2'-CHLOROPENTOSTATIN, A PHARMACEUTICAL COMPOSITION COMPRISING THE COMPOUND AND A NOVEL MICROORGANISM FOR PRODUCING THE COMPOUND

Abstract: The compound 2′-chloropentostatin, which has the for­ mula is a potent inhibitor of the enzyme adenosine deaminase and possesses utility as an agent for potentiating the activity of antiviral agents for the treatment of DNA viruses which agents contain an adenine moiety, such as 9-(beta-D-arabi­ nofuranosyl) adenine. A pure strain of actinomycete, desig­ nated ATCC 38365 which is capable of producing 2′-­ chloropentostatin, a method of producing 2′-chloropento­ statin by aerobic fermentation, and pharmaceutical compo­ sitions including 2′chloropentostatin are also disclosed.

Description: 2'-CHLOROPENTOSTATIN, A PHARMACEUTICAL COMPOSITION COMPRISING THE COMPOUND AND A NOVEL MICROORGANISM FOR PRODUCING THE COMPOUND The efficacy of a number of adenine nucleosides which act as both antitumor and antiviral agents is severely limited due to their rapid deactivation in vivo by the action of adenosine deaminase, an enzyme present in most mammalian body tissues. The compounds (R)-3-(2-deoxy-beta-D-erythropentofuranosyl)-3,6,7,8- tetrahydroimidazo[4,5-d1 [l,3]diazepin-8-ol (commonly known as pentostatin), disclosed in U.S. Patent 3,923,785, and its ribo-analog, (R)-3-(beta-D-ribofuranosyl)-3,6,7,8-tetrahydroimidazo[4,5-d][1,3]- diazepin-8-ol (commonly known as coformycin), disclosed in Japanese Patent 875,639 and U.S. Patent 4,151,347, are potent inhibitors of ádenosine deami nase. 2'-Chloropentostatin is a novel analog of pento- statin which is produced by an isolate of an actinomycete designated ATCC 39365. In accordance with one aspect of the present invention, there is provided a compound having structural formula I EMI2.1 and the name (R)-3-(2-chloro-2-deoxy-beta-D-ribo- furanosyl)-3,6,7,8-tetrahydroimidazo[4,5-d][1,3]- diazepin-8-ol and its pharmaceutically acceptable acid addition salts, which compound possesses potent adenosine deaminase inhibitory activity. The name 2'-chloropentostatin will be used throughout this specification to refer to the compound. In another aspect, the present invention provides a pure strain of the 2'-chloropentostatin-producing microorganism having the identifying characteristics of isolate ATCC 39365. In accordance with another aspect, the present invention provides a method of producing 2'-chloropentostatin by cultivating the isolate of actinomycete identified as ATCC 39365 under aerobic conditions in a medium containing assimilable sources of carbon and nitrogen until a substantial quantity of 2'-chloropentostatin is produced, and subsequently isolating the compound. In another aspect of the present invention, there are provided pharmaceutical compositions useful or the treatment of DNA viruses comprising an effective amount of2'-chloropentostatin or one or more of its pharmaceutically acceptable acid addition salts together with an effective amount of an antiviral agent which contains an adenine moiety such as 9-(beta-D-arabinofuranosyl)adenine and a pharmaceutically acceptable carrier. The compound of the present invention may be employed in a method of treating s viruses in a mammal comprising administering to a mammal in need of such treatment, an effective amount of 2'-chloropentostatin or a pharmaceutically acceptable salt thereof in coirbination with an effective amount o; 9-(beta-Darabinoturanosyl)adenine together witn a pharmaceutically acceptable carrier. Brief Description of the Drawing FIGURE 1 is an Ackerman-Potter plot of the adenosine deaminase inhibitory action of 2'-chloro pentostatin. FIGURE 2 is a plot of the ratio of velocities of uninhibited to inhibited reaction rates of adenosine with adenosine deaminase in the presence of 2'-chloropentostatin. FIGURE 3 is a plot of I50 values of 2'-chloro pentostatin inhibition of adenosine deaminase versus enzyme concentration. In accordance with the present invention, the