Claims:We claim:
1. A single phase composition comprising:
0.001%-1% polyphenol;
0.001%-20% of an iron salt;
0.001%-15% ascorbic acid or derivatives thereof; and
0.001%-15% citric acid or derivatives thereof.

2. The composition as claimed in claim 1, wherein the polyphenol is selected from gallic acid and its esters, tannic acid and its esters, hematoxylin, anthocyanins or a combination thereof.

3. The composition as claimed in claim 2, wherein the polyphenol is gallic acid ester selected from methyl gallate, palmityl gallate, ethyl gallate, propyl gallate, butyl gallate, hexyl gallate, octyl gallate, lauryl gallate, behenyl gallate or a combination thereof;
the anthocyanins are selected from cyanidin, delphinidin, peonidin, malvidin, or their glucosides or a combination thereof.

4. The composition as claimed in claim 1, wherein the iron salt is selected from the group comprising of ferrous chloride, ferrous stearate, ferrous palmitate, ferrous gluconate, ferrous sulfate, ferric chloride or a combination thereof.

5. The composition as claimed in claim 1, wherein the citric acid derivatives are selected from citric acid monohydrate, hydroxy citric acid, citric acid esters of mono- and diglycerides or a combination thereof;
the ascorbic acid derivatives are selected from l-ascorbic acid 2-glucoside, ascorbic acid esters or a combination thereof.

6. The composition as claimed in claim 1, wherein the composition is colorless.

7. The composition as claimed in claim 1, wherein the composition does not stain the skin.

8. The composition as claimed in claim 1, wherein the pH of the composition is in a range of 1-4.

9. The composition as claimed in claim 8, wherein the pH of the composition is in a range of 2.5-3.5.

10. A process for preparing a single phase composition comprising:
mixing 0.001%-1% polyphenol, 0.001%-20% of an iron salt, 0.001%-15% ascorbic acid or derivatives thereof and 0.001%-15% citric acid or derivatives thereof.

11. A hair darkening composition comprising the single phase composition as claimed in claim 1 and one or more excipient.

12. The hair darkening composition as claimed in claim 11, wherein the composition is a water-based composition comprising:
0.001%-1% gallic acid;
0.001%-20% ferrous sulphate heptahydrate;
0.001%-15% ascorbic acid;
0.001%-15% citric acid monohydrate; and
one or more excipient.

13. The hair darkening composition as claimed in claim 11, wherein the composition is an oil-based composition comprising:
0.001%-1% propyl gallate, octyl gallate or a combination thereof;
0.001%-20% ferric chloride;
0.001%-15% ascorbyl palmitate;
0.001%-15% citric acid monohydrate, citric acid esters of mono- and diglycerides or a combination thereof; and
one or more excipient.

14. The hair darkening composition as claimed in any one of claims 11-13, wherein the excipient is selected from solvent, surfactant, moisturizing agent, preservative, viscosity modifier, buffering agent, biological actives, fragrance delivery system or a combination thereof.

15. The hair darkening composition as claimed in claim 14, wherein the solvent is water, an alcoholic solvent selected from ethyl alcohol, propylene glycol, polyethylene glycol, pentylene glycol, panthenol, or a combination thereof, oils selected from safflower hydrolyzed oil, refined sesame oil, isopropyl myristate, refined rice bran oil, refined coconut oil or a combination thereof;
the surfactant is hydrogenated castor oil derivatives, laureth-4 or a combination thereof;
the moisturizing agent is glycerin, vitamin E acetate, fatty acid, dimethicone or a combination thereof;
the preservative is phenoxyethanol, tert-butylhydroquinone or a combination thereof;
the viscosity modifier is polyacrylate cross polymer, silicone polymers or a combination thereof;
the buffering agent is triethanolamine;
the biological actives are selected from apigenin, forskolin, plant extract or a combination thereof; and
the delivery system is phospholipid.

16. The hair darkening composition as claimed in any one of the claims 11-15, wherein the composition is formulated as a liquid, cream, gel or an aerosol.

17. The hair darkening composition as claimed in any one of the claims 11-16 for progressive hair darkening.

Dated this 16th day of July, 2021
For MARICO LIMITED
By their Agent

GIRISH VIJAYANAND SHETH IN/PA- 1022
KRISHNA & SAURASTRI ASSOCIATES LLP
, Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

A SINGLE PHASE COMPOSITION AND A PROCESS FOR PREPARATION THEREOF

MARICO LIMITED, AN INDIAN COMPANY, WHOSE ADDRESS IS 7th FLOOR, GRANDE PALLADIUM, 175, CST ROAD, KALINA, SANTA CRUZ (EAST), MUMBAI-400098, MAHARASHTRA, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
The invention relates to a single phase composition and a process for its preparation.

