WO2021234005A1

WO2021234005A1 - A personal care composition

Info

Publication number: WO2021234005A1
Application number: PCT/EP2021/063304
Authority: WO
Inventors: Shanthi APPAVOO; Maitreyee DUTTA; Nirmala Santosh NAIR; Morris Waskar
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Priority date: 2020-05-22
Filing date: 2021-05-19
Publication date: 2021-11-25
Anticipated expiration: 2022-11-22

Abstract

A personal care composition comprising a substituted 2,2'-dihydroxybiphenyl wherein the substitution is tetra substitution with linear or branched alkyl having carbon atoms from 1 to 10,; and mixtures thereof.

Description

l

A PERSONAL CARE COMPOSITION

Field of the Invention

The present invention relates to a personal care composition. In particular, the present invention relates to a personal care composition that provides even skin tone e.g. that formed during melasma.

Background

People often try to take care of themselves and of their body surfaces e.g. skin, scalp including hairs, axilla and oral cavity, with a desire of enjoying a healthy lifestyle. Some of the benefits people tend to have desire for include, healthy and infection-free skin, even skin tone, adequate moisturization, together with skin glow and protection from ultraviolet rays contained in sunlight.

Skin is the outermost protective covering of living beings; and is the largest organ in the body. It acts as a barrier and protects the body from external factors e.g. dust, dirt, pollution and ultraviolet radiation contained in sunlight. Skin also helps prevent entry of harmful or potentially harmful microbes e.g. bacteria, fungi and viruses, from entering the body thereby preventing infection and/or other ill effects that may be caused.

However, being the outermost covering, skin is always exposed to one or more factors mentioned earlier. As a result, skin is susceptible to developing one or more conditions e.g. dryness, wrinkles, loose/saggy skin, age spots, blotchy skin, melasma, freckle and increased pigmentation, which may lead to less preferred uneven skin tone.

One of the ways to reduce occurrence of such conditions is to avoid exposure to factors causing such conditions. However, in many instances, avoiding exposure to factors e.g. sunlight, is difficult, and at times, unavoidable. For reasons like these, consumers tend to rely on personal care compositions comprising one or more actives that deliver benefits e.g. moisturizing, anti-aging and skin glow with even tone, when applied on a surface of the human body e.g. skin.

A few personal care compositions comprising such actives are known in the prior art. US 2014256830 discloses methods and compositions comprising resorcinol derivatives for the use of treating, regulating or preventing a skin condition characterized by oxidative stress or a designative process. It also discloses methods of preventing, lightening or reducing the appearance of visible discontinuities of the skin resulting from skin pigmentation, skin aging or other disorder.

KR20030092645 discloses a compound comprising 4,4'-dihydroxybiphenyl showing improved tyrosinase inhibition activity compare to conventional hydroquinone based whitening agent. The 4,4'-dihydroxybiphenyl compound is used as an active ingredient in a cosmetic composition for whitening skin by inhibiting the melanin generation and preventing the skin aging. Further, the compound is used in a pharmaceutical composition for treating skin diseases caused by the excessive generation of melanin such as freckles, liver spots, skin spots, hyperpigmentation or senile lentigo.

In personal care, typically, people give more attention towards facial care; and often look forward to personal care compositions comprising new actives, that would deliver benefits e.g. skin lightening with even tone. People also tend to prefer actives that would deliver similar or even enhanced benefit despite being used in reduced amounts as compared to that of known actives.

Need therefore exists to provide a personal care composition comprising new actives that provide benefits e.g. skin lightening. Need also exists to provide a personal care composition where, for obtaining a benefit e.g. skin lightening to a similar extent, a lesser amount of an active would be required as compared to that of known skin lightening agents e.g. 4-hexyl resorcinol (HR).

