Note: Descriptions are shown in the official language in which they were submitted.
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Bactericidal composition
t
Field of the invention
The present invention relates to the use of a chelant as a a bactericidal
compound as well as a bactericidal composition containing a chelant,
suitable for use in deodorants, soaps, oral health care, dermatological
preparations and also in food as a food preservative. More particularly, it
relates to a bactericidal composition comprising a chelant as a bactericidal
agent or as a co-bactericidal agent.
background of the invention
Bacteria may be found in the food or clinic environment. Bacteria strains
are divided into two types: gram negative and gram positive. Gram
negative bacteria types include bacteria such as Salmonella typhimurium,
Bacterioides gingivalis, Actinobacillus actinomycetescomitans, Klebsiella
pneumoniae, Escherichia coli and Pseudomonas aeruginosa while gram
positive bacteria include bacteria such as Staphilococcus aureus,
Streptococcus mutans, Listeria monocytogenes, Streptococcus agalactiae
and Coryneform bacteria.
The presence of such bacteria on food or dermatological or oral substrates
results in contamination and spoilage. This problem is magnified for gram
negative bacteria, especially Pseudomonas aeruginosa as this
microoganism is distributed widely and also spreads rapidly since almost
any condition is suitable for its growth.
To retard and/or prevent such growth, it is known in the art to use
bactericides of the bacterial or chemical type. However, a problem
encountered with such bactericides is that they are expensive and/or
sometimes are not fully active. Not to be bound by theory, it is believed
that the cations present on the cell wall of the bacteria prevent the
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bactericidal action. The Applicant has found that the problems of bacteria
growth and reduced bactericidal activity are particularly troublesome with
bactericidal agents of the chlorophenol and/or quaternary ammonium
type.
The formulator thus faces the challenge of formulating a product which
maximises the bactericidal activity, minimises the contamination and is
also inexpensive.
WO 89/1239 discloses the use of lanthionine containing bacteriocin and a
chelating agent for inhibiting Gram negative bacteria growth. More
particularly disclosed are lanthionine containing bacteriocins with ethylene
diamine tetraacetic acid (EDTA) for inhibiting Pseudomonas aeruginosa
growth.
EP 0,639,636 discloses the use of a cationic germicide with a chelating
agent and a surfactant. More particularly disclosed are cationic
germicides with EDTA and a surfactant for inhibiting gram negative
bacteria growth such as Escherichia coli and Pseudomonas aeruginosa.
The Applicant has now surprisingly found that the use of specific chelants
of the succinic, glutaric or phosphoric class ameliorate these problems.
It is therefore an object of the invention to provide the use of a compound
having a bactericidal activity.
It is another object of the invention to provide bactericidal compositions
containing a chelant.
It is a further object of the invention to provide bactericidal compositions
containing a chelant together with a conventional bactericidal compound,
wherein the combination of said chelant with the conventional bactericidal
compound produce a synergistic bactericidal action.
summary of the invention
The present invention relates to the use of a chelant selected from the
succinic acid, glutaric acid, phosphoric acid classes or any salts thereof
and mixtures thereof as a bactericidal compound.
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Also provided herein are bactericidal compositions containing said chelant
together with or without a conventional bactericidal agent.
Further provided herein is a method for reducing the bacterial growth,
which comprises the step of exposing said bacteria strain with a
bactericidal composition according to the invention.
detailed description of the invention
hel n
An essential component of the invention is a chelant. When used as a
bactericidal compound per se, the chelant will be present in amount of at
least 0.05 % , preferably at least 0.7 % and more preferably at least 1
°6 by
weight of the composition. When used as a co-bactericide, said chelant
will be present in amount from at least 0.05 % , preferably at least 0.5
and more preferably at Ieast 1 % by weight of the composition.
Suitable chelants for the purpose of the invention are compounds selected
from succinic acid, glutaric acid, phosphoric acid classes or any salts
tliereof and mixtures thereof.
hton limiting examples of chelants of the succinic acid class include
ethylenediamine disuccinic acid (EDDS), 2-hydroxypropylenediamine
disuccinic acid (HPDDS) and any salts thereof and mixtures thereof.
