GB2458531A

GB2458531A - Strengthening hair care composition comprising mild reducing agent

Info

Publication number: GB2458531A
Application number: GB0805444A
Authority: GB
Inventors: Stewart Paul Long; Louise Elizabeth Dolan; Sedella Hearson
Original assignee: Boots Co PLC
Current assignee: Boots Co PLC
Priority date: 2008-03-26
Filing date: 2008-03-26
Publication date: 2009-09-30
Also published as: GB0805444D0

Abstract

A method for strengthening and/or repairing damage to hair by activating endogenous transglutaminase enzyme in the hair. The method comprises contacting the hair with a mild reducing agent under conditions suitable for activating endogenous transglutaminase present in the hair. Suitably, the mild reducing agent comprises a reducing sugar including glucose, galactose, mannose, lactose, ascorbyl-2-glucoside, L-cysteine or glutathione, and may have a redox potential of less than 600mV. The hair care composition may be formulated as a shampoo, conditioner, wax, gel, paste, spray, mousse or foam. The composition may also include a calcium ion-containing compound. Hair care compositions comprising at least 0.1% w/w of a mild reducing agent are also provided.

Description

HAIR CARE COMPOSITION

The present invention relates to hair care compositions, and particularly to hair care compositions having hair strengthening, repairing, protecting and/or conditioning properties. The invention extends to methods of using such compositions to treat hair, and to methods for treating damaged hair.

The main causes of damage to human hair are the very processes that are intended to improve its strength, health and aesthetic qualities, eg combing, washing, drying, etc. Most of this damage is inflicted upon the part of the hair known as the cuticle, which is an extensive layer of flattened cells that exists primarily to protect the hair cortex from damage. Unfortunately, processes such as wet/dry combing, styling, towelling and weathering can rapidly degrade the cuticle, exposing the hair cortex and creating an area subject to fibrillation or fracture. Furthermore, the hair is frequently exposed to a number of environmental challenges, which can generate free-radicals, especially on exposure to sunlight and/or heat, and these are also implicated in the process of damage to hair, reduction in shine, poor feel, and fading of hair colour.

Traditionally, polymers have been used in shampoos and conditioners to reduce the damage done to hair by improving lubricity, and this has been partially successful. However, such treatment is not accumulative or permanent. In addition, attempts have been made to permanently condition hair, for example by the addition of various vitamins or amino acids. However, cysteine residues present in the hair need to be reduced before effective conditioning will occur, and therefore adding vitamins or amino acids has limited practical applications.

More recently, the use of transglutaminase enzymes in the cosmetics industry has been investigated. Transglutaminases are a family of enzymes that are thought to play an important role in haemostasis, wound healing and skin repair because of their protein cross-linking activity. As a result, these enzymes are widespread in the tissues and body fluids of humans and a large number of mammals. Transglutaminases are known to be present in the living part of hair, ie the hair follicle, and have been shown to catalyse a Ca2-dependent reaction for cross-linking proteins in hair by the formation of covalent peptide bonds between lysine and glutamine residues. Hair contains a high proportion of glutamic acid, which is the fourth most abundant amino acid in the hair cuticle and the most abundant in the hair medulla. Hence, there are very high levels of glutamine throughout the hair structure which is thought to provide the substrate for transglutaminase enzymes in the hair follicle. Furthermore, because transglutaminase enzymes catalyse the protein cross-linking reaction reactions at ambient temperatures and within a neutral pH range (ie pH 6-8), it is believed that these enzymes may offer an alternative to traditional chemical approaches for permanently modifying, strengthening and/or conditioning hair.

Known hair care compositions have been formulated which contain exogenously added transglutaminase, and which are believed to use the glutamine substrate to form cross-links in the hair. However, problems with such compositions include the expense of obtaining the exogenous enzyme, the possibility of immunological sensitisation from such enzyme-containing formulations, and also the instability of the enzyme when stored in the composition. Furthermore, it is believed that exogenously added enzymes are inefficient at forming cross-links within the hair cortex and medulla due to the barrier to entry formed by the hair cuticle. For these reasons, attempts were made to harness the activity of endogenous transglutaminases that are trapped in growing hair follicle. For example, W006/64405 discloses the incorporation of substrates of endogenous hair transglutaminase enzymes into a hair care composition for the treatment of hair. Suitable substrates require the presence of at least one alkyl amine group. The transglutaminase enzymes are believed to cross-link the substrate through this alkyl amine group to the glutamine residues that are present in the hair.

The cross-linking reaction requires the presence of calcium ions, and it was shown that transglutaminase is activated in the presence of thiols and a strong reducing agent. However, in order to induce the transglutaminase in the hair, high concentrations of enzyme substrates were included in the hair care composition, and this results in dark, aesthetically unpleasing products that stain the hair. Moreover, the addition of thiols and/or strong reducing agents in hair care formulations to induce the transglutaminase has disadvantages as they themselves are so reactive that they tend to damage the hair.

It is therefore an object of the present invention to overcome or mitigate one or more of the problems of the prior art, whether identified herein or elsewhere, and to provide improved hair care compositions, and methods for strengthening or repairing the hair.

The inventors focused their investigations on endogenous transglutaminase enzymes present in growing hair, with a view to finding alternative compounds that could activate these enzymes, for use in hair care products. As described in Examples 1 and 2, the inventors conducted hair fluorescence assays with a large number of compounds to determine whether they induced endogenous transglutaminase activity. Many of the compounds that were tested were unable to activate the endogenous transglutaminases present in the hair or damaged the hair. However, to their surprise, the inventors found that some of the compounds that were tested were able to activate the transglutaminases present in the hair to the same extent as the positive control, ie dithiothreitol (DTT). Furthermore, as demonstrated in Example 3, they found that activation of these endogenous enzymes resulted in strengthening the hair. Accordingly, the inventors believe that these compounds, which acted as transglutaminase activators, may be used to strengthen and condition undamaged hair, as well as repair damaged hair.

Upon analysis of the data, the inventors have concluded that the most efficient endogenous transglutaminase activators are mild reducing agents.

Therefore, according to a first aspect of the present invention, there is provided a method for activating endogenous transglutaminase enzyme in hair, the method comprising contacting hair with a mild reducing agent under conditions suitable for activating endogenous transglutaminase present in the hair.

According to a second aspect of the invention, there is provided use of a mild reducing agent to activate endogenous transglutaminase enzyme in hair.

To date, it was believed that endogenous functional transglutaminase enzymes were only present within the hair follicle, ie the living portion of the hair. However, surprisingly the inventors have now demonstrated that functional transglutaminase enzymes are also retained within the hair shaft, ie the dead portion of the hair. This was unexpected because it had previously been assumed that any enzymes that may be present in the hair shaft were denatured, and therefore non-functional. Furthermore, the inventors have also shown that these endogenous transglutaminase enzymes present in the growing shaft may be activated by mild reducing agents. In addition, the inventors have demonstrated that application of such transglutaminase activators to hair, results in the hair being strengthened. Accordingly, the inventors believe that the method and use according to the invention may be used to strengthen and/or repair hair.

The skilled technician will appreciate that transglutaminases are a family of enzymes that catalyse the formation of a covalent bond between a free amine group on protein-or peptide-bound lysine and the gamma-carboxamide group of protein-or peptide-bound glutamine. By the expression "endogenous transglutaminase", we mean transglutaminase enzyme(s) present within the hair itself (ie not enzyme that could be added exogenously to the hair). The transglutaminase that is activated by the mild reducing agent may be endogenously present in the hair root, but is preferably endogenously present in the hair shaft. The transglutaminase may be endogenously present in the hair medulla (inner layer), the hair cortex (middle layer), or the hair cuticle (outer layer).

