Skin Care Method and Composition

This invention relates to skin care methods and compositions.

These are intended for the treatment or prevention of dry skin conditions and particularly conditions wherein flaky skin cells occur on the surface of the skin. The composition may also be used to alleviate acne or dandruff.

In normal healthy skin there is an imperceptible shedding of peripheral corneocytes, to be replaced by lower level corneocytes, a process named desquamation. This occurs by the breakdown of the cohesive forces binding the peripheral corneocytes. One of the main cohesive elements is the rivet-like desmosome which is a protein complex comprising glycoproteins anchored in the membrane, responsible for corneocyte-corneocyte adhesion. To enable desquamation to occur these glycoproteins have to be degraded by the action of specific proteases.

Under certain circumstances there is an aberrant breakdown of the desmosomes in the peripheral corneocytes leading to the dry-flaky skin condition. This has been demonstrated by retention of desmosomal structures and the desmosomal glycoprotein desmoglein (dg1) in the surface layer of stratum corneum, where in normal skin these cannot be readily detected.

Walsh et al in a paper presented to the British Society of Dermatology in May 1990 have suggested that the oligosaccharide chains of the stratum corneum desmosomal glycoproteins may protect the proteins from proteolytic degradation and that prior treatment with glycosidases, to remove the sugar side chains, may be required before the proteases can breakdown the adhesive proteins.

According to the invention a composition for the treatment of dry skin conditions includes (1) a glycosidase and (2) a protease, the components 1 and 2 being present simultaneously in the composition or being separately presented with indications for the application of component 1 before component 2.

In another aspect of the invention we provide a method of relieving or ameliorating dry skin conditions which includes the topical application to the skin of (1) a glycosidase and (2) a protease, component 2 being applied to the skin not before component 1.

The compositions may be formulated in any conventional manner and include conventional vehicles, adjuncts and additives.

The concentration of each component is of the order of 0.00001 to 50% by weight of the composition, preferably from 0.001 to 20% and most preferably 0.1 to 10%. Preferably component 1 will be applied to the skin or be present in the composition in amounts greater than component 2 in a preferred ratio of between 100:1 and 1:1.

compositions may additionally include lipases at a concentration of from 0.00001 to 50% by weight of the composition, preferably from 0.001 to 20% and most preferably 0.1 to 10%.

Glycosidases may be isolated from animal, plant fungal or bacterial sources. Typical enzymes include neuraminidase, mannosidase, galactosidase, glucosidase, N-acetyl glucosaminidase and N-acetyl galactosaminidase. Preferably these may be isolated from plant sources including almonds, green coffee beans, and spinach, or may be obtained commercially.

Proteases may be isolated from animal, plant fungal or bacterial sources. Suitable enzymes include bromelain, papain, chymotrypsin & chymotrypsin-like enzymes, cathepsin and cathepsin-like enzymes, alcalase, savinase, chymopapain, clostripain, endoproteinase Asp N, protease V8 pronase, proteinase K, subtilisin, trypsin & trypsin-like enzymes thermolysin & plasmin. Preferably the protease may be isolated from plant sources including the seeds of wheat, barley, maize, oilseed rape, cocoa, linseed, illipe, shea nut, palm kernal, jojoba bean, pea, green bean, broad bean, soya bean and sunflower, and olives, papaya, pineapple and figs.

Lipases, or similar lipid modifying enzymes, may be isolated from plant, animal or bacterial sources. Suitable enzymes include lipolase, pancreatic lipases, phospholipases, ceramidase, aryl sulphatase, cholesterol esterase, candida rugosa OF360 lipase, humicola sp. lipase, pseudomonas sp. lipase and candida antarctica A & B lipases.

The composition according to the invention also comprises a vehicle to act as a dilutant, dispersant or carrier for the active ingredients in the composition, so as to facilitate their distribution when the composition is applied to the skin and/or hair. Preferably the vehicle is cosmetically acceptable.

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, glyceryl monostearate, mink oil, cetyl alcohol, isopropyl isostearate, stearic acid, isobutyl palmitate, isocetyl stearate, oleyl alcohol, isopropyl laurate, hexyl laurate, decyl oleate, octadecan-2-ol, isocetyl alcohol, eicosanyl alcohol, behenyl alcohol, cetyl palmitate, silicone oils such as dimethylpolysiloxane, di-n-butyl sebacate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, butyl stearate, polyethylene glycol, triethylene glycol, lanolin, cocoa butter, corn oil, cotton seed oil, tallow, lard, olive oil, palm kernel oil, rapeseed oil, safflower seed oil, evening primrose oil, soybean oil, sunflower seed oil, avocado oil, olive oil, sesame seed oil, coconut oil, arachis oil, castor oil, acetylated lanolin alcohols, petroleum jelly, mineral oil, butyl myristate, isostearic acid, palmitatic acid, isopropyl linoleate, lauryl lactate, myristyl lactate, decyl oleate, myristyl myristate.