BACKGROUND OF THE INVENTION
The desire to alter the color of human hair is not a facet of modern times. The color of human hair has been routinely altered to accommodate the changes of fashion and style. However, the attainment of precise initial colors which are retained by the hair for a desirable period has remained a more elusive goal. The difficulties in the development of hair coloring compositions which can deliver precise long-lasting colors are in part due to the inherent structure of the hair itself and in part due to the necessary conditions of effective hair coloration processes.
There are several hair coloring methods. One is the so-called oxidative dye approach. This is based on the oxidation of a synthetic compounds such as p-phenylenediamine or p-aminophenol by hydrogen peroxide, in the presence of various couplers. This has been in use for a very long time and is used to generate a wide range of shades that are both lighter and darker than natural hair color. Since the final colored molecules are quite large, these hair colors are resistant to removal by shampooing. Such permanent oxidative dyes are usually marketed as two component systems - one containing the dye precursors in an alkaline base, and the other is a solution of hydrogen peroxide.

However, such synthetic hair dyes shows color by the oxidation polymerization reaction. The alkaline agent and hydrogen peroxide used in hair dye damage hair protein. Further, these hair dyes require a skin test to determine if the consumer is allergic to the dye. These dyes have also been known to damage the scalp, and are highly toxic, and may easily cause discomfort such as redness, phlegm and pain in the skin. Also, these dyes stain the scalp while dyeing the hair and give an unnatural appearance to the darkened hair. The dyes permanently stain the fabric and other materials which come in contact with it during the dyeing process. Therefore, precaution must be taken while applying such dyes to avoid staining of hands and clothes.

In order to overcome the disadvantages of the synthetic hair dyes, natural hair colouring compounds are sought after.

Polyphenol compounds such as tannic acid, gallic acid and derivatives of such as acids are coloring compounds that are available naturally and can also be synthesized. These polyphenol compounds are known to react with metal ions preferably iron salts to produce a colored complex which is used for hair darkening.

JPH03193722A relates to a hair dyeing composition comprising a first agent containing a ferrous salt and a second agent containing a compound such as propyl gallate. The composition is capable of dyeing hair by adding a nonionic surfactant to at least one of the first agent and a second agent. In this composition, the first agent and second agent are present in different compositions.

JP2001270812A relates to a hair dye comprising a first agent containing an organic compound and at least one or more dihydric alcohols and a second agent containing iron salt, ascorbic acid, and at least one salt thereof. The first agent and the second agent are prepared separately and applied sequentially to form a color by reaction of the organic compound with the iron salt.

KR101510486B1 relates to a hair dye composition comprising catechin. The composition comprises a first agent containing a green tea catechin and a pH adjusting agent. The second agent contains a mordanting agent which is a salt of metal such as aluminum, copper, chromium, iron, tin and nickel. The first agent and the second agent are present in separate compositions and mixed together before applying on the hair.

US8313537B2 relates to hair dyeing product comprising a softening agent, a dyeing agent and a mordant. The mordant comprises a ferrous salt and an anti-oxidant. The dyeing agent comprises an active dye substance which is selected from the group consisting of gallic acid and salts or esters thereof. The softening agent comprises a disulfide bond reducing agent and an alkalizing agent. The hair is dyed with the product by first applying the softening agent to the hair. In the next step, the dyeing agent and mordant are mixed before use and then applied on the hair.

WO2012129961A2, WO2012139951A1, WO2014139163A1, WO2014139165A1, WO2014139171A1, WO2014139153A1, CN104970989A also disclose a hair dye composition containing polyphenol and iron salt each as a separate composition which is to be mixed before applying on the hair. The hair dye composition in these prior arts are dual phase composition as the polyphenol and iron salt are present in different compositions. The reason for this is to prevent a reaction between the polyphenol and the iron salt to form the colored complex. The colored complex has less stability, so it is preferred to be formed immediately before application on the hair.

However, the dual phase composition has disadvantage that each phase has to be mixed in a defined proportion to achieve the desired hair darkening effect. This requires measuring devices to be supplied with such compositions. Further, when each phase of the composition is mixed in the hand, the mixing may result in spillage of the composition and staining of the hands and clothes of the user. As the colored complex is less stable, the user has to premix an approximate excess quantity than required so that the quantity is sufficient for application which may result in wastage of the composition.

