2,972,630 United States Patent Office Patented Feb. 21, 1961 2 1. considerable activity against other microorganisms which cause disease in animal and especially in humans. The following table illustrates the activity of 4-dimeth . . . . . 2,972,630 ylamino - 14,4a,5,7,8,9,10,12,12a - decahydro - 3,11,12a TETRACYCLINE DERVATIVE AND PROCESS trihydroxy-6-methyl-1,10-dioxo-2-naphthacenecar FoR PREPARATION . . . boxamide against a group of microorganisms which causes Lloyd H. Conover, Quaker Hill, and Charles R.Stephens, various diseases. A number of these microorganisms are Jr., Niantic, Conn., assignors to Chas. Pfizer & Co., resistant to other known antimicrobial agents. The tests Inc., Brooklyn, N.Y., a corporation of Delaware were carried out by serial dilution method described 10 above. For each organism is given the minimum in No Drawing. Filed Sept. 25, 1958, Ser. No. 763,204. hibitory concentration of the present new antibiotic ex 7 Claims. (CI. 260-559) pressed in mcg./ml. - . TABLE 1 Antimicrobial activity in vitro of 4-dimethylamino-1,4, This invention is concerned with a new and useful anti 5 microbial agent and with the process of its production. 4a,5,7,8,9,10,12,12a - decahydro - 3,11,12a - trihydroxy Moreover, this invention relates to methods for the puri 6-methyl-1,10-dioxo-2-naphthacenecarboxamide fication of this antimicrobial agent, and the antimicrobial Microorganism: MIC (mcg../ml.) agent in pure crystalline form. This invention includes Hemophilus influenzae ------200 within its scope the new antimicrobial agent as crude 20 Baceterium ammoniagenes ------200 concentrates and in purified forms. This novel product is Clostridium perfringes ------200 especially useful in combatting microorganisms which are Bacillus subtilis ------is a an arm - - 100 plant pathogens. Erysipelothrix rhusiopathiae ------100 The new and useful antimicrobial agent of this inven Micrococcus pyogenes var. aureus ------100 tion is 4-dimethylamino-1,4,4a,5,7,8,9,10,12,12a-decahy 25 Pasteurella multocida ------100 dro - 3,11,12a - trihydroxy - 6 - methyl - 1,10-dioxo - 2 Vibrio comma ------100 naphthacenecarboxamide which may be represented by Mycobacterium 607 ------100 the following formula: Mycobacterium berolinense ------50 Antibiotic Resistant Strains of Micrococcus pyogenes var. - Cls N(CH3) 30 aureus. Strains O 376 200 OE 400 200 CONE . This invention also includes the process for producing 35 this new antibiotic. It has been found that under certain O E. O conditions the present new antibiotic may be prepared by the catalytic hydrogenation of anhydrotetracycline which as well as the acid and base salts thereof. The present new antibiotic has considerable activity is represented by the formula: against both Gram-positive and Gram-negative especially CH3 N(CH3) those microorganisms that are pathogenic to plants. It is 40 particularly active against Phytomonas tumefaciens which OH is responsible for crown gall. Crown gall is represented by a group of diseases in which the major infection on CoNE, the host is hyperplasia and hypertrophy. Crown gall af fects preferably fruits, for example, apple, peach, apricot, 45 He bhi ( ) plums, grapes and the like. Crown gall usually consists Although it is preferred to use anhydrotetracycline in the of overgrowths varying gradually in size. Such galls present process, tetracycline itself may also serve as a occur normally on the substerranean roots of fruit trees suitable substrate for the present hydrogenation process, and shrubs and may also appear on the grown stems of since, under the conditions of the present process, as leaves of wooday and habaceous plants. The infections 50 hereinafter described, tetracycline is converted to anhy of the hosts usually result in the withering of leaves and drotetracycline in situ. The hydrogenation reaction is fruits. best carried out in the presence of mineral acid which is The present new antibiotic has been found most effec conveniently provided to the reaction mixture by employ tive in inhibiting the growth of Phytomonas tumefaciens. ing the mineral acid salt of the substrate viz. anhydro In vitro tests were carried out to detremine the minimum 55 tetracycline or tetracycline. Of course, it is obvious that inhibitory concentration of this antibiotic against P. tune the mineral acid, for example, hydrochloric acid, hydro faciens. The tests were carried out by serial dilution bromic acid, sulfuric acid, phosphoric acid, nitric acid, technique. According to this technique, a nutrient me and the like, and the substrate may be added separately dium was prepared containing the present new antibiotic to the reaction mixture with the concomitant formation at a concentration of 100 mcg../ml. Aliquots of this me 60 of the substrate mineral acid salt. Usually best results dium were next diluted with varied volumes of water so are