By the expression "activate transglutaminase enzyme", we mean the mild reducing agent is capable of increasing the catalytic activity of the enzyme to form a covalent bond (le cross-links) between a free amine group on protein-or peptide-bound lysine and the gamma-carboxamide group of protein-or peptide-bound glutamine in the hair to a greater extent than would otherwise occur in the absence of the mild reducing agent. For example, the mild reducing agent may be capable of: (i) increasing the affinity of transglutaminase for its substrate, ie lysine and glutamine residues present in the hair; (ii) increasing the release of transglutaminase from intracellular stores; (iii) promoting or increasing the expression, transcription, or translation and therefore concentration of transglutaminase; or (iv) decreasing the rate of degradation of transglutaminase.

Cross-links may also be formed by transglutaminase enzymes between the amine and/or carboxamide groups on hair proteins and amine and/or carboxamide groups on active compounds (eg a hair dye). This may be advantageous if it is desired to incorporate an active into the hair by the formation of cross-links.

Activation of transglutaminase enzymes in the hair may be readily determined using a fluorescence assay, as described in the examples. From their investigations, the inventors have found that mild reducing agents are most suitable for activating the endogenous transglutaminase enzymes present within the hair.

By the term "reducing agent", we mean a substance that is capable of reducing another substance, ie by decreasing the oxidation number of that other substance. The reduction may be caused by donating an electron to that other substance. A result of the reduction reaction is that the reducing agent is itself oxidized, ie its oxidation number increases.

Preferably, the mild reducing agent is incapable of breaking disulphide bonds present in the hair. This is advantageous in order to prevent the hair from being damaged. The term "mild reducing agent" may be defined in terms of its redox potential. Hence, as described in Example 4, the inventors carried out experiments to determine the redox potentials of the preferred mild reducing agents.

Suitably, the redox potential of the mild reducing agent may be less than about 600mV, more suitably less than about 550mV, and even more suitably less than about 500mV. It is preferred that the redox potential of the mild reducing agent is less than about 450mV, more preferably less than about 400mV, and even more preferably less than about 38OmV.

Suitably, the redox potential of the mild reducing agent may be greater than about 1 OOmV, more suitably greater than about I 5OmV, and even more suitably greater than about 200mV. It is preferred that the redox potential of the mild reducing agent is greater than about 250mV, more preferably greater than about 300mV, and even more preferably greater than about 350mV.

The inventors carried out a series of investigations to determine which types of mild reducing agent acted as a transglutaminase activator, and they initially turned their attention to reducing sugars. A reducing sugar is any sugar that, in basic solution, forms some aldehyde or ketone. Examples are glucose, fructose, glyceraldehydes, lactose, arabinose, and maltose. The inventors found that some, but not all, of the reducing sugars that they tested, were able to increase transglutaminase activity in hair. Of those compounds tested, maltose and fructose were unable to activate these enzymes. Other compounds that were tested and which also did not activate transglutaminases in the hair included ethanol, glycerol, and sucrose. Hence, it is preferred that the use or method according to the invention does not involve the use of fructose, maltose, ethanol, glycerol, or sucrose, or any combinations thereof.

However, the inventors did observe that the reducing sugar lactose was able to increase transglutaminase enzyme activity in hair. Hence, the mild reducing agent may comprise lactose.

Although they do not wish to be bound by any hypothesis, the inventors believe that they may have found a pattern that explains which compounds that they have tested can activate transglutaminases, and which do not. They found that those reducing sugars which contain an aldehyde group were able to activate transglutaminases, whereas those sugars containing a ketone group (eg fructose) were unable to activate these enzymes.

Hence, it is preferred that the mild reducing agent comprises at least one aldehyde group, and preferably a plurality of aldehyde groups. Preferably, the mild reducing agent comprises an aldose, or a derivative or analogue thereof.

By the term "aldose", we mean a sugar containing one aldehyde group per molecule, and having a chemical formula of the form, CH2O (in which n �= 3).

The aldose may comprise at least three carbon atoms. A preferred three carbon aldose is glyceraldehyde.

The aldose may comprise at least four carbon atoms. A preferred four carbon aldose may comprise erythrose or threose.

The aldose may comprise at least five carbon atoms. A preferred five carbon aldose may be selected from a group consisting of ribose, arabinose, xylose and lyxose.

Preferably, the aldose comprises at least six carbon atoms. A preferred six carbon aldose may be selected from a group consisting of allose, altrose, glucose, mannose, gulose, idose, galactose, and talose.

As demonstrated in the examples, the sugars galactose, mannose and glucose were the most effective at inducing transglutaminase enzymes in hair.

Hence, preferably the mild reducing agent used in accordance with the invention comprises glucose, galactose and/or mannose.

By the term "derivative or analogue of an aldose", we mean a molecule which is structurally related to an aldose, and which retains its reducing capability.

For example, suitable derivatives or analogues of an aldose may comprise aldose isomers, such as D-or L-isomers of an aldose. For example, the derivative or analogue of the aldose may comprise D-or L-mannose, or D-or L-galactose, or D-or L-glucose, etc. Hence, the mild reducing agent may comprise L-glucose. However, a most preferred mild reducing agent comprises D-glucose (ie dextrose).

The inventors also observed that other mild reducing agents were capable of activating transglutaminases in the hair. For example, they noted that ascorbyl-2-glucoside acted as a transglutaminase activator. Hence, the mild reducing agent used in accordance with the invention may comprise ascorbyl- 2-glucoside.

The inventors have also demonstrated that glutathione was able to activate transglutaminases. Hence, the mild reducing agent used in accordance with the invention may comprise glutathione. Although the inventors do not wish to be bound by any hypothesis, they believe that the presence of a thiol group in glutathione may explain this compound's ability to activate trasnglutaminase in hair.

Based on their findings that certain mild reducing agents are able to activate endogenous transglutaminase enzymes in hair, the inventors have developed a number of hair care formulations (described in Example 5), which may be used as hair care products, for use in treating, strengthening, or repairing hair.

The inventors believe that the minimum concentration of mild reducing agent in a hair care composition that is required to activate endogenous transglutaminase enzymes in the hair is about 0.1 % (w/w).

Hence, according to third aspect, there is provided a hair care composition comprising at least 0.1% (w/w) of a mild reducing agent, wherein the mild reducing agent is capable of activating endogenous transglutaminase enzyme present in hair.

Suitably, the hair care composition according to the third aspect comprises at least 0.2% (w/w) of the mild reducing agent, more suitably at least 0.5% (w/w), and even more suitably at least 1 % (w/w) of the mild reducing agent.

Preferably, the hair care composition comprises at least 1.25% (w/w) of the mild reducing agent, more preferably at least 1.5% (w/w), and even more preferably at least 1.75% (w/w) of the mild reducing agent. Preferably, the composition comprises at least 0.001 M mild reducing agent, more preferably at least 0.O1M mild reducing agent, and most preferably at least 0.1M mild reducing agent.

The inventors believe that addition of too much mild reducing agent may have a negative effect on the hair being treated. Hence, it is desirable that the concentration of mild reducing agent in the hair care composition is not too great. Accordingly, it is preferred that the hair care composition comprises less than 20% (w/w) of the mild reducing agent, more preferably less than 10% (w/w), even more preferably less than 5% (w/w), and still more preferably less than 3% (w/w) of the mild reducing agent, and most preferably less than 2% (w/w) of the mild reducing agent.

