Field of the invention The present invention relates to an antimicrobial composition and more particularly to an antimicrobial composition at the pH of skin.

Background of the invention People try to take good care of the external surfaces of their body as well as those of their pets to enable overall good health. Specific skin related issues that people care about include, good skin health free of infections, good skin tone and adequate moisturization. Oral cavity is another external surface that people try to take active care to maintain. They prefer their oral cavity including the gums and teeth to be free of problems like cavities, tartar, gingivitis, caries, bad breath also known as halitosis and plaque. Typically, people are also concerned with hair and scalp care. They generally prefer to have thick and long hair with minimum hair fall. Dandruff is a commonly occurring scalp problem for which a fungal microorganism has been implicated. A good health for external surfaces including skin, oral cavity and scalp care are typically achieved by keeping them free of infections. One way to tackle infections is to treat it using antimicrobials after the infection has set in. Another approach is to leave a minimal amount of antimicrobial composition on the surface like e.g. skin of the hands, so that any invading microorganisms like e.g. bacteria are killed or inactivated so as to minimize spread of disease. Some bacteria like Escherichia coli (E. coli) and

Staphylococcus aureus (S. aureus) are commonly found on the human skin. These bacteria per se do not trigger a pathogenic effect whilst commonly present on the skin. However, when they enter the human body through cuts on the skin and through acts like ingestion, these bacteria become pathogenic. Therefore, keeping the external surface of the body like e.g. hand and scalp, free of bacteria helps in preventing them from entering the human body thereby achieving the desired hygiene.

There are arts which discloses germicidal composition both for human or warm blooded animal applications. WO 02/50225 A1 (Unilever) discloses antimicrobial cleaning composition suitable for the hygienic cleaning of hard surfaces where the composition comprises at least one surfactant, at least one acid and a mixture of solvents comprising N-alkylpyrrolidone derivative and a co-solvent of general formula R1-0-(EO)m-(PO)n-R2. Particularly preferred acids are one or more selected from adipic acid, glutaric acid and succinic acid.

WO 00/13506 A2 (Alcide Corp.) discloses a topical composition for application to skin, such as the teats of a dairy cow. The composition according to example 4 of D1 is composed of 65 wt% of dipropylene glycol monomethyl ether, 1 wt% of caprylic acid, and 1 wt% of the surfactant glyceryl monolaurate. Dipropylene glycol monomethyl ether is used as a solvent having antifreeze properties.

There are also disclosed various routes for improving the biocidal activity of soap based cleansing compositions. US2008014247A (Lu et al., 2008) discloses a composition having metal containing material, stearic acid and a pharmaceutically acceptable carrier to treat conditions caused by gram-positive, gram-negative, fungal pathogens and/or antibiotic-resistant bacteria. It further provides a method for inhibiting biofilm proliferation. The metal containing material can be silver.

US3050467 B1 (Horowitz et al. 1962) discloses an antimicrobial cleansing composition consisting essentially of a mixture of a water-soluble soap and a silver salt of partially depolymerized alginic acid. The composition provides synergistic antimicrobial activity.

There are also prior arts which disclose antimicrobial composition that contain carboxylic acids which may further contain solvents.

US 2001/0036482 (Dale Lind Fredell) discloses an antimicrobial composition containing an iodine compound and a fatty acid containing 6 to 12 carbon atoms like e.g. heptanoic acid. The application discloses the ratio of fatty acid to titrable iodine can be about 1 :25 to 3.3:1 , in some embodiments from 1 :3 to 1 :2 and in preferred embodiments from 1 :2 to 1 :1 . The composition in preferred embodiment cited therein, is formulated for use as a teat dip for milk producing animals. The compositions cited therein may further include solubilizing agents like glycol ethers and propylene glycol ethers.

US 2005/01 13276 (Taylor et al) discloses an antimicrobial composition comprising aromatic carboxylic acid, a hydric solvent, pH adjuster to provide a pH of about 2 to about 5.5 and water. The composition is free, or essentially free, of a surfactant, includes 0 to 0.2% by weight of a surfactant. In one aspect, the invention provides aromatic carboxylic acid like e.g. benzoic acid and salicylic acid, wherein the aromatic carboxylic acid has a pKa of about 2.5 or greater, and preferably about 3 or greater. In another aspect, the composition provides an antimicrobial composition containing a hydric solvent like ethanol, dipropylene glycol and tripropylene glycol, having a Hansen solubility parameter of about 38 or less, and preferably about 35 or less.

However, addition of soap invariably increases the pH of the composition. High pH composition is harsh on the skin. Consumer also has a preference to use a formulation with pH close to that of skin. Another problem is, most of the soap based antimicrobial compositions has to be applied for sufficiently long time to get the antimicrobial benefit. However most of the people especially kids do not wash their hand/skin for long enough.

On the other hand other solvent and carboxylic acid based antimicrobial composition as disclosed in the arts are found to be not efficient enough to take care of the need of achieving the desired antimicrobial efficacy in relatively short contact time. In addition, usage of solvents in relatively high amount are likely to be associated with skin irritation and dryness.

