AU2011205082A1 - Sanitising antimicrobial compositions - Google Patents

Abstract

Abstract The invention provides antimicrobial compositions comprising an essential oil, an alcohol and a metal ion source and methods of use thereof.

Description

Australian Patents Act 1990 - Regulation 3.2 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Sanitising antimicrobial compositions The following statement is a full description of this invention, including the best method of performing it known to me/us: P/00/01 5102 Sanitising antimicrobial compositions Field of the Invention The present invention relates generally to antimicrobial compositions and to methods 5 of use thereof in, for example, the disinfection and sanitisation of surfaces to provide a long-lasting barrier to the growth of microorganisms, in particular bacteria. More specifically, the invention relates to antimicrobial compositions comprising an essential oil, an alcohol and a metal ion source. 10 Background of the Invention Many microorganisms capable of causing infection and disease are able to survive outside a host organism, including on inanimate surfaces, for extended periods and remain viable. Contact with surfaces harbouring such microorganisms, even simply 15 through touch, can be sufficient to result in infection. Indeed it is well recognised that many contagious diseases are readily transmitted by unsatisfactory cleaning of surfaces and subsequent touching of unsanitised surfaces. This is true not only in bathrooms, kitchens and food preparation areas but also in children's play areas and offices in which increased sharing of resources can result in the rapid spread of 20 infection and disease. The health social and economic impacts of preventable communicable diseases are significant. There is a clear need for effective means of disinfecting and sanitising a range of surfaces to control the growth of microorganisms. 25 Sanitising products and disinfectants have been developed. However typically these suffer from one or more significant disadvantages. For example the efficacy of current products is typically short-lived, thus requiring regular and frequent re application that is time consuming, labour intensive and expensive. Many products, including those developed to have longer-lasting effects, are composed of toxic, 30 poisonous substances that can be harmful to human health, animal health and the environment. Furthermore, many of these products are difficult and inconvenient to use and apply. C:\NRPortb\DCC\GRS\3784218_1.DOC - 29/7/11 2 There is a growing need for the development of long-lasting products for the disinfection and sanitisation of surfaces that are non-toxic and therefore safe for humans and animal exposure and are biodegradable so as to be less environmentally damaging. 5 It has now been surprisingly been found, in accordance with the present invention, that anti-microbial efficacy can be dramatically extended by the combination of natural, non-toxic substances including an essential oil, an alcohol and a metal ion source. 10 Summary of the Invention According to a first aspect the present invention provides an antimicrobial composition comprising an essential oil, an alcohol and a metal ion source. 15 The essential oil may be from a Leptospermum sp. or a Melaleuca sp. In a particular embodiment the essential oil is tea tree oil. The tea tree oil may be lemon-scented tea tree oil. In a particular embodiment the tea tee oil is present at an amount less than about 1% by weight of the total composition, typically less than about 0.5%, 20 more typically between about 0.01% and 0.05%, and more typically about 0.03% by weight of the total composition. In a further particular embodiment, the lemon-scented tea tree oil comprises geranial, neral, citronellal, geraniol, linalool, a-pinene, P-pinene, eugenol, citronellyl acetate 25 and geranyl acetate. These components of the tea tree oil may be present in the following amounts within the tea tree oil: geranial, between about 20% to 30%; neral, between about 25% to 35%; citronellal, between about 15% to 35%; geraniol, between about 1% to 6%; linalool, between about 1% to 6%; a-pinene, between about 0.5% to 5%; p-pinene, between about 0.5% to 5%; eugenol, less than about 30 1%; citronellyl acetate, less than about 1%; and geranyl acetate, less than about 1%. Typically the alcohol is isopropyl alcohol. In a particular embodiment the isopropyl alcohol is present at an amount of between about 1% and 50% by weight of the total C:\NRPortbl\DCC\GRS\3784218 1.DOC - 29/7/11 3 composition, typically between about 10% and 30%, more typically between about 15% and 25%, and more typically about 20% by weight of the total composition. The metal ion source typically comprises silver as a source of silver ions. The silver 5 may be in the form of colloidal silver, silver salt or silver complex. In a particular embodiment the silver is colloidal silver. In an embodiment the colloidal silver is present in an amount between about 50% and 99% by weight of the total composition, typically between about 75% and 99%, and more typically about 80% by weight of the total composition. 