The mild reducing agent in the hair care composition according to the third aspect may be selected from a group consisting of lactose, ascorbyl-2-glucoside and glutath lone.

However, preferably the mild reducing agent in the hair care composition comprises at least one aldehyde group, and preferably a plurality of aldehyde groups. Preferably, the mild reducing agent comprises an aldose, or a derivative or analogue thereof. The aldose may comprise at least three carbon atoms, but preferably comprises at least four carbon atoms, more preferably at least five carbon atoms, and most preferably at least six carbon atoms. A preferred six carbon aldose may be selected from a group consisting of allose, altrose, glucose, mannose, gulose, idose, galactose, and talose. Preferably, the mild reducing agent used in accordance with the composition of the third aspect comprises galactose. Preferably, the mild reducing agent used in accordance with the third aspect comprises mannose.

Most preferably however, the mild reducing agent used in accordance with the third aspect comprises glucose.

The mild reducing agent may comprise a derivative or analogue of an aldose sugar, for example a D-or L-isomer. Hence, the mild reducing agent may comprise D-or L-mannose, or D-or L-galactose, or D-or L-glucose, etc. However, a most preferred mild reducing agent comprises D-glucose (dextrose).

Hence, according to a fourth aspect, there is provided a hair care composition comprising dextrose at a concentration capable of activating endogenous transglutaminase enzyme present in hair.

Suitably, the hair care composition according to the fourth aspect comprises at least 0.1% (w/w) dextrose, more suitably at least 0.2% (w/w), even more suitably at least 0.5% (wlw), and still more suitably at least 1% (w/w) dextrose.

Preferably, the hair care composition comprises at least 1.25% (w/w) dextrose, more preferably at least 1.5% (w/w), and even more preferably at least 1.75% (w/w) dextrose. Preferably, the composition comprises at least 0.OO1M dextrose, more preferably at least 0.O1M dextrose, and most preferably at least 0.IM dextrose.

The inventors believe that addition of too much dextrose may have a negative effect on the hair being treated, for example it may become sticky, or attract insects. Hence, it is desirable that the concentration of dextrose in the hair care composition is not too great. Accordingly, it is preferred that the hair care composition comprises less than 20% (w/w) dextrose, more preferably less than 10% (w/w), even more preferably less than 5% (w/w), and most preferably less than 3% (w/w) dextrose.

By the term "hair care composition", we mean without limitation "hot oil" treatments, shampoos, conditioners (either leave in/leave on conditioners, or wash off conditioners), hair dyes, mousses, foams, gels, creams, waxes, masks, muds, semi-solid structured styling pastes (also known as putties), styling sprays, lotions and rinses. The composition may be in the form of a solution or emulsion.

It will be appreciated that all such compositions are suitable for use on the hair of animals, for example, those of veterinary interest, such as horses, dogs, cats etc. However, it is preferred that the hair care compositions of the invention are especially suitable for use on human hair. The hair care compositions may be suitable for use on hair anywhere on the animal or human body. However, preferably the hair care compositions of the invention are suitable for use on hair on the subject's (human or animal) head.

As described herein, the inventors have found that fructose, maltose, ethanol, glycerol, and sucrose are incapable of activating endogenous transglutaminase enzymes in the hair. Hence, it is especially preferred that the composition of the third or fourth aspect does not contain fructose, maltose, ethanol, glycerol, or sucrose, or any combinations thereof. For example, it is preferred that the composition does not contain fructose in combination with glucose.

Preferably, the hair care composition comprises one or more solvents in which the mild reducing agent or dextrose is dissolved, such as water, denatured alcohol, or cetyl alcohol. The one or more solvent may be present in an amount of from about 1% to about 99% (w/w) of the composition, suitably from about 3% to about 90% (w/w), more suitably from about 10% to about 85% (w/w), and most suitably from about 15% to about 80% (w/w) of the composition.

Preferably, the weight ratio of mild reducing agent (for the composition of the third aspect) or dextrose (for the composition of the fourth aspect) to solvent in the composition is at least about 1:60, preferably at least about 1:70, preferably at least about 1:80, and more preferably at least about 1:90.

Preferably, the weight ratio of mild reducing agent or dextrose to solvent in the composition is at least about 1.5:60, preferably at least about 1.5:70, preferably at least about 1.5:80, and more preferably at least about 1.5:90.

Most preferably, the weight ratio of mild reducing agent or dextrose to solvent in the composition is at least about 1.75:60, preferably at least about 1.75:70, preferably at least about 1.75:80, and more preferably at least about 1.75:90.

The hair care compositions of the third or fourth aspect may comprise one or more hair care additives, the choice of which depends on the intended application of the composition, for example if the hair care composition is a shampoo, or conditioner, etc. Although not essential, it is preferred that the one or more hair care additives do not contain any free amine groups which may be suitable as a transglutaminase substrate. This helps to prevent the additive from being incorporated into the hair structure by the action of the transglutaminase. However, it is envisaged that in some embodiments, there may be a desire to incorporate the hair care additive into the hair, for example where the additive is a hair colouring agent, in which case it may be preferred that the hair care additive has one or more free amine or carboxamide groups.

The composition may comprise one or more conditioning agents, such as polyquatermium-1 0, polyquatermium-1 1, quaternium-80, polyquatermium-7, cetrimon ium chloride, or stearam idopropyl d imethylam me. Alternatively, conditioning oil, such as paraffinum liquidum may be added to the composition. The one or more conditioning agent may be present in an amount of from about 0.01 % to about 10% (w/w) of the composition, and suitably from about 0.1 to about 5% (w/w) of the composition.

Preferably, the weight ratio of conditioning agent to mild reducing agent (for the composition of the third aspect) or dextrose (for the composition of the fourth aspect) in the composition is at least about 0.5:1, preferably at least about 1:1, preferably at least about 3:1, and more preferably at least about 8:1.

The composition may comprise one or more preservatives, such as 2-bromo- 2-nitropropane-1,3-diol (bronopol, which is available commercially under the trade name Myacide RIM), benzyl alcohol, diazolidinyl urea, imidazolidinyl urea, methyl paraben, phenoxyethanol, propyl paraben, sodium methyl paraben, sodium propyl paraben, methylchloroisothiazolinone, or methylisothiazolinone. The one or more preservative may be present in an amount of from about 0.0001 % to about 10% (w/w) of the composition, suitably from about 0.001 to about 5% (w/w) of the composition. Most preferably, the composition comprises methyl chloroisoth iazol inone and/or methylisothiazolinone as preservatives.

The composition may comprise a pH adjusting agent, such as sodium hydroxide, aminomethyl propanol, triethanolamine, suitably in an amount of from about 0.01 % to about 10% (w/w) of the composition. The composition may be buffered by means well known in the art, for example by use of buffer systems comprising succinic acid, citric acid, lactic acid, and acceptable salts thereof, phosphoric acid, mono-or disodium phosphate and sodium carbonate.

Suitably, the composition may have a pH between about 5 and about 10, preferably between about 7 and about 9.5, more preferably between about 8 and 9, and most preferably about 8.5. Such pH values are optimum for activating transglutaminase enzymes present in the hair.

The composition may comprise one or more surfactant, such as cosmetically acceptable salts of alkyl ether suiphates, alkyl and alkylamidoalkyl betaines, ethoxylated alcools, polyethyleneglycol carboxylates, acceptable salts of alkyl sulphates (such as ammonium lauryl sulphate), acceptable salts of alkyl ether sulphates (such as ammonium laureth sulphate or sodium laureth sulphate), sulphosuccinates (such as disodium laureth sulphosuccinate), amphoacetates and amphodiacetates (such as disodium cocoamphodiacetate), alkylpolyglucosides and alcohol sulphonates. The one or more surfactant may be present in an amount of from about 0.1% to about 10% (w/w)of the composition, suitably from about I to about 5% (w/w) of the composition.

