WO2010003806A2

WO2010003806A2 - A method of lightening skin

Info

Publication number: WO2010003806A2
Application number: PCT/EP2009/057715
Authority: WO
Inventors: James P. Bhaskar; Rashmi Mehta; Ramasubramaniam Rajagopal; Bharati R. Sharma; Nagalakshmi Surendra
Original assignee: Unilever Nv; Unilever Plc; Hindustan Unilever Limited
Priority date: 2008-07-10
Filing date: 2009-06-22
Publication date: 2010-01-14
Also published as: MX2011000301A; CN102088948A; EA201100184A1; CZ201110A3; WO2010003806A3; KR20110028344A; ZA201008796B; AU2009268225A1; JP2011527304A; BRPI0910199A2; CL2011000030A1; EP2299967A2

Abstract

The invention relates to a method and a product for lightening of skin and also for blemish removal on the skin. The invention provides for a method of lightening skin comprising the sequential steps, in any order, of; a) applying an alcohol having carbon chain length of 2 to 4, to the skin; and b) applying a skin lightening agent to said skin. The invention also provides for a kit for skin lightening comprising an alcohol having carbon chain length of 2 to 4 and a separately packaged skin lightening agent, along with instructions for their use. It is particularly preferred that the alcohol is impregnated in porous water-insoluble substrate.

Description

A METHOD OF LIGHTENING SKIN

TECHNICAL FIELD The present invention relates to a method for lightening of skin.

BACKGROUND AND PRIOR ART

Many people, especially those from tropical regions like those from Asia and Africa have darker skin as compared to those who live far from the tropics. Such dark skinned people have a desire to have a lighter skin colour. On the other hand, people who live far from the tropics like those from Europe and North America who are generally born with very light skin, like to have a darker skin appearance. They try to achieve this by tanning themselves in the sun. Such attempts at tanning produce uneven dark spots or blemishes on their skin which the people find undesirable. To solve both of the above problems, a lot of research has been done over the last few decades and methods to lighten skin have been developed. Many skin lightening compositions are also commercially available.

Most of these compositions contain two basic ingredients. One ingredient is a skin lightening agent. A skin lightening agent is a compound which is believed to control dispersion of melanosomes or inhibit tyrosinase. Popular skin-lightening agents include niacinamide, carboxylic acids like azelaic acid and kojic acid, plant extracts, hydroquinone etc. Niacinamide, which is a vitamin B3 compound, is one such widely used skin lightening agent in compositions for topical application. The second ingredient in a skin lightening composition is a sunscreen which maintains skin colour against ultra-violet (UV) radiation which are known to cause tanning of skin. These sunscreens act either by absorbing or by blocking the incident UV rays. The sunscreen compounds may be either organic or inorganic in nature; they may be naturally occurring o r could be synthetically prepared, Skin lightening agents along with sunscreen compounds have been combined in skin-lightening compositions to provide synergistic benefits. A popular skin lightening composition is based on GB 2 230 186 (Unilever, 1990). This patent discloses a skin lightening composition comprising niacinamide, one or both of a UV-B sunscreen e.g. Parsol MCX and a UV-A sunscreen e.g. Parsol 1789 and a silicone compound. The composition gave enhanced skin lightening over those compositions known at the time this invention was made. There has been a lot of research done over the years since the publication of the above patent in the area of skin lightening and several patents claim i mprovements. However resea rch is sti ll ongoi ng in developing better and more efficient skin lightening methods and products.

The present inventors have been working on this problem for a few years now and have surprisingly found that a two step process, one step comprising applying an alcohol on the skin preferably through a wipe and another step comprising applying to the skin a skin lightening agent, provides for enhanced skin lightening as compared to known methods. Good results are obtained irrespective of the order of the sequence.