10 In one embodiment the composition comprises about 0.03% lemon scented tea tree oil, about 19.5% isopropyl alcohol and about 80.47% colloidal silver. The composition may be in the form of a solution, emulsion or partial emulsion and 15 may be formulated for application by any suitable means such as for example an aerosol, via a trigger or pump action spray, a liquid to be applied with an applicator or impregnated onto a material such as paper, a cloth, towelette, sponge or brush. The composition may be applied to any environment inhabited or typically inhabited 20 by microorganisms. The environment may comprise an organic or inanimate surface. In particular embodiments the composition is intended for the disinfection and/or sanitisation of inanimate surfaces. The surface may be composed of any material, for example wood, glass, plastic, metal, stone, ceramic, porcelain, paper, natural or synthetic fibre, or laminate. 25 Typically the composition is for the elimination, inhibition or control of growth and/or activity of microorganisms selected from bacteria, fungi, viruses, yeast and protozoa. More typically the composition is for the elimination, inhibition or control of growth and/or activity of bacteria. The bacteria may be gram-positive or gram 30 negative. In particular embodiments the composition provides a residual antibacterial efficacy on a surface to which it is applied lasting more than about 7 days, more than about 14 days, or about 28 days or more. C:\NRPortbl\DCC\GRS\3784218_1.DOC - 29/7/11 4 In a second aspect the invention provides a method for eliminating or inhibiting the growth and/or activity of microorganisms, the method comprising contacting the microorganisms or an environment colonised by, or capable of being colonised by, the microorganisms with an effective amount of an antimicrobial composition 5 according to the first aspect. In a third aspect the invention provides a method for disinfecting or sanitising an environment or surface, the method comprising applying to the environment or surface an effective amount of an antimicrobial composition according to the first 10 aspect. Brief Description of the Drawings Embodiments of the invention are herein described, by way of non-limiting example only, by reference to the following drawings: 15 Figure 1. Killing effect of a sanitising composition according to an embodiment of the invention over a 28 day period on Staphylococcus aureus ATCC 6538 (A) and Escherichia coli NCTC 8196 (B). Detailed Description 20 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 25 In the context of this specification, the terms "a" and "an" are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element. 30 In the context of this specification, the term "about," is understood to refer to a range of numbers that a person of skill in the art would consider equivalent to the recited value in the context of achieving the same function or result. C:\NRPortbl\DCC\GRS\37B4218 1.DOC - 29/7/11 5 In the context of this specification, the term "antimicrobial composition" is understood to mean a composition that is capable of eliminating, preventing, inhibiting or retarding the activity and/or growth of one or more microorganisms, and is typically also capable of exerting a long-lasting sanitising effect to a surface to 5 which the composition is applied by eliminating, preventing, inhibiting or retarding the growth or colonisation of one or more microorganisms on the surface. In the context of this specification, the term "microorganism" is used in its broadest sense and is therefore not limited in scope to prokaryotic organisms. Rather, the 10 term "microorganism" includes within its scope bacteria, yeast, fungi, protozoa, algae and viruses. In particular embodiments, the term microorganism will be understood to refer to Gram-negative and Gram-positive bacteria. Antimicrobial compositions in accordance with the present invention comprise 15 natural, non-toxic and environmentally friendly components which may be applied to any environment or onto any surface colonised by, or capable of being colonised by, microorganisms such as bacteria to eliminate the microorganisms or to otherwise inhibit or control the growth and/or activity of the microorganisms. Accordingly, also provided herein are methods of sanitising and disinfecting surfaces using 20 antimicrobial compositions in accordance with the invention. Of particular significance is the surprising long-lasting antibacterial efficacy