obtained when employing at least about one-half mole that the tubes containing this new antibiotic at a con of mineral acid per mole of substrate although lesser centration of 100, 50, 25, 12.5, 6.25, 3.12, 1.56, 0.78, 0.39, amounts may be employed. It is preferred to employ 0.19 mcg../ml. were obtained. These tubes were then non-oxidizing mineral acids since best yields are realized inoculated with the test organisms, i.e. P. tumefaciens 65 in so doing. and incubated to determine the extent to which the micro The process is carried out by contacting an organic organism grows in the presence of the antibiotic. In solvent solution of anhydrotetracycline or tetracycline this fashion the minimum inhibitory concentration of the with hydrogen in the presence of palladium catalyst and, present new antibiotic was found to be 100 mcg../ml. as mentioned above, a mineral acid. Various solvents In addition to its inhibitory activity against P. tune 70 may be employed for this purpose. Lower alkanols, facients, the present new antibiotic is also possessed of for example, methanol, ethanol, isopropanol and the like c 2,972,630. 3. 4. are particularly suitable, while certain ethers such as resultant solution with an alkali metal hydroxide. The dioxane, tetrahydrofuran, dimethoxyethane and the like resulting crystals of the amphoteric antibiotic are then are also useful. The solvent, must be relatively inert to obtained by the usual method. the reactants and the product formed. In general, the The present new antibiotic has certain definite ad solvent should be relatively dry although a small amount 5 vantages over currently available antibiotic compounds. of moisture does not seriously interfere with the hydro This antibiotic is found substantially stable to air oxida genation process. tion and to acid or base degradation. The stability of The reaction is generally best conducted at super this new antibiotic makes it particularly suitable: for atmospheric pressure of hydrogen gas. Pressures of topical applications where stability is a most important from about 1000 to 2000 pounds/square inch are: found. O factor in the selection of the antimicrobial agent. For to give excellent yields although lower pressures may be, example, the present new antibiotic may be employed in employed, e.g., 30-50 pounds/square-inch. Although the disinfectant solutions: as well as in: topical ointments reaction may be conducted at room temperature, it is. either alone or together with other effective antimicrobial generally preferred to employ somewhat elevated tem agents. For these purposes a 0.2% concentration is peratures, for example, temperatures from about 30° C. 5 useful. to about 60° C. The catalyst, used may be palladium It is of course obvious that chlortetracycline may also Suspended in a carrier, for example, carbon, although be employed as a substrate in the present new process the finely divided metal itself and as well as other forms since, under the conditions of this process, it is reduced of this catalyst are found very suitable. Generally a to tetracycline, i.e. the chlorine. atom of the chlortetra concentration of at least 5% by weight of the substrate 20 cycline nucleus is replaced by hydrogen with concomit used is necessary. In general there is no reason to use ant-formation of hydrogen chloride gas. m more than equal weights of catalysts and substrate. This new antibiotic may be condensed with certain Other hydrogenation catalysts. Such as platinum may be aldehydes to form products, which may possess strong. used in conducting the present process, however, palladi antibacterial activity. For example, the present new lin is found to be most useful. 25 antibiotic may be condensed with such aldehydes as The course of reaction may be conveniently followed p. nitrobenzaldehyde, salicylaldehyde, 5-nitrofurfuralde by measuring the uptake of hydrogen gas. After the hyde, 5-nitrobenzylaldehyde, and the-like. The reaction absorption of 3 moles of hydrogen per mole of substrate conditions employed are generally - well known. The the reaction is complete. Generally, reaction times of starting compounds, are aliowed to react, in the presence from about 1 to 12 hours are required to. produce an 30 of a strong base. Such as an alkali metal-hydroxide, for. appreciable amount of product, although it should be example, sodium, potassium or lithium hydroxide. Usual realized that the time of reaction is dependent on various ly a lower alkanol is employed for this reaction. The other operating conditions for the reaction, i.e. the time crystalline products: are obtained: from the reaction mix of reaction, the temperature, pressure, concentration of ture by known methods. antibiotic used, catalyst which are related. The concen As mentioned above the novel, antibiotic of this inven tration of Substrate in the reaction mixture does