CA2087691A1

CA2087691A1 - Cosmetic compositon

Info

Publication number: CA2087691A1
Application number: CA002087691A
Authority: CA
Inventors: Peter Critchley
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1992-01-23
Filing date: 1993-01-20
Publication date: 1993-07-24
Also published as: EP0556957A1; KR930016085A; AU3201593A; BR9300262A; JPH0680555A; AU652882B2

Abstract

ABSTRACT

COSMETIC COMPOSITION

A cosmetic composition effective in the reduction of water loss through the stratum corneum comprising three components A, B and C, wherein A is a molecule having at least two hydrocarbon chains and a polar head group for which:

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Component B is a molecule having one long hydrocarbon chain and a polar head group; and component C is capable of stabilising any lipid bilayers assisting the formulation of lipid bilayers and formed in the composition; providing that the molar ratio of A:B:C is 1:1.5 to 6.0:1.1 to 8Ø

Description

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- 1 - J32a~7 ~E12~MPO,S I TI ON

FIELD OF THE INVENTION

This invention relates to cosmetic compositions and particularly compositions concerned with the prevention or amelioration of skin wrinkling, chapping or ageing.

BACKGROUND TO THE INVENTION AND PRIOR ART
It is generally understood that ceramides present within the intercellular lipid lamellae of the stratum corneum play an important role in the production and maintenance of the water permeability barrier of the skin.
Ceramides, or substances closely related to them, have been disclosed as components of skin ~are compositions. In particular, Kao Corporation in GB 2 178 312 and GB 2 213 723 discloses the use of natural ceramides extracted from skin in products for topical application.
Also, Kao Corporation in EP 227 994 and EP 282 816 discloses the use of synthetic ceramides, which are similar to their natural counterparts found in skin.

It is also known that in addition to ceramides the lipid lamellae comprises sterols and fatty acids N Y
Schurer, P M Elias (1991) Adv Lip Res 24 27-56 Acad Press.

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It is believed that one of the causes of dry skin and ageing skin is a reduction in the amount of lipid contained within these intercellular lipid lamellae. It is therefore clesirable to be able to successfully replace these depleted lipids by the topical route.

One suitable method for testing the abi].ity o~
cosmetic compositions to effect the desired repair of the water barrier layer (ie the intercellular lipid lamellae) is to study the ability of the cosmetic composition to reduce water loss through the stratum corneum. Although previously proposed cosmetic compositions have shown a nominal level of water loss reduction, the composition according to the present invention shows a significankly improved ability for such a water loss reduction and hence provides a much more efective control of water loss and/or repair of damaye to the water barrier layer in the stratum corneum.

It has been shown in Chapter 16 entitled "Aggregation of Amphiphilic Molecules into Micelles, ~ilayers, Vesicles and Biological Membranes" in Intermolecular and Surface Forces, (1985) Jacob N Isrealachvili, ed Acad Press that suitable lipids for forming a bilayer are those having a polar head group and at least two hydrocarbon chains, such that there exists a clearly defined relationship between the volume occupied by the hydrocarbon chains and the optimum area occupied by the polar head group. This relationship is that:
V should be greater than 0.5 but aOlc less than or equal to 1.0 where V is the volume of the hydrocarbon chains lc is the critical length of the hydrocarbon chains aO is the optimum area of the polar head group , , , 2~7~1 - 3 - ~32~7 DEFINITION OF _HE VENTION

The invention provides a cosmetic composition comprising three components A, B and C, wherein A is a molecule having at least two hydrocarbon chains and a polar head group for which V ~ 0.5 :~ 1.0; component aOlc B is a molecule having one long hydrocarbon chain and a polar head group; and component C is capable of assisting the formation of lipid bilayers and stabilising any lipid bilayers formed in the composition; providing that the molar ratio of A:B:C is 1:1.5 to 6.0:1.1 to 8Ø

DISCLOSURE OF THE INVENTION
The invention provides a composition suitable for topical application to the skin. The site of action of the composition is in the stratum corneum of the skin, and its mode of action is to effectively control water loss and/or to repair damage to the water barrier layer in tha stratum corneum.