Most preferably, the composition comprises sodium laureth sulphate and/or cocamide DEA as a surtactant.

The composition may comprise an emulsifying agent, such as cocamidopropyl betaine or ceteareth-20. The emulsifying agent may be present in an amount of from about 0.1% to about 10% (w/w) of the composition, suitably from about 1 to about 5% (w/w) of the composition.

The composition may comprise a humectant, such as glycerin. The humectant may be present in an amount of from about 0.01% to about 10% (w/w) of the composition, suitably from about 0.05 to about 5% (w/w) of the composition.

The composition may comprise a sunscreen compound, such as benzophenone-4. The sunscreen compound may be present in an amount of from about 0.01% to about 10% (w/w) of the composition, suitably from about 0.02 to about 3% (w/w) of the composition.

The composition may comprise a perfume, which may be added in an amount of from about 0.01% to about 2% (w/w) of the composition. The composition may comprise a water-soluble dye, such as tartrazine, suitably in an amount of from about a trace amount (such as I x105 %)to about 0.1 % (w/w)of the composition. The composition may comprise cosmetically acceptable diluents, carriers and/or propellants, such as dimethyl ether.

The composition may comprise a pearlising agent, such as stearic monoethanolamide, suitably in an amount of from about 0.01 % to about 10% (w/w) of the composition.

The composition may comprise an antidandruff agent, such as salicylic acid or zinc pyrithione or octopyrox, suitably in an amount of from about 0.1% to about 5% (w/w) of the composition.

The composition may comprise a thickener or viscosity modifying agent, such as amine oxides, block polymers of ethylene oxide and propylene oxide (for example, those available from BASF Wyandotte under the trade name "Pluronic" RIM), ethoxylated fatty alcohols, cellulosic derivatives such as hydroxypropylmethyl cellulose, salt (NaCI), phthalic acid amide, polyvinyl alcohols and fatty alcohols. Thickeners and viscosity agents may be present in an amount of from about 0.5% to about 10% (w/w) of the composition, suitably from about I % to about 5% (w/w) of the composition.

The composition may comprise one or more resin, such as octylacrylarnide/acrylates/butyIaminomethacl copolymer (available under the trade name Amphomer RTM); ethyl ester of polyvinylmethyl (PVM)/ methylacrylate (MA) copolymer (available under the trade name Ultrahold 8A RIM); vinyl acetate (VA)/crotonates/ vinyl neodecanate copolymer (available under the trade name Adhesive 282930 NAL); acrylates/acrylamide copolymer (available under the trade name Gantrez ES225 RIM); vinyl acetate/crotonic acid/vinyl propionate copolyrner (available under the trade name Luviset CAP RTM); polyvinylpropionate (PVP)NA/vinylpropionate copolymer (available under the trade name Laviskol VAP RIM); octylacrylam ide/acrylate copolymer (available under the trade names Versatyl 90 RIM or Lovocryl 47 RIM); vinyl caprolactam/PVP/dimethylaminoethyl methacrylate copolymer (available under the trade name (H20 LD EP-1); PVM/MA copolymer (available under the trade name Gantrez RIM); and vinyl acetate/butyl maleate/isobornyl acrylate copolymer (available under the trade name Advantage CP RIM). These resins may be present suitably in an amount of from about 0.1% to about 10% (w/w) of the composition.

The composition may also comprise a gelling agent, such as PVM, MA, or a decadiene cross-polymer (available under the trade name Stabilez 06), suitably in an amount of from about 0.1 % to about 2% (w/w) of the composition.

The composition may also comprise slip aids, such as phenyl trimethicone, suitably in an amount of from about 0.1% to about 10% by weight of the composition.

The composition may comprise vitamins, such as biotin, suitably in an amount of from about 0.01 % to about 1.0% (w/w) of the composition.

The composition may also comprise a wax, such as cocoa butter, suitably in an amount of from about 1 % to about 99% (w/w) of the composition.

The composition may also comprise a calcium ion-containing compound, preferably Ca2 ion-containing compound. The calcium ion-containing compound is provided to ensure that the rate of transglutaminase activity is not limited by the availability of Ca2 ions, which are believed to be required for the catalytic reaction. The calcium ion-containing compound may be a calcium salt, such as calcium chloride or calcium pantothenate. Suitably, the calcium ion-containing compound is provided in amount of from about 0.1 % to 10 % (w/w) of the composition, and preferably from about 0.5 % to 5 % (w/w) of the composition.

Surprisingly, the compositions of the third and fourth aspects of the invention have been shown to strengthen and repair hair. Therefore, the hair care compositions of the present invention may be used to provide improved protection against damage to hair caused by exposure to harmful factors such as sunlight, environmental and/or atmospheric pollution, heat from styling the hair and/or chemical treatment of the hair (for example curling, perming, straightening, dyeing and/or bleaching).

Hence, according to a fifth aspect, there is provided a method of treating a subject's hair, which method comprises applying a hair care composition according to either the third or fourth aspect to a subject's hair.

Hence, according to a sixth aspect, there is provided the use, in a haircare composition, of a mild reducing agent to strengthen and/or repair damage to hair to which the composition is applied, by activating endogenous transglutaminase present in the hair.

Preferably, once applied to the subject's hair, the hair composition is left thereon for a prescribed period of time sufficient for the composition to activate the endogenous transglutaminase enzymes present in the hair before being removed, for example by washing off The inventors have demonstrated in the Examples that endogenous transglutaminases are activated to a greater extent the longer they are left in contact with the enzyme activator compound, ie a mild reducing agent, such as dextrose.

For example, the hair care composition may be left on the subject's hair for at least 30s, and ideally at least 1 minute before being removed from the hair.

Suitably, the hair care composition is left on the hair for at least 2 minutes, more suitably at least 3 minutes, even more suitably at least 5 minutes, and most suitably at least 7 minutes. It is preferred that the hair care composition is left on the hair for at least 10 minutes, more preferably at least 15 minutes, even more preferably at least 20 minutes, and most preferably at least 25 minutes. In most preferred embodiments, the hair care composition may be left on the hair, and not removed. Example 5 describes a preferred hair care composition referred to as a "leave-in conditioner", which is intended to be applied to the hair and then left thereon, in order to act, until the next time the hair needs to be washed.