Thus, there is a need of a single phase composition comprising polyphenol and the iron salt so as to overcome the disadvantages of the dual phase composition. Also, the single phase composition should be such that components are prevented from reacting with each other when present in the same composition.

SUMMARY OF THE INVENTION
In an aspect, the invention relates to a single phase composition comprising 0.001%-1% polyphenol, 0.001%-20% of an iron salt, 0.001%-15% ascorbic acid or derivatives thereof and 0.001%-15% citric acid or derivatives thereof.

In another aspect, the invention relates to a process for preparing a single phase composition. The process comprises mixing 0.001%-1% polyphenol, 0.001%-20% of an iron salt, 0.001%-15% ascorbic acid or derivatives thereof and 0.001%-15% citric acid or derivatives thereof.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: Image of Comparative Compositions 1-3 and Composition 4 of the invention described in Table 1, at room temperature (RT).
Figure 2: Image of the hands of the subject S1 before application of the composition.
Figure 3: Image of the hands of the subject S1 after application of Comparative Composition 1 (left hand) and Comparative Composition 2 (right hand) taken after one minute, after ten minutes and after rubbing and drying the composition.
Figure 4: Image of the hands of the subject S2 before application of the composition.
Figure 5: Image of the hands of the subject S2 after application of Comparative Composition 3 (left hand) and Composition 4 of the invention (right hand) taken after one minute, after ten minutes and after rubbing and drying the composition.
Figure 6: Image of Control white hair swatch and white hair swatches 1-4 before the application of the composition.
Figure 7: Image of hair swatches 1-4 after a single application of the Comparative Compositions 1-3 and Composition 4 of the invention and Control white hair swatch (untreated) taken after time interval of (a) 2 minutes; (b) 10 minutes; (c) 30 minutes; (d) 1 hour; (e) 5 hours and (f) 18 hours.
Figure 8: Graph showing the L*(D65) values for hair swatch treated with Comparative Compositions 1-3, Composition 4 of the invention and Control (untreated hair swatch) at time interval of (a) 2 minutes; (b) 10 minutes; (c) 30 minutes; (d) 1 hour; (e) 5 hours and (f) 18 hours.
Figure 9: Graph of L*(D65) value against time for hair swatch treated with Comparative Compositions 1-3 and Composition 4 of the present invention.
Figure 10: Graph of percent reflectance (R) against wavelength (nm) for hair swatch H-1: a hair swatch containing 100 white hairs and 5000 natural black hair; H-2: a hair swatch containing 100 white hairs and 5000 natural black hair treated with Composition 4 of the invention; H-3: a hair swatch containing 5100 natural black hair; H-4: a hair swatch containing 100 white hairs and 5000 natural black hairs, dyed black with commercial cream based dye containing p-Phenylenediamine (PPD) and H-5: a hair containing 100 white hairs and 5000 natural black hairs dyed black with commercial powder based dye containing PPD.
Figure 11: Graph showing the L*(D65) value after 18 hours for hair swatch treated with Comparative Compositions 1-3, Compositions 4-12 of the present invention and Control (untreated hair swatch).

DETAILED DESCRIPTION OF THE INVENTION
In an aspect, the present invention relates to a single phase composition comprising 0.001%-1% polyphenol, 0.001%-20% of an iron salt, 0.001%-15% ascorbic acid or derivatives thereof and 0.001%-15% citric acid or derivatives thereof.

The polyphenol is selected from gallic acid and its esters, tannic acid and its esters, hematoxylin, anthocyanins or a combination thereof. The esters of gallic acid are selected from methyl gallate, palmityl gallate, ethyl gallate, propyl gallate, butyl gallate, hexyl gallate, octyl gallate, lauryl gallate, behenyl gallate or a combination thereof. The anthocyanins are selected from cyanidin, delphinidin, peonidin, malvidin, or their glucosides or a combination thereof.

Iron salt is selected from the group comprising of ferrous chloride, ferrous stearate, ferrous palmitate, ferrous gluconate, ferrous sulfate (ferrous sulphate heptahydrate), ferric chloride or a combination thereof.

The citric acid derivatives are selected from water soluble derivatives such as citric acid monohydrate and hydroxy citric acid , oil soluble derivatives such as citric acid esters of mono- and diglycerides for example CITREM E472c, or a combination of water soluble and oil soluble derivatives.