WO 01/78678 (Procter & Gamble, 2001) describes a pre-formed device for delivering benefit agents to the skin, hair or nails, the device comprising a solid gel sheet having opposed first and second surfaces wherein the gel sheet comprises one or more gelling agents and at least 10% dermatologically acceptable hydrophilic solvent, characterised in that the first surface is at least partially coated with a discrete coating composition comprising at least one benefit agent for the skin, hair or nails. The benefit agent may be niacinamide among a whole host of actives. Thus wipes with skin lightening agents incorporated therein are known.

JP 5 317 122 (Piase Anise, 1993) describes a cosmetic/sanitary pad which is used to wipe the perspiration from the skin formed of cotton, non-woven cloth, wet tissue paper and others. The cosmetic/sanitary pad is impregnated with cosmetics and disinfectant composed of porous hollow spherical particulates, alcohol, water, allantoin, hydroxy chloride, paraffin, tea extract, L-menthol, perfume and others. Thereby the skin is kept from chapping with a sensation of coolness that is claimed to be long lasting. Thus wipes which contain alcohol are also known. However none of the prior art teach that a two step process, one step involving applying an alcohol and another step comprising applying a skin lightening agent, provides for enhanced skin lightening benefits.

It is thus an object of the present invention to develop a method that provides enhanced skin lightening as compared to known methods.

It is another object of the present invention to provide for a skin lightening product that is more effective in lightening the skin as compared to available products.

It is another object of the present invention to provide for a method and a skin lightening product that is effective in blemish removal on the skin.

SUMMARY OF THE INVENTION According to the first aspect of the present invention there is provided a method of lightening skin comprising the sequential steps, in any order, of a) applying an alcohol having carbon chain length of 2 to 4, to the skin; and b) applying a skin lightening agent to said skin.

It is particularly preferred that the step of applying the skin lightening agent follows the step of applying the alcohol.

According to another aspect of the present invention there is provided a kit for skin l ig htening com prisi ng an a lcohol havi ng ca rbon cha in length of 2 to 4, and a separately packaged skin lightening agent, along with instructions for their use.

DETAILED DESCRIPTION OF THE INVENTION

All parts herein are by weight unless otherwise specified.

The invention provides for a two step method of lightening skin. This method gives skin lightening which is better than those known presently. One step comprises applying to the skin an alcohol. The other step comprises applying to the same area of skin a skin-lightening agent. It is thus a sequential method. Either of the steps may be carried out first followed by the other step. However, the preferred sequence is to first apply the alcohol followed by the step of applying the skin lightening agent. The second step may be carried out immediately after the first step i.e a few seconds after the first step or a few minutes thereafter. Preferably the second step is carried out from about 2 seconds to about 15 minutes after the first step.

The alcohol has a carbon chain length of 2 to 4. The alcohols are preferably volatile at normal ambient temperatures i.e. in the range of 10 to 50 ⁰C. Suitable alcohols for use in the method of the invention are ethyl alcohol or isopropyl alcohol. The alcohol may be formu lated into an a lcohol ic composition. Suita ble forms of the alcohol ic composition are cream, gel, mousse, aerosol spray, stick, powder, or granule. Preferably, the alcohol is impregnated in a porous water-insoluble substrate. It is desirable that the amount of alcohol applied on to the skin is in the range of 5 mg to 50 mg per cm² of the skin surface area. When the alcohol is delivered through an alcoholic composition, the alcohol is preferably present from 10% to 95% by weight of said alcoholic composition.

One preferred method of applying the alcohol on to the skin is from porous water- i nsol uble sheets. Such sheets are a lso known as wi pes. Suitable material of construction of wipes are woven or non-woven polymeric sheets or made of natural materials like cellulose e.g. cotton or paper, and other natural materials like silk, wool, or laminates of the above. Wipes made of cotton are especially preferred. The wipes may be suitably packed to ensure that the alcohol is retained in the wipes during storage and transportation and up until the time of use by the consumer.