All of the features described herein (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined with any of the above aspects in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the following Examples and accompanying Figures, in which:-Figure 1 shows the results of a transglutaminase fluorescence assay following minutes contact time for the control samples, ie positive controls 1 and 2 (DTT), negative controls 1 and 2 (no activator), natural fluorescence of hair 1 and 2, and in the absence of a fluorescent marker I and 2. Each assay was carried out in duplicate; Figure 2 shows the results of a transglutaminase fluorescence assay following minutes contact time with transglutaminase activators, (i) glucose (1 and 2) or (ii) ascorbyl-2-glucoside (1 and 2), both with and without a fluorescent marker; Figure 3 shows the results of a transglutaminase fluorescence assay following minutes contact time for the control samples, ie positive controls 1 and 2 (DTT), negative controls 1 and 2 (no activator), natural fluorescence of hair 1 and 2, and no fluorescent marker 1 and 2; Figure 4 shows the results of a transglutaminase fluorescence assay following minutes contact time with transglutaminase activators (i) glucose (1 and 2) or (ii) ascorbic acid-2-glucoside (1 and 2), both with and without a fluorescent marker; Figure 5 shows the results of a transglutaminase fluorescence assay following minutes contact time for the control samples, ie positive controls I and 2 (DTT), negative controls 1 and 2 (no activator), natural fluorescence of hair I and 2, and no fluorescent marker 1 and 2; Figure 6 shows the results of a transglutaminase fluorescence assay following minutes contact time with transglutaminase activators (i) glucose (1 and 2) or (ii) ascorbic acid-2-glucoside (1 and 2), both with and without a fluorescent marker; Figure 7 shows a selection of images taken from transglutaminase fluorescence assays in which various compounds have been added to hair to assess their capability at inducing transglutaminase activity. The images show the degree of fluorescence induced by DTT (positive control) and where no activator is added (negative control), and for galactose (in duplicate), mannose (in duplicate), maltose and L-cysteine; Figure 8 shows a selection of images taken from transglutaminase fluorescence assays in which various compounds have been added to hair to assess their capability at inducing transglutaminase activity. The images show the degree of fluorescence induced by DTT (positive control) and where no activator is added (negative control), and for ethanol, fructose, glutath lone, glycerine, erythrose, and glucosamine; Figure 9 shows a selection of images taken from transglutaminase fluorescence assays in which various activators have been added to hair to assess their capability at inducing transglutaminase activity. The images show the degree of fluorescence induced by DTT (positive control) and where no activator is added (negative control), and for a honey/wheat composition, the aromatic herb pronalin origanum, DTT/pantothenate, pantothenate alone, mulberry extract, and rosemary extract; and Figure 10 is a consistency chart of treated and untreated hair samples in flex abrasion studies.

Examples

Transglutamjnases are known to catalyse the Ca2-dependent reaction for cross-linking proteins in hair by the formation of covalent peptide bonds between lysine and glutamine residues, ie glutamine-lysine cross-linking.

Hence, the aim of this study was to identify possible activators of transglutaminase enzyme in hair, and to activate any transglutaminase that may be endogenously present in the hair itself. The inventors therefore investigated the effect of various compounds on the activity of endogenous transglutaminase enzymes in the hair. They focused their studies on mild reducing agents. In order to compare the degree of enzyme activity that was induced by different reducing agents, a transglutaminase fluorescence assay was used.

ExamDle 1 -Transclutaminase Fluorescence Assay This assay was designed around the use of the fluorescent molecule, rhodamine cadaverine, which is incorporated into new glutamine-lysine cross-links due to the formation of an isopeptide bond. This reaction is catalysed by endogenous transglutaminase enzymes present in the hair. Previous studies have shown that the natural fluorescence of the hair does not interfere with this assay.

Reagents 0.1M Tris-HCI buffer at pH 8.5 (stored below 5°C) was prepared by adding 31.25g Tris-HCI to 2L of deionised water. The pH was adjusted to 8.5 by adding 10% sodium hydroxide solution dropwise to the buffer.

1:1000 rhodamine cadaverine was prepared by dissolving 0.005g of rhodamine cadaverine in 0.5ml Tris-HCI buffer to give 1:100 dilution stock solution. To obtain a working solution, 0.01 ml of the stock solution was added to 1 ml Tris-HCI buffer. 6Opl aliquots of the solution were stored frozen at -20°C.

100mM calcium chloride was prepared by dissolving 0.3675g of calcium chloride in 25m1 Tris-HCI buffer.

0.01% (vlv) Triton X-100 was prepared by dissolving lOpI Triton X-100 in lOOmI Tris-HCI buffer. I0

0.2M EDTA solution was prepared by dissolving 7.444g of EDTA in lOOmI Tris-HCI buffer. The solution was heated to 40°C for 30 minutes and then allowed to cool to room temperature.

O.02M dithiothreitol (DII) solution was prepared by dissolving 0.0308g DII in 1 ml Tris-HCL buffer.

Unless otherwise stated, all reagent solutions were stored at room temperature. Test solutions were prepared at the appropriate concentrations in Tris-HCI buffer.

Assay method Strands of virgin blonde hair (Banbury Postiche, Banbury, Oxfordshire, UK) were cut from the same hair sample for all replicates. Strands were cut to approximately twice the length of a I.5ml amber Eppendorl tube. Five hair strands were used per tube, and all experiments were carried out in duplicate.

Reagents and test solutions were added to each Eppendorf tube, as shown in

Table 1.

Table 1 -Reagents and test agent volumes Tube ID Iris-Triton Rhodamine Calcium Test agent EDTA Deionised HCI X-100 cadaverine chloride (p1) (p1) water buffer (p1) (p1) (p1) (p1) (p1) Positive 100 10 10 50 50 (DTT) 0 780 control Negative 100 10 10 0 50 (DTT) 50 780 control Test 100 10 10 50 50 (see 0 780

agent Table 2)

Transglutaminases are known to require the presence of Ca2 ions. Hence, the positive control includes calcium chloride, whereas the negative control does not, and instead includes a calcium ion sequestering agent, ie EDTA.

Table 2 -Concentrations of test agents Test agent Test concentration Ascorbyl 2-glucoside 1.5M Glucose 1.5M Fructose 1.5M Galactose 1.5M Mannose 1.5M Cysteine 1.5M Glutathione 1.5M Erythrose 1.5M Maltose 1.5M Glucosamine 1.5M Glycerin 20% (v/v) Ethanol 20% (v/v) Experimental protocol All the Eppendorf tubes containing the hair samples and test reagents were incubated at 37°C for three different contact times, ie 30 minutes, 20 minutes or 10 minutes. After incubation, the test solution was carefully decanted from the Eppendorf, ensuring that the hair samples were not lost, and each tube was washed once with 0.01% (v/v) Triton X-100 solution, and twice with 0.1M Tris-HCI buffer, in order to remove all traces of unbound rhodamine cadaverine. One hair was then taken from each tube and fixed to a glass microscope slide.

Each hair was then examined under an Olympus BX6O fluorescent microscope at a magnification of 1O,000x. Digital images were taken at an exposure time of 5Ops. Fluorescence intensity was measured from these images by taking an ellipse section of the image and measuring the intensity using AnalySiS software. Duplicate readings were taken per hair sample and the mean was calculated for each sample. The mean values were compared to the mean value for the negative control and expressed as a percentage increase in fluorescence.

Results The results of the fluorescence assays are shown in Table 3.

Table 3 -A summary of the results from the screeninQ assays I Activator Tested I intensity of Intensity of Mean % increase in fluorescence fluorescence intensity fluorescence 1 2 compared to negative control Dithiothreitol 248 248 248 51.22 (positive control) Negative control 164 164 164 -Galactose 243 245 244 48.78 Mannose 241 203 222 35.37 Maltose 145 156 150.5 -8.23 L-cysteine 234 248 241 46.95 Ethanol 143 167 155 -5.49 Fructose 187 176 181.5 10.67 Glutathione 243 249 246 50 Glycerin 143 156 149.5 -8.84 Erythrose 149 171 160 -2.44 Glucosamine 201 175 188 14.63 Honey/Wheat 134 154 144 -12.19 Pantothenate 167 161 164 0 DTT/Pantothenate 247 247 247 50.61 Rosemary 159 186 172.5 0.64 Pronalin 184 175 179.5 9.45 Mulberry 186 146 166 1.22 Note the maximum intensity value on this scale is 250 From the data shown in Table 1, it can be seen that most of the compounds that were tested did not generate any significant fluorescence, and hence were unable to activate transglutaminase present in the hair tested. However, clearly, some of the compounds did act as efficient enzyme activators, namely galactose, mannose, L-cysteine, and glutathione.