The ascorbic acid derivatives are selected from water soluble derivative such as l-ascorbic acid 2-glucoside, oil soluble derivatives such as esters of ascorbic acid for example ascorbyl palmitate and ascorbyl tetra palmitate, or a combination of water soluble and oil soluble derivatives.

The single phase composition of the invention is colorless and does not stain the skin and is therefore non-toxic.

The pH of the composition is in a range of pH 1-4. Preferably, the pH of the composition is in a range of 2.5-3.5.

In another aspect, the invention relates to a process for preparing a single phase composition. The process comprises mixing 0.001%-1% polyphenol, 0.001%-20% of an iron salt, 0.001%-15% ascorbic acid or derivatives thereof and 0.001%-15% citric acid or derivatives thereof.

The polyphenol, iron salt and derivatives of ascorbic acid and citric acid are described in the above paragraphs.

The process of the invention reduces number of steps, making current process more economical. Cost reduction in terms of packaging the two separate phases.

The invention also relates to a hair darkening composition comprising the single phase composition and one or more excipient. The hair darkening composition is a water-based composition or an oil-based composition.

In an embodiment, the hair darkening composition is a water-based composition comprising 0.001%-1% gallic acid, 0.001%-20% ferrous sulphate heptahydrate, 0.001%-15% ascorbic acid, 0.001%-15% citric acid monohydrate, and one or more excipient.

In another embodiment, the hair darkening composition is an oil-based composition comprising 0.001%-1% propyl gallate, octyl gallate or a combination thereof, 0.001%-20% ferric chloride, 0.001%-15% ascorbyl palmitate, 0.001%-15% citric acid monohydrate, citric acid esters of mono- and diglycerides or a combination thereof, and one or more excipient.

The excipient is a cosmetically acceptable ingredient and is selected from but not limited to solvent, surfactant, moisturizing agent, preservative, viscosity modifier, buffering agent, biological actives, fragrance, delivery system or a combination thereof.

Solvent includes water, an alcoholic solvent selected from but is not limited to ethyl alcohol, propylene glycol, polyethylene glycol 400, pentylene glycol, D-panthenol or a combination thereof, oils such as safflower hydrolyzed oil, refined sesame oil, isopropyl myristate, refined rice bran oil, refined coconut oil or a combination thereof.

Surfactant includes hydrogenated castor oil derivatives such as but not limited to polyethylene glycol derivative of hydrogenated castor oil for example polyethylene glycol (PEG)-40 hydrogenated castor oil (available under the tradename of Cremophor RH 40), laureth-4 (available under the tradename of Brij L4), or a combination thereof.

Moisturizing agent includes glycerin, vitamin E acetate, fatty acid, dimethicone or a combination thereof. Examples of moisturizing agent include but is not limited to, copolymer of polydimethylsiloxane and organic glycol (available under the tradename of Belsil OW 2100).

Preservative includes hydroquinone derivatives such as tert-Butylhydroquinone (TBHQ), an alcohol such as phenoxy ethanol, or a combination thereof.

Viscosity modifier includes silicone polymers such as cyclomethicone (SF1202), polyacrylate cross polymer such as but not limited to polyacrylate cross polymer-6 (available under the tradename of Sepimax Zen) or a combination thereof.

Buffering agent includes an amine such as triethanol amine.

Biological actives includes flavones such as apigenin, labdane diterpene such as forskolin, plant actives such as aloe vera extract, grapeseed extract etc. Preferably, biological actives are selected from apigenin, forskolin, plant extract, or a combination thereof.

Delivery system includes phospholipid such as but not limited to Lipoid P-75.

The hair darkening composition can be colorless or colored based on the colour of the excipients. For example, the hair darkening composition containing Lipoid P-75 is light brown in color due to the brown color of Lipoid P-75.

The hair darkening composition can be formulated as a liquid, cream, gel or an aerosol. The cream can be a water in oil emulsion or oil in water emulsion.

The hair darkening composition provides a progressive hair darkening effect and being a single phase composition is easy to handle and use.

Whereas in the dual phase composition, polyphenol and iron salt are packaged separately and require mixing of the polyphenol and iron salt prior to application thereby making handling and usage of the composition messy. Also, in such compositions both the parts are required to be mixed in a defined proportion to achieve the desired hair darkening effect. When the dual phase composition is mixed in hand, the reaction between polyphenol and the iron salt produces the colored complex immediately thereby staining the skin. This results in low consumer acceptability of dual phase hair darkening composition.