of compositions in accordance with the invention. Provided herein are compositions capable of maintaining a residual antibacterial activity on a surface for, by way of 25 example, more than 7 days, more than 14 days, more than 28 days, more than 60 days or more than 90 days from the date of application of the composition to the surface. In one aspect, antimicrobial composition is provided, which composition comprises 30 an essential oil, an alcohol and a metal ion source. In a broadest embodiment, the essential oil may be from any plant from which derived oils are known or thought to have antimicrobial activity. In a particular embodiment the essential oil is from a Leptospermum sp. or Melaleuca sp, more C:\NRPortbl\DCC\GRS\3784218_1.DOC - 29/7/11 6 particularly from a tea tree such as Melaleuca alternfolia or the lemon-scented tea tree Leptospermum petersonii. The essential oil may be additionally scented so as to either impart a pleasant fragrance to the composition and/or provide additional antimicrobial activities. It will also be appreciated by those skilled in the art that 5 more than one essential oil may be employed and/or one or more essential oils may be combined with one or more additional antimicrobial agents such as organic acids including citric acid and acetic acid, plant or fungal extracts, or chemicals such as benzalkonium chloride, in formulating compositions in accordance with the invention. The scope of the present disclosure is not to be limited by reference to the 10 nature or number of additional antimicrobial constituents incorporated into the composition. However in particularly advantageous embodiments, the constituents are non-toxic to humans, animals and/or plants and are environmentally friendly (for example biodegradable). 15 In a particular embodiment the lemon-scented tea tee oil is present at an amount less than about 1% by weight of the total composition, and may be present in an amount less than about 0.5%, 0.4%, 0.3%, 0.2% or 0.1%. More typically the lemon-scented tea tee oil may be present at an amount between about 0.001% and 0.05%, more typically between about 0.01% and 0.05% by weight of the total composition. The 20 lemon-scented tea tree oil may be used at an amount of about 0.01%, 0.02%, 0.03%, 0.04% or 0.05% by weight of the total composition. In a further particular embodiment, the lemon-scented tea tree oil comprises geranial, neral, citronellal, geraniol, linalool, a-pinene, p-pinene, eugenol, citronellyl acetate and geranyl acetate. These components of the tea tree oil may be present in the following 25 amounts within the tea tree oil: geranial, between about 20% to 30%; neral, between about 25% to 35%; citronellal, between about 15% to 35%; geraniol, between about 1% to 6%; linalool, between about 1% to 6%; a-pinene, between about 0.5% to 5%; P-pinene, between about 0.5% to 5%; eugenol, less than about 1%; citronellyl acetate, less than about 1%; and geranyl acetate, less than about 1%. 30 Those skilled in the art will understand that the essential oil may be naturally derived from one or more plant parts (such as leaves, twigs, bark, flowers, roots) by any process (such as steam distillation as is well known to those skilled in the art). Those skilled in the art will also understand that by being "derived" from a plant, the C:\NRPortbl\DCC\GRS\3784218_1.DOC - 29/7/11 7 essential oil may be synthesised, in whole or in part, such that the oil is "derived" from the plant in that it mimics or resembles in constituency and function a naturally derived oil. 5 The alcohol present in compositions according to the present invention may be of any suitable type, and is typically water soluble. Exemplary alcohols suitable for use include but are not limited to isopropyl alcohol, n-propyl alcohol and ethyl alcohol. Typically the alcohol is isopropyl alcohol. In particular embodiments the isopropyl alcohol may be present at an amount of between about 1% and 50% by weight of the 10 total composition, typically between about 10% and 30%, more typically between about 15% and 25%, and more typically about 20% by weight of the total composition. Compositions according to the present invention also comprise a metal ion source. 15 The metal ion may be selected from, by way of non-limiting example, Age, Cu 2 + 2+ 2+ 2+ Zn , Fe2+ and Mn . In a particular embodiment, the metal ion source is a form of sliver as a source of silver ions. A variety of forms of silver may be used. Examples include colloidal silver, silver salts, and silver complexes, such as silver bromide, silver chloride, silver citrate, silver iodide, silver lactate, silver nitrate, silver oxide, 20 silver picrate, and the like. In a particular embodiment the silver is colloidal silver. In an embodiment the colloidal silver is present in an amount between about 50% and 99% by weight of the total composition, typically between about 55% and 99%, 60% and 99%, 65% and 99%, 70% and 99%, 75% and 99%, and more typically about 75%, 76%, 77%, 79%, 80%, 81%, 82%, 83%, 84% or 85% by weight of the 25 total composition. It will also be appreciated by those skilled in the art that more than one metal ion source and more than one type of metal ion may be employed in accordance with the invention. For example, combinations of metal salts may be used in compositions of the invention. 