not ap tion is useful in combatting P. tumefaciens. The anti pear to be critical. In general a solution having a con bacterial agent may be applied to the infected hosts in a centration of from about 1% to about 10% of starting variety of forms, for example, in suitable extending material is found satisfactory. More dilute or more con. media, liquid or solid, which are well known in the art, centrated solutions may be used but there is: no particular 40 For example, solutions or suspensions of the antibiotic advantage in so doing. When the: reaction is complete. in suitable solvents may be. employed to introduce the the product may be recovered by any desired means, for agent into the host by root absorption. Alternatively, example, after removal of the catalyst, by concentration solid compositions containing the antibiotic in a solid of the resultant solution. Other methods for obtaining extending agent, such as fullers earth, various types of the crude product may be employed such as the addition 45 clay, peatmoss and the like, may be advantageously ap of a non-solvent of the product to the filtered reaction plied to the roots of the host by conventional means. mixture after concentration. Such... non-solvents include Solutions or suspensions of the antibiotic may be applied diethyl ether, pentane, benzene, toluene and other organic directly to the seat of infection, i.e. the gall, by conven non-polar solvents. ventional means. Treatment may be continued for as The product is, obtained in the form of a salt corre. 50 long as-is' required to combat the phytopathogen. The Sponding to the mineral acid employed in the process: time required of course will vary with the host, the extent If preferred the amphoteric product may be obtained of infection and so forth. from the reaction, mixture by neutralization of the The following examples are given by way of illustra mineral acid before concentration. The use of an alkali tion and are not to be construed as limitations of this metal hydroxide is most convenient for this purpose. 55 invention many variations of which are possible within Of course, the amphoteric substance may be obtained the scope and spirit thereof. from the isolated mineral acid salt by the usual method, for example, treating an aqueous solution of the anti EXAMPLE I biotic acid salt with alkali such as an alkali metal Anhydrotetracycline hydrochloride (25 g.) in 500 ml. hydroxide. 60 of methanol is treated with 10 g. of 5% palladium on The crude ridineral acid salts of the present antibiotic carbon and stirred with hydrogen at 50 C. and 1000 as Well as the amphoteric form may be further purified 1500 p.si-pressure in a stainless steel autoclave for five by convenional methods. The procedure involves dis hours, during which time 3 molar equivalents of hydro Solving the mineral acid salts in water and adjusting the gen are absorbed. The reaction mixture, after cooling pH to between 5 to 6 with aqueous alkali metal hy: 65 and filtering free of catalyst, is evaporated to obtain a droxide. The resultant gummy slurry is then treated crude product as the hydrochloride. The crude hydro with ether after which the amphioteric form of the present chloride (20g) is dissolved in 100ml. of deionized water new antibiotic crystallizes. The crystalline. amphioteric and the solution adjusted to pH 5-6 with 100% aqueous. antibiotic is then dissolved in hot methanoli clarified sodium hydroxide. The resultant gummy slurry is treated With activated carbon and after removal of the carbon, 70 with an equal volume of ether and stirred. The product treated with aqueous mineral acid. The pure crystalline crystallizes as a white precipitate which is separated by mineral acid salt of the antibiotic separates from the mix 1 a is " ...... is t by separation: ture and is filtered and dried by the usual method. Pure of the etherlayer from the itrate and extraction- as ' ' ...of the:i crystalline amphotericantibiotic is obtained by dissolving aqueous layer with 2 equal volumes of ether followed by. the hydrochloride in-hot water and neutralizing the 75 concentration of the combined ether extracts. 2,972,680 5 6 The product is then dissolved in hot methanol, treated the corresponding acid salts: phosphoric, sulfuric, and with activated carbon and then, after filtering off the car nitric. Additionally organic acid salts are formed with bon, with 5% aqueous hydrochloric acid. The pure crys the following strong organic acids: citric, tartaric, gly talline hydrochloride of 4-dimethylamino-1,4,4a,5,7,8,9, collic, gluconic, malic, succinic and glutaric acids. This 10,12,12a - decahydro - 3,11-12a-trihydroxy-6-methyl-1, procedure is also used to form basic salts of the anti 10-dioxo-2-naphthacenecarboxamide separates from the biotic with the following alkali metal and alkaline earth mixture and is filtered and dried by the usual method. metal hydroxides, sodium, potassium, lithium, calcium, The pure crystalline hydrochloride melts at 239-240 C. barium, magnesium and strontium hydroxides. (dec.). When dissolved in 0.01 N HCl in methanol, What is claimed is: exhibited the following ultraviolet absorption maxima: O 1. A compound selected from the group consisting of 4 - dimethylamino - 14,4a,5,7,8,9,10,12,12a-decahydro A max=265 mu, logie 4.55 3,11,12a - trihydroxy-6-methyl-1,10-dioxo-2-naphthacene X. max=346 mp, logie 3.72 carboxamide, the mineral acid salts thereof, the alkali and, when dissolved in 0.01 N sodium hydroxide in meth metal salts thereof and the alkaline earth metal salts there anol, 5 of. N. max=272 mu, log e 4.32 2. 