compound 2'-chloropentostatin is produced by cultivating a selected isolate of actinomycete, designated ATCC 39365, until a substantial amount of 2'-chloropentostatin is formed, and subsequently isolating the compound. The strain of actinomycete suitable for the purposes of this invention was found in a soil sample collected from North Carolina, 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 e soil sample was plated onto the agar medium and incubated at a favorable temperature, particularly 45"C, to allow the development of the soil microorganisms. The 2' -chloropentostatin-producing microorganism that was isolated from the agar plating medium is an as yet 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 collection as ATCC 39365. This organism, which produces 2'-chloropentostatin, 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-886. ATCC 39365 MORPHOLOGY Aerial mycelium Red Spore chains Flexible with a single hook at the end Formation of melanine None or other soluble pigments Reduction of nitrate Negative Liquefaction of gelatin Negative Coagulation of milk Negative CARBON SOURCE UTILIZATION Arabinose Positive Fructose Positive Glucose Positive Inositol Positive/Negative Mannitol Positive Raffinose Positive Rhamnose Positive Sucrose Negative Xylose Positive Sal in Negative Galactose Negative The compound 2'-chloropentostatin, which @@@@@@ potent activity as an inhibitor of adenosine deaminase, is produced by isolate ATCC 39365 during aerobic fermentation under controlled conditions. The fermentation medium consists of sources of carbon, nitrogen, minerals, and growth factors. Examples of suitable carbon sources include glycerol and various simple sugars such as glucose, mannose, fructose, xylose, ribose, or other carbohydrate-containing compounds such as dextrin, starch, corn meal, 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 inorganic, organic, and mixed inorganic-organic nitrogenous materials. Examples of such materials are cottonseed meals, soybean meal, corn germ flour, corn steep liquor, distiller's dried solubles, peanut meal, peptpnized milk, and various ammonium salts. The addition of minerals and growth factors to the fermentation medium is also helpful in the production of 2'-chloropentostatin. Examples of such mineral additives include sodium chloride, potassium chloride, ferrous sulfate, calcium carbonate, cobalt chloride, and zinc sulfate. Sources of growth factors include various yeast and milk products. The preferred method of producing 2'-chloropentostatin is by submerged culture fermentation. According to this method, the fermentation medium ingredients are prepared in solution or suspension in water, and the mixture is subsequently sterilized by autoclaving or steam heating. The mixture is cooled following sterilization to a temperature between about 160C and 450C and the pH is adjusted to preferably between about pH 4 and about pH 8. The cooled, sterile 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 effected by agitating the flask and contents to bring about contact 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 sparging air or oxygen into the agitated mixture. Adequate production of 2'-chloropentostatin is achieved under these conditions after a period of about two to ten days. Alternatively, 2'-chloropentostatin may be produced by solid state fermentation of the microorganism. The following examples are provided to illustrate the fermentative production of 2'-chloropentostatin. The examples are merely illustrative and are not to be read as limiting the scope of the invention as it is defined by the appended claims. Fermentative Production of 2'-Chloropentostatin Shake-Flask Fermentation EXAMPLE 1 The ATCC 39365 culture, following its isolation by the agar plating technique, was transferred from its dormant state to an agar slant tube containing CIM 23 agar medium and incubated at 280C for 7-14 days. A portion of the microbial