30 By way of example only, one exemplary composition in accordance with the invention comprises about 0.03% lemon scented tea tree oil, about 19.5% isopropyl alcohol and about 80.47% colloidal silver. C:\NRPortbl\DCC\GRS\3742181.DOC- 29/7/11 8 The tea tree oil is incorporated due to its known antimicrobial qualities. Without wishing to be bound by theory, it is believed that isopropyl alcohol acts to denature bacterial cell walls resulting in dehydration and death of viable organisms. Colloidal silver provides bioactive properties and oligodynamic effect through 5 denaturation/inactivation of bacterial enzymes. Further, without wishing to be bound by theory, it is believed that the isopropyl alcohol provides a rapid 'first hit' antimicrobial effect reducing bacterial populations to minimal levels. The water then evaporates leaving behind the active components of the silver colloid and the Lemon Scented Tea Tree Oil, effectively coating the surface with active components that 10 provide a long term antimicrobial effect as the surfaces are re-challenged with bacteria from the environment. As exemplified herein compositions according to the invention exhibit long-lasting antibacterial activity on treated surfaces for periods up to 7 days, 14 days and 28 15 days after application. Thus, also provided herein are methods for eliminating or inhibiting the growth and/or activity of microorganisms, comprising contacting the microorganisms or an environment colonised by, or capable of being colonised by, the microorganisms with an effective amount of an antimicrobial composition according to the present invention, and also methods for disinfecting or sanitising an 20 environment or surface, comprising applying to the environment or surface an effective amount of an antimicrobial composition according to the present invention. The environment to which the composition is applied to provide a long-lasting disinfecting and sanitising effect may comprise any organic or inanimate surface or 25 substrate. In particular embodiments the composition is intended for application for the disinfection and/or sanitisation of inanimate surfaces. The surface may be composed of any material, for example wood, glass, plastic, metal, stone, ceramic, porcelain, paper, natural or synthetic fibre, or laminate. As such compositions and methods of the invention find particular application in the disinfection and 30 sanitisation of items such as work surfaces (including kitchen benches, cutting and food preparation boards, desks), telephone handsets, computer keyboards, office furniture, door, cupboard and drawer handles and knobs, light switches, shop counters, cash registers, stair handrails, children's toys, mops and other cleaning equipment as well as most household surfaces for example floors, bathroom vanities C:\NRPortbl\DCC\GRS\374218_1.DOC - 29/7/11 9 and benchtops, taps, toilets and toilet seats, showers, mirrors and windows. The natural, non-toxic makeup of compositions of the invention and the alcohol constituents, combined with the long-lasting antimicrobial efficacy of the compositions mean that once applied to a surface they need not be wiped off. The 5 prolonged contact of the composition with the surface provides a continual microbial killing effect and barrier to colonization or re-colonisation of the surface by new microorganisms for days, weeks and months. The reduced number of applications required also generates considerable savings in terms of expense, time and labour in comparison to existing disinfectants and sanitising products. 10 Compositions of the present invention can be prepared by any suitable process known to those skilled in the art. For example, a composition may be constituted by preparing an aqueous mixture of an alcohol with the essential oil. The composition can then be agitated or mixed with the metal ion source. Alternatively, the 15 composition may be made as an emulsion. By way of example the metal ion source, such as colloidal silver, may be first mixed with the alcohol, such as isopropyl alcohol, stirred and the essential oil then being added to this mixture and stirred to ensure complete mixing of all ingredients. 