It is preferred that skin benefit agents are delivered to the skin through the alcohol/ alcoholic composition. Thus the alcohol/alcoholic composition may have a skin benefit agent dissolved or dispersed in it. Useful skin benefit agents are selected from sunscreens, skin lightening agents, vitamins, pharmaceutical actives, penetration enhancers, skin texture improvers, anti-oxidants, anti-inflammatory agents, or emollients. The skin benefit agent is preferably present from 0.1% to 10 % by weight of the alcohol. Without wishing to be bound by theory it is believed that the skin benefit agent delivered through the alcohol is better transported by way of higher penetration or by any other mechanism to the target sites on the skin. Further benefits agents which may not be compatible in water based or emulsion based compositions can be delivered through the alcohol by way of the present invention.

The alcohol may also be applied on to the skin by way of an aerosol spray. In this method, the mixture of alcohol and pressurised propellants are compressed and filled into a can. The can is provided with a dosage valve which may be used to generate a spray for application on to the skin. The propellant gases may be liquefied petroleum gases like butane or propane.

Another suitable way of applying the volatile alcohol on to the skin is by way of a stick as is usually used for application of deodorants.

The other step of the method of the invention comprises applying a skin lightening agent to the skin. The skin lightening agent is preferably delivered to the skin through a skin lightening composition. Most suitable skin lightening agents are vitamin B3 compounds. Suitable vitamin B3 compounds are selected from niacin, niacinamide, nicotinyl alcohol, or derivatives or salts thereof. The most preferred skin lightening agent is niacinamide. The skin lightening agent is preferably incorporated in 0.05% to 10% by weight of the skin lightening composition. More preferred amount is from

0.1% to 10%, most preferred amount is from 0.2 % to 5 % by weight of the composition.

Other vitamins which act as skin lightening agents can be advantageously included in the skin lightening composition to provide for additional skin lightening effects. These include vitamin B6, vitamin C, vitamin A or their precursors. Mixtures of the vitamins can also be employed in the composition of the invention. An especially preferred additional vitamin is vitamin B6.

Other non-limiting examples of skin lightening agents useful herein include adapalene, aloe extract, ammonium lactate, arbutin, azelaic acid, butyl hydroxy anisole, butyl hydroxy toluene, citrate esters, deoxyarbutin, 1,3 diphenyl propane derivatives, 2, 5 di hyd roxybenzoic acid a nd its derivatives, 2-(4-acetoxyphenyl)-1 ,3 d itha ne, 2-(4- hydroxyphenyl)-1,3 dithane, ellagic acid, gluco pyranosyl-1-ascorbate, gluconic acid, glycolic acid, green tea extract, 4-Hydroxy-5-methyl-3[2H]-furanone, hydroquinone, 4 hydroxyanisole and its derivatives, 4-hydroxy benzoic acid derivatives, hydroxycaprylic acid, inositol ascorbate, kojic acid, lactic acid, lemon extract, linoleic acid, magnesium ascorbyl phosphate, 5-octanoyl salicylic acid, 2,4 resorcinol derivatives, 3,5 resorcinol derivatives, salicylic acid, 3,4,5 trihydroxybenzyl derivatives, and mixtures thereof.

The skin lightening composition optionally comprises a sunscreen. Ultraviolet light is a predominant cause of skin darkening. Thus for purposes of skin lightening, compositions comprising UVA and/or UVB sunscreen are desirable. Organic or inorganic sunscreens/sun-blocks may be suitably employed in the composition.

Preferred sunscreens useful in the present invention are 2-ethylhexyl-p- methoxycinnamate, butylmethoxydibenzoylmethane, 2-hydroxy-4- methoxybenzophenone, octyldimethyl-p-aminobenzoic acid and mixtures thereof. Particularly preferred sunscreen is chosen from 2-ethyl hexyl-p-methoxycinnamate, 4,- t-butyl-4'- methoxydibenzoyl-methane or mixtures thereof.

