Skin care benefits from cosmetic compositions

Abstract

The non-therapeutic use lactic acid, in particular lactic acid, or salt thereof for boosting hyaluronic acid levels in the human skin.

Description

[0001] Skin Care benefits from Cosmetic Compositions

[0002] Field of Invention

[0003] The invention is concerned with the use of cosmetic compositions and components thereof for giving skin care benefits; in particular, it is concerned with boosting the natural level of hyaluronic acid (HA) present within the skin.

[0004] There are numerous cosmetic treatments available for giving skin care benefits. Many of these focus on skin hydration and the prevention of dryness. In recent years, there has been a particular interest in augmenting the skin’s content of hyaluronic acid (HA), a natural component of the human body having very high water retention properties.

[0005] HA may be formulated into a wide range of cosmetic skin care compositions and has been claimed to give numerous skin care benefits.

[0006] EP 2,347,755 B1 (Evonik, 2018) discloses cosmetic compositions comprising HA and other active ingredients for reducing skin wrinkles and / or the reduction of the depth of skin pores.

[0007] WO 2023 / 018959 (Roc Opco LLC, 2023) discloses anhydrous cosmetic compositions comprising HA for use in improving skin qualities, in particular hydration.

[0008] The present invention is concerned with the use of lactic acid and salts thereof for increasing the natural level of HA within the skin, i.e., without the need for topical application of HA itself. The present invention is particularly concerned with the use of lactic acid and its salts for the above purpose when applied from a deodorant or antiperspirant composition.

[0009] Lactic acid and its salts have been used in a wide range of cosmetic compositions, including deodorant and antiperspirant compositions. JP 1040542 A2 (Kobayashi Pharma, 1989) discloses clear gel compositions comprising lactic acid salt, e.g. potassium lactate.

[0010] Mintel GNPD record ID 7109939 discloses Dove Talc Touch antiperspirant roll-on composition (Unilever, 2019) comprising potassium lactate.

[0011] Summary of Invention

[0012] It is an object of the invention to boost the natural level of HA within the skin. It is a particular object of the invention to boost the natural level of HA within the skin after the skin has been stressed, whether by physical or chemical means. This may alternatively be described as a means to help the skin recover its natural HA level after stress.

[0013] Physical stress to the skin may be caused by abrasive treatments, in particular shaving, which commonly causes redness or soreness. Another cause of physical stress is chafing, when the skins rubs against itself or clothing. Skin-to-skin chafing may occur in the underarms or in other areas of the body, such as the inner thighs or buttocks. Hence, the invention may be of particular value when the composition is suitable for application to the whole body; for example, a whole body deodorant or antiperspirant.

[0014] Chemical stress to the skin may be caused by irritant chemical application, including the application of surfactants, in particular anionic surfactants. Other ingredients that can lead to chemical stress include allergens and sensitisers.

[0015] It is an object to boost the natural level of HA within the skin by topical application of lactic acid or salt thereof.

[0016] In certain embodiments of the invention, it is an object to provide deodorancy benefits to the human body and also boost the natural level of HA within the skin. This may be done by any of the topical treatments described above, preferably with the application of an additional deodorant active (vide infra). In certain embodiments of the invention, it is an object to provide antiperspirancy benefits to the human body and also boost the natural level of HA within the skin. This may be done by any of the aforementioned topical treatments, together with the application of an antiperspirant active (vide infra).

[0017] In a first aspect of the invention, there is provided the use of lactic acid or salt thereof for boosting hyaluronic acid levels in the human skin.

[0018] In a second aspect of the invention, there is provided the use of lactic acid for boosting hyaluronic acid levels in the human skin, wherein the lactic acid or salt thereof is applied from a water-in-oil emulsion composition.

[0019] In a third aspect of the invention, there is provided the use of lactic acid or salt thereof for boosting hyaluronic acid levels in the human skin, wherein the lactic or salt thereof is applied from an aqueous polyol mixture.

