ANTIMICROBIAL COMPOSITION COMPRISING A LACTAM AND A HYDROTROPE

The present invention relates to an improved antimicrobial composition comprising a lactam.

WO 2007/085042 and WO 2004/016588 disclose lactams for antimicrobial benefit. Despite the prior art there remains a need for improved antimicrobial

compositions.

Accordingly, and in a first aspect of the present invention there is provided an antimicrobial composition comprising a lactam and a hydrotrope preferably wherein the lactam is of formula (I) or (II):

In a second aspect, there is provided an antimicrobial additive composition containing a lactam and a hydrotrope.

Preferably the anti-microbial composition and additive composition contains 0.000001 to 50% wt. lactam, more preferably 0.001 to 50% wt. even more preferably 0.01 to 5% wt, most preferably 0.01 - 2%. In a third aspect of the invention there is provided an antimicrobial composition comprising an antimicrobial additive composition of the second aspect.

In a fourth aspect there is provided a method for making an antimicrobial composition comprising the steps:

(i) directly mixing a lactam with a hydrotrope to form an antimicrobial additive composition

(ii) mixing the antimicrobial additive composition of (i) with an aqueous carrier.

In a fifth aspect there is provided a method for making an antimicrobial additive composition comprising the step of directly mixing a hydrotrope with a lactam.

In a sixth aspect, the present invention provides the use of an antimicrobial composition according to the first and third aspect or an antimicrobial additive composition according to the second aspect for preventing or disrupting microbial growth.

Preferably the antimicrobial additive composition and the method of making said additive composition is substantially free of further components.

The term "substantially free" as used herein shall be understood to mean relatively little to no amount of any content. Preferably the antimicrobial contains less than 1 wt. % more preferably less than 0.1 wt. % of further components.

Preferably the aqueous carrier is suitable for use as a carrier for a home or personal care product. Preferred personal care products include shampoos, hair conditioners, deodorants, skin cleansing compositions and oral care products such as toothpastes and mouthwashes. Preferred home care products are for example a hard surface cleaner or laundry composition. The antimicrobial additive composition according to the invention can be used as an antimicrobial raw material where it would be diluted in a further composition or the composition may be a consumer product the application of which is intended to provide antimicrobial effect to a substrate or even as a preservative when added to a consumer composition.

Preferably the lactam is of formula (I) or (II):

Preferably the lactam is of formula (I) or (II) wherein:

R1 and R2 are each independently selected from hydrogen, halogen, alkyl, cycloalkyi, alkoxy, oxoalkyi, alkenyl, heterocyclyl, heteroaryl, aryl and aralalkyl; and

R3 is selected from hydrogen, hydroxyl, alkyl, cycloalkyi, alkoxy, oxoalkyi, alkenyl, heterocyclyl, heteroaryl, cycloalkyi, aryl, aralalkyl and -C(O)CR6=CH2;

R4 and R5 are independently selected from hydrogen, aryl, heterocyclyl, heteroaryl, and arylalkyl; and

R6 is selected from hydrogen and methyl; and R7 is selected from hydrogen and -C(O)CR6=CH2; and

Preferably, at least one of R4 and R5 is hydrogen; and Preferably, at least one of R1 and R2 is selected from hetercyclyl, heteroaryl, aryl and arylalkyl; and Preferably, R1 is hydrogen. Preferably, R3 is hydrogen. Preferably, R4 is hydrogen. Preferably, R5 is hydrogen. Preferably, R6 is hydrogen; and

Preferably, R2 is aryl or aralalkyl. More preferably, R2 comprises a halogen substituted phenyl group.

Preferably, the hydrotrope is selected from monopropylene glycol,

dimethylsulphoxide, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene derivatives of castor oil and ethanol. Preferably, the hydroptrope is present at from 0.001 to 25% wt. of the

composition.