Other conventional sunscreen agents that are suitable for use in the skin lightening composition of the invention include 2-hydroxy-4-methoxybenzophenone, octyldimethyl- p-a mi nobenzoic acid, digalloyltrioleate, 2,2-dihydroxy-4- methoxybenzophenone, ethyl-4-(bis(hydroxypropyl)) aminobenzoate, 2- ethylhexyl-2- cyano-3,3-diphenylacrylate, 2-ethylhexylsalicylate, glyceryl- p-aminobenzoate, 3,3,5- trimethylcyclohexylsalicylate, methylanthranilate, p-dimethyl-aminobenzoic acid or aminobenzoate, 2-ethylhexyl-p-dimethyl- amino-benzoate, 2-phenylbenzimidazole-5- sulfonic acid, 2-(p- dimethylaminophenyl)-5-sulfonicbenzoxazoic acid and mixtures of these compounds.

A safe and effective amount of sunscreen may be incorporated in the compositions used in the present invention. The composition preferably comprises from about 0.1% to about 10%, more preferably from about 0.1% to about 5%, of a sunscreen agent. Useful inorganic sun-blocks may also be preferably used in the present invention. These include, for example, zinc oxide iron oxide, silica, such as fumed silica, and titanium dioxide.

Ultrafine titanium dioxide in either of its two forms, namely water-dispersible titanium dioxide and oil-dispersible titanium dioxide is especially suitable for the invention. Water-dispersible titanium dioxide is ultra-fine titanium dioxide, the particles of which are non-coated or which are coated with a material to impart a hydrophilic surface property to the particles. Examples of such materials include aluminium oxide and aluminium silicate.

Oil-dispersible titanium dioxide is ultrafine titanium dioxide, the particles of which exhibit a hydrophobic surface property, and which, for this purpose, can be coated with metal soaps such as aluminium stearate, aluminium laurate or zinc stearate, or with organosilicone compounds.

By "ultrafine titanium dioxide" is meant particles of titanium dioxide having an average particle size of less than 100 nm, preferably 70 nm or less, more preferably from 10 to 40 nm and most preferably from 15 to 25 nm.

By topical application to the skin of a mixture of both water-dispersible ultrafine titanium dioxide and oil-dispersible ultrafine titanium dioxide, enhanced protection of the skin against the harmful effects of both UV-A and UV-B rays is achievable.

Ultrafine titanium dioxide is a preferred inorganic sun-block agent. The total amount of sun block that is preferably incorporated in the composition according to the invention is from 0.1 to 5% by weight of the composition.

The skin lightening composition preferably comprises a cosmetically acceptable vehicle to act as a diluant, dispersant or carrier for other materials present in the composition, so as to facilitate their distribution when the composition is applied to the skin. The skin lightening composition is preferably formulated in the form of a powder, flake, lotion, cream, gel, or mousse. Vanishing cream base is especially preferred. Vanishing cream base is one that comprises both fatty acids and soap of fatty acid. The concentrations of these in vanishing cream base is generally from 5%-25% by weight C₁₂-C₂O fatty acids and 0.1%-10% by weight fatty acid soap.

Vehicles 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, 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, isostearic acid, palmitic acid, isopropyl linoleate, lauryl lactate, myristyl lactate, decyl oleate and myristyl myristate;

Propellants, such as propane, butane, isobutane, dimethyl ether, carbon dioxide and nitrous oxide;

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

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 and ethylene glycol monostearate. The cosmetically acceptable vehicle is usually present from 10 to 99.9%, preferably from 50 to 99% by weight of the skin lightening composition and can, in the absence of other cosmetic adjuncts, form the balance of the composition.

Optional cosmetic ingredients

The compositions of the present invention can comprise a wide range of other optional components. Examples include: antioxidants, binders, biological additives, buffering agents, colorants, thickeners, polymers, astringents, fragrance, humectants, opacifying agents, conditioners, exfoliating agents, pH adjusters, preservatives, natural extracts, essential oils, skin sensates, skin soothing agents, and skin healing agents.