Component A

Component A is a molecule having at least two hydrocarbon chains and a polar head group, providing that the volume occupied by the hydrocarbon chains and the area occupied by the polar head group fulfils the relationship V > 0.5 < 1.0 aOlc where V, lc and aO are as defined above.

Preferably the hydrocarbon chains each have at least 14 carbon atoms. Furthermore it is preferred that hydrocarbon chains having less than 16 carbon atoms are fully saturated, however, hydrocarbon chains having more than 16 carbon atoms may contain 1 to 3 unsaturations if desired.

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_ ~, _ J3247 Suitable polar head groups may be selected from residues such as phosphates, phosphonates, sulphates, sulphonates, sulphones, hydroxyl, ethylene oxide, carboxyl and mixtures thereof. Preferably the polar head group is selected from hydroxyl groups, ethylene oxide units, carboxyl groups and mixtures thereof.

Suitable compounds that may be selected as component A are ceramides; pseudoceramides; phospholipids;
1~ glycolipids having a structure of t:wo or more acyl or alkyl long chains suitably containing from 14 to 50 carbon atoms each, attached to a polar group; specific esters of polyethylene glycol; polyglycerol -n-x oleate (CAS 9007-48~
1); sorbitan dioleate (CAS 29116-98-1); sorbitan sesquioleate (CAS 8007-43-0); long chain alkyl ether versions of phospholipids and glycolipids; and mixtures thereof.

Ceramides Ceramides are preferably selected from ceramides having the general structure (1) R ~ (CHORz) m - C - NH
CH - CH20R4 (1 Rl - A - CHOR3 where A represents - CH2 -; - CHOR5 -; - CH=CH - or - CHOY -R represents a linear or branched, saturated or unsaturated aliphatic hydrocarbon group having from 1 to 49-carbon atoms, preferably from 12 to 49 carbon atoms, or a subgroup (2).

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R1 represents a linear or branched, saturated or unsaturated aliphatic hydrocarbon group having ~rom 8 to 28 carbon atoms, preferably from 13 to 28 carbon atoms;

R2, R3 and X5 individually represent H, a phosphate residue or a sulphate residue;

R4 represents H, a phosphate residue, a sulphate residue or a sugar residue;
a is an integer of f~om 7 to 4g, preferably from ~2 to 49 b is an integer of from 10 to 98, preferably from 2~ to 98 m i5 0 or 1 Y represents H or a residue of a C14.22 fatty acid having the general structure (3) o _ g - (CXHyZz) CH3 (3 where Z is - OH or an epoxy oxygen x is an integer of from 12 to 20 y is an integer of from 20 to 40 and z is 0 or an integer of from 1 to 4 Ceramides having the general structure (1) are naturally occurring and can be isolated from a suitable plant source or from animal tissue such as pig skin or neural tissue. Ceramides can also be synthesised.

Particular preferred examples of ceramides are ceramide I and ceramide II.

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- 6 - J32~7 Pseu oceramides Pseudoceramides are preferably selected froln pseudoceramides (ia synthetic ceramide like structure~) having the general structure (4):
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R6 - ( CHOH ) n - C - N - CH2 fHORy R7 - (P,) p where B represents - OCH2 ~ or CHOH.

R6 represents a linear or branched, saturated or unsaturated aliphatic hydrocarbon group having from 1 to ~9 carbon atoms preferably from 12 to 49 carbon atoms or the subgroup (2).

R7 represents a linear or branched, saturated or unsaturated aliphatic hydrocarbon group having from 8 to 28 carbon atoms preferably from 13 to 28 carbon atoms.
R8 represents H, or a subgroup - (CH2)CCOOH, where c is an integer of from 1 to 6, or a subgroup having the structure (5).

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- ( CH2 ) d ~ - C _ - CHOH (5) _X2 - ' e whera Xl, X~ and X3 each individually represent ~, a Cl5 alkyl or a Cl5 hydroxyalkyl;

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- 7 ~ J32~7 d is 0 or an integer of from 1 to 4 e is 0 or 1 n is 0 or 1 and p is 0 or 1;

R9 represents H, a phosphate residue, a sulphate residue or a sugar residue.