Preferred lactams are: 5-methylene-4-(4'-bromophenyl)-dihydroprrol-2-one (Ref. 295)

5-methylene-4-(2'-fluorophenyl)-dihydropyrrol-2-one (Ref. 310)

5-methylene-4-phenyl-1 H-pyrrol-2(5H)-one (Ref. unsubstituted) methyl 2-(3-(4-fluorophenyl)-2-methylene-5-oxo-2,5-dihydro-1 H-pyrrol-1 -yl) (Ref. 309)

3- Bromo-4-hexyl-5-(bromomethylene)-2(5H)-furanone (Ref. 1 13)

4- (4-Trifluoromethyl)phenyl)-2(5H)-furanone (Ref. 265) 5-Hydroxy-5-methyl-4-(2'-fluorophenyl)-dihydropyrrol-2-one (Ref. 313) 5-(Thiophenyl-3-methylene)furan-(2H)-one (Ref. 350)

The most preferred lactams are:

5-methylene-4-(4'-bromophenyl)-dihydroprrol-2-one (Ref. 295) 5-methylene-4-(2'-fluorophenyl)-dihydropyrrol-2-one (Ref. 310)

5-methylene-4-phenyl-1 H-pyrrol-2(5H)-one (Ref. unsubstituted) methyl 2-(3-(4-fluorophenyl)-2-methylene-5-oxo-2,5-dihydro-1 H-pyrrol-1 -yl) (Ref. 309)

Preferably, the hydrotrope is selected from monopropylene glycol,

dimethylsulphoxide, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene derivatives of castor oil and ethanol.

Preferably, the polyoxyethylene sorbitan fatty ester is a monoester selected from monolaurate, monopalmitate, monostearate and monooleate.

Preferably, the polyoxyethylene sorbitan fatty ester comprises from 5 to 80 oxyethylene units, more preferably from 10 to 45 and most preferably 20.

Examples include Polysorbates 20, 40, 60 and 80.

The most preferred polyoxyethylene sorbitan fatty ester is Polysorbate 20. Preferably, the polyoxyethylene derivative of castor oil comprises from 10 to 50 oxyethylene units, more preferably from 30 to 45 and most preferably 40. Examples include PEG-20, 40 and 60 hydrogenated castor oil. The most preferred polyoxyethylene derivative of castor oil is PEG-40 hydrogenated castor oil.

Preferably, the composition is a home care or personal care product. Preferred personal care products include shampoos, hair conditioners, deodorants, skin cleansing compositions and oral care products such as toothpastes and mouthwashes. Preferred home care products include a hard surface cleaner or laundry composition.

lactams

Suitable lactams are disclosed in WO 2007/085042 and WO 2004/016588 the contents of which with particular regard to the manufacture of lactams and from WO 2007/085042 the manufacture of acrylate polymers with certain lactams associated thereto, is incorporated by reference.

For example:

EXAMPLE 1 The following data illustrates the antimicrobial efficacy of a laundry composition (hereinafter 'base composition') comprising a lactam (Ref. 295 and Ref.

Unsubstituted) and a hydroptrope (monopropylene glycol ) but only where hydroptrope is mixed with lactam before adding to the remainder of the

composition. The test samples were as follows:

A lactam and hydroptrope only

B lactam added directly to base formulation (which contains MPG) - no pre-mixing prior to addition

C lactam pre-mixed with hydrotrope and then added to base formulation

D hydrotrope only added to base formulation

Base Formulation

Test samples were diluted in sterile water to achieve a 1 1 .5ppm level of lactam. Dilute solution (80μΙ) was added to a S. epidermidis suspension (20μΙ) of bacteria at a concentration of 8 logs in a microplate. Growth media (100μΙ tryptone soya broth) was added to each well of the microplate and incubated for 20 hours. Bacterial respiration was measured every 30 minutes and the results werea:

A - lactam + hydrotrope only (respiration of surviving bacteria detected ~4-5h) B - lactam added directly to base formulation (which contains MPG) - no pre- mixing prior to addition (respiration of surviving bacteria detected 4-5hrs)

C - lactam pre-mixed with hydrotrope and then added to base formulation (respiration of surviving bacteria not detected - 20hrs is max detection time) D -hydrotrope added to base formulation (respiration of surviving bacteria detected 3-4hrs). The results are shown in Figure 1 . EXAMPLE 2 The following illustrates the broad application of the invention within the realm of lactams.

The example below is from data obtained when pre-blending lactams with hydrotrope before adding to the remainder of the composition, and diluting to 1 1 .5ppm and 0.575ppm in sterile water in order to assess efficacy against S. epidermidis suspension Dilute solution (80μΙ) was added to a S. epidermidis suspension (20μΙ) of bacteria at a concentration of 8 logs in a microplate. Growth media (1 ΟΟμΙ tryptone soya broth) was added to each well of the microplate and incubated for 20 hours. Bacterial respiration was measured every 30 minutes. Data of the test samples were then compared to un-treated cell suspensions (sterile water added instead of test samples) and percent inhibition calculated.