growth which developed in this slant tube was used to inoculate 5 ml of SD-05 seed medium contained in a 18 x 150 mm tube. The tube contents were shaken on a gyratory shaker at 170 rpm and incubated at 330C for four days. TABLE l Formulation of CIM 23 Agar Medium Amidex corn starch 10 g N-Z Amine, Type A 2 g Beef extract (Difco) 1 g Yeast extract (Difco) 1 q Cobaltous chloride 5H20 20 mg Agar 20 g Distilled Water 1000 ml TABLE 2 Formulation of SD-05 Seed Medium Amberex 1003 (Amberex Laboratories) 5 g Glucose monohydrate ig Dextrin-Amidex B411 (Corn Products) 24 g N-Z Case (Humko Sheffield) 5 g Spray-dried meat solubles (Daylin) 3 g Calcium carbonate 2g Water l000 ml EXAMPLE 2 A 1.0-ml portion of the contents of the seed tube from Example 1 was transferred to a 300-ml shake-flask containing 50 ml of SM-31 screening medium. The inoculated flask contents were incubated at 330C for four days with shaking (170 rpm gyratory shaking, 5 cm throw). TABLE 3 Formulation of SM-31 Screening Medium Glucose monohydrate 15 g Lactose 10 g Distiller's solubles 6.5 g Peptonized milk 3.5 g Torula yeast 2.5 g Water, pH adjusted to 7.0 1000 ml To confirm the fermentation activity of the microorganism, a second microbial seed was prepared as described in Example 2 above and 2 ml of this seed was used to inoculate 50 ml of SM-31 screening medium contained in a 300-ml shake-flask. The inoculated flask was incubated at 3000C for four days with shaking (170 rpm gyratory shaking, 5 cm throw). EXAMPLE 3 The production of 2'-chloropentostatin in the fermentation beer of Example 2 was monitored by screening the beer against the microorganism Streptococcus faecalis 05045. Agar plates containing AM-l0 assay medium were inoculated with this microorganism and paper discs (12.7 mm diameter), impregnated with the fermentation beer, were placed on the inoculated agar medium an6 incubated overnight at 370C. The diameter of the zones of inhibition around each disc were measured. The size of the zone correlated with the amount of 2'-chloropentostatin present in the fermentation beer. The results of these measurements appear in Table 5. TABLE 4 Formulation of AM-10 Assay Medium K2SPO4 3.9 g Dextrose 25.0 g Sodium citrate-2 H2O 34.4 g Casein hydrolysate 6.2 g Asparagine 375 mg L-tryptophan 125 mg Cysteine 312.5 mg Glutathione 0.31 mg Thiamine HCl 250 g Riboflavin 625 pg Ca pantothenate 500 Nicotinic acid 500 g p-aminobenzoic acid 625 Biotin 12.5 g Folic acid 500 Pyridoxine HCl 2.5 mg NaCl 12.5 mg MgSO4 250 mg FeSO4 12.5 mg MnS04.H2O 125.0 mg Tween 80 62.5 mg Adenine sulfate 6.25 mg Aaar 15.0 g Water 1000 ml TABLE 5 Initial Activity of Shake-Flask Fermentation Beers vs. Streptococcus faecalis 05045 Fermentation Stage Activity (zone diameter, mm) Shake-flask I 48 Shake-flask 11 54 The crude fermentation beer also demonstrated antimicrobial activity against the microorganisms Branhamella catarrhalis 03596 and Escherichia coli 05117. Large Batch Fermentation EXAMPLE 4 A cryogenically preserved culture sample of ATCC 39365 was thawed and used to inoculate 600 ml of SD-05 seed medium contained in a 2-liter baffled Erlenmeyer flask. The flask and contents were incubated for 70 hours at 330C with shaking (130 rpm, 5 cm throw). The contents of this shake-flask were used to inoculate 16 liters of SD-05 seed medium contained in a 30-liter stirred-jar fermentor. The jar contents were incubated at 330C for 24 hours with stirring at 300 rpm. During the incubation period, the jar contents were sparged with air at a rate of 1 volume air/volume medium/minute. EXAMPLE 5 The contents of the stirred-jar of Example 4 were used to inoculate 160 gallons (605.7 liters) of SM-31 fermentation medium contained in a 200 gallon (757.1 liter) fermentation tank. The fermentation medium was sterilized by steam heating for 40 minutes at 1210C and then cooled to 330C. The cooled fermentation medium was inoculated with about 15 liters of the seed from Example 4 and allowed