One of the preferred ways consumers make use of antimicrobial compositions is through personal washing and cleansing compositions that provide antimicrobial benefit. Consumers tend to prefer those personal washing and cleansing compositions which tend to provide high amount of foam. In fact consumers tend to associate the amount of foam generated with efficacy of such compositions. They prefer

compositions which generates high amount of foam. Hence, there is a need to provide an antimicrobial composition at skin pH with the ability to provide the desired antimicrobial benefits at relatively short contact time without compromising on the foamability of the such composition It is therefore an object of the present invention to provide an antimicrobial

composition.

It is another object of the present invention to provide an antimicrobial composition at the pH close to that of human skin.

It is another object of the present invention to provide an antimicrobial composition with the ability to provide the antimicrobial benefit at relatively short contact time.

It is another object of the present invention to provide an antimicrobial composition with the ability to provide the antimicrobial benefit without compromising on foamability of the composition.

The present inventors have surprisingly found that a combination of a particular amount of solvent comprising an alkyl glycol ether, an aromatic carboxylic acid having pKa greater than 4 or an aliphatic carboxylic acid having pKa greater than 4.5 or mixtures thereof and a particular amount of anionic surfactant, provides synergistic antimicrobial efficacy at relatively short contact time without compromising on foamability of the composition, thereby stratifying one or more above mentioned object.

Summary of the invention

In a first aspect, the present invention relates to an antimicrobial composition comprising: a. 0.5 to 20% by weight of a solvent comprising an alkyl glycol ether, b. 0.1 to 20% by weight of a carboxylic acid selected from an aromatic carboxylic acid having pKa greater than 4 or an aliphatic carboxylic acid having pKa greater than 4.5 or mixtures thereof; and

c. 1 to 80% by weight of an anionic surfactant.

In a second aspect, the present invention relates to a method of cleaning or disinfecting a surface comprising the step of applying on to the surface an antimicrobial composition of the first aspect. ln a third aspect, the present invention relates to use of the composition of the first aspect for antimicrobial effect.

In a fourth aspect, the present invention relates to use of the composition of the first aspect for improved hand hygiene.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of". In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Unless specified otherwise, numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed description of the invention Antimicrobial composition as mentioned herein above preferably means any

composition, which is capable of killing or at least cause substantial reduction of the common disease causing microbes. The common disease causing gram-positive organisms includes Staphylococcus, Streptococcus and Enterococcus spp. Some of common disease causing gram-negative organisms includes Escherichia coli,

Salmonella, Klebsiella and Shigella. Escherichia coli and Salmonella can cause severe gastrointestinal illnesses.

The present invention relates to an antimicrobial composition comprising a combination of alkyl glycol ether with an aromatic carboxylic acid having pKa greater than 4 or an aliphatic carboxylic acid having pKa greater than 4.5 or mixtures thereof and anionic surfactnat. Various components of the antimicrobial composition are described below. The compositions of the present invention are preferred for non-therapeutic use. More particularly, the compositions are preferred for use in obtaining antimicrobial effect when applied to surfaces of the human body that includes skin, hair or oral cavity. The most preferred use of the composition of the present invention on human skin, scalp or oral surface. The compositions may also be preferably used for hard surface cleaning applications. AlkyI glycol ether

AlkyI glycol ether are well known solvents. One of the essential element of the present invention is alkyl glycol ether, which is having the following structure: OH C C O R

Wherein R is an alkyl group.

E.g. the structure of propylene glycol n-propyl ether (PnP) is as follows:

OH

CH3 ■CH, ■O- ■ CH ₂ CH ₂ CH ₃

Examples of suitable alkyl glycol ethers that may be used in the invention include propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether (PnP), dipropylene glycol n-propyl ether, tripropylene glycol n-propyl ether, propylene glycol n-butyl ether (PnB), dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol n-butyl ether, diethylene glycol hexyl ether, ethylene glycol propyl ether, ethylene glycol n-butyl ether and ethylene glycol hexyl ether. Preferred alkyl glycol ethers that may be used in the invention are PnP, PnB, dipropylene glycol n-propyl ether and mixtures thereof.

The antimicrobial composition comprises from 0.5 to 20%, preferably from 1 to 18%, more preferably from 5 to 15%, even more preferably from 8 to 13% and further more preferably from 10 to 12% by weight of alkyl glycol ether.

Carboxylic Acid: The composition of the present invention also comprises 0.1 to 20%, preferably 0.1 to 15%, more preferably 0.2 to 10% and most preferably 0.2 to 5% by weight of an aromatic carboxylic acid having pK _a greater than 4 or an aliphatic carboxylic acid having pKa greater than 4.5. Carboxylic acids are organic acids having (- COOH) group as a part of their structure. An acid dissociation constant (K _a ) represents the strength of an acid in a solution. The negative logarithm of K _a is represented by pKa, which is quite relevant for practical applications of K _a . pK _a = - log™ K _a

The higher the value of pK _a , the lower the extent of dissociation at a given pH. This is governed by the well-known Henderson-Hasselbalch equation. According to the present invention an aliphatic carboxylic acid having pK _a greater than 4.5, more preferably greater than 4.6 and most preferably greater than 4.7. Preferably, the range of pK _a is in between 4.5 to 7, more preferably in between 4.5 to 6.5, and most preferably 4.5 to 6 in case an aliphatic carboxylic acid is used. According to the present invention an aromatic carboxylic acid having pK _a greater than 4, more preferably greater than 4.2. Preferably, the range of pKa is in between 4 to 7, more preferably 4.2 to 6.5 and most preferably 4.5 to 6 in case an aromatic carboxylic acid is used. Preferably, the carboxylic acid is selected from fatty acid having chain length C ₄ to C16, more preferably C6 to C12 and most preferably from C6 to C10. The carboxylic acids are preferably selected from aromatic carboxylic acids or linear or branched aliphatic carboxylic acids, cyclic aliphatic carboxylic acids and mixtures thereof. Substituted Carboxylic acid with the above defined pKa range may also be preferably used. The most preferred substitution are methyl and/or ethyl.

