NEW ANTIBIOTICS OF THE MUREIDOMYCIN GROUP, THEIR PREPARATION, AND THEIR THERAPEUTIC USE

Abstract: New antibiotics of the mureidomycin group have the formula wherein X represents the group and wherein R represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, an alkenyl group having from 2 to 7 carbon atoms, an alkynyl group having from 3 to 7 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an aralkyl group having from 7 to 10 carbon atoms, or one of the said aryl or aralkyl groups substituted with at least one halogen atom and/or at least least one alkyl group having from 1 to 5 carbon atoms. The compound in which X represents 8-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl is named mureidomycin E and the compound in which X represents 6-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl is named mureidomycin F. This group of compounds and their pharmaceutically acceptable esters and salts are useful as antibiotics for the treatment of bacterial infections. Mureidomycins E and F can be obtained by fermentation of a suitable Streptomyces strain, in particular Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347). ALternatively, all of the compounds can be obtained synthetically by reacting the previously known compound mureidomycin A with an aldehyde of the formula R - CHO.

Description: The present invention relates to certain novel antibiotics of the mureidomycin group, and also provides methods for preparing them and an antibacterial composition containing at least one of them as the active ingredient. As resistance to conventional antibiotics becomes increasingly established in common strains of pathogenic bacteria, the need for a wider variety of antibiotics for use in the fight against such bacteria becomes ever more crucial. Although this need can be, and sometimes is, met by chemical modification of existing classes of antibiotic, the discovery of a wholly new class of antibiotic leads to exciting possibilities in the treatment of diseases caused by pathogenic bacteria. Such a new class of antibiotics, named the "mureidomycins", is disclosed in our previous E.P. patent application number 0,253,413 filed on May 18, 1987 and prior art under Art 54(3) EPC only. In this we have disclosed the isolation of the first four members of this class, mureidomycins A, B, C and D, from the fermentation broth produced by a then newly discovered microorganism, Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347). We have now discovered two new members of this class of antibiotics, herein named "mureidomycins E and F", together with their salts and esters and certain other derivatives, which are particularly effective against Gram-negative bacteria, most especially strains of the genus Pseudomonas . Mureidomycins E and F can also be isolated from the fermentation broth of Streptomyces strain SANK 60486. Alternatively, these two new mureidomycins as well as certain of their derivatives can be prepared by subjecting mureidomycin A to chemical reaction. Mureidomycins A to F referred to herein can be represented by the following planar structural formula: wherein:- for Mureidomycin A , R¹ represents 2,4-dioxopyrimidin-1-yl and R² represents α-amino-3-hydroxyphenethyl; for Mureidomycin B , R¹ represents 2,4-dioxodihydropyrimidin-1-yl and R² represents α-amino-3-hydroxyphenethyl; for Mureidomycin C , R¹ represents 2,4-dioxopyrimidin-1-yl and R² represents α-glycylamino-3-hydroxyphenethyl; for Mureidomycin D , R¹ represents 2,4-dioxodihydropyrimidin-1-yl and R² represents α-glycylamino-3-hydroxyphenethyl; for Mureidomycin E , R¹ represents 2,4-dioxopyrimidin-1-yl and R² represents 8-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl; and for Mureidomycin F , R¹ represents 2,4-dioxopyrimidin-1-yl and R² represents 6-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl. Thus, the invention provides, as new compounds, mureidomycins E and F and derivatives thereof which can be represented by the following planar structural formula: wherein X represents the group and wherein R represents hydrogen, alkyl, alkenyl, alkynyl, aryl or aralkyl. Mureidomycin E is the compound of the above formula (I) wherein X represents the group (i.e. the 8-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl group) and mureidomycin F is the compound of the above formula (I) wherein X represents the group (i.e. the 6-hydroxy-1,2,3,4-tetrahydroisoquinolan-3-yl group). The invention also provides pharmaceutically acceptable salts and esters of the above compounds of formula (I). The invention further provides a process for producing mureidomycin E or F or a salt or ester thereof, by cultivating a mureidomycin E or F producing microorganism of the genus Streptomyces in a culture medium therefor and isolating mureidomycin E or F or a salt thereof from the cultured broth, and optionally salifying, desalifying or esterifying the compound thus isolated. The invention still further provides a pharmaceutical composition, useful for the treatment or prophylaxis of bacterial infections, comprising a compound of the above formula (I), or a salt or ester thereof, in admixture with a pharmaceutically acceptable carrier or diluent. In the accompanying drawings:- Figure 1 shows the ultraviolet absorption spectrum of mureidomycin E; Figure 2 shows the infrared absorption spectrum of mureidomycin E; Figure 3 shows the nuclear magnetic resonance spectrum of mureidomycin E; Figure 4 shows the ultraviolet absorption spectrum of mureidomycin F; Figure 5 shows the infrared absorption spectrum of mureidomycin F; Figure 6 shows the nuclear magnetic resonance spectrum of mureidomycin F; Figures 7A and 7B show the ultraviolet absorption spectrum of mureidomycin A; Figure 8 shows the infrared absorption spectrum of mureidomycin A; Figure 9 shows the nuclear magnetic resonance spectrum of mureidomycin A; Figure 10 shows the nuclear magnetic resonance spectrum of methylmureidomycin E; and Figure 11 