The single phase hair darkening composition of the present invention is colorless and does not stain the skin during application. Citric acid is a bleaching agent and an antioxidant and therefore can effectively remove the stains. Ascorbic acid is an anti-oxidant. Presence of both citric acid and ascorbic acid in the single phase composition reverses the oxidation state of iron salts from Fe+3 (ferric) to Fe+2 (ferrous), thereby delaying the reaction between polyphenol and Fe+3 ions which results in a dark colored complex. This delays the colouring effect till the composition is applied on the hair, thereby preventing staining of skin during application. The delayed reaction between polyphenol and iron salt provides an improved compatibility between the ingredients thereby making it possible to incorporate both in a single composition which overcomes the need of separate packaging and mixing prior to application as required in dual phase composition. The hair darkening composition does not stain the skin therefore, gloves are not required to be worn by the user for applying the composition on hair. The hair darkening composition provides progressive hair darkening. This means that the darkening effect of hair increases with time. Also, the hair darkening composition does not stain the scalp thereby providing a natural appearance to the darkened hair unlike the commercial synthetic hair dyes which stain the scalp while applying to hair, thereby providing a higher consumer acceptability.

EXAMPLES
Example 1
Preparation of single phase composition
A single phase composition according to the invention (Composition 4) was prepared by mixing 0.17 % gallic acid, 0.27% ferrous sulphate heptahydrate (FeSO4.7H2O), 1.08% ascorbic acid and 1.05% citric acid monohydrate.

Comparative Examples
Composition 1 contained 0.17 % gallic acid, 0.27% ferrous sulphate heptahydrate but did not contain ascorbic acid and citric acid.

Composition 2 contained 0.17 % gallic acid, 0.27% ferrous sulphate heptahydrate and 1.08% ascorbic acid but did not contain citric acid.

Composition 3 contained 0.17 % gallic acid, 0.27% ferrous sulphate heptahydrate, 1.05% citric acid monohydrate but did not contain ascorbic acid.

The pH of Comparative Compositions 1-3 and Composition 4 of the present invention was in range of 1-4. Table 1 shows the composition of Comparative Compositions 1-3 and Composition 4 of the present invention.

Table 1
Ingredients (% wt.)
Comparative Composition 1 Comparative Composition 2 Comparative Composition 3 Composition 4
Gallic Acid 0.17 0.17 0.17 0.17
FeSO4.7H2O 0.28 0.28 0.28 0.28
Ascorbic acid
(Vitamin C) - 1.08 - 1.08
Citric acid monohydrate - - 1.05 1.05
pH 2.58 2.63 2.01 2.12

Evaluation of Composition
Figure 1 shows the image of the Comparative Compositions 1-3 and Composition 4 of the invention described in Table 1, at room temperature (RT).

From the figure it can be seen that Comparative Composition 1 without citric acid and ascorbic acid was dark colored this was due to the reaction between gallic acid and ferrous sulphate.

Comparative Composition 3 containing gallic acid, ferrous sulphate and citric acid was light green colored.

While Comparative Composition 2 and Composition 4 of the invention was colorless.

This indicates that single phase composition containing ascorbic acid was colorless.

Example 2
Evaluation of skin staining by the single phase composition
The skin staining by the Comparative Compositions 1-3 and Composition 4 of the invention described in Example 1 was evaluated visually by taking the composition in hand. The image of the hands of the subjects (S1 and S2) before application of composition was taken. Then, a small amount each composition was applied in the palm of the hand and images were taken at time intervals of one minute, ten minutes and after rubbing and drying the composition. The images before and after application were compared to evaluate skin staining.

Figure 2 shows the image of the hands of the subject S1 before application of the composition.

Figure 3 shows the image of the hands of the subject S1 after application of Comparative Composition 1 (left hand) and Comparative Composition 2 (right hand). The images were taken after one minute, after ten minutes and after rubbing and drying the composition. Comparing the image of left hand after rubbing and drying the composition with the image before application and after one minute of application of the composition, it can be seen that Comparative Composition 1 containing only gallic acid and ferrous sulphate resulted in darkening of the skin of the hand.