Propellants, such as air, propane, butane, isobutane, dimethyl ether, carbon dioxide, nitrous oxide.

Solvents, such as ethyl alcohol, methylene chloride, isopropanol, acetone, ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dimethyl sulphoxide, dimethyl formamide, tetrahydrofuran.

Powders, such as chalk, talc, fullers earth, kaolin, starch, gums, colloidal silica sodium polyacrylate, tetra alkyl and/or trialkyl aryl ammonium smectites, chemically modified magnesium aluminium silicate, organically modified montmorillonite clay, hydrated aluminium silicate, fumed silica, carboxyvinyl polymer, sodium carboxymethyl cellulose, ethylene glycol monostearate.

The vehicle will usually form from 10 to 99.9%, preferably from 50 to 99% be weight of the emulsion, and can, in the absence of other adjuncts, form the balance of the composition.

A particularly convenient form of the composition according to the invention is an emulsion, in which case an oil or oily material will normally be present, together with an emulsifier to provide either a water-in-oil emulsion or an oil-in-water emulsion, depending largely on the average hydrophillic-lyophilic balance (HLB) of the emulsifier employed.

The composition according to the invention can optionally comprise one or more oils or other materials having the properties of an oil.

Examples of suitable oils include mineral oil and vegetable oils, and oil materials, such as those already proposed herein as emollients. Other oils or oily materials include silicone oils, both volatile and non-volatile, such as polydimethyl siloxanes.

The oil or oily material, when present for the purposes for forming an emulsion, will normally form up to 90%, preferably from 10 to 80% by volume of the composition.

The composition according to the invention can also optionally comprise one or more emulsifiers the choice of which will normally determine whether a water-in-oil or an oil-in-water emulsion is formed.

When a water-in-oil emulsion is required, the chosen emulsifier or emulsifiers should normally have an average HLB value of from 1 to 6. When an oil-in-water emulsion is required, a chosen emulsifier or emulsifiers should have an average HLB value of>6.

Examples of suitable emulsifiers are set out below in Table 1 in which the chemical name of the emulsifiers is given together with an example of a trade name as commercially available, and the average HLB value.

The foregoing list of emulsifiers is not intended to be limiting and merely exemplifies selected emulsifiers which are suitable for use in accordance with the invention.

It is to be understood that two or more emulsifiers can be employed if desired.

The amount of emulsifier or mixtures thereof, to be incorporated in the composition of the invention, when appropriate is from 1 to 50%, preferably from 2 to 20% and most preferably from 2 to 10% by weight of the composition.

The composition of the invention can also comprise water, usually up to 98%, preferably from 5 to 80% by volume.

The composition of the invention can also optionally comprise a high molecular weight silicone surfactant which can also act as an emulsifier, in place of or in addition to the optional emulsifier(s) already mentioned.

The silicone surfactant is a high molecular weight polymer of dimethyl polysiloxane with polyoxyethylene and/or polyoxypropylene side chains having a molecular weight of from 10,000 to 50,000 and having the structure: ##STR1## where the groups R' and R" are each chosen from --H, C.sub.1--18 alkyl and ##STR2## a has a value of from 9 to 115, b has a value of from 0 to 50,

x has a value of from 133 to 673,

y has a value of from 25 to 0.25.

Preferably, the dimethyl polysiloxane polymer is one in which:

a has a value of from 10 to 114

b has a value of from 0 to 49

x has a value of from 388 to 402

y has a value of from 15 to 0.75 one of groups R' and R" being lauryl, and the other having a molecular weight of from 1000 to 5000.

A particularly preferred dimethyl polysiloxane polymer is one in which:

a has the value 14

b has the value 13

x has the value 249

y has the value 1.25

The dimethyl polysiloxane polymer is conveniently provided as a dispersion in a volatile siloxane, the dispersion comprising, for example, from 1 to 20% by volume of the polymer and from 80 to 99% by volume of the volatile siloxane. Ideally, the dispersion consists of a 10% by volume of the polymer dispersed in the volatile siloxane.

Examples of the volatile siloxanes in which the polysiloxane polymer can be dispersed include polydimethyl siloxane (pentamer and/or hexamer).

A particularly preferred silicone surfactant is cyclomethicone and dimethicone copolyol, such as DC 3225C Formulation Aid available from DOW CORNING. Another is laurylmethicone copolyol, such as DC Q2-5200, also available from Dow Corning.