to ferment for five days at 330C with stirring at 155 rpm. The stirred tank contents were sparged with air at a rate of about 1 volume airZvolume medium/minute during the fermentation. Antifoam P-2000 was used to control foaming as needed. The production of 2'-chloropentostatin was monitored throughout the process by the assay described in detail above in Example 3 and the pH and percent growth, measured as sedimentation values, were recorded. The results of these tests appear in Table 6. TABLE 6 Fermentation % Growth Zone Diatime (hers) pH (sedimentation values) meter (mm) 0 5.95 12 6.2 4.0 24 6.7 5.3 36 7.3 10.0 48 7.0 11.3 71 7.0 16.7 96 6.9 18.7 119 6.85 20.7 48 EXAMPLE 6 A cryogenically preserved l-ml sample of culture ATCC 39365 was thawed and aseptically transferred to a 2-liter baffled Erlenmeyer flask containing 600 ml of sterile 59-05 seed medium. The inoculated flask contents were incubated at 330C for 71 hours with shaking (130 rpm, 5 cm throw). After 71 hours1 the contents of the flask were aseptically transferred to 16 liters of sterile SD-05 seed medium contained in a 30-liter stirred-jar fermentor. This inoculum was incubated at 330C for 22 hours with stirring at 300 rpm and sparging with air at a rate of 1 volume air/volume medium/minute. EXAMPLE 7 SM-19 medium (300 gallon, 1135.6 liters), contained in a 500-gallon (1892.7 liter) fermentation tank were sterilized by heating with steam at 1210C for 40 minutes. The medium was cooled to 336and then inoculated with 30 liters of inoculum prepared as described in Example 6. The inoculated medium was allowed to ferment for five days at 330C with stirring at 84 rpm and sparging with air at a rate of 0.375 volume air/volume median/minute. Dow-Corning Sc" antifoam agent was used to control foaming as needed. TABLE 7 Formulation of SM-l9 Fermentation Medium Dextrin 1.5% Lactose 1.0% Distiller's solubles 0.65% Peptonized milk 0.35% Torula yeast 0.25% Tap water 100.0% pH adjusted to 7.0 with NaOH The production of 2'-chloropentostatin was monitored throughout the fermentation cycle using Streptococcus faecalis 05045 as described in Example 3. Additional fermentation parameters such as pH and percent sedimentation were also recorded. The results of these observations appear in Table 8. TABLE 8 Fermentation in a 500-Gallon (1892.7 liters) Tank Fermentation % Growth Zone Diatime (hrs) pH (sedimentation values) meter (mm) * 0 6.3 12 6.55 4.7 24 7.20 . 10.0 42 36 7.30 10.0 46 48 7.20 10.7 48 60 7.35 16.7 50 72 7.20 30.0 52.5 88 7.30 50.0 53.5 96 7.40 56.0 53.5 112 6.90 59.9 54.0 120 7.25 96.6 54.0 Measured activity against Streptococcus faecalis 05045 Chemical Isolation of 2'-Chloropentostatin A 680-liter portion of the harvested beer from Example 7 was adjusted to pH 6.5 and mixed with 31 kg of Celite 545 and filtered through a plate and frame filter press. The filtrate (680 liters) was mixed with 30 kg (4*4% w/v) Darco G-60 and, after the addition of 15.5 kg of Celite 545, filtered once more through a clean plate and frame filter press. The filter cake was washed with deionized water (185 liters), then eluted by circulating acetone-water (1:1, 151 liters) through the press three times. The acetone-water eluates, which contained most of the 2'-chloropentostatin, were combined and concentrated to 21 liters. An eighteen-liter portion of the above 21 liter concentrate was stirred with 500 grams of Elite 545 and then filtered. Following the adjustment of pH from 6.5 to 5.1, the resulting filtrate (17 liters) was passed over ten liters of Dowex-50 X 2 resin (hydrogen form). After washing the resin with deionized water (19 liters), the column was eluted with 1N ammonium hydroxide (42 liters). The ammonium hydroxide eluate, which contained all of the 2'-chloropentostatin (as determined by HPLC assay), was concentrated to 400 milliliters and passed over 10 liters of Sephadex G-10. The column was eluted with deionized water, and nine 0.5-liter fractions