A, suitable chelant of the glutaric acid class is ethylenediamine diglutaric
acid (EDDG) or salt thereof.
r~on limiting examples of chelants of the phosphoric acid class include
ethylenediaminetetrakis (methylenephosphonic acid), diethylene triamine
penta (methylene phosphoric acid), ethylene diamine tri (methylene
phosphoric acid), hexamethylene diamine tetra (methylene phosphoric
acid), oc-hydroxy-2 phenyl ethyl diphosphonic acid, methylene
diphosphonic acid, hydroxy 1,1-hexylidene diphosphonic acid, vinylidene
1,1 diphosphonic acid, 1,2 dihydroxyethane 1,1 diphosphonic acid and
hydroxy-ethane l,l diphosphonic acid and any salts thereof and mixtures
thereof.
Preferred from the above phosphoric acid species is hydroxy-ethane 1,1
diphosphonic acid.
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More preferably, said chelants are selected from ethylenediamine
disuccinic acid, ethylenediamine diglutaric acid, 2-
hydroxypropylenediamine disuccinic acid, hydroxy ethane 1,1
diphosphonic acid or any salts thereof and mixtures thereof.
Especially preferred is ethylenediamine-N,N°-disuccinic acid or the
alkali
metal, alkaline earth metal, ammonium, or substituted ammonium salts
thereof, or mixtures thereof. Preferred EDDS compounds are the free
acid form and the sodium or magnesium salt or complex thereof.
Examples of such preferred sodium salts of EDDS include Na2EDDS and
Na3EDDS. Examples of such preferred magnesium complexes of EDDS
include MgEDDS and Mg2EDDS.
In an embodiment of the invention is provided a bactericidal composition
comprising a chelant, wherein said chelant is as defined herein before.
In another embodiment of the invention, the bactericidal composition of
the invention may further comprise one or more conventional bactericidal
agents. The combination of said conventional bactericidal agent with said
chelant is seen to produce a synergistic action on bacteria strain,
particularly on Gram negative bacteria types and more specifically on
Pseudomonas aeruginosa.
Furthermore, the said combination allows the use of a reduced amount of
conventional bactericides. More specifically, the combination produces a
reduction in the minimum inhibitory concentration (MIC) of the
conventional bactericide used per se.
By MIC is meant the "Minimum Inhibitory Concentration", e.g the
minimum level necessary of such conventional bactericides to inhibit the
bacteria growth.
Determination of said MIC is described hereinafter.
conventional bactericidal agents
Conventional bactericidal agents of use herein, for the purpose of the
invention, will be selected from agents having their original MIC (e.g
when used without the presence of a chelant of the invention) reduced by
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at least 50 % , preferably 70 % and more preferably at least 90 % when in
the presence of said chelant.
Most preferred conventional bactericidal agents which may be used for
the purpose of the invention are bactericidal agents selected from
chlorophenol and quaternary ammonium species and mixtures thereof.
Preferred among the chlorophenol species are compounds selected from
2,4,4' trichloro-2'-hydrozydiphenyl ether available under the trademark
Irgasan DP 300 from Ciba Geigy, 2,2'-dihydrozy-5,5'-dibromo-Biphenyl
ether and mixtures thereof.
Preferred among the quaternary ammonium species is cetyl trimethyl
ammonium bromide.
More preferably, these conventional bactericides are selected from 2,4,4'
trichloro-2'-hydrozydiphenyl ether (Irgasan DP 300), cetyl trimethyl
ammonium bromide and mixtures thereof. A most preferred conventional
bactericide to be used in combination with a chelant of the invention is
2,4,4' trichloro-2'-hydrozydiphenyl ether (Irgasan DP 300).
Additional compounds may also be added to the composition. Such
additional compounds should not be detrimental to the bactericidal
composition of the invention.
Non limiting examples of classes of suitable additional compounds which
may be of use herein include surfactants, binders and thickeners.