The most preferred aliphatic carboxylic acids are selected from hexanoic acid (pKa: 4.88), cyclohexanoic acid (pKa: 4.91 ), 2-ethyl hexanoic acid (pKa: 4.72), octanoic acid (pKa: 4.89), 4-methyl octanoic acid (pKa: 4.93) and mixtures thereof.

The most preferred aromatic carboxylic acids is benzoic acid (pKa: 4.2).

Aliphatic carboxylic acids with pKa greater than 4.5 is preferred over aromatic carboxylic acid with pKa greater than 4.2.

Anionic surfactant:

The composition of the present invention also comprises an anionic surfactant.

Preferred anionic surfactants include alkyl ether sulfate and sulfonates, alkyl sulfates and sulfonates, alkylbenzene sulfonates, alkyl and dialkyi sulfosuccinates, C8-C20 acyl isethionates, acyl glutamates, C8-C20 alkyl ether phosphates and mixtures thereof.

The composition comprises from 1 to 80%, preferably from 5 to 75%, more preferably from 10 to 70% and even more preferably from 15 to 65% by weight of a surfactant. One of the objective of the present invention is to provide a composition at skin pH.

Therefore, pH of the composition of the present invention is preferably in the range of 4 to 6.5, more preferably 4.2 to 6 and most preferably about 5.

The composition of the present invention is a synergistic antimicrobial composition. The synergy effects is observed by combining 0.5 to 20% by weight of a solvent comprising an alkyl glycol ether and 0.1 to 20% by weight of an aromatic carboxylic acid having pKa greater than 4 or an aliphatic carboxylic acid having pKa greater than 4.5 or mixtures thereof in presence of an anionic surfactant. The inventors have found to their utter surprise that while solvents comprising alkyl glycol ether or aromatic carboxylic acids having pKa greater than 4 or aliphatic carboxylic acids having pKa greater than 4.5 by themselves, do not provide any considerable antimicrobial effect in relatively short contact time, a combination of the two at select concentrations provides a synergistic antimicrobial effect. Moreover, such antimicrobial effect is obtained in relatively short contact times e.g. 30 seconds. Such antimicrobial effect is especially important in a wash off processes where the contact time of the antimicrobial actives with the surface is low like e.g. less than 5 minutes, preferably less than 2 minutes, further more preferably less than a minute and in many cases less than 45 seconds. In addition, such antimicrobial effect is obtained without compromising foamability of the composition.

The synergistic antimicrobial composition of the present invention also comprises a cosmetically acceptable base. The base formulation may be varied depends on the kinds of application.

The composition of the present invention preferably in the form of a leave-on composition. The leave-on composition may be in the form of vanishing cream or may be in the form of a sanitizer composition. The most preferred application being the hand sanitization.

The antimicrobial composition may be in the form of a wipe, i.e. an antimicrobial wipe. The cosmetically acceptable base is preferably a cream, lotion, gel or emulsion. Personal care compositions (leave-on) may be prepared using different cosmetically acceptable emulsifying or non-emulsifying systems and vehicles. A highly suitable base is a cream. Vanishing creams are especially preferred. Tough it is not preferred to have soap in the composition of the present invention. However, a small amount soap which does not make the pH of the formulation greater than 7.5 is alsowithin the scope of the present invention. Vanishing cream bases generally comprise 5 to 25% fatty acid and 0.1 to 10% soap. Vanishing cream base gives a highly appreciated matty feel to the skin. C12 to C20 fatty acids are especially preferred in vanishing cream bases, further more preferred being C14 to C18 fatty acids. The most preferred fatty acid is stearic acid. The fatty acid in the composition is more preferably present in an amount in the range of 5 to 20% by weight of the composition. Soaps in the vanishing cream base include alkali metal salt of fatty acids, like sodium or potassium salts, most preferred being potassium stearate. The soap in the vanishing cream base is generally present in an amount in the range of 0.1 to 10%, more preferably 0.1 to 3% by weight of the composition. Generally, the vanishing cream base in personal care compositions is prepared by taking a desired amount of total fatty matter and mixing with potassium hydroxide in desired amounts. The soap is usually formed insitu during the mixing. An especially suitable cosmetically acceptable base is one which comprises a water-in- oil emulsion comprising silicone oils as the continuous phase. The water in oil emulsions preferably comprise a cross-linked silicone elastomer blend.