shows the nuclear magnetic resonance spectrum of methylmureidomycin F. In the above formula (I), where R is alkyl, it is straight or branched C₁-C₁₀, preferably C₁-C₅, most preferably C₁-C₃ alkyl, for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, 1,1-dimethylbutyl, 1,3-dimethylbutyl, heptyl, octyl, 2-ethylhexyl, nonyl or decyl. Where R is alkenyl, it is straight or branched C₂-C₇, more preferably C₂-C₄ alkenyl, for example vinyl, allyl, methallyl, 2-butenyl, 3-butenyl, 3-pentenyl, 4-hexenyl or 5-heptenyl. Where R is alkynyl, it is straight or branched C₃-C₇, more preferably C₃-C₄ alkynyl, for example ethynyl, 1-propynyl, 2-propynyl, 2-butynyl, 3-pentynyl, 3-hexynyl or 4-heptynyl. Where R is aryl, it is C₆-C₁₀ aryl, for example phenyl or naphthyl, and more preferably phenyl. Where R is aralkyl, it is C₇-C₁₀, more preferably C₇-C₈ aralkyl, for example benzyl, phenetyl, α-methylbenzyl, 3-phenylpropyl or 4-phenylbutyl. Where R is aryl or aralkyl, the aryl nucleus can be unsubstituted or may optionally carry one or more substituents, such as straight or branched C₁-C₅ alkyl (e.g.methyl, ethyl, propyl, butyl or pentyl) or halogen (e.g. chlorine, fluorine or bromine). Preferably R is hydrogen, C₁-C₁₀ alkyl, phenyl, (C₁-C₅ alkyl)phenyl or halophenyl, and most preferably R is hydrogen, C₁-C₅ alkyl or phenyl Since the compounds of formula (I) are amphoteric in character, they are capable of forming salts and esters, and these salts and esters also form part of the present invention. The nature of such salts and esters is not critical, except that, where they are to be used for medicinal, or veterinary purposes, they must be medicinally acceptable, i.e. they must not, or must not to a significant extent, either have increased toxicity or have reduced activity, as compared with the free unsalified or unesterified compound. Examples of suitable acids for the formation of such salts include inorganic acids, such as hydrochloric, sulphuric or phosphoric acid; organic carboxylic acids, such as acetic, citric, tartaric, malonic, maleic, malic, fumaric, itaconic, citraconic or succinic acid; and organic sulphonic acids, such as methanesulphonic, benzenesulphonic, naphthalenesulphonic or p -toluenesulphonic acid. The carboxy group present in the said compounds may also form salts with appropriate bases. Examples of such salts include salts with metals, especially alkali and alkaline earth metals, such as the lithium, sodium, potassium, calcium and magnesium salts, the ammonium salts, salts with organic amines, such as cyclohexylamine, diisopropylamine or triethylamine, and salts with basic amino acids, such as lysine or arginine. Examples of suitable esters of the said compounds of formula (I) include: C₁-C₆, more preferably C₁-C₄, alkyl esters, for example the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl and hexyl esters; aralkyl, including diarylalkyl, esters, such as the benzyl, p -nitrobenzyl and benzhydryl esters; alkoxycarbonylalkyl esters, in which the alkoxy and alkyl moieties suitably each have from 1 to 4 carbons, especially alkoxycarbonylmethyl esters such as the ethoxycarbonylmethyl and t-butoxycarbonylmethyl esters; alkoxycarbonyloxyalkyl esters in which the alkoxy and alkyl moieties suitably each have from 1 to 4 carbons, especially 2-alkoxycarbonyloxyethyl esters such as the 2-methoxycarbonyloxyethyl, 2-ethoxycarbonyloxyethyl and 2-t-butoxycarbonyloxyethyl esters; and other specific esters, such as the phthalidyl, substituted phthalidyl, phenacyl, substituted phenacyl (e.g. p -nitrophenacyl) and (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl esters. Mureidomycins E and F and salts thereof are produced by the cultivation of a Streptomyces strain herein identified as Streptomyces sp. SANK 60486, and which has the following mycological properties. These characteristics were determined by cultivation on various media prescribed by the ISP (International Streptomyces Project) or with the media recommended by S.A. Waksman in Volume 2 of "The Actinomycetes", in all cases at a temperature of 28°C, except where otherwise stated. 1. Morphological characteristics Generally, on an agar medium, the substrate hyphae of the microorganism branch and elongate well and the aerial hyphae of the microorganism branch simply. The spore chain forms straight to curved lines. It is observed that the number of spores formed on a spore chain are mostly from ten to fifty, but may be more. The spores are ellipsoidal, in the size range from 0.5 - 0.8 µm x 0.7 - 1.1 µm, and with a smooth surface. No special organs, such as wheel axle branching of the aerial hyphae, sclerotia, sporangia and the like, were observed. 2. Culture characteristics on various media After culturing on various kinds of culture media at 28°C for 14 days, the properties are shown in Table 1. Representation of the colour tones is shown by using the colour tip numbers given in the "Guide to Color Standard" edited by Nippon Shikisai Kenkyusho. In this Table, the following abbreviations are used: G: growth; AM: aerial mycelium; R: reverse; SP: soluble pigment. 3. Physioilogical properties The physiological properties of strain SANK 60486 are shown in Table 2. After culturing on Pridham Gottlieb agar medium (ISP 9) at 28°C for 14 days, assimilability of carbon sources by strain SANK 60486 is shown in Table 3. 