Referring to Figures 1 to 6, there are shown photographs of hair having undergone the fluorescence assay in duplicate, in which the contact time of the activator solution with the hair was varied. Figures 1 and 2 show the effect of the compounds tested following 30 minutes contact time, Figures 3 and 4 show the effect following 20 minutes contact time, and Figures 5 and 6 show the effect after 10 minutes contact time. The difference in fluorescence intensity between the positive and negative controls in Figure 1 is clear. The high level of fluorescence in the positive controls (ie the known transglutan-iinase activator DII) suggests that transglutaminase is indeed present in the hair and has been successfully activated by DTT. The negative controls show little or no fluorescence, and so it can be assumed that the transglutaminase enzymes have not been activated. This demonstrates that transglutaminases require the presence of calcium ions to catalyse the cross-linking of proteins in hair by the formation of covalent peptide bonds between lysine and glutamine residues. The lack of natural fluorescence shown in Figure 1 provides a useful comparison with the positive control. The samples with no fluorescent marker (ie the rhodamine cadaverine) added illustrate the need for such a marker to be used for the fluorescence assay to Referring to Figure 2, the four upper photographs show the fluorescence caused upon contacting with glucose or ascorbyl-2-gJucoside (in the presence of rhodamine cadaverine required for the assay). Clearly, these four photographs indicate that both glucose and ascorbyl-2-glucoside have activated the endogenous transglutaminase enzyme, as the intensity of the fluorescence compares favourably with the positive controls illustrated in Figure 1. There appears to be little difference in the degree of fluorescence between the glucose-and ascorbyl-2-glucoside-actjvated hairs. Accordingly, the inventors believe that both of these compounds act as efficient transglutaminase activators. The bottom four photographs of Figure 2 show that fluorescence is produced in the absence of the fluorescence marker, rhodamine cadaverine.

Referring to Figures 3 and 4, there are shown the effects of various test compositions on fluorescence following 20 minutes contact time with hair.

The images in Figures 3 and 4 provide similar conclusions regarding the activity of the enzyme, ie that glucose or ascorbyl-2-glucoside act as useful transglutaminase activators. However, the intensity of the fluorescence in the positive controls and activated samples is reduced from the previous assay due to the lower contact time, ie 20 minutes instead of 30 minutes for Figures 1 and 2. This suggests that the reduced contact time between the hair and the activator solution (20 minutes) has reduced the activity of the transglutaminase enzyme, particularly in the case of the ascorbyl-2-glucoside activated samples.

Referring to Figure 5 and 6, there are shown the effects of various test compositions on fluorescence following 10 minutes contact time with hair. In Figures 5 and 6, very little fluorescence can be seen in the positive controls and in the hairs treated with the two activators, glucose and ascorbyl-2-glucoside. This provides further evidence that any reduction in the contact time between the hair and the activator solution results in reduced activation of the transglutaminase enzyme.

Referring to Figures 7 to 9, there are shown photographs of hair having undergone the fluorescence assay, in which hair was exposed to a range of other compounds, some of which acted as transglutaminase activators, and some of which did not. Table 3 provides mean intensity values for all of the controls used, and for hairs treated with various compounds in solution.

When compared to the mean values for the positive and negative controls, it is clear that only a few of the compounds appear to have activated the transglutaminase enzyme. It can be seen that L-cysteine and glutathione have induced a high level of fluorescence. Otherwise, it is only the isomeric forms of glucose (ie dextrose, mannose and galactose) that appear to have activated the transglutaminase. Of these, galactose has provided the highest mean average for fluorescence intensity, closely followed by glutathione and cysteine. The inventors were interested to observe the high level of fluorescence achieved by the combination of DTT and calcium pantothenate, which was used as an alternative to calcium chloride to provide the calcium ions required for the reaction.

Example 2 -Fluorescence-based assay to detect clutamine-lysine cross-links through the activation of transglutaminase with dextrose Following on from the positive results generated in Example 1, the inventors wished to further investigate the enzyme-inducing activity of D-glucose (dextrose). As for Example 1, this assay was based on the incorporation of the fluorescent substrate, rhodamine cadaverine, into the hair structure by way of an isopeptide bond, the reaction being catalysed by endogenous transglutaminase enzymes present in the hair.

The tests were carried out using three different incubations: (a) the test incubation containing dextrose; (b) a negative control incubation without dextrose; and (C) a negative control incubation containing dextrose, but using boiled hair, in which the transglutaminase enzyme had been inactivated by denaturing.

Method The method used was similar to that used in Example I. Strands of untreated (virgin) blonde hair (Banbury Postiche, Banbury, Oxfordshire, UK) were cut from the same sample. Strands were cut to approximately 1cm in length with strands being used per Eppendorl tube. Hair for the boiled negative control was heated to 100°C in water for 20 minutes, and then removed from the water, and left to dry for 10 minutes. Reagent and test solutions were then added to each Eppendorf tube as given in Table 4.

Table 4 -Reagent volumes for each experiment Test Negative control Negative control (+ Dextrose) (-Dextrose) (+ Dextrose, + boiled ________________ hair) Tris-HCI lOOpI lO0pl lOOpI 1.5M Dextrose lO0pl OpI l00pl Deionised water 780p1 88Opl 780pl 0.01% Triton X lOpI lOpi lOpi 1/1000 lOpI lOpl lOpI Rhodamine Cadaverine The Eppendorf tubes containing hair strands and reagents as shown in Table 4 were incubated at 37°C for 30 minutes. Following incubation, any unincorporated fluorescence was removed through washing in 1 ml 0.01 % Triton X, followed by two washes in 0.1M Tris-HCI and then a final sonication step for 20 minutes in PBS. Hairs were then mounted onto microscope slides and were examined under an Olympus BX6O fluorescent microscope at a magnification of x 20,000. Photographs were taken at is (snap shot screen) and 250ms (preview shot screen) in greyscale, and the optical density (or intensity) of fluorescence for each hair was measured using ImagePro software. The experiments were carried out twice to ensure the reproducibility of the results.

Results Table 5-Fluorescence results for dextrose Mean Optical Density (Fluorescence) Negative Control Test (Dextrose-Negative Control (Boiled Hair with Treated) (No Dextrose) Dextrose) Hair 1 2101.892 1126.538 972.4424 Hair 2 1771.244 898.8763 1983.051 Hair 3 2647.333 1363.472 1561.838 Hair4 2688.236 1439.562 2072.156 Hair5 1763.888 1828.779 1465.396 Hair 6 2471.744 1438.194 1600.372 Hair 7 1740.325 1591.178 1543.901 Hair 8 2103.485 1260.118 1060.634 Hairg 2492.864 1371.333 2110.307 Hair 10 2285.633 1091.92 1562.598 Hair 11 2265.635 1876.914 1404.716 Hair 12 1617.288 1093.273 1555.861 Hair 13 1035.299 1486.957 1303.537 Hair 14 1705.488 1503.522 590.1868 Hair 15 2263.308 1797.568 1034.371 Hair 16 2264.754 1660.397 1131.936 Hair 17 1883.035 1635.796 1451.462 Hairl8 2113.432 1450.428 1142.728 Hair 19 2148.01 1565.663 1435.22 Hair2O 1923.066 702.6891 2217.484 [Mean Value 2064.29795 1409.15887 1460.00986 The normality of the data was confirmed through the calculation of Kurtosis and skewness. 1-test values were calculated to see if there was a significant statistical difference in the fluorescence of the test incubation versus the negative controls, as follows.