4 - dimethylamino - 14,4a,5,7,8,9,10,12,12a-decahy A max=349 mp, log e 4.54 dro - 3,11,12a-trihydroxy-6-methyl-1,10-dioxo-2-naphtha The pK values in water of this hydrochloride are 4.1, cenecarboxamide. 8.4 and about 12.2. 3. A mineral acid salt of 4-dimethylamino-1,4,4a,5,7, Elemental analysis gave the following results: 20 8,9,10,12,12a - trihydroxy-6-methyl-1,10-dioxo-2-naphtha Calculated for C22H2NOCl: C, 58.6; H, 6.0; N, 6.2; cenecarboxamide. C. 7.9. Found: C, 58.6; H, 6.0; N, 5.8; Cl, 8.0. 4. An alkali metal salt of 4-dimethylamino-1,4,4a,5,7, The pure crystalline hydrochloride was converted to 8,9,10,12,12a - trihydroxy-6-methyl-1,10-dioxo-2-naphtha pure amphoteric compound by dissolving one gram in 5 cenecarboxamide. ml. of hot water and neutralizing to about pH 7.0 with 5. An alkaline earth metal salt of 4-dimethylamino Sodium hydroxide. The resulting crystals (0.8 g.) were 1,4,4a,5,7,8,9,10,12,12a - trihydroxy-6-methyl-1,10-dioxo filtered and recrystallized from methanol to yield a crys 2-naphthacenecarboxamide. talline product, 4-dimethylamino-1,4,4a,5,7,8,9,10,12,12a 6. A process for the preparation of a mineral acid salt decahydro - 3,11,12a - trihydroxy-6-methyl-1,10-dioxo-2- of 4 - dimethylamino-1,4,4a,5,7,8,9,10,12,12a-decahydro naphthacenecarboxamide which melted at 209-211 C. 30 3,11,12a - trihydroxy-6-methyl-1,10-dioxo-2-naphthacene Elemental analysis of the product gave the following re carboxamide which comprises contacting an inert organic Sults: solvent solution of a tetracycline compound selected from Calculated for Ca2H26NOs: C, 64.0; H, 6.3; N, 6.8. the group consisting of tetracycline and anhydrotetra Found: C, 63.8; H, 6.4; N, 6.5. cycline with hydrogen in the presence of a palladium EXAMPLE 35 catalyst and a mineral acid at a temperature of from about 30 to about 60° C. and under a pressure up to Preparation of aldehyde derivatives of 4-dimethylamino about 2000 pounds per square inch until approximately 14,4a,5,7,8,9,10,12,12a-decahydro-3,11,12a-trihydroxy three moles of hydrogen have reacted with each mole 6-methyl-1,10-dioxo-2-naphthacenecarboxamide of said tetracycline compound. Four and one-half grams of the hydrochloride of 4 40 7. A process for the preparation of a mineral acid salt dimethylamino - 14,4a,5,7,8,9,10,12,12a-decahydro-3,11, of 4 - dimethylamino-1,4,4a,5,7,8,9,10,12,12a-decahydro 12a - trihydroxy - 6-methyl-1,10-dioxo-2-naphthacenecar 3,11,12a - trihydroxy-6-methyl-1,10-dioxo-2-naphthacene boxamide (0.01 mole) and 1.06 g. (0.01 mole) of benz carboxamide, which comprises contacting an inert polar aldehyde in 100 ml. of ethanol containing 2.0 g. of po organic solvent solution of a tetracycline compound se tassium hydroxide was stirred for seven hours. The re 45 lected from the group consisting of tetracycline and an Sulting slurry was acidified with hydrochloric acid, diluted hydrotetracycline with hydrogen in the presence of a pal with 100 ml. of water and the resultant solution adjusted ladium catalyst and a mineral acid at a temperature of to pH 6.0 to 7.0 with alkali (NaOH). The crystalline from about 30 to about 60° C. and under a pressure benzal derivative separated and was filtered. up to about 200 pounds per square inch until approxi Employing the procedure, the corresponding 5-nitrofur 50 nately three moles of hydrogen have reacted with each fural, p-nitrobenzaldehyde, salicylaldehyde and other al mole of said tetracycline compound. dehyde derivatives are prepared. The p-nitrobenzaldehyde derivative had a bioassay of References (Cited in the file of this patent 22 oxytetracycline units/mg. in the K. pneumoniae plate UNITED STATES PATENTS assay. 55 The crystalline amphoteric antibiotic is converted to 2,731,497 McCormick ------Jan. 17, 1956 acid salts by dissolving in hot methanol followed by ad 2,744,932 Waller ------May 8, 1956 dition of the acid to the resultant solution. The crystal FOREIGN PATENTS line acid salt separates from the mixture on standing or 167,750 Australia ------May 25, 1956 after concentration of the mixture. Employing this pro 60 534,498 Canada ------Dec. 18, 1956 cedure the following mineral acids are used to form