions were prepared in the indicated solvents at concentrations of 2.0 mg/ml and assayed for purity against a standard sample of CL 1957A by HPLC techniques at various intervals.

This instability of CL-1957A in the pure, solid form, or in solution preparations in certain pharmaceutically acceptable solvents, presents particular difficulties relating to the preparation of pharmaceutical compositions containing the compound or one of its salts, since any commercially viable pharmaceutical preparation containing CL-1957A must have acceptable shelf life.

As evidenced by the data of Table XVI, however, the compound has been found to be stable in solutions in lower alcohols such as 95% ethanol, absolute ethanol, and propylene glycol, and such solutions are sufficiently stable for use as pharmaceutical preparations.

TABLE XVI______________________________________Stability of CL-1957A Solutions Stored atRoom Temperature Percent Remaining AfterSolvent 1 Month 2 Months 5 Months______________________________________Abs. ethanol 100 100 10095% Ethanol 100 100 100Propylene glycol 100 100 100Propylene glycol 100 100 100(stored at 37.degree. C.)95% Ethanol + 2.5 mg 100 100 100ascorbateDimethylacetamide 95 93 --Dimethylsulfoxide 93 90 --______________________________________

Preferably, the pharmaceutical preparation is in unit dosage form. In such form, the preparation is subdivided into unit doses containing appropriate quantities of the active component. The unit dosage form can be a packaged preparation, the package containing discrete quantities of preparation, for example, packeted tablets, capsules, and powders in vials or ampoules. The unit dosage form can also be a capsule, cachet, or tablet itself or it can be the appropriate number of any of these in packaged form.

The quantity of active compound in a unit dose of preparation may be varied or adjusted from 0.1 mg to 500 mg preferably to 5 to 100 mg according to the particular application and the potency of the active ingredient. The compositions can, if desired, also contain other compatible therapeutic agents.

In therapeutic use, the mammalian dosage range for a 70 kg subject is from 1 to 1500 mg/kg of body weight per day or preferably 2 to 750 mg/kg of body weight per day. The dosages, however, may be varied depending upon the requirements of the patient, the severity of the condition being treated, and the compound being employed. Determination of the proper dosage for a particular situation is within the skill of the art. Generally, treatment is initiated with smaller dosages which are less than the optimum dose of the compound. Thereafter the dosage is increased by small increments until the optimum effect under the circumstances is reached. For convenience, the total daily dosage may be divided and administered in portions during the day if desired.

Claims

1. An antibiotic compound in substantially pure form designated CL-1957A having the structural formula ##STR3## or a pharmaceutically acceptable salt thereof; compound CL-1957A characterized by:

(a) a molecular weight of 540 atomic mass units;

(b) a melting point of 41.degree.-44.degree. C. (with prior softening);

(c) an optical rotation, [.alpha.].sub.D.sup.23 of -157.degree. (0.7 in chloroform);

(d) an ultraviolet absorption spectrum in methanol (free acid form) showing an inflection at 290 nm and end absorption below 260 nm;

(e) an ultraviolet absorption spectrum in methanol (carboxylate anion form) showing maxima at 240 nm (a =61.1), 287 nm (a =6.6), and 378 nm (a =3.5);

(f) an infrared absorption spectrum in chloroform showing principal absorption peaks at 2975, 2940, 1715, 1700 (shoulder), 1645, 1455, 1375, 1255, 1105, and 965 reciprocal centimeters;

(g) a 360 MHz proton magnetic resonance spectrum in deuterochloroform solution showing signals at 0.77 (doublet, 3 protons), 0.97 (doublet, 3 protons), 1.03 (triplet, 3 protons), 1.05 (doublet, 3 protons), 1.10 (doublet, 3 protons), 1.13 (doublet, 3 protons), 1.73 (multiplet, 1 proton), 1.80 (singlet, 3 protons), 1.88 (doublet of doublets, 1 proton), 2.06 (triplet, 2 protons), 2.11 (singlet, 3 protons), 2.17 (multiplet, 1 proton), 2.17 (quartet, 2 protons), 2.51 (multiplet, 1 proton), 2.65 (multiplet, 1 proton), 2.80 (multiplet, 1 proton), 3.56 (triplet, 1 proton), 3.64 multiplet, 1 proton), 4.97 (doublet of doublets, 1 proton), 5.06 (doublet, 1 proton), 5.21 (doublet, 1 proton), 5.57 (multiplet, 1 proton), 5.66 (singlet, 1 proton), 5.70 (doublet of doublets, 1 proton), 5.97 (doublet, 1 proton), 5.98 (doublet, 1 proton), 6.62 (doublet, 1 proton), and 6.93 (doublet of doublets, 1 proton) parts per million downfield from tetramethylsilane; and h) a 90.5 MHz .sup.13 C nuclear magnetic resonance spectrum in deuterochloroform solution showing principal signals at 215.08, 171.01, 164.30, 161.06, 15l.47, 137.90, 136.44, 135.53, 135.18, 130.18, 128.14, 128.01, 122.76, 120.05, 116.85, 81.49, 74.32, 46.74, 45.70, 45.65, 40.84, 33.58, 32.21, 26.61, 20.85, 18.65, 16.08, 13.68, 13.62, 13.08, 12.61, and 12.38 parts per million downfield from tetramethylsilane.

2. A pharmaceutical composition comprising a solution of the compound CL-1957A as defined in claim 1 and absolute ethanol.

3. A pharmaceutical composition comprising a solution of the compound CL-1957A as defined in claim 1 and 95% ethanol.

4. A pharmaceutical composition comprising a solution of the compound CL-1957A as defined in claim 1 and propylene glycol.

5. A pharmaceutical composition in accordance with claim 3 further containing ascorbic acid.