[0020] In a fourth aspect of the invention, there is provided the use of lactic acid or salt thereof for boosting hyaluronic acid levels in the human skin, wherein the lactic acid or salt thereof is applied from an oil-in-water emulsion composition.

[0021] In a fifth aspect of the invention, there is provided the use of lactic acid or salt thereof for boosting hyaluronic acid levels in the human skin and for deodorising human skin. Surprisingly, we have found that boosting hyaluronic acid levels and deodorising human skin may be achieved in accordance with invention without the use of an additional deodorant active.

[0022] Detailed Description

[0023] Herein, features expressed as “preferred” with regard to a particular aspect of the invention should be understood to be preferred with regard to each aspect of the invention (likewise, features expressed as “more preferred”, “particularly preferred” or “most preferred”). “Preferred” features typically aid the delivery of one or more of the objects of the invention. Herein, preferred features of the invention are particularly preferred when used in combination with other preferred features (likewise, features expressed as “more preferred”, “particularly preferred” or “most preferred”).

[0024] Herein, “ambient conditions” refer to 20°C and 1 atmosphere pressure, unless otherwise indicated.

[0025] Herein, “water insoluble” refers to materials having a solubility in water of less than 0.1 g / 100g, under ambient conditions.

[0026] Herein, all percentages, ratios and amounts are by weight, unless otherwise indicated.

[0027] Herein, amounts and concentrations of ingredients are percentages by weight of the total composition, unless otherwise indicated.

[0028] Herein, references to amounts of components such as “deodorant active” or “rheological modifier” relate to the total amount of such components present in the composition.

[0029] Herein, the word “comprising” is intended to mean “including” but not necessarily “consisting of’, i.e. , it is non-exhaustive.

[0030] Herein, the word “boosting” is intended to mean increasing in amount or concentration. In preferred embodiments, the boosting is by an amount significant at the 95% level of confidence.

[0031] Herein, all uses, methods and compositions should be understood to mean cosmetic uses, methods and compositions; that is to say, non-therapeutic uses, methods and compositions.

[0032] Herein, references to the dermis refer in particular to the papillary dermis, the top level of the dermis located immediately below the epidermis. The lactic acid or a salt thereof used in the present invention serves as a skin care active.

[0033] The lactic acid promotes the natural level of HA within the skin, particularly within the epidermis and especially within the dermis.

[0034] Surprisingly, the promotion or boosting of HA levels within the skin can be done by topical application of a composition that does not itself comprise HA. Indeed, it is preferred that compositions used in conjunction with the invention exclude, i.e. are free from, HA.

[0035] A preferred component in compositions used in the present invention is a cosmetically acceptable carrier. These may be selected from any of those known in the art. In most preferred embodiments, the cosmetically acceptable carrier comprises a carrier oil, i.e. a water insoluble substance which is liquid under ambient conditions.

[0036] The total amount of lactic acid and salts thereof is preferably at least 0.1 , more preferably at least 0.5% and most preferably at least 1%. At the upper levels of incorporation, the lactic acid and salts thereof is preferably 20% or less, more preferably 12% or less and most preferably 6% or less. Preferred ranges may be formed from any of the lower and upper incorporation preferences indicated in this paragraph; e.g., from 0.5 to 20%.

[0037] Water is a preferred carrier in compositions used in the present invention.

[0038] The lactic acid is applied from an aqueous composition in preferred embodiments of the invention.

[0039] Herein, an aqueous composition is to be understood as a composition comprising water.

[0040] Aqueous compositions used in the invention have a preferred water content of at least 10%, more preferably at least 15% and most preferably at least 20%.

[0041] In preferred embodiments, the lactic acid or salt thereof is topically applied. This is typically done from a cosmetic composition also comprising a cosmetically acceptable carrier. In preferred embodiments, the lactic acid or salt thereof is topically applied from a leave on cosmetic composition, such as an antiperspirant or deodorant composition.