It has now been found that a personal care composition comprising a 2,2’- dihydroxybiphenyl substituted as described hereinafter, provides skin lightening. It has also been found that the skin lightening obtained is at par with that obtained using known skin lightening agents e.g. HR. Moreover, such comparable skin lightening is obtained using reduced amounts of the substituted 2,2’-dihydroxybiphenyl as compared to that of HR.

Summary of the invention In a first aspect, the present invention relates to a personal care composition comprising from 0.001 to 10 wt% of a substituted 2,2’-dihydroxybiphenyl, wherein the substitution is linear or branched alkyl having carbon atoms from 1 to 10and mixtures thereof.

In a second aspect, the present invention relates to a method of providing even tone on skin wherein, the method comprises: a. applying onto the skin a personal care composition according to the first aspect; and b. optionally, rinsing with water.

In a third aspect the present invention relates to use of the composition according to the first aspect for even skin tone.

In a fourth aspect the present invention relates to use of 3,3',5,5'-tetra-tert-butyl-2,2'- dihydroxybiphenyl for even skin tone. Detailed description of the invention

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. 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”. 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 "x to y", it is understood that all ranges combining the different endpoints are also contemplated. Unless specified otherwise, amounts as used herein are expressed in percentage by weight based on total weight of the composition and is abbreviated as “wt%”. The use of any and all examples or exemplary language e.g. “such as” provided herein is intended merely to better illuminate the invention and does not in any way limit the scope of the invention otherwise claimed. In a first aspect, the present invention relates to a personal care composition comprising from 0.001 to 10 wt% of a substituted 2,2’-dihydroxybiphenyl, wherein the substitution is linear or branched alkyl having carbon atoms from 1 to 10, or cyclic alkyl having carbon atoms from 4 to 10, or linear or branched alkoxy having carbon atoms from 1 to 10; and mixtures thereof.

Substituted 2,2’dihvdroxybiphenyl

Substituted 2, 2’-dihydroxybiphenyl is a substance where an OH group is attached to binding sites 2 and 2’ in the general structure of 1,1 ’-biphenyl shown below; and any or all of the other binding sites are substituted with the same or different substitutions disclosed hereinbelow:

A general structure of 1,1 ’-biphenyl When the composition according to the present invention (the composition) comprises 2,2’-dihydroxybiphenyl that is substituted with linear or branched alkyl having carbon atoms from 1 to 10, the same is preferably selected from the group consisting of methyl, ethyl, propyl (n-propyl and iso-propyl), butyl (n-butyl, sec-butyl, iso-butyl and tert-butyl), pentyl (n-pentyl, iso-pentyl, neo-pentyl, tert-pentyl, sec-pentyl, 3-pentyl, sec- isopentyl), linear or branched hexyl, linear or branched heptyl, linear or branched octyl, linear or branched nonyl and linear or branched decyl groups.

It will be understood that different binding sites on 2,2’-dihydroxybiphenyl may be substituted with different alkyl substitutions disclosed above at the same time. For example, a methyl substitution at binding site 4; and hexyl substitution at binding site 4’ at the same time. It will be also understood that any of the disclosed substitutions, linear or branched alkyl, may be present on any of the free binding sites on 2,2’-dihydroxybiphenyl structure at the same time. For example, any one or all of the free binding sites on 2,2’- dihydroxybiphenyl may be substituted by e.g. alkyl viz. n-hexyl. Likewise, it will also be understood that any one of the disclosed substitutions may be present in addition to any one of the remaining substitutions disclosed, at the same time.