Surfactant
Non limiting examples of surfactants useful herein, typically at levels
from 1 ~b to 95 °~ , preferably 19b to 55 °~ by weight, include
the
conventional C 11-C 1 g alkyl benzene sulfonates ("LAS ") and primary,
branched-chain and random C l p-C20 alkyl sulfates ("AS"), the C l p-C 1 g
secondary (2,3) alkyl sulfates of the formula CH~(CH~z(CHOS03-Ivi+)
CH3 and CH3 (CH~y(CHOS03-M ) CH2CH3 where z and
(y + 1) are integers of at least ?, preferably at least 9, and M is a
water-solubilizing cation, especially sodium, unsaturated sulfates such as
oleyl sulfate, the C l p-C 1 g alkyl alkozy sulfates ("AEzS" ; especially EO
1-7 ethozy sulfates), Clp-Clg alkyl alkozy carbozylates (especially the
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EO 1-5 ethoxycarboxylates), the C10.1g glycerol ethers, the Cgp-Clg
alkyl polyglycosides and their corresponding sulfated polyglycosides, and
C 12-C 1 g alpha-sulfonated fatty acid esters. If desired, the conventional
nonionic and amphoteric surfactants such as the C12-Clg alkyl
ethoxylates ("AE"), including the so-called narrow peaked alkyl
ethoxylates and C6-C12 alkyl phenol alkoxylates (especially ethoxylates
and mixed ethoxy/propoxy), C12-Clg betaines and sulfobetaines
("sultaines "), C lp-C 1 g amine oxides, and the like, can also be included in
the overall compositions. The C10-Clg N-alkyl polyhydroxy fatty acid
amides can also be used. Typical examples include the C12-Cgg N-
methylglucamides. See WO 9,206,154. Other sugar-derived surfactants
include the N-alkoxy polyhydroxy fatty acid amides, such as Clp-Clg N
(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C12-C18
glucamides can be used for low sudsing. C10-C20 conventional soaps
may also be used. If high sudsing is desired, the branched-chain Clp-
C16 soaps may be used.
Other suitable surfactants suitable for the purpose of the invention are the
anionic alkali metal sarcosinates of formula:
R-CON(R1)CH2COOM
wherein R is a C9-C1~ linear or branched alkyl or alkenyl group, Rl is a
C 1-C4 alkyl group and M is an alkali metal ion. Preferred examples are
the lauroyl, cocoyl (C12-C14), myristyl and oleyl methyl sarcosinates in
the form of their sodium salts.
Mixtures of anionic and nonionic surfactants are especially useful. Other
conventional useful surfactants are listed in standard texts.
Binders and thickeners such as sodium carboxymethylcellulose, xantham
gum, gum arabic may also be included, as well as synthetic polymers
such as polyacrylates, copolymers of polyvinylmethylether with malefic
anhydride, copolymers of malefic acid with acrylic acid, terpolymers of
maleic/acrylic/vinyl alcohol and hydroxy alkyl cellulose ethers.
Flavours such as peppermint and spearmint oils may also be included, as
well as preservatives, opacifying agents, colouring agents, pH-adjusting
agents and sweetening agents.
Form of the compositions
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'The compositions of the invention can be formulated in any desirable
form such as powders, granulates, pastes, liquids, tablets, capsules, pills,
solutions, suspensions, salves and gels.
j '1~. uid compositions
'The compositions of the present invention may be formulated as liquid
compositions. Such liquid compositions typically comprise from 94 % to
3~5 % by weight, preferably from 90 % to 40 % by weight, most preferably
from 80% to 50% by weight of a liquid carrier, e.g., water, preferably a
mixture of water and organic solvent.
!Gel compositions
The compositions of the present invention may also be in the form of gels.
Such compositions are typically formulated with polyalkenyl polyether
having a molecular weight of from about 750,000 to about 4,000,000.
Solid com~QSitions
1'he compositions of the invention may also be in the form of solids, such
as powders, tablets, capsules, pills and granules.
In another embodiment of the invention there is provided a method for
reducing the growth of a bacteria strain, which comprises the step of
exposing said bacteria strain to a bactericidal composition of the
invention.
A particularly effective action is seen on gram negative bacteria and more
specifically Pseudomonas aeruginosa.