Test Result (inhibition of bacterial

respiration versus water control)

5-methylene-4-(2'-fluorophenyl)- 79.4%

dihydropyrrol-2-one

5-methylene-4-(4'-bromophenyl)- 82.5%

dihydroprrol-2-one

5-methylene-4-phenyl-1 H-pyrrol-2(5H)- 82.5%

one EXAMPLE 3

The aim of this example was to investigate methods of achieving solubility of 5- methylene-4-phenyl-1 H-pyrrol-2(5H)-one (Ref. unsubstituted) into the following above described base formulation.

An Ultrasonic mixer was used to obtain determine solubility.

We used a Hielscher UP200S (200W) Sonic Tip on batches of 5-20ml. We sonicated for up to 60 minutes.

% lactam in Mixing method Observations of Observations when solvent solvent solution added to base @ 5%

3% in Magnetic stirring -25% of lactam Clear solution with a

Polysorbate 1 hour solubilised. large quantity of 20 Particles particles visible

visible.

3% in PEG- Magnetic stirring -25% of lactam Clear solution with a 40 1 hour solubilised. large quantity of

Hydrogenated Particles particles visible

Castor Oil visible.

3% in Magnetic stirring No solubility

Isopentyldiol 1 hour observed.

3% in MMB Magnetic stirring No solubility

1 hour observed.

3% in Magnetic stirring No solubility

Diglycerin 1 hour observed.

3% in Magnetic stirring No solubility

Diglycerin 1 hour observed.

3% in Magnetic stirring No solubility

Pentylene 1 hour observed. Glycol

3% in Magnetic stirring No solubility -

Hexylene 1 hour observed.

Glycol

3% in Magnetic stirring No solubility -

Hexylene 1 hour observed.

Glycol

3% in PEG- Magnetic stirring ~10% of lactam Cloudy in solution

60 1 hour solubilised.

Hydrogenated Particles

Castor Oil visible.

3% in Magnetic stirring ~10% of lactam Cloudy and gel-like

Polysorbate 1 hour, 50C solubilised. lumps in solution

60 Particles

visible.

3% in Magnetic stirring ~10% of lactam Cloudy and gel-like

Polysorbate 1 hour solubilised. lumps in solution

80 Particles

visible.

3% in Magnetic stirring -5% of lactam -

Dipropylene 1 hour solubilised

Glycol (slight colour

change

observed

showing this.

Particles

visible.

3% in Magnetic stirring -5% of lactam Cloudy when cooled

Sorbitan 1 hour, 50C solubilised or added to M30

Oleate (slight colour

change observed

showing this.

Particles

visible.

3% in Magnetic stirring -5% of lactam Cloudy solution with

Sisterna 1 hour solubilised large number of

SP30-C (slight colour particles visible.

change

observed

showing this.

Particles

visible.

3% in Magnetic stirring -5% of lactam Hazy solution with

Sisterna 1 hour solubilised large number of

SP50-C (slight colour particles visible.

change

observed

showing this.

Particles

visible.

3% in Magnetic stirring -5% of lactam Cloudy solution with

Sisterna 1 hour solubilised large number of

SP70-C (slight colour particles visible.

change

observed

showing this.

Particles

visible.

The polysorbates and Pegylated castor oil were considered suitable enough to pursue further experimentation. Further evaluations with each candidate solubiliser

We then tested the candidate solubilisers with 1 % lactam, both with 72 hours high speed magnetic stirring (with held temperature of ~50C in the cases of solubilisers that solidify alone at room temperature) and also 20 minutes Sonication.

Preparation of the lactam solutions In each case we incorporated the lactam powder into the solubilisers (at the levels indicated in the below table) using high speed stirring to avoid lumps from forming. Once the powder was added, the described mixing method (either continued high speed stirring or Ultrasonic mixing) commenced. In the cases of Sorbitan Oleate and Polysorbate-60, we applied initial heating to approx. 50C to ensure the solubilisers were fully liquid prior to commencing addition of the lactam. Both of these materials are non-flowing at room temperature. PEG-40 Hydrogenated Castor required initial heating to ~35C to ensure complete fluidity prior to commencing. Incorporation of the lactam solutions into base

The base sample provided had a 5% 'gap' purposely left out as space for the lactam solution to be added. We ensured the lactam solutions were fully uniform through constant mechanical agitation (to avoid the settling of any unsolubilised lactam material) and added them to base using slow speed stirring to incorporate them without generating aeration.