[0042] In some preferred embodiments, the composition used is in the form of an emulsion, which may be a water-in-oil emulsion or an oil-in-water emulsion. Water-in-oil emulsions are preferred when the composition is in the form of a stick, solidified with a structuring agent. Oil-in-water emulsions are preferred when the composition is in the form of roll-on, lotion, or cream.

[0043] In accordance with the second aspect of the invention, a cosmetic composition comprising lactic acid or salt thereof in a water-in-oil emulsion is used for boosting hyaluronic acid levels in the human skin. Such compositions are preferably solidified with a structuring agent to give an emulsion stick, typically an opaque emulsion stick (OES).

[0044] Herein, “solidified” refers to a state of matter incapable of flow at a temperature of 25°C and a pressure of 1 atmosphere.

[0045] The structuring agent employed in emulsion sticks used in accordance with the invention may be a single structurant or a mixture of structurants. The amount of the structuring agent used is preferably from 5%, more preferably from 7% and most preferably from 8%. The upper amount is preferably up to 25%, more preferably up to 20% and most preferably up to 15%. The preferred ranges of solidifying agent may be selected from any of the lower and upper amounts indicated in this paragraph.

[0046] The structuring agent mentioned immediately above is preferably a wax. More preferably the structuring agent is a polyolefin wax, in particular a polyethylene wax. Such waxes are typically synthetic waxes, i.e. waxes synthesised from olefins in the case of polyolefin waxes and waxes synthesised from ethylene in the case of polyethylene waxes.

[0047] The aqueous phase of water-in-oil emulsions used in accordance with the invention typically comprises from 30 to 68% of the total composition. Preferably, it comprises from 40 to 65% and more preferably from 45 to 60% of the total composition. As well as water, the aqueous phase typically includes the lactic acid or salt thereof. A preferred additional component of compositions used in the invention is an antiperspirant active. Such an active is preferably an astringent aluminium salt or aluminium-zirconium salt. Such salts are typically dissolved in an aqueous disperse phase of an emulsion and are commonly present in emulsion sticks used in accordance with the invention.

[0048] We have found that it is very difficult to formulate HA with antiperspirant actives, due incompatibility issues. Hence, the use of lactic acid or a salt thereof to boost HA levels in the skin when applied from an antiperspirant composition is particularly innovative. This is particularly true when an antiperspirant active comprising aluminium is included in the composition, as is the case with most commercial antiperspirant compositions.

[0049] A preferred antiperspirant active is aluminium sesquichlorohydrate (ASCH). ASCH has the chemical formula of AI2OH4.4CI1.6 to AI2OH4.9CI1.1. Most commercial ASCH samples are of chemical formula AI2OH4.7CI1.3 to AI2OH4.9CI1.1 and it is particularly preferred to use actives of this formula.

[0050] Particularly preferred AP actives comprise calcium and particularly preferred actives also comprise an amino acid, in particular glycine. Such actives are described in WO 2014 / 187685 (Unilever, 2014). The calcium is typically added in the form of calcium chloride. It is especially preferred that such actives are calcium-activated ASCH salts.

[0051] AP actives that are complexes with glycine are preferred, particularly when they also comprise calcium and / or are activated by calcium.

[0052] In certain especially preferred embodiments, a calcium-activated ASCH glycine complex is used.

[0053] The proportion of antiperspirant salt is calculated excluding the weight of any water of hydration but including any complexing agent that may be present, such as glycine and any activating agent, such as calcium chloride. The weight concentration of the antiperspirant salt in the aqueous phase is commonly not higher than 50% and is advantageously at least 10%. In preferred embodiments its weight concentration is from 15 to 40% and in more preferred embodiments it is from 20 to 30%.

[0054] The weight of antiperspirant salt in the entire composition is usually at least 6% and is commonly up to 30%. The range of antiperspirant salt concentration for the composition is preferably from 8% to 25% and more preferably from 10 to 20%.

[0055] A preferred additional component of the aqueous phase of water-in-oil emulsions used in accordance with the invention is glycerol. The amount of glycerol is preferably from 1 to 25%, more preferably from 5 to 22% and most preferably from 10 to 20%. These preferred ratios aid with the sensory properties of the product.