Test (dextrose) incubation vs. Negative control (no dextrose) incubation, p = 9.46E-07.

Test (dextrose) incubation vs. Negative control (boiled dextrose) incubation, p=0.00003 Hence, the results were significant at a 95% confidence level. The results show that fluorescence caused upon exposure to dextrose was increased by 41% compared to fluorescence when no dextrose was added, and by 46% compared to fluorescence in the boiled hair control.

Conclusions

Hair incubated in dextrose exhibits significantly more fluorescence than hair incubated without dextrose or in hair in which the transglutaminase has been inactivated. This suggests that there is an increase in glutamine-lysine cross-linking in the hair, which is a known predictor of hair strength.

ExamDle 3 -Flex Abrasion Tests Human hair undergoes a variety of stresses throughout its life, including photochemical oxidation, exposure to cosmetic treatments and mechanical action. The main causes of hair breakage is not the direct pulling apart of a hair into two pieces, but rather the constant bending and straightening of hair and the effects of friction, which leads to longitudinal splitting and fibre breakage. The flex abrasion test is used to evaluate hair fibres treated with cosmetic treatments, eg shampoo and conditioners, in order to see if applying these treatments has an effect on the breakage of the hair fibre. Therefore, flex abrasion tests were carried out on hair samples in order to determine whether or not a compound which had been shown to successfully induce transglutaminase activity in the hair (ie glucose), resulted in strengthening of the hair. This test determines the time or action required to cause this breakage with and without product (glucose) treatment.

For the test, there can be single or multiple applications of product(s) to each hair fibre taken from a hair swatch. Products may also be applied in conjunction with another product, eg shampoo and conditioner, if desired.

The amount and length of application will vary with each test depending on the type of product being examined.

Apparatus Apparatus was set up as described in Swift eta! "Flexabrasion: A Method for evaluating hair strength", Cosmetics & Toiletries magazine, 2001, Vol. 116, No.12, 53-60, and included:- 1) 1 hair swatch (mid or dark brown, 1.5g and 17cm long per swatch) -(from which 20 hair strands are needed) 2) 20 x 1 cm and 2 cm pins (hypodermic needle sections) 3) Loctite Super Glue 4) Flexabrasion unit 5) Angle poise magnifying lamp 6) Plastic tweezers 7) 20g weights x 20 (including grub screws) 8) Metal tray 9) White paper roll Reagents All reagents were made up on the day of the experiment, with the experiment being carried out over two days. 200ml of Tris-HCI buffer (0.1 M) was prepared by dissolving 3.152g of Tris-HCI in 200m1 of de-ionised water. A 0.01% solution of Triton X-100 was prepared by adding I Opi of Triton X-100 to ml of de-ionised water. ImI of this solution was added to the 200m1 of Tris-HCI. Then, 0.147g of the CaCI2 was added to the buffer to give 200m1 of a 0.005M CaCl2 reaction buffer. lOOml of this solution was then taken, and I.351g of glucose added to it to create a O.075M glucose activator solution, whilst the other lOOmI was used as a negative control buffer.

Flex abrasion method (i) Prearation of hair swatches Thin hairs tend to be easier to strengthen and are less prone to damage than thicker hair. Hence, hairs of the same thickness were used in order to help reduce variability of data. Individual hair fibres were selected from a hair swatch to give sufficient samples for the examination (ie. 20 hairs for 20 control and 20 test runs). The first centimetre from each root end was removed and discarded. Measuring from the root end, two adjacent 2cm sections were cut from each hair fibre, and these were laid on a piece of white paper in such a way that it is clear which end is the root end, and which end is the tip end.

20 weighing boats were then labelled 1-20 for the test (1) samples eg 11, 21, 31, etc, and for control (C) samples, eg Cl, C2, C3, etc. A pair of plastic tweezers was used to hold the hair and, using a magnifying angle poise lamp, the hairs were inserted into a 1 cm hypodermic needle and fixed in place with superglue. When each section had been glued, the needle end was placed in bluetack or polystyrene. It was important not to get any super glue on to the hair shaft as this would cause brittleness.

Once the glue had set (for at least 30 minutes), the opposing end of the cut section was then thread into a 2cm hypodermic needle and again fixed in place with superglue. The needles carrying the hair were then placed in the weighing boats in matched pairs, and left over night. The 2cm needle, attached to the hair section, was then placed into the locating hole of a 20g weight and fix in place using a grub screw. The hairs were then treated with glucose (transglutaminase activator) or a control solution (not containing glucose). A small volume of the test solution (containing the glucose) was then added to the test boats labelled Ti -20 and a small volume of the control buffer (without glucose) was added to the control boats labelled Ci-20. All of the boats were then incubated at 37°C for 30 minutes, before being removed by tweezers and then left to dry for a further 30 minutes. The 20g weights were then added to all of the sample hairs (via the 2cm needle at one end) and the flex abrasion test was carried out.

(ii) Measurement of Hair SamDles After 1 hour, each hair section was fitted via the attached 1cm needle, into a holder on the reciprocating arm of the Hair Abrasion Unit. It was important to ensure that the corresponding control hair was placed in the holder adjacent to the test hair. The counters were set to zero, and the speed was set to 146 cycles/mm. The unit was then switched on. Once all the hairs had broken, the unit was stopped, and the number of completed cycles before the breakage of each hair for the control and the adjacent test for all replicates was recorded. The process was repeated with the remainder of the replicates so that another 20 values could be obtained (ie 10 control and 10 test values) giving a total of 20 control values and 20 test values. The test results (counter values) were entered into a raw data' worksheet to check for outliers (rogue results), and consistency. In cases where the results were not consistent, further replicates were required.

Results The results from the flex abrasion tests (carried out in duplicate) are summarised in Table 6 below.

Table 6 -Flex abrasion on treated hair (with glucose) and untreated hair (without glucose) Sample No. Counter No. Counter No. Counter No. Counter No. _____________ Treated Untreated Treated Untreated 1 2345 1353 3052 178 2 1932 2680 1516 2345 3 2907 1418 3198 1379 4 3047 619 2675 986 3722 2397 2693 966 6 2040 3427 898 3565 7 4405 220 1861 3996 8 5551 1059 2964 1347 9 350 2250 3593 3803 4298 2002 2621 4215 11 2642 1212 2321 1764 12 3456 1430 2100 1763 13 4711 951 3009 1701 14 3001 2014 1952 2432 3521 1716 1645 3045 16 2845 1874 1023 3453 17 2123 2001 1234 3244 18 1789 1544 1983 5421 19 2589 976 2343 2344 4564 2231 2345 4324 The numbers in bold denote a void count (ie an outlier) on either the treated or untreated hair, ie the counter was too low or too high in either case. These values were therefore omitted from the calculations and statistical analysis.

Referring to Figure 10, there is shown the level of consistency between the data obtained from the treated and untreated samples. The graph has been constructed by plotting the replicate number on the X-axis and the cumulative standard error (cum se) / cumulative mean (cum mean) on the Y-axis. From a review of Figure 10, the level of the consistency between the two sets of results (ie treated and untreated sets of hair) was considered to be satisfactory because the two plotted lines run approximately parallel with each other for a sufficient amount of replicates. Statistical analysis in the form of a 1-test and an ANOVA (analysis of variance) was therefore carried out using the Microsoft Excel package, and the results of the statistical analysis are

shown in Table 7.