4. Cell wall constitution The cell wall of strain SANK 60486 was examined according to the method of B. Becker et al . [Applied Microbiology, 12 , 421 - 423 (1964)]. L , L -Diaminopimelic acid and glycine were detected in it. Identification of strain SANK 60486 was carried out in accordance with The International Streptomyces Project; Bergey's Manual of Determinative Bacteriology, 8th edition; "The Actinomycetes" edited by S. A. Waksman and other recent literature relating to the Streptomycetes. On the basis of the above data, the strain was identified as a strain of Streptomyces flavidovirens and is here referred to as Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347). The strain SANK 60486 has been deposited with the Fermentation Research Institute, Agency of Industrial Science and Technology, Ministry of International Trade and Industry, Japan, on February 4, 1986 under the accession number FERM P-8636 and was re-deposited in accordance with the conditions stipulated by the Budapest Treaty with said Fermentation Research Institute on April 17, 1987 under the accession number FERM BP-1347. It has been established that strain SANK 60486 produces mureidomycins E and F. However, as is well known, the properties of microorganisms falling within the general category of the actinomycetes can vary considerably and such microorganisms can readily undergo mutation, both through natural causes and as the result of induction by artificial means. Accordingly, the process of the present invention embraces the use of any microorganism which can be classified within the genus Streptomyces and which shares with the strain SANK 60486 the characteristic ability to produce mureidomycins E and F. The microorganism employed in the process of the present invention is preferably a strain of the species Streptomyces flavidovirens , and more preferably Streptomyces flavidovirens SANK 60486 (FERM BP-1347). The cultivation of microorganisms of the genus Streptomyces in accordance with the present invention to produce mureidomycins E and F can be performed under conditions conventionally employed for the cultivation of actinomycetes species, preferably in a liquid culture, and desirably with shaking or stirring and aeration. The nutrient medium used for the cultivation is completely conventional and contains such constituents as are commonly used in the cultivation of the actinomycetes. Specifically, the medium should contain one or more assimilable carbon sources, suitable examples of which include glucose, maltose, sucrose, mannitol, molasses, glycerol, dextrin, starch, soybean oil and cottonseed oil; one or more assimilable nitrogen sources, suitable examples of which include soybean meal, peanut meal, cottonseed meal, pharmamine, fish meal, corn steep liquor, peptone, meat extract, live yeast, pressed yeast, yeast extract, sodium nitrate, ammonium nitrate or ammonium sulphate; and one or more inorganic salts, such as sodium chloride, phosphates, calcium carbonate and trace metal salts. Where cultivation is effected in a liquid medium, it is generally desirable to incorporate an anti-foaming agent (for example silicone oil, vegetable oil or a suitable surfactant) in the medium. The cultivation is suitably performed at a substantially neutral pH value and at a temperature of from 20 to 37°C, more preferably at about 22°C. The production of mureidomycins as cultivation proceeds may be monitored by a variety of conventional microbiological assay techniques for monitoring the production of antibiotics (when they are produced by microbial culture) and which require little or no elaboration here. A suitable technique might be the paper disc-agar diffusion assay (using, for example, a paper disc of diameter about 8 mm produced by Toyo Kagaku Sangyo Co., Ltd) and using, for example, Pseudomonas aeruginosa strain SANK 70579 as the test organism. The amount of mureidomycins produced normally reaches a maximum after cultivation has proceeded for 72 - 96 hours and it is clearly desirable to separate the mureidomycins from the culture medium no later than the time when this maximum has been reached. However, this period may vary, depending upon the cultivation conditions and techniques, and a shorter or longer period may be appropriate, depending upon the circumstances. The correct cultivation time may readily be assessed for every case by routine experiment, using suitable monitoring techniques, e.g. as described above. Mureidomycins E and F are mainly released into the liquid portion of the cultured broth and can thus be recovered by removing solid matter, including the mycelium, for example by filtration (preferably using a filter aid such as diatomaceous earth) or by centrifugation. They can then be recovered from the separated liquid portion by conventional techniques and, if desired, then purified and/or separated from each other. The antibiotics, mureidomycins E and F, may be separated, collected and purified by utilizing their physico-chemical properties. For example, suitable methods include: extraction with solvents; ion-exchange through resins, for example, anion exchange resins such as Dowex SBR-P (Dow Chemical Co.) or cation exchange resins such as Dowex 50 W (Dow Chemical Co.) or IRC-50, CG-50 (Rohm & Haas Co.); chromatography through active carbon as the absorbent or through non-ionic absorption resins such as Amberlite XAD-2, XAD-4 or XAD-7 (Rohm and Hass Co.) or Diaion HP 10, HP 20, CHP 20P or HP 50 (Mitsubishi Chemical Industries, Ltd.); and chromatography through silica gel or alumina. Furthermore, separation, collection and purification of the metabolites may be performed by using any one or more of the following operations, which may be combined in any order or repeated, if desired: partition colum chromatography over cellulose such as Avicel (Asahi Chemical Industry Co., Ltd.) or Sephadex LH-20 (Pharmacia Co.); gel filtration using Sephadex G-10, G-25, G-50 or G-100 (Pharmacia Co.) or Toyopearl HW-40 (Toyo Soda Manufacturing Co., Ltd.); crystallization; and recrystallization. ("Dowex", "Amberlite", "Diaion", "Avicel", "Sephadex" and "Toyopearl" are all trade marks.) Depending upon the culture conditions, mureidomycins E and F can exist in the mycelium from the culture and can be extracted therefrom by conventional techniques. For example, they can be extracted with a hydrophilic organic solvent (such as an alcohol or acetone), and then the solvent removed from the extract to leave a residue, which is dissolved in an aqueous medium. The mureidomycins can be