[0056] In accordance with the third aspect of the invention, the compositions are preferably homogeneous and / or single phase compositions. They preferably comprise propylene glycol (PG) and / or dipropyleneglycol (DPG) and a structuring agent to give a solid stick composition. More preferably they comprise PG, DPG, water and a structuring agent.

[0057] The structuring agent that may be employed for the purpose indicated in the paragraph immediately above may be a single structurant or a mixture of structurants. Preferably, the structurant is present at from 0.5 to 15%, more preferably 1 to 10 wt.% and most preferably from 2 to 8%.

[0058] The structuring agent mentioned immediately above is preferably a C12 to C24 fatty acid or salt thereof. More preferably the structuring agent is a C16 to C18 fatty acid and most preferably it is sodium stearate.

[0059] In the use of aqueous compositions comprising and both DPG and PG, the ratio of DPG to PG is preferably greater than 5:1. More preferably from 5.5:1 to 10:1 , even more preferably from 6:1 to 10:1 , and most preferably from 7:1 to 10:1. The total level of DPG and PG is preferably from 30 to 70%, more preferably from 35 to 60% and most preferably from 40 to 50%. DPG is preferably present at from 25 to 55%, more preferably from 30 to 50% and most preferably from 35 to 45%. PG is preferably present at from 3 to 10%, more preferably from 4 to 8% and most preferably from 4.5 to 6.5%. Each of the preference levels for DPG may be combined with each od the preference levels for PG. These amounts and ratios help with the sensory properties of the product and the deodorancy benefit that it delivers.

[0060] Aqueous compositions as used in accordance with the invention must comprise water. Preferably water is present at from 18 to 40%, more preferably from 20 to 36% and most preferably from 22 to 30%. Independently or additionally, the ratio of water to glycols is preferably from 20: 80 to 50: 50 and more preferably from 25: 75 to 45: 55. These amounts and ratios help to reduce or eliminate insoluble matter in stick compositions.

[0061] In the use of aqueous compositions comprising and both PG and DPG, glycerol is a preferred additional component. In such compositions, the ratio of dipropylene glycol to glycerol is preferably from 1 :1 to 3:1, more preferably from 1.5:1 to 2.75:1, and most preferably from 2:1 to 2.5:1. The amount of glycerol is preferably from 1 to 25%, more preferably from 5 to 22% and most preferably from 10 to 20%. These preferred ratios aid with the sensory properties of the product.

[0062] When an aqueous polyol mixture is used it is preferably a composition that is free of aluminium; in particular it is free of astringent aluminium salts that may serve as antiperspirant agents. In addition, it preferably has deodorising properties, i.e. it reduces the malodour on the surface of the human body following topical application.

[0063] In accordance with the fourth aspect of the invention, a cosmetic composition comprising lactic acid or salt thereof in an oil-in-water emulsion is used for boosting hyaluronic acid levels in the human skin. In preferred embodiments according to this aspect of the invention, the composition is also used to deliver a deodorancy benefit and in particularly preferred embodiments, the composition is also used to deliver an antiperspirancy benefit. When an oil-in-water emulsion composition is employed, the aqueous phase is typically the predominant phase, preferably comprising greater than 60%, more preferably greater than 75%, and most preferably greater than 80% by weight of the total composition.

[0064] A preferred additional component in compositions used in the invention is a humectant selected from glycerol and / or a PEG oligomer of weight average molecular weight of from 180 to 420. Glycerol is an especially preferred humectant. The humectant may enhance the skin care properties of the composition. When employed, the humectant is present at a preferred level of from 1 to 25%, more preferably from 5 to 22% and most preferably from 10 to 20%, these levels being particularly relevant when the humectant is glycerol.

[0065] A preferred additional component in compositions used in the invention, and particularly in emulsion compositions, is a water soluble vitamin, such as Vitamin B3 or niacinamide. Such vitamins are present at a level at a preferred level of from 0.1 to 8%, more preferably from 0.5 to 6% and most preferably from 1 to 5% by weight of the total composition. Such vitamins may enhance the skin care properties of the composition.