PhospholiPids Phospholipids may be advantageously used because th~y are derivahle from plant sources. An example of a suitable phospholipid material is a mixture of phospholipids derived from a particular fraction in a continuous soya bean phospholipid extraction and is sold under the trade name Ceramax by Quest International of Ashford, Kent, UK.

Glycolipids Suitable glycolipids are those having a structure of two or more acyl or alkyl long chains suitably containing from 14 to 50 carbon atoms each, attached to a polar head group. The polar head group may be selected from residues such as phosphates, phosphonates, sulphates, sulphonates, sulphones, hydroxyl, ethylene oxide, carboxyl and mixtures thereof. Preferably the polar head group is hydroxylated.

Suitable examples are glycosyl glycerides or diacyl or dialkyl saccharides, eg sucrose diesters with two or more long chain ester groups. An example of the latter type of material is obtainable from Ryoto under the appellation Ryoto sugar esters such as Ryoto sugar ester S270, and S1570.

~o~7~1 - 8 - ~32~7 Esters of PolYethylene Glycol Suitable esters are:

(i) succinic acid esters having t:he general structure (6) o Rl 1 R12 Il l l 11 RlUO(Cq~2qO)fC - cH - CH - C - (OCqH2q~9 -- OR13 (6) in which R10 represents an alkyl, alkenyl, mono- or dihydroxyalkyl or hydroxyalkenyl group having from 6-22 carbon atoms;

Rll and Rl2 individually represent H or an alkyl or alkenyl group having from 12 to 22 carbon atoms; providing that when Rll is ~, R12 is an alkyl or ~lkenyl group and when R12 is H, Rll is an alkyl or alkenyl group;

Rl3 represents hydrogen, an alkyl, alkenyl, mono- or dihydroxyalkyl or hydroxyalkenyl group having from 6 to 22 carbon atoms or the group (7~:

R12 Rll O
- C - CH - CH - C - (CqH2qO3f - ORlo (7) q is an integer of from 2 to 3 f and g are average degrees of alkoxylation, namely f is from 0 to 20 and g is from 1 to 20.

In structure (6), the group R13 preferably represents H, while the group Rlo preferably represents an alkyl group having from 16 to 22 carbon atoms and most preferably from 20 to 22 carbon atoms.

Also with reference to structure (6), q is preferably 2 and (f+g) is preferably from 1 to 20.

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_ 9 _ J3~47 Such succinic acid esters are synthesised using known methods of preparative chemistry, these methods are described in our co-pending patent application GB 9223578.7 filed 11 November 1992.

(ii~ Polyethylene glycol r-dilaurate (CAS 9005-02-1) and polyethylene glycol r-distearate (CAS 9005-08-7).

(iii~Polyethylene glycol r-distearammorlium chlorides.
These may be derived from polyethylene glycol r-tallow amine (CAS 61791) by alkylating the nitrogen with an alkyl halide having more than 8 carbon atoms.

(iv) Polyethylene glycol derivatives of long chain alkyl derivatives of malic, tartaric, maleic, malonic and glyceric acid.

where r is the number of ethylene oxide groups within the molecule and is preferably from 1 to 8, most preferably from 2 to 4.

Preferably component A comprises a mixture of the above mentioned compounds. More preferably this mixture is such that a range of chain lengths are present. Most preferred are mixtures of ceramide and phospholipids, particularly the phospholipid mixture having the trade name Ceramax, wherein the ratio of ceramide to Ceramax is from 1:1000 to l:l! preferably from 1:50 to 1:1 and most preferably from 1:10 to 1:5 by weight.
Component B

Component B is a molecule having one long hydrocarbon chain and a polar head group. A wide variety of simple co-surfactants are functional. Preferred co-surfactants are straight-chained mono carboxylic acids having 14 to 30 carbon atoms, straight-chained fatty alcohols having 14 to .
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- 10 - J32~7 carbon atoms, sugar esters, alkylated sugars and mixtures thereof.