The amount of silicone surfactant, when present in the composition will normally be up to 25%, preferably from 0.5 to 15% by weight of the emulsion.

Examples of conventional adjuncts which can optionally be employed include preservatives, such as para-hydroxy benzoate esters; antioxidants, such as butyl hydroxy toluene; humectants, such as glycerol, sorbitol, 2-pyrrolidone-5-carboxylate, dibutylphthalate, gelatin, polyethylene glycol, preferably PEG 200-600; buffers, such as lactic acid together with a base such as triethanolamine or sodium hydroxide; surfactants, such as glycerol ethers, ceramides of synthetic, animal or plant origin; phospholipids; waxes, such as beeswax, ozokerite wax, paraffin wax; plant extracts, such as Aloe vera, cornflower, witch hazel, elderflower, cucumber; thickeners; activity enhancers; colourants; perfumes; and sunscreen materials such as ultrafine titanium dioxide and organic sunscreens such as p-aminobenzoic acid and esters thereof, ethylhexyl p-methoxycinnamate, 2-ethoxyethyl p-methoxycinnamate and butyl methoxydibenzoylmethane and mixtures thereof.

Metal chelators such as EDTA may be optionally included in the composition to increase activity/decrease inhibition of the enzyme(s).

The composition according to the invention is intended primarily as a product for topical application to human skin, for treating dry flaky skin and to enhance the quality of skin. The composition may also be used to alleviate acne and dandruff.

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

The topical skin and/or hair treatment composition of the invention can be formulated as a lotion having a viscosity of from 4,000 to 10,000 mPas, a fluid cream having a viscosity of from 10,000 to 20,000 mPas or a cream having a viscosity of from 20,000 to 100,000 mPas, or above. The composition can be packaged in a suitable container to suit its viscosity and intended use by the consumer. For example, a lotion or fluid cream can be packaged in a bottle or a roll-ball applicator or a propellant-driven aerosol device or a container fitted with a pump suitable for finger operation. When the composition is a cream, it can simply be stored in a non-deformable bottle or squeeze container, such as a tube or a lidded jar. The composition may be used for general lotions and creams, leave-on-creams, wash-off cleansers, face masks shampoos and bath oils.

The invention accordingly also provides a closed container containing a cosmetically acceptable composition as herein defined.

The following examples are to illustrate compositions for topical application embodying the present invention.

A typical oil-in-water cream:

A typical lotion:

A high internal phase, water-in-oil emulsion:

To establish the effectiveness of the composition treatment in vivo, a dry flaky skin is induced in subjects with soap washing over a two week period in the winter months. When dryness has been produced, the subjects are treated with a composition comprising a suitable vehicle and (a) glycosidase alone, (b) protease alone, (c) protease and glycosidase simultaneously, (d) glycosidase followed by protease, and (e) an otherwise-identical composition lacking both glycosidase and protease. Each day the subject's skin condition is assessed by visual grading of the skin, on a scale of 1 to 5 of increasing dryness. No significant improvement is observed in (a), (b) or (e), but there is significant improvement with (c) and even greater improvement with (d).

Stratum corneum cells with desmosomes still attached were obtained by tape stripping human or animal skin. To release the cells from the tape the whole tape is placed into hexane and the cells were collected by centrifugation after which the hexane is aspirated. Alternatively, human plantar stratum corneum, a tissue rich in desmosomes, was ground in liquid nitrogen and dried. The cells are then dispersed into buffer containing (a) glycosidase alone, (b) protease alone, (c) to ascertain the effect of prior treatment with glycosidases on the proteolytic digestion of desmosomes stratum corneum cells or plantar stratum corneum were incubated with a mixture of almond meal extract and neuramidase before addition of the protease, (d) no enzymes.

Desmosome digestion can then be followed microscopically by examining cell dissociation using an optical microscope. When enzymes fail to digest the desmosome the cells remain attached to each other. Thus, counting the number of dispersed cells or measuring the dispersed cell mass using a protein assay can be used as a measure of enzyme efficiency. To ensure enzymes were specifically degrading desmosomes, desmosome digestion was followed as described below. The desmosomal protein, desmoglein (dg1) was isolated from the squames by extraction in a urea/SDS/.beta.-Mercaptoethanol buffer with subsequent purification of the dg1 glycoprotein using Concavalin A affinity chromatography. The Concavalin A eluate was fractionated by sodium dodecyl sulphate polyacrylamide gel electrophoresis and electrophoretically transferred to PDVF membrane for immunoblotting. The dg1 was identified using a specific antiserum with low levels of the antigen being indicative of desmosomal digestion. Results obtained are shown in Table 1.

This methodology allows the screening of enzymes prior to testing the most efficacious enzymes.