Method for disinfection using a 1,n-bis(N.sup.5 -trifluoromethyl-phenyl-N.sup.1 -biguanido)-alkane

Abstract

A novel disinfectant is disclosed. Said disinfectant is a compound 1,n-bis(N.sup.5 -m-, or p-trifluoromethyl-phenyl-N.sup.1 -biguanido)-C.sub.3 -C.sub.10 -alkane. The m-trifluoro-C.sub.6 derivative is a known compound. The compounds of the present invention exhibit germicidal effect against Pseudomonas aeruginosa, Proteus vulgaris and Alcaligenes faecalis at concentrations of 1/4-1/8 of the effective concentration for chlorhexidine. Against other microorganisms, the compounds are effective at the same level as chlorhexidine.

Description

FIELD OF THE INVENTION

The present invention relates to a disinfectant. More particularly, the present invention relates to a group of bisbiguanide compounds and pharmaceutically acceptable salts thereof which are used as disinfectants.

BACKGROUND OF THE INVENTION

Chlorhexidine represented by the formula ##STR1## is a compound, which was developed in 1954 as a disinfectant, exhibits disinfecting effect on a wide range of general bacteria and is used in a very wide area because of its quick effect and low toxicity. Especially it is used as gluconate salt, which has high solubility in water, for disinfection of hands and fingers, operation localities and operation instruments in the medical field because of wide range germicidal activity.

However, chlorhexidine has a defect that it is less effective against some Gram-negative bacteria, especially Pyocyaneus bacilli. Further, recently Pyocyaneus bacillus strains and Pseudomonas cepacia strains, which are resistant to this drug, have been reported and now this is a problem in medical institutions. Chlorhexidine sometimes causes shock symptoms when it is administered to mucous membranes in a conventionally employed concentration and, therefore, administration thereof to mucous membranes other than conjunctivae is now prohibited.

Under the circumstances, a substitute for chlorhexidine, which retains the wide antibacterial spectrum of chlorhexidine and is provided with improved germicidal effect and medical applicability. That is, there is a demand for a chlorhexidine type disinfectant for medical use, which can be used in a low concentration so as to be safely applicable to mucous membranes, has improved germicidal activity especially against Pyocyaneus bacilli and is suitable as topical disinfectants for surgical operations.

V. D. Warner et al reported on dental plaque inhibiting (antiplaque) activities of bis-susbstituted 1,6-bis-biguanidohexane derivatives in Journal of Medical Chemistry, 1973, Vol. 16, No. 6, pages 732-733. It had been known that variation in the end substituents of 1,6-bis-biguanidine radically changes antibacterial activity of the compound. Warner et al reported that the bis-phenyl-substituted derivative exhibited no antiplaque activity, the bis-cyclohexyl-substituted and the bis-1-adamanthyl-substituted derivatives exhibited antiplaque activity at the same level as chlorhexidin or better and the bis(m-trifluoromethylphenyl) derivative exhibited superior antiplaque activity at lower concentrations.

It is more than twenty years since this report appeared and we know no report on further study on general germicidal activities of 1,6-bis-biguanidohexane derivatives.

We have taken up some .alpha.,.omega.-bis-biguanidoalkane derivatives and checked their antibacterial activities and we noted that 1,n-bis(N.sup.5 -m- or p-trifluoromethylphenyl-N.sup.1 -biguanido)-C.sub.3 -C.sub.10 alkanes exhibited excellent antibacterial activities.

SUMMARY OF THE INVENTION

This invention provides a disinfectant comprising 1,n-bis(N.sup.5 -trifluoromethylphenyl-N.sup.1 -biguanido)-alkane represented by the formula ##STR2## wherein n is an integer of 3-10 and the trifluoromethyl group is located at the m- or p-position, or a pharmaceutically acceptable salt thereof. One of these compounds, 1,6-bis(N.sup.5 -m-trifluroromethylphenyl-N'-biguanido)hexane is known and the others are novel compounds.

These compounds can be easily synthesized in accordance with the process described in J. Chem. Soc., 4422 (1956) for instance. That is, the compounds of which n is 6 can be synthesized by reacting 1,6-hexanediamine dihydrochloride with sodium dicyanamide to form 1,6-bis(N.sup.3 -cyano-N.sup.1 -guanido)hexane and reacting the obtained 1,6-bis(N.sup.3 -cyano-N.sup.1 -guanido)hexane with p- or m-trifluoromethylaniline hydrochloride. Each reaction is known per se and need not be described in detail.