and seven 1-liter fractions were collected. Most of the 2'-chloropentostatin was present in fractions fifteen and sixteen, each of which was concentrated to 200 ml and lyophilized to yield 6.3 g and 6.0 g, respectively, of amorphous solid. The 6.3 g of solid from fraction fifteen was treated with hot absolute ethanol (50 ml) affording 3.86 g of crystalline 2'-chloropentostatin upon cooling. Recrystallization from water (35 ml) yielded 2.9 g of colorless needles. Similar treatment of the 6.0 g of solid from fraction sixteen afforded 1.55 g of recrystallized 2'-chloropentostatin. Properties of 2'-Chloropentostatin Melting Point: decomposition at approximately 1800C Ultraviolet Absorption Spectrum may (E), Methanol 284 nm (9380) Amax ( E)t 0.05 M methanolic HC1 266 nm-(8473) Optical Rotation 23 [a]D + 28.50 (1.26% in 0.1 M pH 7 phosphate buffer) Elemental Analysis %C %H @@@ @@@ Calcd. for C11H15ClN4O4 43.64 4.99 11.75 18.51 Found 43.83 4.96 11.76 18.62 Mass Spectrum (via fast atom bombardment) Calcd. for C11H16C1N4O4 [M + H] 303.0860 m/z Found 303.0868 m/z Infrared Absorption Spectra in KBr Principal absorptions at 3350, 1635, 1625, 1198, 1100, 1065, and 1048 reciprocal centimeters 360 MHz Proton Magnetic Resonance Spectrum in D2O Principal signals at: (s=singlet, d=doublet, dd=doublet of doublets, m=multiplet) 3.26 m (2H), 3.65 m (2H), 4.11 m (lH), 4.33 dd (lH), 4.71 dd (lH), 4.98 d (lH), 5.87 d (lH), 7.01 s (lH), and 7.55 s (lB} parts per million downfield from sodium 2,2-dimethyl-2-silapentane-S-sulfonate (DSS). 90.4 MHz Carbon-13 Magnetic Resonance Spectrum in D20 Principal signals at: peak number chemical shift* 1 152.9 2 138.1 3 134.8 4 131.6 5 90.8 6 87.9 7 73.3 8 69.5 9 63.9 10 63.5 11 49.9 * parts per million downfield from tetramethylsilane High Pressure Liquid Chromatography Column: pBondapak¯ C18 silica gel (3.9 mm I. D. X 30 cm) Solvent: 0.02 M pH 7.0 sodium phosphate buffer-acetonitrile (90:10) Flow rate: 1.0 ml/min Detection: ultraviolet absorption at 280 nm Retention time: 5.1 minutes Thin Layer Chromatography on Silica Gel 60 F254 (E. Merck) Solvent: chloroform-ethanol-0.5 M sodium acetate pH 5.5 (40:70:20) Detection: iodine vapor Rf: 0.51 The compound of the invention forms pharmaceuti- cally acceptable salts with organic and inorganic acids. Examples of suitable acids for salt formation are hydrochloric, sulfuric, phosphoric, acetic, citric, oxalic, malonic, salicylic, malic, fumaric, succinic, masonic, ascorbic, maleic, methanesulfonic and the like. The salts are prepared by contacting the free base form with an equivalent amount of the desired acid in the conventional manner. The free base form may be regenerated by treating the salt form with a base. For example, dilute aqueous base solutions may be utilized. Dilute aqueous sodium hydroxide, potassium carbonate, ammonia and sodium bicarbonate solutions are suitable for this purpose. The free base form differs from its respective salt form somewhat in certain physical properties such as solubility in polar solvents, but the salts are otherwise equivalent to the free base form for purposes of the invention. Antimicrobial Activity Paper disks (12.7 mm in diameter) impregnated with an aqueous solution containing varying amounts of 2'-chloropentostatin were placed on a layer of agar containing AM-lO assay medium (Table 4) and inoculated with Streptococcus faecalis 05045. After incubation at 370 overnight the following zones of inhibition were observed: Concentration Zone diameter 2000 pg/ml 64 mm 200 vg/ml 61 mm 20 pgfml 55 mm 2 ug/ml 47 mm 0.2 p/ml 40 mm Adenosine Deaminase Activity of 2'-Chloropentostatin The potency of 2'-chloropentostatin as an adenosine deaminase inhibitor was determined using the following methods. The velocity (in moles/minute/ml) of the reaction of adenosine deaminase with adenosine was measured for several concentrations of the enzyme in the presence of various concentrations of the inhibitor, 