Stability testing

We conducted stability testing on all test variants that looked positive (i.e. a reasonable proportion of lactam was solubilised). We prepared samples of the test variants in clear plastic jars and placed them at various temperature conditions:

^* Ambient temperature.

* 40C.

* 50C.

^* Refrigerator.

^* High light ('shop' window).

The aim was to observe any difference in colour, viscosity, solubility or general physical stability. The samples were evaluated every day and compared to the ambient temperature sample to note any changes. All samples were allowed to equilibrate to ambient temperature before being evaluated.

Isopentyldiol

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

1 % in Magnetic stirring 72 No solubility

Isopentyldiol hours observed at any

stage.

1 % in 20 minutes -5% of lactam

Isopentyldiol sonication. Temp solubilised

reached 60-70C (forced). Large

number of

particles visible. 3-Methoxy-3-methyl-1 -butanol

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

1 % Magnetic stirring 72 No solubility

hours observed at any

stage.

1 % 20 minutes -5% of lactam

sonication. Temp solubilised

reached 60-70C (forced). Large

number of

particles visible.

Diglycerin

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

1 % Magnetic stirring 72 No solubility

hours observed at any

stage.

1 % 20 minutes No solubility

sonication. Temp observed.

reached 60-70C Pentylene Glycol

PEG-60 Hydrogenated Castor Oil

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

1 % Magnetic stirring 72 -25% of lactam Cloudy in solution.

hours at 50C solubilised. Particles visible.

Particles visible.

1 % 20 minutes -25% of lactam Cloudy in solution.

sonication. Temp solubilised. Particles visible. reached 60-70C Particles visible. Polysorbate 60

Polysorbate 80

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

1 % Magnetic stirring 72 -25% of lactam Cloudy in solution.

hours at 50C solubilised. Particles visible.

Particles visible.

1 % 20 minutes -25% of lactam Cloudy in solution.

sonication. Temp solubilised. Particles visible. reached 60-70C Particles visible.

Sisterna SP30-C

Sisterna SP50-C Sisterna SP70-C

Polysorbate 20

% lactam Mixing method Observations of Observations in solvent solvent solution when added to

M30 @ 5%

3% Magnetic stirring 1 -25% of lactam Clear solution with hour solubilised. a large quantity of

Particles visible. particles visible

4.2% Magnetic stirring. 24 -25% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

4.2% Magnetic stirring. 24 -25% of lactam Clear solution with hours. solubilised, a large quantity of

Particles visible. particles visible Initially stirred for

2, 4 and 6 hours.

No real changed

observed during

this time (all max. 25% solubilised).

20 minutes -50% of lactam Clear solution with sonication. Temp solubilised. a large quantity of reached 60-70C Particles visible particles visible

60 minutes -60-70% of lactam Clear solution with sonication. Temp solubilised. a large quantity of reached 90C Particles visible particles visible

20 minutes -90% of lactam Clear solution. A sonication. Temp solubilised. Dark very small number reached 60-70C colour formed of remaining

unsolubilised lactam particles visible

60 minutes 90% of lactam Clear solution with sonication. Temp solubilised. Some a minute number reached 90-100C small particles of particles visible.

visible.

Magnetic stirring. 48 -25% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

Magnetic stirring. 24 -50% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

Magnetic stirring. 48 -75% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

Magnetic stirring, -50% of lactam Clear solution with heated to 50C. 8 solubilised, a large quantity of hours. Particles visible. particles visible

20 minutes -50% of lactam Clear solution with sonication. Temp solubilised. a large quantity of reached 60-70C Particles visible particles visible

% lactam in Mixing method Observations of Observations solvent solvent solution when added to base @ 5%

3% 60 minutes -60-70% of lactam Clear solution with sonication. Temp solubilised. a large quantity of reached 90C Particles visible particles visible

1 % Magnetic stirring. 24 -75% of lactam Clear solution with hours solubilised, a few particles

Particles visible. visible

1 % Magnetic stirring. 72 -95% of lactam Clear solution with hours solubilised A few a few particles particles visible. visible

After 48 hours it

was approx. 80- 85%.