Inclusion of silicone elastomer blend in a water-in-oil emulsion may be used as the cosmetically acceptable base for preparing the compositions of the present invention. While silicone fluids may be used, silicone elastomers which are cross-linked, are especially preferred. The creation of cross-linkages between linear polymers, such as dimethicone, converts the linear polymer into a silicone elastomer. In contrast to silicone fluid polymers, the physical properties of elastomers are typically dependent on the number of cross-linkages, rather than molecular weight. The ability of silicone elastomers to swell makes them ideal thickeners for oil phases. The elastomers have a very smooth and soft feel when applied to skin or hair. They can also be used as delivery agents for fragrances, vitamins and other additives in cosmetic compositions. Suitable silicone elastomer blends or gels which are commercially available and suitable for inclusion in the composition of the invention and found to provide the enhanced stability are: Dow Corning® EL-8051 IN Silicone Organic Elastomer Blend [I NCI Name: Isodecyl Neopentanoate (and) Dimethicone/Bis Isobutyl PPG-20

Crosspolymer]; EL-8050 [I NCI Name: Isododecane (and) Dimethicone/Bis-lsobutyl PPG 20 Crosspolymer] DC 9040, DC9041 , DC9045 (Dimethicone crosspolymer); DC 9506, 9509 (Dimethicone vinyl dimethicone crosspolymer); Shin-Etsu KSG-15, KSG- 16, KSG-17 (Dimethicone vinyl dimethicone crosspolymer). It is further preferred that the composition comprises 5 to 50% silicone elastomer by weight of the composition. In the case of wash-off composition, In addition to the essential ingredients as described earlier, preferred embodiments of the cleansing compositions may also include other optional and preferred ingredients for their known benefits. The type and content will largely depend on the nature and type of cleansing composition as well as general principles of formulation science.

Preferably, the composition further comprises an additional surfactant selected from nonionic surfactant, cationic surfactant, amphoteric surfactants and mixtures thereof. In general, the surfactants may be chosen from the surfactants described in well-known textbooks like "Surface Active Agents" Vol. 1 , by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, and/or the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981 . Preferred nonionic surfactants are those with a C10-C20 fatty alcohol or acid hydrophobe condensed with from 2 to 100 moles of ethylene oxide or propylene oxide per mole of hydrophobe, C2-C10 alkyl phenols condensed with from 2 to 20 moles of alkylene oxide, mono- and di- fatty acid esters of ethylene glycol, fatty acid monoglyceride, sorbitan mono- and di- C8-C20 fatty acids, block copolymers (ethylene oxide/propylene oxide), polyoxyethylene sorbitan and mixtures thereof. Alkyl polyglycosides and saccharide fatty amides (e.g. methyl gluconamides) are also suitable nonionic surfactants.

Examples of suitable cationic detergent surfactant include cetyl trimethylammonium bromide, benzalkonium halides that are also also known as alkyldimethylbenzylammonium halides. Preferred cationic surfactant that may be used in the composition is benzalkonium chloride, also known as alkyldimethylbenzylammonium chloride (or ADBAC).

Examples of suitable amphoteric detergent surfactant include amide, betaine and amine oxide type. Particular examples of amphoteric detergent surfactants include cocodiethanol amide and cocomonoethanol amide, cocoamidopropyl betaine and coco amido propyl amine oxide. A preferred amphoteric detergent surfactant that may be used as detergent surfactant in the composition is cocoamidopropyl betaine. When incorporated the antimicrobial composition comprises from 1 to 80%, preferably from 5 to 75%, more preferably from 10 to 70% and even more preferably from 15 to 65% by weight of one or more of these additional surfactants selected from nonionic surfactant, cationic surfactant, amphoteric surfactants and mixtures thereof.

When the product is in the solid form for hard surface cleaning applications, surfactants are preferably selected from primary alkyl sulphate, secondary alkyl sulphonates, alkyl benzene sulphonates, or ethoxylated alkyl sulphates. The antimicrobial composition of the invention is useful in oral care compositions e.g. in a dentifrice/ toothpaste or oral rinse product. In such applications, preferred surfactants are anionic, nonionic or amphoteric in nature, preferably anionic or amphoteric.

The antimicrobial composition may be in form of a solid, a liquid, a gel or a paste. A person skilled in the art can prepare compositions in various formats by choosing one or more carrier materials and/or surfactant. The antimicrobial compositions of the present invention are useful for cleansing and care, in particular for skin cleansing and skin care. It is envisaged that the antimicrobial composition can be used as a leave-on product or a wash-off product, preferably a leave-on product. The antimicrobial composition of the present invention can also be used for cleansing and care of hard surfaces such as glass, metal, plastic and the like. The antimicrobial composition may be in the form of an antimicrobial wipe. By wipe is it meant a disposable substrate such as a porous or absorbent sheet or cloth which has been pre-treated with the composition comprising the acid and the polymer of the invention (as defined above) so as to incorporate the composition of the invention into or onto the substrate prior to its use by a consumer.