Preferably, the composition comprises a substituted 2,2’-dihydroxybiphenyl where the substitution is linear or branched alkyl having carbon atoms from 1 to 10 preferably 2 to 6 carbon atoms as disclosed above. More preferably, the composition comprises a substituted 2,2’-dihydroxybiphenyl that is substituted with linear alkyl having carbon atoms from 1 to 10 as disclosed above. In an alternate preferred aspect, the substituted 2,2’-dihydroxybiphenyl is tetra substituted with a linear or branched alkyl group having 1 to 10 carbon atoms. Even more preferably, the composition comprises a substituted 2,2’-dihydroxybiphenyl where the substitution is a branched or linear carbon chain having 4 carbon atoms i.e. a butyl group. In an especially preferred aspect the present invention relates to a personal care composition comprising from 0.001 to 10 wt% substituted 2,2’-dihydroxybiphenyl, wherein the substitution is tetra substitution with linear or branched alkyl having carbon atoms from 1 to 10; and mixtures thereof. Most preferably, the composition comprises butyl substitution at binding sites 3, 3’, 5 and 5’ on the structure of 2,2’-dihydroxybiphenyl so that the substance is 3,3’,5,5’-tetra-tert-butyl-2,2’-dihydroxybiphenyl (TTBDB; CAS 6390-69-8) that has the following structure:

3,3’,5,5’-tetra-tert-butyl-2,2’-dihvdroxybiphenyl

The composition comprises from 0.001 to 10 wt%, preferably from 0.005 to 9 wt%, more preferably from 0.01 to 8 wt%, even more preferably from 0.005 to 7 wt%, further more preferably from 0.1 to 6 wt%, still more preferably from 0.1 to 5 wt%, yet more preferably from 0.1 to 3 wt% and still further more preferably from 0.1 to 1 wt% substituted 2,2’-dihydroxybiphennyl.

Preferably, the composition further comprises one or more skin lightening agents. These one or more skin lightening agents may be selected from niacinamide, picolinamide, iso-nicotinamide, resorcinol, phenylethyl resorcinol, 4-alkyl resorcinol, vitamin B6, vitamin C, vitamin A, glutathione precursors, galardin, adapalene, ammonium lactate, arbutin, azelaic acid, butyl hydroxy anisole, butyl hydroxy toluene, citrate esters, deoxyarbutin, 1,3-diphenyl propane derivatives, 2,5-dihydroxybenzoic acid and its derivatives, 2-(4-acetoxyphenyl)-1,3-dithiane, 2-(4-hydroxyphenyl)-1,3- dithiane, ellagic acid, gluco pyranosyl-1 -ascorbate, gluconic acid, glycolic acid, 4- Hydroxy-5-methyl-3[2H]-furanone, 4-hydroxyanisole and its derivatives, 4- hydroxybenzoic acid derivatives, hydroxycaprylic acid, inositol ascorbate, lactic acid, , linoleic acid, magnesium ascorbyl phosphate, 5-octanoyl salicylic acid, salicylic acid, 3,4,5-trihydroxybenzyl derivatives, acetylglucosamine, symwhite, calcium pantothenate (Melano-block), seppiwhite, 12-hydroxystearic acid and mixtures thereof. When used in the composition, 12-hydroxystearic acid is used as a skin lightening agent and not as a fatty acid. More preferably the composition further comprise one or more additional skin lightening agent selected from the group consisting of niacinamide, picolinamide, isonicotinamide, 12-hydroxystearic acid, resorcinol, phenylethyl resorcinol, 4-alkyl resorcinol and galardin. Even more preferably, the composition comprise an additional skin lightening agent selected from niacinamide and 4-alkyl resorcinol; and mixtures thereof. Examples of 4-alkyl substituted resorcinol include 4-methyl resorcinol, 4-ethyl resorcinol (ER), 4-propyl resorcinol, IPR, 4-butyl resorcinol (BR), 4-pentyl resorcinol, HR, 4-heptyl resorcinol, 4-octyl resorcinol and mixtures thereof. Preferred 4-alkyl substituted resorcinol are ER, BR, HR and mixtures thereof. More preferred 4-alkyl substituted resorcinol are ER, HR and mixtures thereof. The alkyl group in 4-alkyl substituted resorcinol can be straight chain alkyl or branched chain alkyl. For example, the alkyl group can be straight chain alkyl as in the case of 4-propyl resorcinol or it can be a branched chain alkyl like as in the case of 4-isopropyl resorcinol (IPR). Preferably the composition comprises from 0.001 to 10 wt%, more preferably from 0.005 to 9 wt%, even more preferably from 0.01 to 8 wt%, further more preferably from 0.005 to 7 wt%, still more preferably from 0.1 to 6 wt%, yet more preferably from 0.1 to 5 wt%, still further more preferably from 0.1 to 3 wt% and yet further more preferably from 0.1 to 1 wt% additional skin lightening agent.