20 Compositions of the invention may be formulated to be dispensed from containers or holding vessels for application to surfaces to be treated by any suitable means and may be in any suitable form to enable ease of use. For example, the composition may be in a liquid, gel or cream form to be applied to a surface by way of an applicator such as paper, towelette, cloth, sponge or brush. Alternatively, the 25 composition may be formulated for dispensing as an aerosol or as a liquid from for example a squeeze bottle, spray bottle, such as a trigger pump spray bottle or depression pump spray bottle. Additionally, applicators such as towelettes, cloths, sponges and brushes may be impregnated with compositions of the invention for ease of use. Such impregnated applicators may be packaged individually or in bulk. 30 C:\NRPortbl\DCC\GRS\378421k.DOC - 29/7/11 10 Examples Example 1 - Sanitising composition An antimicrobial composition for disinfecting and sanitising surfaces was prepared, the composition comprising lemon-scented tea tree oil at 0.03% by weight, isopropyl 5 alcohol at 19.5% by weight and colloidal silver in water at 80.47% by weight. The tea tree oil is comprised of: geranial (20 to 30%); neral (25 to 35%); citronellal (15 to 35%); geraniol (1 to 6%); linalool (1 to 6%); a-pinene (0.5 to 5%); b-pinene (0.5 to 5%); eugenol (<1%); citronellyl acetate (<1%); and geranyl acetate (<1%). 10 Due to the nature of the formulation an emulsion is used - the Lemon Scented Tea Tree oil on its own will not mix with the water. The isopropyl alcohol within the formulation provides an avenue through which the oil and the water can form a partial emulsion. It was observed during development of the formulation that a minor exothermic reaction occurs. Thus, to ensure the oil is not evaporated away 15 during this reaction a mixing procedure was formulated that follows the steps: 1) Add required quantity of colloidal silver to the mixing tank 2) Add required quantity of isopropyl alcohol 3) Allow the heat generated to dissipate through stirring 4) Add required quantity of Lemon Scented Tea Tree Oil 20 5) Stir at a slow speed to ensure complete mixing 6) Decant and package. Example 2 - Antibacterial activity of sanitising composition The sanitising composition from Example 1 was tested for its ability to kill both 25 gram positive bacteria (Staphylococcus aureus) and gram negative bacteria (Escherichia coli). Inoculated carrier surfaces to be treated were allowed to dry, and subsequently treated with samples of the sanitising composition according to Example 1), 30 alongside controls (no sample treatment) in duplicate. Sample treatment involved a 2-step application of sanitising compositions. First, carriers were sprayed four times at 10cm distance from the inoculated carrier with Ecogreen Instant Natural Sanitiser C:\NRPortbI\DCC\GRS\3784218-1.DOC - 29/7/11 11 (Environmental Technologies Australia Pty Ltd). This was left for 5 minutes and then dabbed dry with a sterile wipe, and subsequently the carriers were sprayed with the sanitising composition according to Example 1 above (4 sprays and 10cm distance from the carrier). 5 On each challenge day (days 0, 2, 7, 14 and 28) both treated and untreated carriers were re-challenged with 102 cfu/ml microorganism. Two microorganisms were used, the Gram-positive Staphylococcus aureus ATCC 6538 and the Gram-negative Escherichia coli NCTC 8196. In addition to challenging the substrates with the 10 cultured bacteria, organic soil (5% horse serum) was also applied. On each challenge day carriers were neutralized after 60 minutes with the validated neutraliser T6 (a mixture of Tryptone Soy Broth, Lecithin and Tween 80). Carriers remained at room temperature throughout the experiments. 15 The results are shown in Tables 1 and 2 below and in Figures IA (Staphylococcus aureus) and Figure 1 B (Escherichia coli). Table 1: Staphylococcus aureus ATCC 6538 challenge Day Test Control Inoculum <1.0 x 10' <1.0 4.7 x 10' 0 cfu >4.67 Log reduction (5.67) <1.0 x 10' 0 4.7 x 10' 2 cfu 3.67 Log reduction (3.67) <1.0 x 10' 0 4.7 x 10 7 Cfu 2.57 Log reduction (2.57) <1.0 x 101 0 4.7 x 10 5 14 Cfu 2.53 Log reduction (2.53) <1.0 x 101 0 4.7 x 10' 28 cfu 2.52 Log reduction (2.52) 20 25 C:\NRPortbI\DCC\GRS\3784218.1.DOC - 29/7/11 12 Table 2: Escherichia coli NCTC 8196 challenge Day Test Control Inoculum Cfu/ml L gin <1.0 x 10' <1.0 3.6 x 10' 0 cfu >4.56 Log reduction (5.56) 0 0 1.4 x 10 3 2 cfu 3.15 Log reduction (3.15) 0 0 3.4 x 10 2 7 cfu 2.53 Log reduction (2.53) 0 0 4.3 x 10 2 14 cfu 2.63 Log reduction (2.63) 0 0 4.3 x 10 2 28 cfu 2.63 Log reduction (2.63) 5 It can clearly be seen that the sanitizing composition according to Example I achieved a greater than 99.99% log reduction in numbers of both Staphylococcus aureus and Escherichia coli, as an immediate effect and 99% log reduction as a longevity effect up to 28 days. 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Claims (21)