Examples of suitable sugar est:ers and alkylated sugars are monopalmitoyl or 6~cetyl glucose and ~ or ~ methyl 6-cetyl glucoside.

Pre~erably the co-surfactants are chosen from straighk chained mono-carboxylic acids having 14 to 24 carbon atoms, fatty alcohols having 14 to 24 carbon a~oms and mixtures thereof.

The mono-carboxylic acids may be used as 50 100%
sodium or potassium soap.
A particularly preferred component B is linoleic acid, since linoleic acid assists in the absorption of ultraviolet light and furthermore is a vital component of the natural skin lipids constituting the moisture barrier in the stratum corneum.

Component B may comprise a mixture of compounds, for example a fatty acid mixture of palmitic, oleic and stearic acid at 3:2:1 by weight may be employed, however particularly useful fatty acids from the point of view of availability are linoleic and stearic acid.

component c Component C is a compound capable of stabilising any lipid bilayers which may be formed in the composition.

Suitable compounds may be selected from 3~-sterols;
squalene; squalane; saponins or sapogenins of the plant steroid or triterpenoid type; di and tri terpenes such as phytol, retinol and amyrin; and mixtures thereo~.

:' ' ~r~91 ~ J32~7 Preferably component C is a 3~ sterol having a tail on the 17 position and having no polar groups, for example cholesterol, sitostero]., stigmast~rol and ergosterol.

A particularly preferred component C is the 3~-sterol ergosterol since this is well known to convert in situ into vitamin D2 (calciferol) on reception of ultraviolet liyht.

It is essential that the molar ratio in which the components A, B and C are present is from 1:1.5 to 6.0:1.1 to 8.0 respectively, in order to ensure adequate control o~
water flux.

Preferably components A, B and C are present from 1:1.5 to 400:1.1 to 4.0 respectivsly and most preferably from 1:1.8 to 3.6:1.2 to 3Ø

The composition according to the invention may include a cosmetically acceptable vehicle to act as dilutant, dispersant or carrier for the components. Suitable vehicles include water, squalene, squalane, volatile silicone, liquid or solid emollients, solvents, humectants, thickeners and powdPrs.

Preferably the composition includes up to 5% by weight humectant, either as the vehicle or in addition to another vehicle, most preferably the humectant is glycerol.

Examples of particular mixtures include:
(i) A - Distearyl lecithin phospholipid B - Octadecanol C - Stigmasterol (ii) A - Ceramide II (having two C16 chains) B - a long chain fatty acid of C16 to C18 C - cholesterol .

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Use of the Composition The composition according to the invention is intended primarily as a product for topical application to human S skin, especially as an agent for reducing the permeability of the skin to water, particularly when the skin is dry or damaged, in order to reduce moisture loss and generally to enhance the quality and flexibility of the skin. The composition can also be applied to hair and nails.
The composition may be used as a product for topical application to human skin to treat dry or ayeing skin.

In use, a small quantity of the composition, for example from 1 to 5 ml, is applied to exposed areas of the skin, from a suitable container or applicator and, if necessary, it is then spread over and/or rubbed into the skin using the hand or fingers or a suitable device.

Examples The invention is illustrated by the following examples.

Examples 1-15: Comparative Examples A-F

Compositions formulated according to the invention were tested to measure the reduction in water flux by the following method.
In Vitro Measurement of Water Vapour Transmission Rate The reduction in water permeability of the skin following topical application of the composition according to the invPntion can be determined by in vitro measurement of the water vapour transmission rate (WVTR) using a water transmission cell adapted from that described by Blank X H, J Invest Dermatol, [1952], 18, 433-440.

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- 13 - J32~7 _retreatment of Porcine Stratum Corneum Isolated porcine stratum corneum was floated on propan-2-ol contained in a glass petri dish. The dish was gently agitated for 1 hour at 40C and the sample of extracted stratum corneum was then removed, floated in saline ~olution onto spectra mesh and air dried overnight.