Preferably, the composition further comprises a fatty acid selected from the group consisting of fatty acids having carbon atoms preferably in the range 10 to 22, more preferably 12 to 22, even more preferably 14 to 22, further more preferably 16 to 22, yet more preferably from 18 to 22. Examples of fatty acids that may be used in the composition include lauric, myristic, palmitic, stearic, isostearic, oleic, linoleic, arachidic, behenic, erucic acid and mixtures thereof. More preferably, the fatty acid selected are from the group consisting of stearic acid, palmitic acid mixtures thereof. Even more preferably, the fatty acid is preferably hystric acid which is substantially (generally about 90 to 95%) a mixture of stearic acid and palmitic acid in a ratio of between 55:45 to 45:55.

Preferably, the composition comprises from 4 to 25 wt%, more preferably from 6 to 20 wt%, even more preferably from 8 to 18 wt%, further more preferably from 10 to 18 wt%, still more preferably from 12 to 18 wt% and yet more preferably from 14 to 18 wt% fatty acid.

Preferably, the composition further comprises from 0.1 to 10 wt%, more preferably from 0.1 to 8 wt%, even more preferably from 0.1 to 7 wt%, further more preferably from 1 to 5 wt% and still more preferably from 1 to 3 wt% soap. The soap is preferably an alkali metal salt of fatty acids e.g. sodium or potassium salt, preferably potassium salt of the fatty acids. The soap may be obtained in-situ by adding sodium hydroxide or potassium hydroxide, preferably potassium hydroxide in the composition that may comprises fatty acids. Thus, inclusion of a fatty acid e.g. hystric acid and its soap prepared in-situ, is within the scope of the present invention. When present, the fatty acid together with soap, provides a so-called vanishing cream, i.e. a composition, when applied on to the human skin, vanishes on the skin leaving behind no significant streaks of the composition. Preferably, the composition further comprises UVA organic sunscreens that absorbs UVA radiations and prevent them from reaching a surface e.g. skin of a user. Examples of UVA organic sunscreens that may be used in the composition include dibenzoyl methane compound, bisdisulizole disodium (commercially available as Neo Heliopan® AP), diethylamino hydroxy benzoyl hexyl benzoate (commercially available as Uvinul® A Plus), Ecamsule (commercially available as Mexoryl SX) and Methyl anthranilate and also the class of water soluble sunscreens e. g. benzophenone

Bisdisulizole disodium and disodium phenyl do benzimidazole tetrasulphonate Preferably, UVA organic sunscreen that may be used as UVA sunscreen in the composition is selected from a dibenzoylmethane compound. Examples of sunscreen of dibenzoyl methane compound that may be used as UVA organic sunscreen in the composition include 4-tert-butyl-4'-methoxydibenzoylmethane (BMDM; commercially available as Parsol® 1789 or Avobenzone), 2-methyldibenzoylmethane, 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. Most preferably, dibenzoylmethane compound that may be used as UVA organic sunscreen is BMDM.

When incorporated in the composition, UVA organic sunscreens may preferably be incorporated from 0.01 to 10 wt%, more preferably from 0.1 to 7 wt%, even more preferably from 1 to 5 wt%, further more preferably from 1 to 3.5 wt%, yet more preferably 1 to 3 wt%, still more preferably 1 to 2.5 wt% in the composition.