The invention is illustrated in the following non limiting examples.
method of determination of the bactericidal activity
1-Preparation of the inoculum
Cultures of the test bacterium were prepared with Pseudomonas
aeruginosa in nutrient broth and subcultured at 30°C daily for between
three and five successive days before they were required. The inocula
were prepared by diluting each of the overnight broth cultures 1:100 in
0.1 % Peptone Water immediately prior to use.
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2-Determination of the Minimum Inhibitory Concentration (MIC) of
EDDS
Sml of the solution of 32.4 % trisodium EDDS were added to Sml of
double strength nutrient broth and mixed. 5 ml of this mixture were taken
and added to Sml of single strength broth and mixed. Further halving
dilutions were prepared in the same manner until a total of ten dilutions of
the product had been prepared.
3-Preparation of solutions of antibacterials
Solutions or suspensions of the antibacterials were prepared in sterile
distilled water or water/ethanol mixtures immediately before use.
4-Preparation of nutrient broth containing EDDS
Single strength (0.745 % ) solutions of EDDS in nutrient broth were
prepared by adding 2.3m1 of 32.4% trisodium EDDS to 97.7m1 single
strength nutrient broth. Double strength (1.49 % ) solutions of EDDS in
double strength nutrient broth were prepared by adding 4.6m1 of 32.4%
trisodium EDDS to 95.4m1 double strength nutrient broth.
5-Preparation of dilutions of the antibacterials
Sml of the solution or suspension of antibacterial were added to Sml of
double strength nutrient broth and mixed; Sml of this mixture were taken
and added to Sml of single strength broth and mixed. Further halving
dilutions were prepared in the same manner until a total of ten dilutions of
the product had been prepared. This operation was repeated but this time
all dilutions were prepared in nutrient broth containing EDDS prepared as
in point 4.
6-Determination of the MIC of the conventional bactericidal agents
Halving dilutions in nutrient broth of each antibacterial prepared in
triplicate as in point 5 were inoculated with 10 microlitres of the inoculum
and mixed. The inoculated broths were incubated at 30°C for 3 days and
then examined for visual turbidity. The presence of turbidity, noted " +
°'
in the examples, was taken as an indicator of bacterial growth and
multiplication.
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~o m
1VIIC of trisodium salt of EDDS (Concentration in dilution Nol=16.2%)
1 2 3 4 5 6 7 8 9 10
~
- - + + + + +
+ + + + +
- - + + + + +
lViIC = 0.506-1.013 %
At levels of at least 0.7 % , EDDS is seen to produce an effective
bactericidal action against Pseudomonas aeruginosa bacteria.
~xarnnle 2
rviIC of Cetyl trimethyl ammonium bromide (ex BDH) (Concentration in
dilution No 1= 0.5
1 2 ~ 3 4 5 6 7 8 9 10
~
- - + + + + + +
- - - + + + + + +
- - - + + + + + +
l~ilC = 0.0313-0.0625
tVIIC of Cetyl trimethyl ammonium bromide in broth containing 0.745 %
I~DDS (Concentration in dilution Nol =0.5
1 2 3 4 5 6 7 8 9 10
_ _ _ _ _ _ _ _
_ _ _ _ _ _ +
1VIIC = 0.000977-0.00195 %
It can be seen that the combination of EDDS and cetyl trimethyl
ammonium bromide produce a synergistic bactericidal action.
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Example 3
MIC of 2,4,4' trichloro-2'-hydroxydiphenyl ether (Irgasan DP 300 ex
Ciba-Geigy) (Concentration in dilution Nol =0.5 % )
1 2 3 4 5 6 7 8 9 10
- + + + + + + + + +
- + + + + + + + + +
- + + + + + + + + +
MIC = > 0.5 % -inhibition in dilution No 1 due to presence of ethanol
MIC of 2,4,4' trichloro-2'-hydroxydiphenyl ether (Irgasan DP 300) in
broth containing 0.745 % EDDS (Concentration in dilution No 1=0.5
1 2 3 4 5 6 7 8 9 10
- - - + + + +
- - - + + + +
- - + + +
MIC = 0.00781-0.0156%
It can be seen that the combination of EDDS and 2,4,4' trichloro-2'-
hydroxydiphenyl ether (Irgasan DP 300) produce a synergistic
bactericidal action.