According to the another aspect of the present invention there is provided a kit for skin lightening comprising an alcohol having carbon chain length of 2 to 4 and a skin lightening agent, which is separately packaged along with instructions for their use. The instruction for use includes the sequence in which the contents of the two separate packages have to be used. The instructions also include the time when the contents of the second package have to be used after using the contents of the first package.

In the kit, the alcoholic composition is preferably impregnated in a plurality of porous water-insoluble sheets. Alternately the alcoholic composition is packed in an aerosol can along with propellant.

The invention is now further described by way of the following non-limiting examples.

EXAMPLES

Examples 1 to 3: Efficacy of the method of the system as compared to known method in a short trial.

A trial was carried out for 5 days with 16 volunteers. The trial consisted of the procedure as described below: Example 1

A specific portion of the volunteer's forearm was marked out and 3 mg/cm² of a commercial skin lightening composition "Fair & Lovely" containing 1.25 % of a skin lightening active niacinamide was applied five times daily, once every about 1.5 hours.

Example 2

A similar specific portion of the volunteer's forearm was marked and washed with a soap once every morning for ten days. The washing consisted of rubbing a soap bar 10 times over the marked area followed by rinsing the marked portion free of soap with a large quantity of water to remove all the soap. Once the soap was rinsed and the area dabbed dry, the same skin lightening composition as used in example 1, was applied five times a day, once every about 1.5 hours.

Example 3 A similar specific portion of the volunteer's forearm was wiped with a muslin cloth soaked with 0.1 ml of a solvent (ethyl alcohol) once a day in the morning. Skin lightening composition as used in example 1 was applied five times a day, once every about 1.5 hours.

The skin lightening score was measured by expert assessors using a colour ruler on a scale of 1 to 10. The data in table 1 summarizes the average skin lightening score that is the change in skin colour with respect to the initial skin colour. A more negative score indicates a higher degree of skin lightening.

Table 1

The data in table 1 indicates that significantly higher degree of skin lightening is observed using the method of the invention (example 3) as compared to methods of the prior art. Examples 4 to 6: Efficacy of the method of the system as compared to known method in an extended trial.

A trial was carried out for 8 weeks with 36 volunteers. The trial consisted of the procedure as described below:

Example 4

A specific portion of the volunteer's dorsal forearm (sun exposed part of the forearm) was marked out and 0.5 grams of a commercial skin lightening composition "Fair & Lovely" containing 1.25% of a skin lightening active, niacinamide, was applied two times daily, once in the morning and once again after a gap of about four hours.

Example 5

A different portion of the volunteer's dorsal forearm was marked out and wiped with a cotton wipe containing 2 ml of ethyl alcohol once a day in the morning. A skin lightening composition as used in example 4 was thereafter applied on this marked out portion after 15 minutes. The entire procedure of wiping with the alcohol soaked wipe followed by applying the skin lightening composition was repeated on the same day after a gap of four hours.

Example 6

A treatment similar to example 5 was carried out on a similar portion of the volunteer's dorsal forearm except that the alcohol contained 3% ascorbic acid.

The skin lightening score was measured by expert assessors using a colour ruler on a scale of 1 to 10. The data in table 2 summaries the average skin lightening score that is the change in skin colour with respect to the initial skin colour at week zero. A more negative score indicates a higher degree of skin lightening.

Table 2

The data in table 2 indicates that significantly higher degree of skin lightening is obtained using the method of the invention (examples 5 and 6) as compared to method of the prior art.

Examples 7 and 8: Effect of the sequence of steps

A trial was carried out for 5 days with 5 volunteers. The trial consisted of the procedure as described below:

Example 7 A specific portion (1 cm² area) of the volunteer's forearm was marked out and 3 mg/cm² of a commercial skin lightening composition "Fair & Lovely Multivitamin" containing 1.25% of a skin lightening active niacinamide was applied five times daily, once every about 1.5 hours.