Preferably, the composition further comprises UVB organic sunscreens that absorbs UVB radiations and prevent them from reaching a surface e.g. skin of a user. Examples of UVB organic sunscreens that may be used in the composition include compounds from the class of cinnamic acid, salicylic acid, diphenyl acrylic acid and derivatives thereof. Examples of such compounds include 2-ethylhexyl salicylate (commercially available as OctisalateTM), 3,3,5-Trimethylcyclohexyl 2-hydroxybenzoate (commercially available as HomosalateTM), Ethylhexyl Methoxycinnamate (commercially available as NeoHelipan® AV), 2-ethylhexyl 2-cyano-3,3- diphenylacrylate (OCR; commercially available as OctocryleneTM), 2-Hydroxy-4- methoxybenzophenone (commercially available as OxybenzoneTM), 2-ethyl-hexyl-4- methoxy cinnamate (MCX; commercially available as Parsol MCXTM) and mixtures thereof. Examples of water soluble UVB organic sunscreens include phenyl benzimidazole sulphonic acid.

Preferably, UVB organic sunscreens that may be used in the composition are selected from OCR, MCX and mixtures thereof.

When incorporated in the composition, UVB organic sunscreens may preferably be incorporated from 0.01 to 10 wt%, more preferably from 0.1 to 7 wt%, even more preferably from 1 to 5 wt%, further more preferably from 1 to 3.5 wt%, yet more preferably from 1 to 3 wt%, still more preferably 1 to 2.5 wt% in the composition.

Preferably, the composition further comprises a nonionic surfactant having HLB value in the range 9 to 20, preferably 10 to 19, more preferably 12 to 18, even more preferably 13 to 17 and yet more preferably 15 to 17. HLB is calculated using the Griffin method wherein HLB = 20 x Mh / M wherein Mh is the molecular mass of the hydrophilic portion of the molecule and M is the molecular mass of the whole molecule, giving a result on an arbitrary scale of 0 to 20. Typical values for various surfactants are given below: A value <10 : Lipid soluble (water insoluble)

A value >10 : Water soluble A value from 4 to 8 indicates an anti-foaming agent A value from 7 to 11 indicates a W/O (water in oil) emulsifier A value from 12 to 16 indicates oil in water emulsifier A value from 11 to 14 indicates a wetting agent A value from 12 to 15 is typical of detergents A value of 16 to 20 indicates a solubiliser or a hydrotrope. Preferably, the nonionic surfactant having HLB value in the range 9 to 20 is selected from fatty alcohol ethoxylates, alkyl phenol ethoxylates, polyoxyethylene sorbitan alkyl esters and mixtures thereof. Preferably, the nonionic surfactants are ones with at least 9 alkylene oxide groups preferably at least 9 ethylene oxide groups.

Examples of fatty alcohol ethoxylates that may be used as nonionic surfactants in the composition include polyoxyethylene lauryl ether (HLB= 16.9; commercially available as Brij® 35), polyoxyethylene (20) cetyl ether (HLB=16; commercially available as Brij® 58), polyethylene glycol octadecyl ether (HLB= 18.8; commercially available as Brij® 700) and Laureth - 9 (C12E09; HLB=14.3; commercially available as Brij® L9).

Examples of alkyl phenol ethoxylates that may be used as nonionic surfactant in the composition include octylphenol ethoxylate (HLB=15.5; commercially available as TritonTM X165), octylphenol ethoxylate (HLB=17.6; commercially available as TritonTM X405) and octylphenol ethoxylate (HLB=18.4; commercially available as TritonTM X705).

Examples of polyoxyethylene sorbitan alkyl esters that may be used as the nonionic surfactant in the composition include polyoxyethylenesorbitan monolaurate (HLB=13.3; commercially available as Tween® 21), polyoxyethylenesorbitan monolaurate (HLB=16.7; commercially available as Tween® 20), Polyoxyethylenesorbitan monopalmitate (HLB=15.6; commercially available as Tween® 40) and polyoxyethylene sorbitan monostearate (HLB= 14.9; commercially available as Tween® 60).