extracted from the resulting solution and purified as described above. Mureidomycins E and F are preferably separated from each other by chromatography. Where the mureidomycin E or F is isolated in the form of a salt, it may be converted to the free unsalified compound by conventional means, such as the use of ion-exchange resins or of adsorbents for reverse phase chromatography. Equally, the free unsalified compound may be salified by conventional means, for instance by treatment with an appropriate acid, such as one of those listed above, or with an appropriate base (e.g. a metal hydroxide or carbonate, such as sodium or potassium hydroxide, or sodium or calcium carbonate). Esters may be prepared by conventional esterification procedures, such as by reaction with an appropriate alcohol under acid catalysis. Mureidomycins E and F thus obtained have the physical and chemical properties described below. Mureidomycin E has the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D -34.2° (c 1.17, 50% v/v aqueous methanol); 3) Elemental analysis: C, 48.57%; H, 5.35%; N, 11.34%; S, 3.00% - measured as the hydrate; 4) Molecular weight: 852 [high resolution mass spectrum FAB MS: 853.3212 (QM⁺)] (FAB MS is Fast Atom Bombardment Mass Spectroscopy); 5) Molecular formula: C₃₉H₄₈N₈O₁₂S; 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 8-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid; 7) Ultraviolet absorption spectrum, 258 nm (252) in neutral water; 258 nm (247) in 0.01 N aqueous hydrochloric acid; 240 nm (432), 265 nm (235, shoulder) and 295 nm (80, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figure 1 of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 2 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 3 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulphuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.39; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 4.7 minutes. Mureidomycin F has the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D -40.3° (c 1.05, 50% v/v aqueous methanol); 3) Elemental analysis: C, 50.40%; H, 5.53%; N, 11.20%; S, 2.92% - measured as the hydrate; 4) Molecular weight: 852 [high resolution mass spectrum FAB MS: 853.3180 (QM⁺)] 5) Molecular formula: C₃₉H₄₈N₈O₁₂S: 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 6-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid; 7) Ultraviolet absorption spectrum 258 nm (232) in neutral water; 258 nm (232) in 0.01 N aqueous hydrochloric acid; 240 nm (352), 265 nm (200, shoulder) and 295 nm (64, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figure 4 of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 5 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 6 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulphuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.34; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 5.3 minutes. Mureidomycins E and F and their derivatives as well as their salts and esters, represented by the above general formula (I), can alternatively be obtained by reacting mureidomycin A, having the formula: or a salt or ester thereof, with an aldehyde of the formula: R-CHO (IV) (wherein R is as defined above) and optionally salifying, desalifying or esterifying the compound thus obtained. This preparation can be carried out by reacting about one mole of mureidomycin A or salt or ester thereof with about 3 to 6 moles of aldehyde of the above formula (IV). The reaction is preferably performed in an inert solvent. There are no specific limitations on the choice of solvent, provided that it does not interfere with the course of the reaction, and suitable examples include water, ethers such as tetrahydrofuran and dioxane, and mixtures of water with such organic solvents. The reaction temperature will usually be in the range of 5-100°C, and preferably between room temperature and 80°C. The reaction time will depend on the nature of the reactants and the temperature employed, but will usually be in the range of from 1 to 24 hours. On completion of the reaction, the desired product may be isolated and purified by the same techniques as already mentioned above for the product obtained by the microbial fermentation route. If desired, the product can also be salified, desalified or esterified, as already described above. Mureidomycin A, used as starting material in the above reaction, can be obtained by cultivation of the same Streptomyces flavidovirens SANK 60486 as is used in the present invention for the production of mureidomycins E and F. Mureidomycin A may be separated, collected and purified from the liquid portion of the culture broth of Streptomyces flavidovirens SANK 60486 by utilisation of its physico-chemical properties. The micro-oraganism is cultivated, preferably in a liquid culture, in a conventional medium for cultivation of actinomycetes containing one or more assimilable carbon source, nitrogen source and inorganic salt. Cultivation is performed at a substantially neutral pH and at a temperature of from 20 to 37°C and the production of mureidomycin A can be monitored using standard procedures. Procedures are more fully described in co-pending European application 0,253,413. Mureidomycin A has the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D +40.9° (c 0.69, 50% v/v aqueous methanol); 3) Elemental analysis: C, 49.73%; H, 5.65%; N, 12.08%; S, 3.40% - measured as the hydrate; 4) Molecular weight: 840 [high resolution mass spectrum FAB MS: 841.31798 (QM⁺)] (FAB MS is Fast Atom Bombardment Mass Spectroscopy); 5) Molecular formula: C₃₈H₄₈N₈O₁₂S; 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 7) Ultraviolet absorption spectrum, 260 nm (348) in neutral water; 258 nm (358) in 0.01 N aqueous hydrochloric acid; 240 nm (499), 265 nm (330, shoulder) and 295 nm (78, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figures 7A and 7B of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 8 