The compounds of which n is other than 6 can be prepared in the same manner using corresponding .alpha.,.omega.-alkane diamines dihydrochloride.

The obtained compounds can be converted to their base by treating them with a base. Appropriate salts can be prepared by contacting the base with a corresponding acid. Of course it is possible to prepare a base first and to convert to a suitable salt.

Preferred acids are hydrochloric acid, acetic acid, gluconic acid, maleic acid, etc.

SPECIFIC DISCLOSURE OF THE INVENTION

The invention will now be specifically described by way of working examples. However, these examples are merely illustrative and the invention is not limited thereto.

Example 1

Preparation of 1,6,bis(N.sup.5 -p-trifluoromethylphenyl-N.sup.1 -biquanido)-hexane

1,6-Hexanediamine dihydrochloride (9.5 g, 50 mmol) and sodium dicyanamide (10.3 g, 100 mmol) were reacted in n-butanol under refluxing for 10 hours and 1,6-bis(N.sup.3 -cyano-N.sup.1 -guanido)hexane (14.4 g (47.4 mmol)) was obtained.

The 1,6-bis(N.sup.3 -cyano-N.sup.1 -guanido)hexane and 4-trifluoromethylaniline hydrochloride (24.9 g (126 mmol)) were reacted in 2-ethoxyethanol under refluxing for 15 hours. The deposited solid material was separated by filtration and combined with the solid material which was obtained by concentration of the filtrate and the combined solid material was recrystallized from a 50% acetic acid solution. Thus 21.8 g of hydrochloric acid salt of 1,6-bis(N.sup.5 -p-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane dihydrochloride was obtained as a white solid material.

The collected material was dissolved in 400 ml of a 1.5N hydrochloric acid solution and 100 ml of a 8N sodium hydroxide solution was added dropwise to the resulting solution. A solid substance deposited, which was collected, washed with water and recrystallized from ethanol. Thus 1,6-bis(N.sup.5 -p-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane was obtained. Identification data was as follows.

NMR Spectrum:

.sup.1 H-NMR (270 MHz, DMSO-d.sub.6 /TMS); .delta.1.32 ppm (brs, 4H), .delta.1.46 ppm (m, 4H), .delta.3.12 ppm (brs,4H), .delta.5.11 ppm (brs. 4H), .delta.6.97 ppm (d, 4H, J=8.0 Hz), 57.49 ppm (d, 4H, J=8.0 Hz), .delta.7.0-7.8 ppm (brs. 6H);

.sup.13 C-NMR (67.8 MHz, DMSO-d.sub.6 /TMS); .delta.26.07 ppm. .delta.29.12 ppm, .delta.40.17 ppm, .delta.120.04 ppm, (q. J.sub.CF =31.2 Hz), .delta.122.96 ppm, .delta.124.96 ppm (q. J.sub.CF =270.9 Hz), .delta.125.78 ppm (q. J.sub.CF =3.2 Hz), .delta.154.68 ppm, .delta.158.07 ppm, .delta.158.18 ppm;

.sup.19 F-NMR(254 MHz, DMSO-d.sub.6 /TMS); .delta.59.22 ppm; IR Absorption spectrum (KBr tablet, cm.sup.-1):

870, 1065, 1104. 1163, 1261, 1327, 1386, 1412, 1550, 1630, 1676, 3080; Mass Spectrum (20 eV, m/e):

161 (10.1%), 163 (21.4%), 204 (9.6%), 205 (9.6%), 188 (100%), 553 (0.3%), 571 (2.0%), 572 (2.1%)

Example 2

Preparation of digluconic acid salt

To 1,6-bis-(N.sup.5 -p-trifluoromethylphenyl-N.sup.1 -biguanido-heane, 2 molar equivalent of gluconic acid (a 50% solution in distilled water) was added and the solution was suitably diluted. Thus 1,6-bis(N.sup.5 -p-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane digluconate aqueous solution was obtained.

Example 3

Evaluation of germicidal activity of the compound of Example 1

Germicidal activity of the compound prepared in Example 1 (Compound I) was evaluated by the minimum growth inhibition concentration method (based on the standard method stipulated by Japan Society of Chemotherapy) and the phenol coefficient method.