More preferably, the nonionic surfactant having HLB value in the range 9 to 20 that may be present in the composition is fatty alcohol ethoxylate with saturated carbon chain having HLB higher than 15.5.

Preferably, the composition comprises 0.5 to 5 wt%, more preferably 1 to 4 wt%, even more preferably from 2 to 3 wt% nonionic surfactant having HLB in the range 9 to 20. ll

Preferably, the composition further comprises a polymer. The polymer acts as thickener in the composition and improves sensorial properties of the composition. The polymer is preferably selected from the following classes: acrylate / R-methacrylate copolymer e.g. acrylates/ steareth-20 methacrylate copolymer (commercially available as AculynTM 22) and acrylates/ beheneth-

25 methacrylate copolymer (commercially available as AculynTM 28), acrylate / R-methacrylate crosspolymer e.g. acrylates/steareth-20 methacrylate crosspolymer (commercially available as AculynTM 88), acrylates copolymer (commercially available as AculynTM 33), - acrylate/R-alkyl acrylate crosspolymer e.g. acrylates/C 10-C30 alkyl acrylate crosspolymer (commercially available as PemulenTM TR-2), copolymer of ammonium acryloyldimethyltaurate with vinyl pyrrolidone (commercially available as Aristoflex® AVC), copolymer of sodium acryloyldimethyltaurate with vinyl pyrrolidone (commercially available as Aristoflex® AVS); and crosspolymer of acryloyldimethyltaurate with R-alkyl acrylate and methyacrylate e.g. Ammonium acryloyldimethyltaurate/ beheneth-25 methacrylate crosspolymer (commercially available as Aristoflex® HMB and Aristoflex®

BLV); and mixtures thereof.

More preferably, the polymer is selected from acrylate / R-methacrylate copolymer, acrylates copolymer and mixtures thereof.

Preferably, the composition comprises 0.1 to 5 wt%, more preferably 0.5 to 4.5 wt%, even more preferably 1 to 4 wt%, further more preferably from 1.5 to 3.5 wt%, still more preferably from 2 to 3 wt% polymer.

Preferably, the composition further comprises emollients. Examples of emollients that may be used in the composition include stearyl alcohol, glyceryl monoricinoleate, mink oil, cetyl alcohol, isopropyl isostearate, 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, din-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, isopropyl linoleate, lauryl lactate, myristyl lactate, decyl oleate, myristyl myristate and mixtures thereof.

Preferably, the composition further comprises solvents. Examples of solvents that may be used in the composition include ethyl alcohol, isopropanol, acetone, ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether and mixtures thereof.

Preferably, the composition further comprises preservatives to protect against the growth of potentially harmful microorganisms. Examples of ingredients that may be used as preservatives in the composition include alkyl esters of para hydroxybenzoic acid, hydantoin derivatives, propionate salts, and a variety of quaternary ammonium compounds. More preferably, ingredients that may be used as preservative in the composition are sodium benzoate, iodopropynyl butyl carbamate, methylisothiazolinone, iodopropynylbutylcarbamate, phenoxyethanol, methyl paraben, propyl paraben, imidazolidinyl urea, sodium dehydroacetate, ethylhexylglycerin, benzyl alcohol, alkane diols and mixtures thereof. The alkane diols that are suitable for use as preservative are C6-C12 alkanes that are vicinally substituted with hydroxy groups. Illustrative examples include 1,2-octane diol (caprylyl glycol), 2,3-octane diol, 1,2- nonane diol, 1,2-decane diol, 1,2-hexane diol, 3,4-octane diol, mixtures thereof or the like where caprylyl glycol is typically the most preferred. When present in the composition, preservatives are added preferably in an amount 0.001 to 5 wt%, more preferably 0.01 to 3 wt% and most preferably 0.02 to 2 wt%.