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (400 MHz) was measured in dimethyl sulphoxide using tetramethylsilane as external standard and is shown in Figure 9 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulphuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.36; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 3.92 minutes. The minimal inhibitory concentrations (MIC) of mureidomycins E and F against various Gram-positive and Gram-negative bacteria were determined by the agar dilution method, using a Mueller-Hinton agar medium (produced by Difco). The results are shown in Table 4. Tests also show that methylmureidomycins E and F and phenylmureidomycins E and F inhibit the growth of Pseudomonas aeruginosa SANK 70579. From the above data, mureidomycins E, F and their derivatives are seen to be active against Gram-negative bacteria, particularly against bacteria of the genus Pseudomonas . No toxicity was observed in mice receiving intravenously 400 mg/kg of mureidomycin E or F or one of their derivatives From the above findings, it can be seen that mureidomycins E and F and their derivatives can be used as antibiotics against various diseases caused by bacterial infections. The route of administration can vary widely and may be parenteral (e.g. by subcutaneous, intravenous or intramuscular injection or by suppository) or oral (in which case it may be administered in the form of a tablet, capsule, powder or granule). The dose will, of course, vary with the nature of the disease to be treated, the age, condition and body weight of the patient and the route and time of administration; however, for an adult human patient, a daily dose of from 0.1 to 10 grams is preferred and this may be administered in a single dose or in divided doses. The invention is further illustrated by the following Examples. EXAMPLE 1 Mureidomycins E, F and A by fermentation One platinum loopful growth of Streptomyces flavidovirens SANK 60486 was inoculated into a 500 ml Erlenmeyer flask containing 80 ml of medium A, which has the following composition (percentages are by weight): The microorganism was then cultured for 84 hours at 22°C, using a rotary shaker at 220 r.p.m. 25 ml of the resulting seed culture were inoculated into each of four 2-litre Erlenmeyer flasks, each containing 500 ml of medium A, which has the composition described above. The microorganism was then cultured at 22°C for 24 hours, using a rotary shaker at 220 r.p.m. The resulting cultured broths were combined. 750 ml of this broth were then inoculated into each of two 30 litre jar fermentors, each containing 15 litres of medium A, and the microorganism was then cultured at 22°C for 96 hours, whilst aerating at the rate of 15 litres per minute and agitating at 150 r.p.m. At the end of this time, the two batches of cultured broth were combined, Celite 545 (a registered trade mark for a product of Johns-Manville Products Corp, New Jersey, U.S.A.) filter aid was added and the mixture was filtered, to give 30 litres of a filtrate. This filtrate was adsorbed on 3 litres of Amberlite XAD-2 in a chromatography column. The column was washed, in turn, with 15 litres of deionized water and then with 12 litres of water containing 15% v/v methanol, after which it was eluted with 15 litres of water containing 40% v/v methanol. The methanol was then removed from the fractions containing active components by distillation under reduced pressure, after which the residual solution was lyophilized, to give 17.4 g of a crude product as a powder. 17 g of this crude powder were dissolved in 3 litres of deionized water, and the solution was passed through a column containing 800 ml of Amberlite CG-50 (H⁺), to adsorb the active component. The active component was eluted from the column with 0.5 M aqueous ammonia. The eluted active fractions (4 litres) were collected and concentrated to a volume of 1.0 litre by evaporation under reduced pressure. The concentrate (1.0 litre) was passed through 500 ml of DE-52 ion exchanger (Whatman Ltd.), which had been pre-equilibrated with a 0.1 M aqueous solution of ammonium bicarbonate and the active component was adsorbed on the column. The column was eluted with 0.2 M aqueous ammonium bicarbonate. The fractions (1 litre) containing the active component were collected and adsorbed on a column containing 200 ml of Diaion HP 20 (Mitsubishi Chemical Industries, Ltd.), after which the column was eluted with 500 ml of 50% v/v aqueous acetone, to give an active component. The fractions containing the active component were concentrated by evaporation under reduced pressure and lyophilized to afford 15 g of a crude powdery product containing mureidomycins E, F and A. 14 g of this crude powder was dissolved in 500 ml of deionized water, and the active component was adsorbed on a column containing 500 ml of DE-52, which had been pre-equilibrated with 0.05 M aqueous ammonium bicarbonate. The column was washed with 0.05 M aqueous ammonium bicarbonate, and then eluted with 0.1 M aqueous ammonium bicarbonate to give fractions, each containing 20 ml of the eluent. Fractions 80 to 130 containing the active components were collected and adsorbed on a column containing HP 20, in order to deionize them. The deionized eluent was concentrated by evaporation under reduced pressure, and the residue was lyophilized to afford 3.1 g of a partially purified powder. 