Evaluation of germicidal activity 1 (minimum growth inhibition concentration)

A portion of the digluconate salt of the compound of Example 1 was dissolved in water and the solution was heated to dryness on a water bath. The dried salt was dissolved in acetic acid (potentiometric titration grade) and the concentration thereof was determined by potentiometric titration using a perchloric acid solution. The gluconate acid salt solution, whose concentration was thus determined, was diluted to predetermined concentrations with sterilized water. Each 1 ml of the solution of each concentration was placed in a Petri dish, 9 ml of Mueller-Hinton agar (supplied by Difco) was added thereto and well mixed. Thus sensitivity test media were prepared. The concentrations of the compound were 200 .mu.g/ml and 2.sup.n times wherein (n=-8 to 2). Separately, microorganism strains indicated in Table 1 were subcultured in propagation media (using Mueller-Hinton broth supplied by Difco) at 37.degree. C. for 24 hours. The microorganism concentration was adjusted to 10.sup.6 /ml. The thus obtained cultures were respectively inoculated on a series of sensitivity measuring culture media using an inoculation rod. The minimum concentration at which growth of the microorganism was completely inhibited was determined. The results are shown in Table 1 together with the result on chlorhexidine as a control.

TABLE 1______________________________________ MIC (.mu.g/ml)Microorganism CHXD Ex. 1______________________________________Alcaligenes faecalis IPO 13111 50 6.25Achromobacter xylosoxidans RIMD 0101001 25 50Flavobacterium meningosepticum RIMD 0614002 200 200Klebsiella pneumoniae IID 865 6.25 3.13Proteus vulgaris IID 874 200 25Pseudomonas aeruginosa IID 1042 100 12.5Pseudomonas aerugimosa (clinically collected) 100 12.5Serratia marcescens IID 602 6.25 6.25Escherichia coli IID 861 1.56 3.13Escherichia coli IID 951 1.56 3.13Escherichia coli NIHJ JC-2 1.56 3.13Pseudomonas cepacia (collected Chiba Univ.) 100 50Staphylococcus epidermis IID 866 1.56 1.56Staphylococcus aureus FDA 209-P 0.78 1.56Staphylococcus aureus (clin'ly col'ted MRSA) 6.25 6.25Staphylococcus aureus (clin'ly col'ted MRSA) 3.13 1.56______________________________________ CHXD: chlorhexidine (digluconate) Ex. 1: compound of Example 1 (digluconate)

As seen in Table 1, the compound of Example 1 of the present invention exhibits germicidal effect against Pseudomonas aeruginosa, Proteus vulgaris and Alcaligenes faecalis at concentrations of 1/4-1/8 of the effective concentration for chlorhexidine. Against other microorganisms, the compound is effective at the same level as chlorhexidine.

Evaluation of germicidal activity 2 (test for immediate effect)

Immediate effect of this compound was evaluated in accordance with the phenol coefficient method described in "Directions for Hygienic Tests" compiled by the Ministry of Health and Welfare of Japan. The method is as follows.

(1) Culture medium

Each 10 ml of the bouillon described below was taken into test tubes and they were sterilized with high pressure steam at 120.degree. C. for 20 minutes.

Bouillon medium for testing disinfectants

______________________________________Peptone (product of Nippon Seiyaku) 10 gMeat extract (product of Kyokuto Seiyaku) 5 gNaCl (product of Kokusan Kagaku, special grade) 5 gPurified water 1000 mlpH 6.8______________________________________

(2) Test method

Diluted solutions of a series of concentrations of the sample compound were prepared for each of microorganisms listed in Table 2. Each 10 ml of the solutions was put into an appraisal test tube and the test tubes were placed in a thermostat bath kept at 20.degree. C. Each microorganism was subcultured in the above described bouillon medium for testing disinfectants for three generations (37.degree. C. for 48 hours). Each 1 ml of each culture was placed in each of the above-described series of appraisal test tubes and well mixed. After 2.5, 5, 10 and 15 minutes, 0.1 ml of the content of each appraisal test tube was taken and inoculated onto each portion of the bouillon medium for testing disinfectants. The portions were incubated at 37.degree. C. for 48 hours and were observed for growth of the microorganisms. Each test was carried out three times. Immediate effect of disinfectants was compared by number of test runs in which microorganism growth was observed. The results are summarized in Table 2.