2.1 % Magnetic stirring, -75% of lactam Clear solution with heated to 50C. 72 solubilised, a large quantity of hours. Particles visible. particles visible

1 .5% Magnetic stirring. 48 -50% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

1 .5 Magnetic stirring, -75% of lactam Clear solution with heated to 50C. 72 solubilised, a large quantity of hours. Particles visible. particles visible

1 .5% 20 minutes -75% of lactam Clear solution with sonication. Temp solubilised. Some a number of reached 60-70C Particles visible particles visible

1 .5% 60 minutes -95% of lactam Clear solution with sonication. Temp solubilised. a minute number reached 80-90C Particles visible. of particles visible Dark brown colour.

2.1 % 60 minutes 90% of lactam Clear solution with sonication. Temp solubilised. Some a minute number reached 80C small particles of particles visible.

visible.

PEG-40 Hydrogenated Castor Oil

% lactam Mixing method Observations of Observations in solvent solvent solution when added to

M30 @ 5%

3% Magnetic stirring 1 -25% of lactam Clear solution with hour solubilised. a large quantity of

Particles visible. particles visible

4.2% Magnetic stirring. 24 -25% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

4.2% Magnetic stirring. 24 -25% of lactam Clear solution with hours. solubilised, a large quantity of

Particles visible. particles visible Initially stirred for

2, 4 and 6 hours.

No real changed

observed during

this time (all max.

25% solubilised).

4.2% Magnetic stirring. 48 -25% of lactam Clear solution with hours solubilised, a large quantity of Particles visible. particles visible

Magnetic stirring. 24 -50% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

Magnetic stirring. 48 -75% of lactam Clear solution with hours solubilised, a large quantity of

Particles visible. particles visible

20 minutes 50% of lactam Clear solution with sonication. Temp solubilised. Large a large number of reached 60-70C number of particles visible particles visible.

Very dark colour.

60 minutes 75% of lactam Some fragments sonication. Temp solubilised. Very visible in M30, reached 1 10C dark colour. suggesting partial breakdown of solvent.

60 minutes 75% of lactam Fragments sonication. Temp solubilised. Very avoided due to reached 80C dark colour. temperature

control. Clear solution with some small particles visible.

20 minutes 90% of lactam Clear solution with sonication. Temp appeared to a small number of reached 80C solubilise however black particles small amount of visible

'burnt' spots

visible.

60 minutes lactam solubilised. Some fragments sonication. Temp Very dark colour. visible in M30, reached 1 10C suggesting partial breakdown of solvent.

2.1 % Magnetic stirring, -50% of lactam Clear solution with heated to 50C. 8 solubilised, a large quantity of hours. Particles visible. particles visible

% lactam in Mixing method Observations of Observations solvent solvent solution when added to

M30 @ 5%

3% 20 minutes -75% of lactam Clear solution with sonication. Temp solubilised. a large quantity of reached 60-70C Particles visible particles visible

3% 60 minutes -75% of lactam Clear solution with sonication. Temp solubilised. a large quantity of reached 80C Particles visible particles visible

1 % Magnetic stirring. 24 -75% of lactam Clear solution with hours solubilised, a few particles

Particles visible. visible

1 % Magnetic stirring. 72 -90% of lactam Clear solution with hours solubilised, A few a few particles particles visible

1 % Magnetic stirring. 72 -99% of lactam Clear solution with hours with temp, at solubilised, A tiny a very small 50C number of number of

particles remained particles visible

2.1 % 30 minutes lactam appeared Clear solution with sonication. Temp to solubilise a small number of reached 90C however 'burnt' black particles spots visible. visible Observation and Formulation rules

Temperature and colour change

One of our first observations was the colour change which was visible in all successful (or partially successful) samples. We saw development of a slight amber tinge to the solution when some lactam was starting to become solubilised. This colour change progressed rapidly when samples exceeded 50C, resulting in a dark brown colour. When the temperature reached 65C, the dark brown colour was virtually opaque ^* .

^* This level of temperature was only tested for the Polysorbate-20 and PEG-40 Hydrogenated Castor Oil variants.

From observations throughout the project, we concluded that ~50C was the optimum temperature for solubilising the lactam.

Mixing conditions

Very long periods of mechanical stirring (48-72 hours) resulted in improvements in solubilisation compared to shorter periods; however we did not find this length of mixing to be sufficient for full solubilisation. Ultrasonic mixing did prove to be far more successful and we concluded would be required for effective solubilisation, certainly with the shortlisted Polysorbate-20 and PEG-40 Hydrogenated Castor Oil candidates.

From all of the trials conducted, we believe with the right Ultrasonic mixing conditions (of energy versus batch size versus controlled max. 50C temperature), efficient solubilisation could be achieved.