3.0 g of this partially purified powder were subjected to column chromatography through a column containing 100 g of silica gel, which was eluted with a mixture of butanol, propanol and water (8:4:1) to give fractions each containing 20 ml of the eluent. Fractions 13 to 70 were collected, mixed with water, concentrated under reduced pressure and lyophilized, to give 320 mg of crude powdery product containing antibiotics mureidomycins E, F and A. A solution of 300 mg of the crude powder thus obtained dissolved in 30% v/v aqueous methanol was adsorbed on a column containing 1000 ml of Toyopearl HW-40, and the column was eluted with 30% v/v aqueous methanol to give fractions, each containing 10 ml of the eluent. Fractions 95 to 105 were collected as active fractions, and these were adsorbed on a column containing 10 ml of Amberlite CG-50 (H⁺ type), which was then eluted with 0.5 M aqueous ammonia. The fractions containing active components were collected, concentrated by evaporation under reduced pressure and lyophilized, to afford 15 mg of mureidomycin E having the physico-chemical properties set out above. Eluent fractions 80 to 90 and 50 to 70, respectively, were similarly worked up, to afford 32 mg of mureidomycin F and 24 mg of mureidomycin A, each having the respective physico-chemical properties set out above. EXAMPLE 2 Mureidomycins E and F from mureidomycin A 270 mg of mureidomycin A were dissolved in 60 ml of deionized water, 300 µl of 30% aqueous formaldehyde were added to the solution, and the resulting mixture was allowed to stand overnight in order to complete the reaction. The reaction mixture was then adsorbed onto a 1500 ml Toyopearl column, which was eluted with 30% aqueous, methanol, to give fractions each containing 15 ml of eluent. Fractions 81 to 88 containing active components were collected, concentrated by evaporation under reduced pressure, and lyophilized to give 65 mg of mureidomycin F having the physico-chemical properties set out above. Fractions 92 to 100 were similarly worked up to give 64 mg of mureidomycin E having the physico-chemical properties set out above. EXAMPLE 3 Methylmureidomycins E and F from mureidomycin A 200 mg of mureidomycin A were dissolved in 50 ml of deionized water, 500 µl of acetaldehyde were added to the solution, and the resulting mixture was kept stirred at 70 °C for 3 hours to complete the reaction. The reaction mixture was then adsorbed onto a 1500 ml Toyopearl column, which was eluted with 30% aqueous methanol, to give fractions each containing 15 ml of eluent. Fractions 85 to 90 containing active components were collected, concentrated by evaporation under reduced pressure, and lyophilized to give 30 mg of methylmureidomycin F having the physico-chemical properties set out below. Fractions 93 to 98 were similarly worked up to give 27 mg of methylmureidomycin E having the physico-chemical properties set out below. Methylmureidomycin E 1) Character and appearance: Amphoteric, soluble in water; 2) Molecular weight: 866; 3) Molecular formula: C₄₀H₅₀N₈O₁₂S; 4) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 10 of the accompanying drawings (including conformational isomer); 5) Thin-layer chromatography: Rf value: 0.27; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 6) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 4.5 minutes. Methylmureidomycin F 1) Character and appearance: Amphoteric, soluble in water; 2) Molecular weight: 866: 3) Molecular formula: C₄₀H₅₀N₈O₁₂S; 4) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 11 of the accompanying drawings (including conformational isomer); 5) Thin-layer chromatography: Rf value: 0.27; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 6) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 5.2 minutes. EXAMPLE 4 Phenylmureidomycins E and F from mureidomycin A 200 mg of mureidomycin A were dissolved in 50 ml of deionized water, 500 µl of benzaldehyde were added to the solution, and the resulting mixture was kept stirred at 70 °C for 3 hours to complete the reaction. The reaction mixture was then adsorbed onto a 1500 ml Toyopearl column, which was eluted with 30% aqueous methanol, to give fractions each containing 15 ml of eluent. Fractions 91 to 98 containing active components were collected, concentrated by evaporation under reduced pressure, and lyophilized to give 15 mg of phenylmureidomycin F having the physico-chemical properties set out below. Fractions 101 to 106 were similarly worked up to give 8 mg of phenylmureidomycin E having the physico-chemical properties set out below. Phenylmureidomycin E 1) Character and appearance: Amphoteric, soluble in water; 2) Molecular weight: 928; 3) Molecular formula: C₄₅H₅₂N₈O₁₂S; Phenylmureidomycin F 1) Character and appearance: Amphoteric, soluble in water; 2) Molecular weight: 928; 3) Molecular formula: C₄₅H₅₂N₈O₁₂S; EXAMPLE 5 Mureidomycin E capsules for oral administration The following powders were mixed: and passed through a 30-mesh sieve (Tyler standard). The mixture (350 mg) was sealed into gelatin capsule No. 2 to yield the desired capsule. EXAMPLE 6 Mureidomycin F capsules for oral administration The following powders were mixed: and passed through a 30-mesh sieve (Tyler standard). The mixture (350 mg) was sealed into a gelatin capsule No. 2 to yield the desired capsule. EXAMPLE 7 Mureidomycin E Injection 1.0 g of mureidomycin E was dissolved in 5.0 ml of a 1/15 M phosphate buffer solution (pH 6.9) and the solution was sealed into a 5 ml ampoule. The ampoule was sterilized by a conventional procedure to yield the desired injectible liquid. EXAMPLE 8 Mureidomycin F Injection 1.0 g of mureidomycin F was dissolved in 5.0 ml of a 1/15 M phosphate buffer solution and the solution was sealed into a 5 ml ampoule. The ampoule was sterilized by a conventional procedure to yield the desired injectible liquid.