Water soluble/dispersible polymers is an optional ingredient that is highly preferred to be included in composition. These polymers can be cationic, anionic, amphoteric or nonionic types with molecular weights higher than 100,000 Dalton. They are known to increase the viscosity and stability of liquid cleanser compositions, to enhance in-use and after-use skin sensory feels, and to enhance lather creaminess and lather stability. Amount of the polymers, when present, may range from 0.1 to 10% by weight of the composition. Examples of water soluble/or dispersible polymers include the carbohydrate gums such as cellulose gum, microcrystalline cellulose, cellulose gel, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, methyl cellulose, ethyl cellulose, guar gum, gum karaya, gum tragacanth, gum arabic, gum acacia, gum agar, xanthan gum and mixtures thereof; modified and nonmodified starch granules and pregelatinized cold water soluble starch; emulsion polymers such as Aculyn® 28, Aculyn® 22 or Carbopol® Aqua SF1 ; cationic polymer such as modified

polysaccharides including cationic guar available from Rhone Poulenc under the trade name Jaguar® C13S, Jaguar® CHS, Jaguar® C17, or Jaguar® C16; cationic modified cellulose such as UCARE® Polymer JR 30 or JR 40 from Amerchol; N-Hance® 3000, N-Hance® 3196, N-Hance® GPX 215 or N-Hance® GPX 196 from Hercules; synthetic cationic polymer such as Merquat® 100, Merquat® 280, Merquat® 281 and Merquat® 550 sold by Nalco; cationic starches such as StaLok® 100, 200, 300 and 400 sold by Staley Inc.; cationic galactomannans such as Galactasol® 800 series by Henkel, Inc.; Quadrosoft® LM-200; and Polyquaternium-24®. Also suitable are high molecular weight polyethylene glycols such as Polyox® WSR-205 (PEG 14M), Polyox® WSR-N- 60K (PEG 45), and Polyox® WSR-301 (PEG 90M).

The composition of the invention may additionally comprise a skin-lightening agent. Apart from niacinamide which is anyway presence as one of the essential component of the present compostion, other well known skin lightening agents e.g. aloe extract, ammonium lactate, arbutin, azelaic acid, kojic acid, butyl hydroxy anisole, butyl hydroxy toluene, citrate esters, 3 diphenyl propane derivatives, 2, 5 dihydroxybenzoic acid and its derivatives, ellagic acid, fennel extract, gluco pyranosyl-1 -ascorbate, gluconic acid, glycolic acid, green tea extract, hydroquinone, 4 hydroxyanisole and its derivatives, 4- hydroxy benzoic acid derivatives, hydroxycaprylic acid, lemon extract, linoleic acid, magnesium ascorbyl phosphate, mulberry root extract, 2,4 resorcinol derivatives, 3,5 resorcinol derivatives, salicylic acid, vitamins like vitamin B6, vitamin B12, vitamin C, vitamin A, a dicarboxylic acid, resorcinol derivatives, hydroxycarboxylic acid like lactic acid and their salts e.g. sodium lactate, and mixtures thereof.

Preferably, the composition may have sunscreen. Any sunscreen that can be suitably used with the base may be added. Both, UVA and UVB sunscreens may preferably be added. The composition of the invention preferably comprises a UV- A sunscreen which is a dibenzoylmethane or its derivatives. Preferred dibenzoylmethane derivatives are selected from 4-tert-butyl-4'-methoxydibenzoylmethane, 2-methyldibenzoylmethane, 4- methyl-dibenzoylmethane, 4-isopropyldibenzoyl-methane, 4-tert- butyldibenzoylmethane, 2,4-dimethyldibenzoylmethane, 2,5- dimethyldibenzoylmethane, 4,4'-diisopropyl-dibenzoylmethane, 2-methyl-5-isopropyl-4'- methoxydibenzoylmethane, 2-methyl-5-tert-butyl-4'-methoxy-dibenzoyl methane, 2,4- dimethyl-4'- methoxy dibenzoylmethane or 2,6-dimethyl-4-tert-butyl-4'-methoxy- dibenzoylmethane. The most preferred dibenzoylmethane derivative is 4-tert.-butyl-4'- methoxydibenzoylmethane. The composition of the invention preferably comprises 0.1 to 10%, more preferably 0.2 to 5%, further more preferably 0.4 to 3%, by weight dibenzoylmethane or a derivative thereof based on total weight of the composition and including all ranges subsumed therein. The composition preferably comprises a UV-B organic sunscreen selected from the class of cinnamic acid, salicylic acid, diphenyl acrylic acid and derivatives thereof. Illustrative non-limiting example of UV-B sunscreens which are commercially available and useful for inclusion in the composition of the invention are OctisalateTM,

HomosalateTM, NeoHelipanTM, OctocryleneTM, OxybenzoneTM or Parsol MCXTM. The UV-B sunscreen is most preferably 2-ethyl-hexyl-4-methoxy cinnamate which is commercially available as Parsol MCX. The UV-B organic sunscreen is preferably included in 0.1 to 10%, more preferably 0.1 to 7 % by weight of the composition. It has been observed that presence of an organic UV-B sunscreen like 2-ethyl-hexyl-4- methoxy cinnamate causes further rapid degradation of the UV-A dibenzoylmethane sunscreen in the presence of UV radiation. The presence of the rosmarinic acid ester compound is found to be very efficacious in stabilizing the composition even when UV- B sunscreens are present.

Useful inorganic sun-blocks are also preferably used in the present invention. These include, for example, zinc oxide, iron oxide, silica, such as fumed silica, and titanium dioxide.