[0066] A preferred additional component in compositions used in the invention is a fragrance oil, alternatively known as a perfume oil. The fragrance oil may comprise a single fragrance component or, more commonly, a plurality of fragrance components. Herein, fragrance oils impart an odour, preferably a pleasant odour, to the composition. Preferably, the fragrance oil imparts a pleasant odour to the surface of the human body the composition is applied to the same.

[0067] The amount of fragrance oil in the composition is preferably up to 3%, advantageously is at least 0.5% and particularly preferably from 0.8% to 2%.

[0068] In certain embodiments, it is preferred to include an oil, other than a fragrance oil, that has a relatively low viscosity, by which is meant less 250 cS (mm2.s’1). Such oils, termed “non-fragrance oils”, can improve the sensory properties of the composition on application and can lead to other benefits such as emolliency. Preferred non-fragrance oils are alkyl ether oils having a boiling point of above 100°C and especially above 150°C, including polyalkyleneglycol alkyl ethers. Such ethers desirably comprise between 10 and 20 ethylene glycol or propylene glycol units and the alkyl group commonly contains from 4 to 20 carbon atoms. The preferred ether oils include polypropylene glycol alkyl ethers such as PPG-14-butylether and PPG-15-stearyl ether.

[0069] Other preferred non-fragrance are triglyceride oils. The triglyceride oils commonly comprise the alkyl residues of aliphatic C?to Cis acids, the total number of carbon atoms being selected in conjunction with the extent of olefinic unsaturation and / or branching to enable the triglyceride to be liquid at 20°C. Particularly preferably, in the triglyceride oil the alkyl residues are linear Cis groups having one, two or three olefinic degrees of unsaturation, two or three being optionally conjugated, many of which are extractable from plants (or their synthetic analogues), including triglycerides of oleic acid, linoleic acid, conjugated linoleic acids, linolenic acid, petroselenic acid, ricinoleic acid, linolenelaidic acid, trans 7-octadecenoic acid, parinaric acid, pinolenic acid, punicic acid, petroselenic acid and stearidonic acid.

[0070] Suitable oils can include those derived from unsaturated Cis acids, including coriander seed oil, impatiens balsimina seed oil, parinarium laurinarium kernel fat oil, sabastiana brasilinensis seed oil, dehydrated castor seed oil, borage seed oil, evening primrose oil, aquilegia vulgaris oil, sunflower (seed) oil and safflower oil. Other suitable oils are obtainable from hemp, and maize corn oil. An especially preferred oil by virtue of its characteristics is sunflower (seed) oil.

[0071] Further suitable oils, that can also be emollient oils, comprise alkyl or alkyl-aryl ester oils having a boiling point of above 150°C (and a melting point of below 20°C). Such ester oils include oils containing one or two alkyl groups of 12 to 24 carbon atoms length, including isopropyl myristate, isopropyl palmitate and myristyl palmitate. Other nonvolatile ester oils include alkyl or aryl benzoates such C12-15 alkyl benzoate, for example Finsolv TN™ or Finsolv Sun™.

[0072] Oil-in-water emulsion compositions used in accordance with the invention are preferably stabilised with a nonionic emulsifier system. Preferably, the nonionic emulsifier system comprises a low HLB ethoxylated alcohol (HLB less than 8) and a high HLB ethoxylated alcohol (HLB more than 12). More preferably, the low HLB ethoxylated alcohol has a HLB less than 5 and the high HLB ethoxylated alcohol has a HLB of more than 15.

[0073] When a nonionic emulsifier system as described in the paragraph immediately above is employed, it is preferred that the ratio of the low HLB ethoxylated alcohol to the high HLB ethoxylated alcohol is from 1 : 1 to 1 : 10 and more preferably from 2: 3 to 1 : 8.

[0074] The non-ionic emulsifier system preferably comprises from 0.5 to 10%, more preferably from 1 to 8%, and most preferably from 1 to 6%.