Preferably the composition further comprises a range of other optional ingredients that include antioxidants, binders, buffering agents, colorants, astringents, fragrance, opacifying agents, conditioners, exfoliating agents, pH adjusters, skin soothing agents, skin healing agents and powders. Examples of powders that may be used in the composition include 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 and mixtures thereof.

The composition is preferably formulated in the form of a powder, flake, lotion, cream, gel or mousse. More preferably, the composition is formulated in the form of cream or lotion and most preferably in the form of cream. The composition can be a leave-on or wash-off type of composition. The composition is preferably a leave-on type of composition. The packaging for the composition of this invention can be a patch, bottle, tube, roll-ball applicator, propellant driven aerosol device, squeeze container or lidded jar.

According to a second aspect, the present invention relates to a method of providing even tone on skin wherein, the method comprises: a. applying on to the skin a personal care composition according to the first aspect; and b. optionally, rinsing with water.

When the composition according to the first aspect is applied on to the skin, it provides even tone on skin with concomitant lightening. The step of applying the composition may be optionally followed by rinsing with water. If rinsing is carried out, it is preferably carried out after 30 min, more preferably after 25 min, even more preferably after 20 min, further more preferably after 15 min, still more preferably after 10 min, yet more preferably after 5 min and most preferably after 1 min from applying it on to the skin. Preferably, the method is non-therapeutic.

In a third aspect, the present invention relates to use of the composition according to the first aspect for skin lightening. When the composition according to the first aspect is used on to the skin, skin lightening is obtained. Preferably, the use is non-therapeutic.

Preferably, the composition may also be used for providing even toned skin. Preferably, the use is non-therapeutic. Preferably, the composition may also be used for applying it selectively on unevenly pigmented spots for example, those formed during melasma, to obtain even toned skin. One of the factors that is known to cause melasma is changing levels hormones such as estradiol, progesterone and a-MSH. Accordingly, the composition may preferably be also used as a composition for spot correction. Preferably, the use is non-therapeutic. In a fourth aspect, the present invention relates to use of TTBDB for skin lightening. When TTBDB is applied on to the skin, skin lightening is obtained. Preferably, the use is non-therapeutic.

Preferably, non-therapeutic; as referred to in the second, the third and the fourth aspect, means a cosmetic improvement in skin appearance in healthy subjects, rather than treating any underlying medical disease or disorder.

Examples

Cell culture

Lightly pigmenting human epidermal neonatal melanocytes (HEMn-LP) were procured from Thermo Scientific, USA. Cells were grown in the recommended medium called Medium 254 supplemented with human melanocyte growth supplement-2 (HMGS-2) and maintained at 37°C in a humidified incubator with 5% CO2 atmosphere. The maintenance and sub-culturing of cells were carried out as per the manufacturer’s instructions. Cells between passages 3 to 6 were used for experimentation. Materials

17p-Estradiol (E2758, Sigma),

Progesterone (P8783, Sigma),

NDP-MSH (3013, Tocris),

4-Hexyl Resorcinol (209465, Sigma), 3,3',5,5'-Tetra-tert-butyl-2,2'-dihydroxybiphenyl (2417-04-1 , TCI), 4,4'-Dihydroxybiphenyl (168734, Sigma),

2,2'-Dihydroxybiphenyl (115819, Sigma)

Dimethyl sulfoxide (D2650, Sigma),

Calcein-AM (17783, Sigma), Sodium Hydroxide (106469, Merck); and

Distilled water. Treatment of melanocytes

HEMn-LP were seeded at a density of 2.5 ^c 10⁴ cells/well in a 24 well plate in Medium 254 + HMGS-2 for 72 h at 37°C under 5% CO2. Followed by this, the cells were subjected to treatments as shown in table 1 , followed by incubation at 37°C under 5% CO2 for 1h post which, a mixture of hormones containing 25nM "^-Estradiol + 25nM Progesterone + 50nM NDP-MSH, was added. Post incubating the cells for 72 h at 37°C under 5% CO2, the cells were harvested for viability and melanin content assay as described below. All actives and hormone stocks were prepared in 100% Dimethyl sulfoxide (DMSO) except NDP-MSH which was prepared in distilled water.