Preservatives can also be added into the compositions to protect against the growth of potentially harmful microorganisms. Suitable traditional preservatives for compositions of this invention are alkyl esters of para-hydroxybenzoic acid. Other preservatives which have more recently come into use include hydantoin derivatives, propionate salts, and a variety of quaternary ammonium compounds. Particularly preferred preservatives are phenoxyethanol, methyl paraben, propyl paraben, imidazolidinyl urea, sodium dehydroacetate and benzyl alcohol. The preservatives should be selected having regard for the use of the composition and possible incompatibility between the preservatives and other ingredients. Preservatives are preferably employed in amounts ranging from 0.01 % to 2% by weight of the composition. A variety of other optional materials may be formulated into the compositions. These may include: antimicrobials such as 2-hydroxy-4,2',4'-trichlorodiphenylether (triclosan), 2,6-dimethyl-4-hydroxychlorobenzene, and 3,4,4'-trichlorocarbanilide; scrub and exfoliating particles such as polyethylene and silica or alumina; cooling agents such as menthol; skin calming agents such as aloe vera; and colorants.

In addition, the compositions may further include 0 to 10% by weight of opacifiers and pearlizers such as ethylene glycol distearate, titanium dioxide or Lytron® 621

(Styrene/Acrylate copolymer); all of which are useful in enhancing the appearance or properties of the product.

Diluents other than water can include liquid or solid emollients, solvents, humectants, thickeners and powders. Examples of each of these types of vehicle, which can be used singly or as mixtures of one or more vehicles, are as follows: Emollients, such as stearyl alcohol, glyceryl monoricinoleate, mink oil, cetyl alcohol, isopropyl isostearate, stearic acid, isobutyl palmitate, isocetyl stearate, oleyl alcohol, isopropyl laurate, hexyl laurate, decyl oleate, octadecan-2-ol, isocetyl alcohol, eicosanyl alcohol, behenyl alcohol, cetyl palmitate, silicone oils such as

dimethylpolysiloxane, di-n-butyl sebacate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, butyl stearate, polyethylene glycol, triethylene glycol, lanolin, cocoa butter, corn oil, cotton seed oil, olive oil, palm kernel oil, rape seed oil, safflower seed oil, evening primrose oil, soybean oil, sunflower seed oil, avocado oil, sesame seed oil, coconut oil, arachis oil, castor oil, acetylated lanolin alcohols, petroleum jelly, mineral oil, butyl myristate, isostearic acid, palmitic acid, isopropyl linoleate, lauryl lactate, myristyl lactate, decyl oleate, myristyl myristate;;

Solvents, such as ethyl alcohol, isopropanol, acetone, ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether;

In case of soap bars, it may contain particles that are greater than 50 μηη in average diameter that help remove dry skin. Not being bound by theory, the degree of exfoliation depends on the size and morphology of the particles. Large and rough particles are usually very harsh and irritating. Very small particles may not serve as effective exfoliants. Such exfoliants used in the art include natural minerals such as silica, talc, calcite, pumice, tricalcium phosphate; seeds such as rice, apricot seeds, etc; crushed shells such as almond and walnut shells; oatmeal; polymers such as polyethylene and polypropylene beads, flower petals and leaves; microcrystalline wax beads; jojoba ester beads, and the like. These exfoliants come in a variety of particle sizes and morphology ranging from micron sized to a few mm. They also have a range of hardness. Some examples are talc, calcite, pumice, walnut shells, dolomite and polyethylene. Advantageously, active agents other than skin conditioning agents defined above may be added to the composition. These active ingredients may be advantageously selected from bactericides, vitamins, anti-acne actives; anti-wrinkle, anti-skin atrophy and skin repair actives; skin barrier repair actives; non-steroidal cosmetic soothing actives; artificial tanning agents and accelerators; skin lightening actives; sunscreen actives; sebum stimulators; sebum inhibitors; anti-oxidants; protease inhibitors; skin tightening agents; anti-itch ingredients; hair growth inhibitors; 5-alpha reductase inhibitors; desquamating enzyme enhancers; anti-glycation agents; or mixtures thereof; and the like.

These active agents may be selected from water-soluble active agents, oil soluble active agents, pharmaceutically acceptable salts and mixtures thereof. The term "active agent" as used herein, means personal care actives which can be used to deliver a benefit to the skin and/or hair and which generally are not used to confer a skin conditioning benefit, such are delivered by emollients as defined above. The term "safe and effective amount" as used herein, means an amount of active agent high enough to modify the condition to be treated or to deliver the desired skin care benefit, but low enough to avoid serious side effects. The term "benefit," as used herein, means the therapeutic, prophylactic, and/or chronic benefits associated with treating a particular condition with one or more of the active agents described herein. What is a safe and effective amount of the active agent(s) will vary with the specific active agent, the ability of the active to penetrate through the skin, the age, health condition, and skin condition of the user, and other like factors.

Powders, such as chalk, talc, fullers earth, kaolin, starch, gums, colloidal silica sodium polyacrylate, tetra alkyl and/or trialkyl aryl ammonium smectites, chemically modified magnesium aluminium silicate, organically modified montmorillonite clay, hydrated aluminium silicate, fumed silica, carboxyvinyl polymer, sodium carboxymethyl cellulose, ethylene glycol monostearate. The cosmetically acceptable base is usually from 10 to 99.9%, preferably from 50 to 99% by weight of the composition, and can, in the absence of other personal care adjuncts, form the balance of the composition.

The composition of the invention may comprise a conventional deodorant base as the cosmetically acceptable carrier. By a deodorant is meant a product in the stick, roll- on, or propellant medium which is used for personal deodorant benefit e.g. application in the under-arm area which may or may not contain anti-perspirant actives.