[0075] Oil-in-water emulsion compositions used in accordance with the invention are preferably thickened with a rheology modifier.

[0076] Preferred rheology modifiers are C16-C22 linear fatty alcohols and / or C16-C22 fatty acid glycerides. It is particular preferred to use both a C16-C22 linear fatty alcohol and a C16- C22 fatty acid glyceride.

[0077] When a C16-C22 linear fatty alcohol is employed, it is preferably a C18 linear fatty alcohol and more preferable stearyl alcohol.

[0078] When employed, C16-C22 linear fatty alcohol is preferably used at from 1 to 12% of the total composition and more preferably at from 2 to 7% by weight of the total composition.

[0079] When employed, C16-C22 fatty acid glyceride is preferably rich in monoglyceride content, meaning that it comprises at least 25% C16-C22 fatty acid monoglyceride and more preferably at least 30% C16-C22 fatty acid monoglyceride.

[0080] When employed, C16-C22 glyceride preferably comprises at least 25% glyceryl monostearate and more preferably at least 30% of said monoglyceride.

[0081] When employed, C16-C22 fatty acid glyceride is preferably used at from 1 to 12% of the total composition and more preferably at from 2 to 7% by weight of the total composition. When both a C16-C22 linear fatty alcohol and a C16-C22 fatty acid glyceride are employed, including combinations of the preferred and more preferred selections indicated above, there are certain preferred ratios between the two. The ratio of the C16- C22 linear fatty alcohol to the C16-C22 fatty acid glyceride is preferably from 1: 4 to 4: 1, more preferably from 1 : 3 to 3: 1 and most preferably from 1: 2 to 2: 1, by weight.

[0082] When employed, the total content of the rheological modifier consisting of a C16-C22 linear fatty alcohol and / or a C16-C22 fatty acid glyceride is preferably from 4 to 20%, more preferably from 5 to 15% and most preferably from 6 to 13%, by weight of the total composition.

[0083] In some preferred embodiments of the invention, compositions used in the invention are typically shear-thinning, i.e. they are non-Newtonian fluids that decrease in viscosity as the shear rate is increased. At a shear rate of / 10s, they have a viscosity of from 10,000 cPs to 300,000 cPs / s at 10 / s, measured at 20°C. Preferably, they have a viscosity of from 25,000 cPs to 300,000 cPs / s at 10 / s and more preferably a viscosity of from 50,000 cPs to 250,000 cPs / s at 10 / s, all measured at 20°C.

[0084] Other components that may be included in composition used in the invention include those described in the following paragraphs.

[0085] Wash-off agents may be included, often in an amount of up to 10%, to assist in the removal of the formulation from skin or clothing. Such wash-off agents are typically nonionic surfactants such as esters or ethers containing a Cs to C22 alkyl moiety and a hydrophilic moiety comprising a polyoxyalkylene group (POE or POP).

[0086] Skin-feel improvers (e.g. talc or finely divided high molecular weight polyethylene), may be included, typically in an amount from 1 up to 10%.

[0087] An optional component is a preservative system, such as sodium benzoate / citric acid and / or an antioxidant such BHT (butyl hydroxy toluene), each typically in an amount of from 0.01 to 0.5%. Examples

[0088] The following Examples are illustrative of the invention and non-limiting as to its scope.

[0089] The preparation of the Examples in Table 1 involved a preliminary step of ‘activating’ the ASCH with calcium chloride and glycine to give an “activated ASCH” (AASCH) solution. In this preliminary step, the ASCH, calcium chloride and glycine were heated together with the water for 2 hours at 87°C. The final solution comprised 27.0% ACH, 3.4% calcium chloride and 2.6% glycine.

[0090] The emulsion stick compositions indicated in Table 1 were prepared by methods known in the art using the aqueous solution of AASCH prepared as described above. The sticks were water-in-oil emulsions structured by the polyethylene wax. They had good deodorancy and antiperspirancy performance as a result of AASCH solution added to each. They differed only in the presence of potassium lactate in one and its replacement by water in the other. The Examples had good solidity and stability.