Cell viability by Calcein-AM method and melanin content assay For melanin estimation, cell viability was first determined using the Calcein-AM method. Briefly, cell culture spent media was removed and cells were washed once with 0.2 ml_ of 1X PBS/well. Fresh 1mM calcein-AM in PBS buffer was added to each well, including control wells without cells. Plates were covered with aluminium foil and incubated for 30 min at 37°C in a CO2 incubator. Calcein fluorescence was then measured (excitation at 490 nm and emission at 520 nm) in TECAN M1000 plate reader. After calcein fluorescence readings were obtained, culture wells were drained and lysed for 1 h at 60°C in a shaker incubator using 1 N NaOH containing 10% DMSO. The supernatant was then transferred to a 384 well plate and melanin was measured in a Tecan plate reader (405 nm filter). Melanin content (MC) was expressed after correction for cell numbers (MC/Calcein) and represented as %melanin. Error bars denote +/- standard error (S.E.).

Table 1

The data above shows that 3,3',5,5'-Tetra-tert-butyl-2,2'-dihydroxybiphenyl provided skin lightening effect at par with that provided by known skin lightening actives e.g. HR. Moreover, such effect was obtained using lesser amount of 3,3',5,5'-Tetra-tert-butyl- 2,2'-dihydroxybiphenyl (8 mM) than that of 4-HR (10 pM).

Claims

Claims:

1. A personal care composition comprising from 0.001 to 10 wt% substituted 2,2’- dihydroxybiphenyl, wherein the substitution is tetra substitution with linear or branched alkyl having carbon atoms from 1 to 10,; and mixtures thereof.

2. The composition as claimed in claim 1 wherein the substitution is linear or branched alkyl having carbon atoms from 2 to 6. 3. The composition as claimed in any one of claims 1 or 2 wherein the substituted

2,2’-dihydroxybiphenyl is 3,

3',5,5'-tetra-tert-butyl-2,2'-dihydroxybiphenyl.

4. The composition as claimed in any one of claims 1 to 3 further comprising 0.001 to 10 wt% of an additional skin lightening agent selected from niacinamide, picolinamide, isonicotinamide, 12-hydroxystearic acid, 4-alkyl substituted resorcinol and mixtures thereof.

5. The composition as claimed in claim 4 wherein 4-alkyl substituted resorcinol is selected from 4-ethyl resorcinol, 4-isopropyl resorcinol, 4-butyl resorcinol, 4- pentyl resorcinol, 4-hexyl resorcinol and mixtures thereof.

6. The composition as claimed in any one of claims 1 to 5 wherein the composition further comprises from 4 to 25 wt% fatty acid.

7. The composition as claimed in any one of claims 1 to 6 wherein the composition further comprises from 0.1 to 10 wt% soap.

8. The composition as claimed in any one of claims 1 to 7 wherein the composition further comprises from 0.1 to 10 wt% of at least one UV-A organic sunscreen.

9. The composition as claimed in any one of claims 1 to 8 wherein the composition further comprises from 0.1 to 10 wt% of at least one UV-B organic sunscreen.

10. A personal care composition according to any one of claims 1 to 9, wherein the composition is a leave-on composition.

11. A method of providing even tone on skin wherein, the method comprises: i. applying onto the skin a personal care composition according to any one of claims 1 to 10; and ii. optionally, rinsing with water.

12. Use of the composition according to any one of claims 1 to 10 for even skin tone.

13. Use of 3,3',5,5'-tetra-tert-butyl-2,2'-dihydroxybiphenyl for delivering even skin tone.