Deodorant compositions can generally be in the form of firm solids, soft solids, gels, creams, and liquids and are dispensed using applicators appropriate to the physical characteristics of the composition. Deodorant compositions which are delivered through roll-ons generally comprise a liquid carrier. Such liquid carrier can be hydrophobic or comprise a mixture of both hydrophilic and hydrophobic liquids. They may be in the form of an emulsion or a microemulsion. The liquid carrier or mixture of carriers often constitutes from 30 to 95% by weight of the composition and in many instances from 40 to 80%. Hydrophobic liquid carriers commonly can comprise one or more materials selected within the chemical classes of siloxanes, hydrocarbons, branched aliphatic alcohols, esters and ethers that have a melting point not higher than 25°C and a boiling point of at least 100°C. Hydrophilic carrier liquids that can be employed in compositions herein commonly comprise water and/or a mono or polyhydric alcohol or water-miscible homologue. Monohydric alcohols often are short chain, by which is meant that they contain up to 6 carbons, and in practice is most often ethanol or sometimes iso-propanol. Polyhydric alcohols commonly comprise ethylene or propylene glycol, or a homologue can be employed such as diethylene glycol. Other than this suitable other vehicle and component used for deodorant composition can be added.

Preferably, when the composition is in the form of a hand sanitizer composition the cosmetically acceptable base may comprises of alcohol and water. The most preferred alcohols are ethyl alcohol and isopropyl alcohol. Even a mixture of two or more alcohol can preferably be used in the hand sanitizer composition. The amount of alcohol preferably in the range of 50 to 95%, more preferably 60 to 80% and most preferably 65 to 80% by weight of the hand sanitizer composition.

The compositions of the present invention can comprise a wide range of other optional components. The CTFA Personal care Ingredient Handbook, Second Edition, 1992, which is incorporated by reference herein in its entirety, describes a wide variety of non-limiting personal care and pharmaceutical ingredients commonly used in the skin care industry, which are suitable for use in the compositions of the present invention. Examples include: antioxidants, binders, biological additives, buffering agents, colorants, thickeners, polymers, astringents, fragrance, humectants, opacifying agents, conditioners, pH adjusters, natural extracts, essential oils, skin sensates, skin soothing agents, and skin healing agents.

The present invention also discloses a method of cleaning or disinfecting a surface comprising the steps of applying a composition according to the invention on to said surface in case of a leave-on composition. This method optionally comprises an additional step of at least partially removing the composition from the surface if it is in the form of a wash-off composition. Preferably, the step of at least partially removing the composition is carried out less than 5 minutes after the step of applying the composition on the substrate. The present invention also discloses a use of a composition of the present invention as disclosed above for antimicrobial benefit. Therefore, the composition of the present invention able to provide prolonged/long-lasting antimicrobial benefits. The preferred intended use/method of the composition of the present invention is non-therapeutic and/or cosmetic.

The present invention also discloses a use of a composition of the present invention as disclosed above for hand hygiene. Preferably, the present invention also provides the use of a combination of (a) 0.5 to 20% by weight of a solvent comprising an alkyl glycol ether, (b) 0.1 to 20% by weight of a carboxylic acid selected from an aromatic carboxylic acid having pKa greater than 4 or an aliphatic carboxylic acid having pKa greater than 4.5 or mixtures thereof; and (c) 1 to 80% by weight an anionic surfactant, in a composition for improved antimicrobial benefits.

The use is preferably non-therapeutic.

The invention is now described further with the help of non-limiting examples provided below.

Examples

Protocols

All the compositions shown in examples below were prepared using amounts (in % by weight) of alkyl glycol ether and carboxylic acids as shown in respective examples and procedure as follows: All the solvents including alkyl glycol ether used were prepared from the original 100% stock by diluting in distilled water. Any lower desired concentrations were achieved by further diluting it in distilled water. All the carboxylic acids were used from the original 100% stock and diluted in distilled water to get desired concentrations. Before carrying out the assay for antimicrobial efficacy using contact kill assay, pH of all the samples were adjusted to 5.2 ± 0.2 using 0.1 N sodium hydroxide or hydrochloric acid.

Assessment of antimicrobial efficacy:

Assessment of antimicrobial efficacy was carried out as per (American Standard Test Method 2783). The test organisms were grown on tryptic soya agar (TAS) plates overnight (22 ± 2 h). The organisms were not more than 3 passages removed from the original source. The cell number was adjusted based on optical density (OD) of the cells by re-suspending it in a suitable amount of physiological saline sufficient to achieve the required cell number. The OD at 620 nm of the cells was standardized to a cell number for each test organism using a spectrophotometer. A minimum final suspension of 1 ^χ 10 ⁹ colony forming units (CFU) /mL was achieved by adjusting the OD to 2.0 in saline for the contact kill assay.