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, FR, GB, IT, LI, LU, NL, SE Compounds having the formula wherein X represents the group and wherein R represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, an alkenyl group having from 2 to 7 carbon atoms, an alkynyl group having from 3 to 7 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an aralkyl group having from 7 to 10 carbon atoms, or one of the said aryl or aralkyl groups substituted with at least one halogen atom and/or at least one alkyl group having from 1 to 5 carbon atoms; and pharmaceutically acceptable salts and esters thereof. Compounds as claimed in Claim 1, wherein R represents a hydrogen atom, an alkyl group having from 1 to 3 carbon atoms, an alkenyl group having from 2 to 4 carbon atoms, an alkynyl group having from 3 to 4 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an aralkyl group having from 7 to 8 carbon atoms, or one of the said aryl or aralkyl groups substituted with at least one halogen atom and/or at least one alkyl group having from 1 to 5 carbon atoms. Compounds as claimed in Claim 1, wherein R represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, a phenyl group, a halophenyl group, or an alkylphenyl group having from 1 to 5 carbon atoms in the alkyl moiety. Compounds as claimed in Claim 1, wherein R represents a hydrogen atom, an alkyl group having from 1 to 5 carbon atoms or a phenyl group. A compound according to Claim 1, wherein X represents the 8-hydroxy-1,2,3,4-tetrahydro- isoquinolin-3-yl group, and pharmaceutically acceptable salts and esters thereof. A compound according to Claim 1, wherein X represents the 6-hydroxy-1,2,3,4-tetrahydro- isoquinolin-3-yl group, and pharmaceutically acceptable salts and esters thereof. A compound named mureidomycin E, which is obtainable by fermentation from Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347) and isolation from the culture broth, and which is characterised by the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D -34.2° (c 1.17, 50% v/v aqueous methanol); 3) Elemental analysis: C, 48.57%; H, 5.35%; N, 11.34%; S, 3.00% - measured as the hydrate; 4) Molecular weight: 852 [high resolution mass spectrum FAB MS: 853.3212 (QM⁺)] (FAB MS is Fast Atom Bombardment Mass Spectroscopy); 5) Molecular formula: C₃₉H₄₈N₈O₁₂S; 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 8-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid; 7) Ultraviolet absorption spectrum, 258 nm (252) in neutral water; 258 nm (247) in 0.01 N aqueous hydrochloric acid; 240 nm (432), 265 nm (235, shoulder) and 295 nm (80, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figure 1 of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 2 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 3 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulphuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.39; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 4.7 minutes; and pharmaceutically acceptable salts and esters thereof. A compound named mureidomycin F, which is obtainable by fermentation from Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347) and isolation from the culture broth, and which is characterised by the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D -40.3° (c 1.05, 50% v/v aqueous methanol); 3) Elemental analysis: C, 50.40%; H, 5.53%; N, 11.20%; S, 2.92% - measured as the hydrate; 4) Molecular weight: 852 [high resolution mass spectrum FAB MS: 853.3180 (QM⁺)] 5) Molecular formula: C₃₉H₄₈N₈O₁₂S; 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 6-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid; 7) Ultraviolet absorption spectrum, 258 nm (232) in neutral water; 258 nm (232) in 0.01 N aqueous hydrochloric acid; 240 nm (352), 265 nm (200, shoulder) and 295 nm (64, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figure 4 of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 5 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 6 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulphuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.34; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 5.3 minutes; and pharmaceutically acceptable salts and esters thereof. A process for producing the antibiotic mureidomycin E or F having a structure as defined in claim 1, or a salt or ester thereof, which comprises cultivating a mureidomycin E or F producing microorganism of the genus Streptomyces in a culture medium therefor and isolating mureidomycin E or F or a salt thereof from the cultured broth and, if necessary, salifying, desalifying or esterifying the compound thus isolated. A process as claimed in Claim 9, wherein said microorganism is Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347). A process for preparing a compound as claimed in Claim 1, which comprises reacting mureidomycin A having the following formula: or a salt or ester thereof with an aldehyde of the formula: R - CHO wherein R is as defined in Claim 1, and optionally salifying, desalifying or esterifying the compound thus obtained. A pharmaceutical composition comprising a compound of formula (I), as set out in Claim 1, or a pharmaceutically acceptable salt or ester thereof, in admixture with a pharmaceutically acceptable carrier or diluent. A pharmaceutical composition comprising mureidomycin E, as defined in Claim 7, or a pharmaceutically acceptable salt or ester thereof, in admixture with a pharmaceutically acceptable carrier or diluent. A pharmaceutical composition comprising mureidomycin F, as defined in Claim 8, or a pharmaceutically acceptable salt or ester thereof, in admixture with a pharmaceutically acceptable carrier or diluent. Claims for the following Contracting States : ES, GR A process for preparing a compound of formula wherein X represents the group and wherein R represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, an alkenyl group having from 2 to 7 carbon atoms, an alkynyl group having from 3 to 7 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an aralkyl group having from 7 to 10 carbon atoms, or one of the said aryl or aralkyl groups substituted with at least one halogen atom and/or at least one alkyl group having from 1 to 5 carbon atoms; or a pharmaceutically acceptable salt or ester thereof, which process comprises reacting mureidomycin A having the formula: or a salt or ester thereof with an aldehyde of the formula: R - CHO wherein R is as defined above and optionally salifying, desalifying or esterifying the compound thus obtained. A process as claimed in Claim 1, wherein R represents a hydrogen atom, an alkyl group having from 1 to 