1. An antimicrobial composition comprising an essential oil, an alcohol and a metal ion source. 5

2. The composition of claim I wherein the essential oil is tea tree oil.

3. The composition of claim 2 wherein the tea tree oil is lemon-scented tea tree oil. 10

4. The composition of claim 2 or 3 wherein the tea tree oil is present at about 0.03% by weight of the total composition.

5. The composition of claim 3 wherein the lemon-scented tea tree oil comprises geranial, neral, citronellal, geraniol, linalool, ax-pinene, p-pinene, eugenol, citronellyl 15 acetate and geranyl acetate, optionally in the following amounts within the tea tree oil: geranial, between about 20% to 30%; neral, between about 25% to 35%; citronellal, between about 15% to 35%; geraniol, between about 1% to 6%; linalool, between about 1% to 6%; ax-pinene, between about 0.5% to 5%; p-pinene, between about 0.5% to 5%; eugenol, less than about 1%; citronellyl acetate, less than about 20 1%; and geranyl acetate, less than about 1%.

6. The composition of any one of claims I to 5 wherein the alcohol is isopropyl alcohol. 25

7. The composition of claim 6 wherein the isopropyl alcohol is present at about 20% by weight of the total composition.

8. The composition of any one of claims 1 to 7 wherein the metal ion source comprises silver as a source of silver ions. 30

9. The composition of claim 8 wherein the silver is colloidal silver.

10. The composition of claim 9 wherein the colloidal silver is present at about 80% by weight of the total composition. C:\NRPortbl\DCC\GRS\3784218O.DOC-29/7/11 14

11. The composition of any one of claims I to 10 comprising about 0.03% lemon scented tea tree oil, about 19.5% isopropyl alcohol and about 80.47% colloidal silver. 5

12. The composition of any one of claims I to II wherein the composition is an emulsion of partial emulsion.

13. The composition of any one of claims 1 to 12 wherein the composition is formulated for application via a trigger or pump action spray. 10

14. The composition of any one of claims 1 to 12 wherein the composition is impregnated onto a material such as paper, a cloth, towelette or sponge.

15. The composition of any one of claims I to 14 wherein the composition is for 15 application to organic or inanimate surface.

16. The composition of any one of claims 1 to 15 wherein the composition is for the disinfection and/or sanitisation of inanimate surfaces. 20

17. The composition of claim 16 wherein the surface is composed of any material, for example wood, glass, plastic, metal, stone, ceramic, porcelain, paper, natural or synthetic fibre, or laminate.

18. The composition of any one of claims 1 to 17 wherein the composition is for 25 the elimination, inhibition or control of growth and/or activity of bacteria.

19. The composition of any one of claims I to 18 wherein the composition provides a residual antibacterial efficacy on a surface to which it is applied lasting more than about 7 days, more than about 14 days, or about 28 days or more. 30

20. A method for eliminating or inhibiting the growth and/or activity of microorganisms, the method comprising contacting the microorganisms or an environment colonised by, or capable of being colonised by, the microorganisms C:\NRPortbl\DCC\CRS\3784218.1.DOC - 29/7/11 15 with an effective amount of an antimicrobial composition according to any one of claims I to 19.

21. A method for disinfecting or sanitising an environment or surface, the method 5 comprising applying to the environment or surface an effective amount of an antimicrobial composition according to any one of claims I to 19. C:\NRPortbl\DCC\GRS\3784218_1.DOC - 29/7/11