[0091] The Examples / products were tested in the following 3-day study. The results are indicated at the base of Table 1.

[0092] Human skin explants of average diameter 12 mm were prepared from tissue removed in an abdominoplasty procedure. The explants were kept in survival in BEM culture medium (BIO-EC’s bespoke Explant medium) at 37°C in a humid, 5% CO2 atmosphere.

[0093] On day 1 of the study, explants were treated topically with a paper disk soaked with a 1.25% w / w aqueous solution of sodium dodecyl sulphate (SDS), to induce irritation stress in the explants. Doing this increases the sensitivity of the explants to subsequent treatments. It also enables the subsequently applied treatments to be tested as to their ability to help skin recover from stress events. The paper disks were removed after 24 hours of contact and the products to be tested were applied immediately afterwards. Products were applied topically at 2 l per 1 cm2explant (or ca. 2 mg / cm2) and spread using a spatula. The culture medium was half renewed (1 ml) on day 1 and fully renewed (2 ml) on day 2. Control explants did not receive any treatment except the culture medium renewal.

[0094] On day 3 of the study, FFPE (formal-fixed paraffin-embedded) skin sections of the explants were prepared. These were sliced into 5 micron sections using a microtone. Hyaluronic acid immunostaining of the FFPE sections was performed with a biotinylated hyaluronic acid binding protein (HABP, Amsbio ref. AMS.HKD.BC41) diluted at 1:400 in PBS, BSA 0.3% for 1 hour at room temperature, with a biotin / streptavidin amplifying system and revealed by VIP (Vector laboratories, Ref. SK-4600), a substrate of peroxidase giving a violet stain once oxidised. The immunostaining was assessed by microscopical observation and semi-quantified by image analysis using the software cellSens (Olympus).

[0095] Samples from the epidermal layer and papillary dermis layer of the skin were analysed and a comparison made between those treated with the Examples indicated in Table 1 and control samples treated as described above. The average results and standard deviations (n = 9) are given at the base of Table 1. The HA levels quoted refer to the percentage of the sample surface on which HA was found to be present.

[0096] Treatment with the 1.25% SLS solution reduced the hyaluronic acid level of the epidermis by 56% by day 3 of the study: from 22.2% coverage to 9.8% coverage. When the epidermis was post-treated with P1 , the HA level was increased by 32% compared with the SLS treatment alone. When the epidermis was post-treated with P2, the HA level was increased by 58% compared with the SLS treatment alone, this difference being significant at the 99% level.

[0097] Table 1 - Water-in-Oil Emulsion Compositions

[0098] Treatment with the 1.25% SLS solution reduced the hyaluronic acid level of the dermis by 59% by day 3 of the study: from 45.8% coverage to 18.6% coverage. When the explants were post-treated with P1 , the HA level was increased by 90% compared with the SLS treatment alone. When the explants were post-treated with P2, the HA level was increased by 167% compared with the SLS treatment alone. This difference in performance between P1 and P2 was significant at the 95% level. The deodorant stick compositions indicated in Table 2 were prepared by methods known in the art. They differed only in the presence of potassium lactate in one and its replacement by water in the other. The Examples indicated in Table 2 were tested using the same 3-day study used to test the Examples of Table 1. The average results and standard deviations (n = 9) are indicated at the base of Table 2. As before, the HA levels quoted refer to the percentage of the sample surface on which HA was found to be present. Table 2 - Deo Stick Compositions Treatment with the 1.25% SLS solution reduced the hyaluronic acid level of the epidermis by 43% by day 3 of the study: from 22.1% coverage to 12.5% coverage. When the explants were post-treated with P3, the HA level was increased by 64% compared with the SLS treatment alone. When the explants were post-treated with P4, the HA level was increased by 48% compared with the SLS treatment alone. Both of these results were significant at the 99%; however, there was no significant difference between the two treatments.