TABLE 2______________________________________ Conc. Contact Time (min)Microorganism (%) Sample 2.5 5.0 10.0 15.0______________________________________Escherichia coli IID 861 0.001 Ex. 1 3 3 2 1 CHXD 3 3 3 3Pseudomonas aeruginosa 0.03 Ex. 1 0 0 0 0IID 1042 CHXD 2 1 0 0Staphylococcus aureus 0.0005 Ex. 1 0 0 0 0FDA 209-P CHXD 3 1 0 0______________________________________ Ex. 1: compound of Example 1 (digluconate) CHXD: chlorohexidine (digluconate)

Example 4

Compounds of formula I, wherein the trifluoromethyl group is located at the p-position and n is 2, 3, 5, 8 and 11, were prepared starting from ethylene diamine dichloride, 1,3-propane diamine dichloride, 1,5-pentane diamine dichloride, 1,8-octane diamine dichloride or 1,11-undecane diamine dichloride, sodium dicyanamide and 4-trifluoromethyl aniline hydrochloride in accordance with the procedures as described above and minimum growth inhibition concentration (MIC) was determined in the same manner as above. The results are shown in Table 3.

TABLE 3______________________________________Micro- MIC (.mu.g/ml)organism *n = 2 n = 3 n = 5 n = 6 n = 8 n = 11______________________________________Pseudomonas 200 50.0 12.5 12.5 25.0 400aeruginosaIID 1042Serratia 50 6.25 6.25 6.25 6.25 100marcescensIID 602Escherichia 12.5 1.56 3.13 3.13 1.56 50coli IID 951Staphyl- 25.0 0.78 0.78 1.56 1.56 12.5ococcusaureusFDA 209-P______________________________________ *Compounds of formula I, wherein the trifluoromethyl group is located at the pposition and n is 2, 3, 5, 6, 8 and 11

Example 5

Preparation of 1,6-bis(N.sup.5 -m-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane

The procedures of Example 1 were repeated using 3-trifluoromethylaniline hydrochloride instead of 4-trifluoromethylaniline hydrochloride and 1,6-bis(N.sup.5 -m-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane hydrochloride was obtained. Identification data was as follows.

NMR Spectrum:

.sup.1 H-NMR (270 MHz, DMSO-d.sub.6 /TMS); .delta.1.30 ppm (brs, 4H), .delta.1.47 ppm (m, 4H), .delta.3.12 ppm (d, 4H, J=6.8 Hz), .delta.6.8-8.3 ppm (m.18 H);

.sup.13 C-NMR (67.8 MHz, DMSO-d.sub.6 /TMS); .delta.25.90 ppm. .delta.28.62 ppm, .delta.40.90 ppm, .delta.116.81 ppm, .delta.118.17 ppm, .delta.124.15 ppm (q. J.sub.CF =-272.2 Hz), .delta.124.38 ppm. .delta.129.34 ppm (q,J=31.1 Hz), .delta.129.68 ppm, .delta.142.90 ppm, .delta.155.26 ppm; .delta.159.58 ppm;

.sup.19 F-NMR(254 MHz, DMSO-d.sub.6 /TMS); .delta.60.76 ppm; IR Spectrum (KBr tablet, cm.sup.-1):

700, 798, 8 98. 1120, 1170, 1335, 1457, 1550, 1650, 3190, 3310; Mass Spectrum (20 eV, m/e):

161 (37.7%), 161 (37.7%), 163 (83.4%), 188 (100%), 204 (31.0%), 2.5 (30%), 415 (51.7%), 571(1.1%), 572 (1.0%)

Example 6

Preparation of digluconic acid salt

To 1,6-bis-(N.sup.5 -m-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane, 2 molar equivalent of a 50% aqueous solution of gluconic acid (in distilled water) was added and the solution was suitably diluted. Thus 1,6-bis(N.sup.5 -m-trifluoromethylphenyl-N.sup.1 -biguanido)-hexane digluconate aqueous solution was obtained.

Example 7

Evaluation of Disinfecting Effect

Disinfecting effect of the above-prepared compounds was tested by measurement of minimum growth inhibition concentration and by the test for immediate effect in the same manner as in Example 3. The results were as follows.