Example 8

To a similar specific portion of the volunteer's forearm a skin lightening composition as used in example 7 was applied. Fifteen minutes after this, the same area was wiped with a muslin cloth soaked with 0.1 ml of ethyl alcohol. This procedure was repeated five times a day, every about 1.5 hours.

The skin lightening scores on the specific portions were measured by expert assessors using a colour ruler on a scale of 1 to 10. The data in table 3 summaries the average skin lightening score that is the change in skin colour with respect to the initial skin colour on day zero. A more negative score indicates a higher degree of skin lightening

Table 3

The data in table 3 indicates that better skin lightening is also obtained when the sequence of steps comprises first applying a skin lightening composition followed by applying alcohol on the skin as compared to prior art method. Examples 9 and 10: Effect of the method of the invention in skin blemish lightening - Extended trial

A trial was carried out for 8 weeks with 16 volunteers. The trial consisted of the procedure as follows.

A blemish of interest on the cheek of a volunteer was identified. The blemish colour was graded using a blemish colour ruler on a scale of 0.5 to 10.

Example 9 About 0.25 g of "Fair & Lovely Skin Clarity" a commercial product having 1.25% niacinamide as the skin lightening agent was applied on the blemish of interest. This was done twice a day at an interval of 90 minutes.

Example 10 The procedure consisted of wiping the blemish of interest with a cotton swab soaked with about two ml ethyl alcohol. A few seconds ( 2 to 5 seconds) after this a skin lightening composition as used in example 12 was applied. This was done twice a day at an interval of 90 minutes.

The skin lightening score on each of the specific blemishes was measured by expert assessors using a colour ruler on a scale of 0.5 to 10. The data in table 4 summarizes the average skin lightening score that is the change in skin colour with respect to the initial skin colour at week zero. A more negative score indicates a higher degree of skin lightening.

Table 4

The data in table 4 indicates that the method of the invention provides for better skin lightening of blemishes as compared to known methods even on use over an extended period.

Claims

1. A method of lightening skin comprising the sequential steps, in any order, of; a) applying an alcohol having carbon chain length of 2 to 4, to the skin; and b) applying a skin lightening agent to said skin.

2. A method as claimed in claim 1 comprising step (a) followed by step (b).

3. A method as claimed in claim 1 or claim 2 wherein said alcohol is ethyl alcohol or isopropyl alcohol.

4. A method as claimed in any one of the preceding claims wherein said alcohol is impregnated in a porous water-insoluble substrate.

5. A method as claimed in any one of the preceding claims wherein a skin benefit agent is dissolved or dispersed in the alcohol.

6. A method as claimed in any one of the preceding claims wherein the skin lightening agent is a vitamin B3 compound.

7. A method as claimed in claim 6 wherein the vitamin B3 compound is selected from the group consisting of niacin, niacinamide, nicotinyl alcohol derivatives thereof and salts thereof.

8. A method as claimed in any one of the preceding claims wherein the skin lightening agent is delivered to the skin through a skin lightening composition.

9. A method as claimed in claim 8 wherein the vitamin B3 compound is present from 0.2 % to 5 % by weight of the skin lightening composition.

10. A method as claimed in any one of the preceding claims 8 or 9 wherein the skin lightening composition comprises 0.1 % to 10 % by weight sunscreen.

11. A method as claimed in any one of the preceding claims 8 to 10 wherein the skin lightening composition comprises (i) 5-25% by weight C₁₂-C₂₀ fatty acids and (ii) 0.1-10% by weight fatty acid soap.

12. A kit for skin lightening comprising an alcohol having carbon chain length of 2 to 4 and a separately packaged skin lightening agent, along with instructions for their use.

13. A kit as claimed in claim 12 wherein the alcohol is impregnated in a porous water-insoluble substrate.