2'-chloropentostatin. The data has been plotted in Figure 1 in the form of an Ackerman-Potter plot (see W. W. Ackerman and V. R. Potter, Proc. Soc. Exp. Biol. Med., 72:1 (1949)). The fact that the traces, at higher concentrations of substrate, become parallel is indicative of the fact that 2'-chloropentostatin is a so-called "tight-binding" or "pseudo-irreversible" inhibitor of the enzyme, adenosine deaminase. In Figure 2, the ratio of the velocity of the uninhibited reaction of adenosine with adenosine deaminase to the velocity of the same reaction in the presence of the inhibitor, 2'-chloropentostatin, has been plotted for several concentrations of substrate versus the micromolar concentrations of 2'-chloropentostatin. The values of VO/Vi = 2 for each curve yield the I50 for the enzyme inhibitor at each substrate concentration. These I50 values have been plotted versus substrate concentration in Figure 3. Extrapolation of the linear plot of Figure 3 permits the determination of Ki = 1 x 10-10 molar for 2'-chloropentostatin. The compound of the present invention 2'-chloropentostatin is a very useful substance not only for the analysis of the causes of disease involving metabolism of adenosine and nucleic acids, but also as an agent for potentiating the activity of antiviral agents which contain an adenine mqiety such as the substance 9-(beta-D-arabinofuranosyl)adenine. The latter substance is disclosed in U.S. Patent 3,616,208 (incorporated herein by reference) as a useful agent for the treatment of DNA viruses, especially herpes and vaccinia viruses in mammals. The biological efficacy of adenine-derived antiviral agents such as 9-(beta-D-arabinofuranosyl)adenine, is greatly diminished by the rapid deamination of such materials in vivo by the enzyme, adenosine deaminase. 2'-Chloropentostatin is administered in conjunction with adenine-derived antiviral agents to potentiate the activity of the latter by inhibiting adenosine deaminase enzymes. In a preferred embodiment, 2'-chloropentostatin is combined in a pharmaceutical composition with the antiviral agent 9-(beta-D-arabinofuranosyl)adenine. More particularly, 2'-chloropentostatin is adminiseered in combination with an adenine-derived antiviral agent in ratios of from about 0.005 to about 0.5 parts of 2'-chloropentostatin to about 1 part of the antiviral agent. The preferred range is from 0.01 to 0.25 parts of 2'-chloropentostatin to 1 part of the antiviral agent. In the particular case where 2'-chloropentostatin is administered together with 9-(beta-D-arabinofuranosyl)adenine, the preferred range is from 0.01 to 0.25 parts of the compound of this invention to 1 part of 9-(beta-D arabinofuranosyl)adenine. More specifically, when the composition is administered parenterally, prefr- ably intravenously, injectable solutions are given so as to provide the host with from 0.1 mg to 5.0 mg of 9-(beta-D-arabinofuranosyl)adenine per kg of body weight and 0.0005 mg to 0.1 mg of the compound of this invention per kg of body weight per day. The preferred quantity which is administered on a daily basis is from about 0.5 mg to 5.0 mg of 9-(beta-D-arabino- furanosyl)adenine per kg of body weight to about .005 mg to 0.02 mg of the compound of this invention per kg of body weight. The pharmaceutical composition may be in bulk form containing 0.005 to 0.5 parts of the compound of this invention to about 1 part of 9-(beta-D-arabinofuranosyl)adenine which is placed in solution at time of use by the addition of a solvent which is appropriate for injectables. In the alternative, the pharmaceutical composition may be an aqueous solution containing a ratio of from 0.005 to 0.5 parts of the compound of this invention to about 1 part of 9-(beta D-arabinofuranosyl)adenine and other materials such as preservatives, buffering agents, agents intended to adjust the isotonicity of the solution, etc. The volume of water is not critical and may vary from less than 1 ml to about 500 ml.