[0099] Treatment with the 1.25% SLS solution reduced the hyaluronic acid level of the dermis by 24% by day 3 of the study: from 47.8% coverage to 36.2% coverage. When the explants were post-treated with P3, the HA level was not significantly effected compared with the SLS treatment alone. When the explants were post-treated with P4, the HA level was increased by 26% compared with the SLS treatment alone, this difference being significant at the 95% level. This result shows how an aqueous polyol mixture comprising potassium lactate can increase HA levels in the skin.

[0100] The cosmetic cream compositions indicated in Table 3 were prepared by methods known in the art. They differed only in the presence of potassium lactate in one and its replacement by water in the other.

[0101] The Examples indicated in Table 3 were tested using the same 3-day study used to test the Examples of Table 1. The average results and standard deviations (n = 9) are indicated at the base of Table 3. As before, the HA levels quoted refer to the percentage of the sample surface on which HA was found to be present.

[0102] Table 3 - Oil-in-Water Emulsion Compositions Treatment with the 1.25% SLS solution reduced the hyaluronic acid level of the epidermis by 84% by day 3 of the study: from 4.9% coverage to 0.8% coverage. When the explants were post-treated with P5, the HA level was increased by 22% compared with the SLS treatment alone, which was not a significant increase. When the explants were posttreated with P6, the HA level was increased by a massive 1828%, significant at the 95% level.

[0103] Treatment with the 1.25% SLS solution reduced the hyaluronic acid level of the papillary dermis by 41 % by day 3 of the study: from 53.4% coverage to 31.7% coverage. When the explants were post-treated with P5, the HA level was increased by 31% compared with the SLS treatment alone, this difference being significant at the 95% level. When the explants were post-treated with P6, the HA level was increased by 85% compared with the SLS treatment alone, this difference being significant at the 99% level. In addition, the P6 treatment resulted in a significantly greater increase in dermal HA than the P5 treatment (p < 0.05).

Claims

Claims1. The non-therapeutic use of lactic acid or salt thereof for boosting hyaluronic acid levels in the human skin.

2. The non-therapeutic use of lactic acid or salt thereof according to claim 1 for boosting hyaluronic acid levels in the human epidermis.

3. The non-therapeutic use of lactic acid or salt thereof according to claim 1 for boosting hyaluronic acid levels in the human dermis.

4. The non-therapeutic use of lactic acid or salt thereof according to any one of the preceding claims, wherein the lactic acid or salt thereof is applied following the application of physical or chemical stress to the skin.

5. The non-therapeutic use of lactic acid or salt thereof according to claim 1 , wherein the lactic acid or salt thereof is topically applied.

6. The non-therapeutic use of lactic acid or salt thereof according to claim 4, wherein the lactic acid or salt thereof is topically applied from a cosmetic composition together with a cosmetically acceptable carrier fluid.

7. The non-therapeutic use of lactic acid or salt thereof according to claim 5, wherein the cosmetic composition comprises an antiperspirant active.

8. The non-therapeutic use of lactic acid or salt thereof according to claim 5 or claim 6, wherein the cosmetic composition comprises water.

9. The non-therapeutic use of lactic acid or salt thereof according to claim 8, wherein the cosmetic composition is an emulsion.

10. The non-therapeutic use of lactic acid or salt thereof according to claim 9, wherein the emulsion is a water-in-oil emulsion.

11. The non-therapeutic use of lactic acid or salt thereof according to claim 9, wherein the water-in-oil emulsion is solidified with a structurant.

12. The non-therapeutic use of lactic acid or salt thereof, topically applied from an aqueous polyol mixture.

13. The non-therapeutic use of lactic acid according to claim 11 , wherein the aqueous polyol mixture comprises at least two polyols.

14. The non-therapeutic use of a cosmetic composition according to claim 11 or claim 12, wherein the aqueous polyol mixture is in the form of a stick structured by a fatty acid soap.

15. The non-therapeutic use of lactic acid or salt thereof, topically applied from an oil- in-water emulsion.

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