3 carbon atoms, an alkenyl group having from 2 to 4 carbon atoms, an alkynyl group having from 3 to 4 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an aralkyl group having from 7 to 8 carbon atoms, or one of the said aryl or aralkyl groups substituted with at least one halogen atom and/or at least one alkyl group having from 1 to 5 carbon atoms. A process as claimed in Claim 1, wherein R represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, a phenyl group, a halophenyl group, or an alkylphenyl group having from 1 to 5 carbon atoms in the alkyl moiety. A process as claimed in Claim 1, wherein R represents a hydrogen atom, an alkyl group having from 1 to 5 carbon atoms or a phenyl group. A process as claimed in Claim 1, wherein X represents the 8-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl group or the 6-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl group. A process for producing the antibiotic mureidomycin E or mureidomycin F having the formula: wherein X represents the 8-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl or the 6-hydroxy-1,2,3,4-tetrahydroisoquinolin-3-yl group or a pharmaceutically acceptable salt or ester thereof, which process comprises cultivating a mureidomycin E or F producing microorganism of the genus Streptomyces in a culture medium therefor and isolating mureidomycin E or F or a salt thereof from the cultured broth and, if necessary, salifying, desalifying or esterifying the compound thus isolated. A process according to claim 6 for producing the antibiotic mureidomycin E which is characterised by the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D -34.2° (c 1.17, 50% v/v aqueous methanol); 3) Elemental analysis: C, 48.57%; H, 5.35%; N, 11.34%; S, 3.00% - measured as the hydrate; 4) Molecular weight: 852 [high resolution mass spectrum FAB MS: 853.3212 (QM⁺)] (FAB MS is Fast Atom Bombardment Mass Spectroscopy); 5) Molecular formula: C₃₉H₄₈N₈O₁₂S; 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 8-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid; 7) Ultraviolet absorption spectrum, 258 nm (252) in neutral water; 258 nm (247) in 0.01 N aqueous hydrochloric acid; 240 nm (432), 265 nm (235, shoulder) and 295 nm (80, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figure 1 of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 2 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 3 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulfuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.39; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 4.7 minutes; or a pharmaceutically acceptable salt or ester thereof, which process comprises cultivating a mureidomycin E producing microorganism of the genus Streptomyces in a culture medium therefor and isolating mureidomycin E or a salt thereof from the cultured broth and, if necessary, salifying, desalifying or esterifying the compound thus isolated. A process according to claim 6 for producing the antibiotic mureidomycin F which is characterised by the following physico-chemical properties: 1) Character and appearance: Amphoteric, soluble in water, white powder; 2) Specific rotation: [α] 25 / D -40.3° (c 1.05, 50% v/v aqueous methanol); 3) Elemental analysis: C, 50.40%; H, 5.53%; N, 11.20%; S, 2.92% - measured as the hydrate; 4) Molecular weight: 852 [high resolution mass spectrum FAB MS: 853.3180 (QM⁺)] 5) Molecular formula: C₃₉H₄₈N₈O₁₂S; 6) Products resulting from acid hydrolysis: uracil; m-tyrosine; 2-amino-3- N -methylaminobutyric acid; 6-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid; 7) Ultraviolet absorption spectrum, 258 nm (232) in neutral water; 258 nm (232) in0.01 N aqueous hydrochloric acid; 240 nm (352), 265 nm (200, shoulder) and 295 nm (64, shoulder) in 0.01 N aqueous sodium hydroxide; the spectra are shown in Figure 4 of the accompanying drawings; 8) Infrared absorption spectrum (KBr) ν max cm⁻¹: the spectrum measured in a KBr disk is shown in Figure 5 of the accompanying drawings; 9) Nuclear magnetic resonance spectrum, δ ppm: the spectrum (270 MHz) was measured in deuterium oxide using tetramethylsilane as external standard and is shown in Figure 6 of the accompanying drawings (including conformational isomer); 10) Solubility: Soluble in water and methanol, slightly soluble in acetone, and insoluble in ethyl acetate, chloroform and benzene; 11) Color reactions: Positive to ninhydrin, sulfuric acid, iodine, ferric chloride and Baeyer reactions; 12) Thin-layer chromatography: Rf value: 0.34; Adsorbent: Silica gel plate (Merck, Kieselgel 60 F₂₅₄); Developing solvent: a 4:2:1 by volume mixture of butanol, propanol and water; 13) High performance liquid chromatography: Column: Aquasil SS 372-N (Senshu Kagaku Co.); Developing solvent: a 200:100:100:40 by volume mixture of chloroform, isopropanol, methanol and water; Flow rate: 1.0 ml/minute; Retention time: 5.3 minutes. or a pharmaceutically acceptable salt or ester thereof, which process comprises cultivating a mureidomycin F producing microorganism of the genus Streptomyces in a culture medium therefor and isolating mureidomycin F or a salt thereof from the cultured broth and, if necessary, salifying, desalifying or esterifying the compound thus isolated. A process as claimed in any of Claims 6 to 8, wherein said microorganism is Streptomyces flavidovirens SANK 60486 (BIKOKEN JOHKI 1347; FERM BP-1347). The use of a compound having the formula (I), as defined in Claim 1, or of a pharmaceutically acceptable ester or salt thereof, for the manufacture of an antibiotic preparation.

Inventors: HANEISHI, TATSUO C/O SANKYO COMPANY LIMITED, INUKAI, MASATOSHI C/O SANKYO COMPANY LIMITED, ISONO, FUJIO C/O SANKYO COMPANY LIMITED, KINOSHITA, TAKESHI C/O SANKYO COMPANY LIMITED, SAKAIDA, YOSHIHARU C/O SANKYO COMPANY LIMITED, SHIMIZU, KEIKO C/O SANKYO COMPANY LIMITED
Applicants: SANKYO COMPANY LIMITED
Application year: 1988
Main classification: C07K5
IPC codes: A61K38, C07K5