Claims: CLAIMS (for BE,CH,DE,FR,GB,IT,LI.LU,NL,SE)= 1. The compound 2'-chloropentostatin having adenosine deaminase inhibitory activity and possessing the structure EMI22.1 and its pharmaceutically acceptable acid addition salts. 2. A pharmaceutical composition, useful for the treatment of DNA viruses comprising an effective amount of a compound selected from 2'-chloro pentostatin and its pharmaceutically acceptable acid addition salts in combination with an ef fec- tive amount of an antiviral agent containing an adenine moiety and a pharmaceutically acceptable carrier or diluent. 3. A pharmaceutical composition in accordance with claim 2 wherein said antiviral agent is 9-(beta-D-arabinofuranosyl) adenine. 4. A process for the production of 2'-chloro pentostatin which comprises cultivating a strain of actinomycete, identified as ATCC 39365, under aerobic conditions in a culture medium containing assimilable sources of carbon and nitrogen until a substantial amount of 2'-chloropentostatin is produced and subsequently isolatinq said 2'-chloropentostatin compound. 5. A purified isolate of an actinomycete having the identifying characteristics of ATCC 39365, which isolate is capable of producing 2'-chloropento statin under conditions of aerobic fermentation in a culture medium containing assimilable sources of carbon and nitrogen. CLAIMS (for AT): =1 1. A process for the production of 2'chloropentostatin having the structure EMI24.1 and its pharmaceutically acceptable acid addition salts, which process comprises cultivating a strain of actinomycete, identified as ATCC 39365, under aerobic conditions in a culture medium containinq assimilable sources of carbon and nitrogen until a substantial amount of 21-chloropentostatin is produced and subsequently isolatinq said 2'-chloropentostatin compound; and optionally forming a pharmaceutically acceptable acid add ton salt thereof. 2. A process for preparing a pharmaceutical composition useful for the treatment of DNA viruses, which process comprises combining an effective amount of 2'chloropentostatin or a pharmaceutically acceptable acid addition salt thereof prepared by a process as claimed in Claim 1, together with an effective amount of an antiviral agent containing an adenine moiety and a pharmaceutically acceptable carrier or diluent. 3. A process according to Claim 2, wherein said antiviral agent is 9-(beta-D-arabinofuranosyl) adenine. 4 . A purified isolate of an actinomycete having the identifying characteristics of ATCC 39365, which isolate is capable of producing 2'-chloropento statin under conditions of aerobic fermentation in a culture medium containing assimilable sources of carbon and nitrogen.

Inventors: FRENCH, JAMES C., HOKANSON, GERARD C., SCHAUMBERG, JOHN P., TUNAC, JOSEFINO B., UNDERHILL, MARJORIE A.
Applicants: WARNER-LAMBERT COMPANY
Application year: 1985
Main classification: C07H19
IPC codes: A61K31, C07H19, C12P19, A61P43, A61P31, C12R1