In each test, 9.9 mL of a test sample was taken in 100 mL sample container. 0.1 mL of culture was added to the test samples at time zero and the timer was started within 1 second. The test solution was immediately vortexed upon addition of culture. At the first time point e.g. 30 seconds, 1 .0 mL aliquot was removed from the tube and immediately transferred to a 9.0 mL neutralizer (D/E neutralizing broth from BD Difco reference number 281910) in a glass tube. Serial ten-fold dilutions of the neutralized samples were prepared using 9.0 mL dilution blanks and enumerated, in duplicate, using standard plating techniques (pour plate). The plating of all the samples were completed within 30 min of completing the neutralization step. The plates were incubated at 37C for 24 to 48 h. The colonies were counted and the counts were converted to log values. The log reduction was calculated as:

Log io Reduction (LR) = Log-io of control - Log-io of test sample. Log reduction greater than 5 means 99.99% reduction in the number of CFU and log reduction less than 0.5 means no reduction in the number of CFU that means no antimicrobial efficacy. Log reduction greater than 5 also denotes complete kill. Assessment of foam volume:

In a 250 mL graduated stoppered glass cylinder, 40 mL of 1 :1 diluted test composition is taken. The cylinder is swung up and down ten times using hands. The foam volume is calculated by subtracting the volume of liquid.

In a first set of experiments, PnP (From Dow Chemicals, Dowanol PnP) was tried either alone or in combination with different carboxylic acids. The carboxylic acids tested were as follows: Octanoic acid - (pKa = 4.89; from Aldrich, catalogue number O3907),

Cyclohexanoic acid - (pKa = 4.92; from Aldrich, catalogue number 101834); and Benzoic acid - (pKa = 4.2; from Merck, catalogue number MK4M542724).

Table 1

The above compositions were then tested for its antimicrobial efficacy using the protocol as discussed in the previous section. The results of the antimicrobial efficacy testing is summarized below in table 2:

Table 2

Example No. Log Reduction Value at 30 Seconds

For E. coli For S. aureus

A <0.5 0.6 ± 0.08

B <0.5 0.8 ± 0.21 c <0.5 <0.5

D <0.5 <0.5

1 >5 >5

2 >5 >5

3 4.3 ± 0.2 1.7 ± 0.3

From the table above, it is evident that neither PnP nor the carboxylic acids by themselves, provides any considerable antimicrobial efficacy. However, on the other hand the compositions that are within the scope of the invention (examples 1 to 3) provides antimicrobial efficacy. In particular, example 1 and 2 where aliphatic carboxylic acids having pKa greater than 4.5 when used in combination with PnP, complete kill (99.9%) is obtained hence the log reduction is greater than 5. On the other hand, when aromatic carboxylic acid having pKa greater than 4 is used in combination with PnP, considerable antimicrobial efficacy was obtained.

In a second set of experiments, solvents other than the solvent of the present invention e.g. Dipropylene Glycol (DPG; from Aldrich, Cat. No: D215554), were tested with carboxylic acids of the present invention.

Table 3

The above compositions were then tested for its antimicrobial efficacy using the protocol as discussed in the previous section. The results of the antimicrobial efficacy testing is summarized below in table 4: Table 4

As can be seen from the data in table 4, solvents other than the solvents of the present invention like DPG, alone or in combination with aromatic carboxylic acid having pKa greater than 4, does not provide any antimicrobial efficacy. Further, DPG when combined with aliphatic carboxylic acids having pKa greater than 4.5, does not show any considerable antimicrobial efficacy within shorter contact times like 30 seconds. In a third set of experiments, different aliphatic carboxylic acids having pKa less than 4.5 were tested with PnP. These carboxylic acids and their pKa are as follows:

Succinic acid - (pKa = 4.2 from Sigma Aldrich, catalogue number 398055),

Malic acid - (pKa = 3.4 from Sigma Aldrich, catalogue number M8304); and

Citric acid - (pKa = 3.13 from Sigma Aldrich, catalogue number C83155).

Table 5

Example J K L M

PnP 10 10 10 10

Succinic acid 0.5 - -

Malic acid - 0.5 -

Lactic acid - - 0.5

Citric acid 0.5 The above compositions were then tested for its antimicrobial efficacy using the protocol as discussed in the previous section. The results of the antimicrobial efficacy testing is summarized below in table 6: Table 6

As can be seen from the data in table 6 above, PnP when combined with the aliphatic carboxylic acids having pKa less than 4.5, does not show any antimicrobial efficacy.

In a fourth set of experiment, dipropylene glycol monomethyl ether was combined in varying amounts with octanoic acid and sodium lauryl ether sulfate as shown in the table below to test the foaming property.

Table 7

The compositions in the table above were assayed for foam volume as describe earlier. The foam volume data is provided in table below: Table 8

Example Foam Volume (mL)

N 180

O 10

4 165 As can be seen from the data in table 8 above, when dipropylene glycol monomethyl ether was used in amounts 65% which is outside the scope of the present invention, foam volume was reduced drastically to as low as only 5.5% (from 180 mL to 10 mL) of the foam volume obtained from the control. However, when the ether was used in an amount (10%) within the scope of the present invention, foam volume was found to be 91 .6% (180 mL to 165 mL) compared to that of control.

In conclusion, from the above description and examples it is evident that, alkyl glycol ether when combined with an aromatic carboxylic acid having pKa greater than 4 or an aliphatic carboxylic acids having pKa greater than 4.5 in presence of an anionic surfactant, provides synergistic antimicrobial efficacy. Moreover, the antimicrobial efficacy is obtained in relatively shorter contact time like 30 seconds and in absence of soap at pH around 5.2 and such antimicrobial efficacy is obtained without compromising on foamability of the composition.