Measurement of Initial WVTR Prior to Treatment 750 ~l distilled waker was placed in the centre well of the cell and a sample o~ pretreated stratum corneum (see above) was care~ully laid onto a stainless steel grid over the well ensuring that the stratum corneum completely covered the 0-ring, such that a watertight seal was achieved. Care was taken to avoid wrinkles, tears and holes in the stratum corneum sample. The top of the transmission cell was then screwed into position and allowed to equilibrate at xoom temperature be~ore an initial measurement was made. The cell was weighed after 5 minutes, then placed in an incubator at 37C, 5% RH. Two further weight measur~ments were taken at suitable intervals over a period of 24 hours at the end of which time a test or control solution was applied and three more measurements were taken during a further 21 hours. Five cells were used for each test or control treatment.

Study of the Effect of Topical Ap~lication of Test Material For each test, a solution of test material in chloroform/methanol (2:1 v/v) was prepared at 15 mg/ml concentration. 15 ~l of this solution was applied to the previously selected propan-2-ol extracted skin samples as described above. The chloroform/methanol quickly evaporated. The five cells containing the skin samples were weighed after 5 minutes prior to placing in the incubator at 37C, 5% RH. As mentioned above, three weight ;~37~9~
~ J32~7 measurements were then taken at intervals over a period of 21 hours.

A control measurement was made using other selected skin samples. This was carried out in the same way using an equal guantity of chloroform/methanol (2:1) containing no test material.

Calculation of the WVTR
The WVTR was calculated for each sample (pre and post topical application) as follows:

wei.ght loss WVTR (mg/cm2/hr) Area of exposed tissue x time The mean WVTR for each group of cells was then calculated from these values. The ~tandard deviation was calculated from the observed changes (relative increase or decrease) in WVTR measured before and after the topical application. It was then determined whether any obssrved reduction in WVTR was significant compared to the control measurement by use of the Duncan's Multiple Range Test.
Results are shown in table 1, structures mentioned in this table are as follows.

Structure 8 o o Il 11 C~H37 - O - C - CH - CH2 - C(OC2H4) 7-8EO - OH
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(9) ClsH3l -- CH2 Structure 10 Il I . , C6Hl3 - CHOH - C - N ~ CH2 (10) I

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C14H29 - CHOH - C - N - CH2 (11) I

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Claims

1. A cosmetic composition comprising three components A, B and C, wherein A is a molecule having at least two hydrocarbon chains and a polar head group for which:

;
component B is a molecule having one long hydrocarbon chain and a polar head group; and component C is capable of assisting the formation of lipid bilayers and stabilising any lipid bilayers formed in the composition; providing that the molar ratio of A:B:C is 1:1.5 to 6.0:1.1 to 8Ø

2. A cosmetic composition according to claim 1 wherein the molar ratio of A:B:C is 1:1.5 to 4.0:1.1 to 4Ø

3. A cosmetic composition according to claim 1 wherein component A is selected from the group consisting of ceramides; pseudoceramides; phospholipids; glycolipids having a structure of two or more acyl or alkyl long chains suitably containing from 14 to 50 carbon atoms attached to a polar head group; specific esters of polyethylene glycol;
polyglycerol-n-x-oleate; sorbitan dioleate; sorbitan sesquioleate; long chain alkyl ether versions of phospholipids and glycolipids; and mixtures thereof.

4. A cosmetic composition according to claim 1 wherein component B is selected from the group consisting of straight-chained mono carboxylic acids having 14 to 30 carbon atoms, straight chained fatty alcohols having 14 to carbon atoms, sugar esters, alkylated sugars and mixtures thereof.

5. A cosmetic composition according to claim 1 wherein component C is selected from the group consisting of 3.beta.-sterols; squalene; squalane; saponins or sapogenins of the plant sterol or triterpenoid type; di and tri terpenes; and mixtures thereof.

6. A cosmetic composition according to claim 1 wherein the composition additionally comprises a cosmetically acceptable vehicle.

7. A cosmetic composition according to claim 1 wherein the composition additionally comprises up to 5% by weight humectant.

8. A cosmetic composition according to claim 7 wherein the humectant is glycerol.

9. The use of a composition according to claim 1 in the topical treatment of dry, ageing or detergent damaged human skin or hair.

10. A cosmetic composition as claimed in claim 1 and substantially as described herein.