Evaluation of germicidal activity 1(minimum growth inhibition concentration)

TABLE 4______________________________________ MIC (.mu.g/ml)Microorganisms CHXD Ex. 5______________________________________Alcaligenes faecalis IPO 13111 50 6.25Achromobacter xylosoxidans RIMD 0101001 25 25Flavobacterium meningosepticum RIMD 0614002 200 200Klebsiella pneumoniae IID 865 6.25 1.56Proteus vulgaris IID 874 200 12.5Pseudomonas aeruginosa IID 1042 100 25Pseudomonas aerugimosa (clinically collected) 100 25Serratia marcescens IID 602 6.25 6.25Escherichia coli IID 861 1.56 1.56Escherichia coli IID 951 1.56 1.56Escherichia coli NIHJ JC-2 1.56 1.56Pseudomonas cepacia (collected Chiba Univ.) 100 50Staphylococcus epidermis IID 866 1.56 1.56Staphylococcus aureus FDA 209-P 0.78 0.78Staphylococcus aureus (clin'ly col'ted MRSA) 6.25 3.13Staphylococcus aureus (clin'ly col'ted MRSA) 3.13 1.56______________________________________ CHXD: chlorhexidine (digluconate) Ex. 5: compound of Example 5 (digluconate)

For some microorganism strains, the results are apparently the same as the results with respect to the compound of Example 1. In the case of a dilution method, this will happen when the effects of two compounds are of the same level.

Effect of Germicidal Activity 2 (test for immediate effect

The results of the immediate effect test are indicated in Table 5.

TABLE 5______________________________________ Conc. Contact Time (min)Microorganism (%) Sample 2.5 5.0 10.0 15.0______________________________________Escherichia coli IID 861 0.001 Ex. 1 2 1 0 0 CHXD 3 3 3 3Pseudomonas aeruginosa 0.03 Ex. 1 0 0 0 0IID 1042 CHXD 2 1 0 0Staphylococcus aureus 0.0005 Ex. 1 0 0 0 0FDA 209-P CHXD 3 1 0 0______________________________________

Example 8

Compounds of formula I, wherein the trifluoromethyl group is located at the m-position and n is 2, 3, 5 and 8, 11 were prepared starting from ethylene diamine dihydrochloride, 1,3-propane diamine dihydrochloride, 1,5-pentane diamine dihydrochloride, 1,8-octane diamine dihydrochloride or 1,11-undecane diamine dihydrochloride, sodium dicyanamide and 3-trifluoromethylaniline hydrochloride in accordance with the procedures of Example 4 and germicidal activity thereof were determined in the same manner. The results are shown in Table 6.

TABLE 6______________________________________Micro- MIC (.mu.g/ml)organism *n = 2 n = 3 n = 5 n = 6 n = 8 n = 11______________________________________Pseudomonas 200 50.0 12.5 25.0 25.0 400aeruginosaIID 1042Serratia 50 12.5 6.25 6.25 6.25 100marcescensIID 602Escherichia 12.5 3.13 3.13 1.56 1.56 25coli IID 951Staphyl- 12.5 3.13 0.78 0.78 1.56 12.5ococcusaureusFDA 209-P______________________________________ *Compounds of formula I, wherein the trifluoromethyl group is located at the mposition and n is 2, 3, 5, 6, 8 and 11

Claims

1. A method for disinfecting hands and fingers, operation localities, and operation instruments from one or more bacteria species selected from the group consisting of Pseudomonas aeruginos, methicillin-resistant Staphylococcus aureus, Alcaligenes faecalis, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas cepacia, said method comprising using a solution of (i) a 1,n-bis(N.sup.5 -trifluoromethylphenyl-N.sup.1 -biguanido)-alkane represented by the formula: ##STR3## wherein n is an integer of 5 or 6 and the trifluoromethyl group is located at the m-position or p-position or (ii) a pharmaceutically acceptable salt thereof.

2. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from one or more bacteria species selected from the group consisting of Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus.

3. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from Pseudomonas aeruginosa.

4. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from methicillin-resistant Staphylococcus aureus.

5. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from Alcaligenes faecalis.

6. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from Klebsiella pneumoniae.

7. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from Proteus vulgaris.

8. The method of claim 1 wherein said hands and fingers, operation localities, and operation instruments are disinfected from Pseudomonas cepacia.

9. The method as claimed in claim 1, wherein the trifluoromethyl group is located at the p-position.

10. The method as claimed in claim 9, wherein n is 6.

11. The method as claimed in claim 4, wherein the trifluoromethyl group is located at the m-position.

12. The method as claimed in claim 11, wherein n is 6.