Table 7 -Statistical analysis from the flex abrasion tests on the treated/untreated hair No. in Mean No. Median P-value P-value sample of counts No. of from T-test from counts ANOVA Treated 34 2739.1 2631.5 0.0488159 0.019863 Untreated 34 2158.6 1937.5 Both of the P-values are below the 0.05 significance level. Hence, the results from Table 7 show that the average number of counts required to break the untreated hair was less than the number required to break the hair treated with glucose. The two statistical tests show that this is a significant difference, and therefore indicate that the hair treated with the glucose activator solution is stronger as a result of increased transglutaminase activity.

ExamJe 4 -Determination of redox Dotential for various sugar solutions The inventors wished to characterise the various compounds which they had shown to activate transglutaminase enzymes. As they believe that the compounds which were able to activate the enzyme were mild reducing agents, they believed it would be used to determine the redox potential of each compound. Hence, the inventors conducted redox potential assays using the following equipment: a Mettler Toledo 7 Easy pH meter S20K, a Mettler Toledo Redox Probe, a Redox Cable, beakers, and deionised water.

Method Firstly, a series of solutions of dextrose, galactose, and lactose were prepared at different concentrations (0%, 1 %, 3%, 5%, 10% and 20% w/v for dextrose and lactose). The pH meter set up to read reducing /oxidising (redox) potential, and the redox probe was attached. The probe was placed in a test solution, and the reading was recorded. Three readings of the redox potential were taken for each solution. The probe was washed with distilled water between each reading. The results are shown in Table 8.

Table 8 -Redox Potential (mV) for a series of sugar solutions Material Concentration (% w/v) ________ 0 1 3 5 10 20 Dextrose 251 380 403 397 361 372 _________ 388 396 399 414 413 ________ ________ 391 398 401 406 418 ________ _________ 386 399 399 394 401 Galactose 350 416 429 433 409 Not tested ________ ________ 411 432 433 403 Not tested ________ ________ 420 431 424 401 Not tested ________ ________ 416 431 430 404 Not tested Lactose 338 411 404 420 404 405 ________ _________ 407 404 412 407 398 ________ _________ 401 407 407 401 396 ________ _________ 406 405 413 404 400 The average redox value for dextrose is 396. The average redox value for galactose is 420. The average redox value for lactose is 406.

ExamDle 5 -Hair care formulations The inventors have devised three different hair care formulations (a shampoo, a "wash-off' conditioner, and a "leave-in" conditioner), each of which include the transglutaminase activator, D-glucose (Dextrose), at a concentration of 1.8% (wlw). Each formulation also contains I % (w/w) calcium pantothenate, which provides the transglutaminases with Ca2 ions. The compositions of each of these three formulations are listed in the following tables.

Table 9 -Shampoo

Ingredient Function % (w/w) Water Solvent 82.47 Sodium laureth sulphate Detergent 8.24 D-Glucose TG activator 1.80 Sodium chloride Thickening agent 2.81 Cocamidopropyl betaine Detergent 2.10 Cocamide DEA Detergent 1.00 Polyquaternium-1 0 Conditioner 0.30 Quaternium-80 Conditioner 0.15 Glycerin Humectant 0.08 Polyquatern ium-7 Conditioner 0.05 Citric acid pH adjuster 0.03 Disodium phosphate Buffer 0.02 Benzophenone-4 Sunscreen agent 0.02 Methylchloroisoth iazol inone Preservative 0.0012 Methyl isoth iazol inone Preservative 0.000175 Calcium pantothenate Ca2 source 1.00 It will be appreciated that the shampoo is used on the hair first in order to clean it. The shampoo includes 1.8% (w/w) dextrose in order to activate the endogenous transglutaminase enzymes present in the hair. Ideally, the shampoo should be left to act on the hair for at least 10 minutes, and ideally at least 20 minutes, in order to give the glucose time to activate the transglutaminases. Following treatment with the shampoo, it is then washed off. The cleaned hair should then be treated with the "Wash-off' conditioner

listed in Table 10.

Table 10 -"Wash-off' Conditioner Ingredient Function % (w/w) Water Solvent 89.67 Cetyl alcohol Solvent 4.00 D-Glucose TG activator 1.80 Stearamidopropyl Conditioner 0.90 dimethylamine Phenoxyethanol Preservative 0.60 Cetrimonium chloride Conditioner 0.50 Ceteareth-20 Emulsifier 0.50 Paraffinum liquidum Conditioning oil 0.49 Perfume Fragrance 0.30 Citric acid pH adjuster 0.24 Calcium pantothenate Ca2 source 1.00 This "Wash-off' conditioner should be left on the hair to act for as long as possible. As with the shampoo, it is desirable to leave the conditioner on the hair for at least 10 minutes, but ideally longer, such as at least 20 minutes or more. In some embodiments of the invention, a user may opt to apply "Leave-in" conditioner as set out in Table 11.

Table 11 -"Leave-in" Conditioner Ingredient Function % (wlw) Denatured Alcohol Solvent 50.00 Water Solvent 46.30 D-Glucose TG activator 1.80 PEG-40 hydrogenated Solubiliser 0.50 castor oil Perfume Fragrance 0.50 Polyquaternium-1 1 Conditioner 0.20 Calcium pantothenate Ca2 source 1.00 This conditioner may be safely left on the hair. Clearly, by leaving the formulation on the hair for long periods provides sufficient time for the dextrose to activate the transglutaminase enzymes in the hair to form the cross-links. Accordingly, use of any or all of these hair care formulations results in the treated hair being strengthened. Furthermore, it should be appreciated that the formulations of the invention may be used to repair damaged hair, and not just strengthen healthy hair.

Claims

Claims 1. A method for strengthening and/or repairing damage to hair by activating endogenous transglutaminase enzyme in said hair, the method comprising contacting said hair with a mild reducing agent under conditions suitable for activating endogenous transglutaminase present in said hair.
2. A method according to Claim 1 wherein the redox potential of the mild reducing agent is less than 600mV.
3. A method according to Claim 1 or Claim 2 wherein the transglutaminase activator is a reducing sugar.
4. A method according to Claim 3 wherein the mild reducing agent comprises an aldose, or a derivative or analogue thereof.

Ct')
5. A method according to Claim 4 wherein the mild reducing agent is selected from glucose, galactose or mannose. IC)
6. A method according to Claim 5 wherein the mild reducing agent comprises D-g I ucose.
7. A method according to Claim 1 wherein the mild reducing agent comprises lactose.
8. A method according to Claim I wherein the mild reducing agent is selected from ascorbyl-2-glucoside, L-cysteine or glutathione.
9. A method according to any one of the previous claims comprising administering a hair care composition comprising 0.1 to 10% w/w of mild reducing agent.
10. A hair care composition comprising at least 0.1% w/w of a mild reducing agent, wherein the mild reducing agent is capable of activating endogenous transglutaminase enzyme present in hair.
11. A composition according to Claim 10 wherein the mild reducing agent is selected from glucose, galactose, mannose, lactose, ascorbyl-2-glucoside, L-cysteine or glutathione.
12. A composition according to Claim 11 wherein the mild reducing agent is selected from glucose, galactose or mannose.
13. A composition according to any one of claims 10 to 12 further comprising a calcium ion-containing compound.
14. A composition according to any one of claims 10 to 13 in the form of a solution or emulsion. Cs')
15. A composition according to any one of claims 10 to 14 in the form of a hot oil treatment, a shampoo, a conditioner, a hair dye, a mousse, a foam, a gel, a cream, a wax, a mask, a hair mud, a semi-solid structured styling paste, a styling spray, a lotion and a rinse.
16. The use of a mild reducing agent in the manufacture of a composition for strengthening and/or repairing damage to the hair by activating endogenous transglutaminase enzyme in the hair.