The image of the right hand after one minute of applying the Comparative Composition 2 containing gallic acid, ferrous sulphate and ascorbic acid showed that the composition was colorless. While after ten minutes, the composition darkened in color. After rubbing and drying the composition, the skin of the right hand appeared darker than the skin before application of Comparative Composition 2 and after one minute of application of the composition. This was attributed to the presence of ascorbic acid which delayed (slower rate) the oxidation and thereby delayed the staining in comparison to Comparative Composition 1.

Figure 4 shows the image of the hands of the subject S2 before application of the composition.

Figure 5 shows the image of the hands of the subject S2 after application of Comparative Composition 3 (left hand) and Composition 4 of the invention (right hand). The images were taken after one minute, after ten minutes and after rubbing and drying the composition.

The image of the left hand after one minute of application of Comparative Composition 3 comprising gallic acid, ferrous sulphate and citric acid showed that composition appeared to be very light green in color. After ten minutes, the was no change in the color of the composition. Even, after rubbing and drying Comparative Composition 3, no darkening of skin of the hand was observed in comparison with the image taken before application of the composition.

The image of the right hand after one minute of application of Composition 4 of the invention comprising gallic acid, ferrous sulphate, ascorbic acid and citric acid showed that composition appeared to be colorless. After ten minutes, there was no change in the color of the composition and after rubbing and drying the Composition 4, no darkening of skin of the hand was observed in comparison with the image taken before application of the composition. This was attributed to the presence of both citric acid monohydrate and ascorbic acid which further delayed the oxidation reaction such that there was no staining even after 10 minutes and after rubbing and drying the composition on the skin.

The above results indicate that the Comparative Compositions 1-2 stained the skin either immediately after application or after rubbing and drying the composition. While Comparative Composition 3 did not stain the skin, but the composition had a light green color and was not colorless as Composition 4 of the invention.

Composition 4 comprising gallic acid, ferrous sulphate, ascorbic acid and citric acid did not stain the skin. This was attributed to the presence of citric acid and ascorbic acid. Ascorbic acid is an anti-oxidant. Citric acid is a bleaching agent and an antioxidant that effectively removes stains. Also, during the testing period complete oxidation of both citric and ascorbic acid had not taken place thereby preserving the Fe+2 state (ferrous) of the iron salt and not allowing formation of Fe+3state (ferric) which gives dark colour with gallic acid.

From the results of Example 1 and Example 2, it can be seen that the single phase composition of the invention comprising both ascorbic acid and citric acid, synergistically provided a colorless composition that also did not stain the skin. This is advantageous when the single phase composition is a part of a hair darkening composition as the composition darkens the hair without staining the scalp thereby providing a natural dark appearance to the hair unlike that achieved by commercial synthetic hair dyes which stain the scalp and hair and visually indicate dyeing of hair.

Example 3
Evaluation of progressive hair darkening by the single phase composition of the present invention.
The CIELAB color space (also known as CIE L*a*b* or sometimes abbreviated as simply "Lab" color space) is a color space defined by the International Commission on Illumination (CIE) in 1976. It expresses color as three values: L* for the lightness from black (0) to white (100), a* from green (-) to red (+), and b* from blue (-) to yellow (+). CIELAB was designed so that the same amount of numerical change in these values corresponds to roughly the same amount of visually perceived change.

The CIE 1976 L*a*b* color space (also referred to as CIELAB) is one of the most popular color spaces for measuring object colors. It was defined by International Commission on Illumination (abbreviated CIE) in 1976 for color communication and is widely adopted today in many industries for color control and management.

In the L*a*b* color space, L* indicates lightness and a* and b* are chromaticity coordinates, a* and b* are color directions: +a* is the red axis, -a’ is the green axis, +b* is the yellow axis and -b* is the blue axis.

Area around the center represents achromatic colors and moving outwards, color saturation increases. If we measure the apple with a spectrophotometer or chroma meter, we get the following values:
L* = 43.31, a* = 47.63, b* = 14.12

Plotting the a* and b* on the color space shows the chromaticity of the apple and the L* expresses the lightness of the color.

Comparative Compositions 1-3 and Composition 4 of the invention described in Table 1 were applied to white hair swatches and CIE L* value (index of whiteness/darkness) of these hair swatches was measured at different time intervals with their photographs. A hair swatch not treated with the composition was used a Control.

Figure 6 shows the image of the white hair swatches before the application of the composition.

Figure 7a-7f shows the image of hair swatches after a single application of the Comparative Compositions 1-3 and Composition 4 of the invention. The images were taken after time interval of 2 minutes, 10 minutes, 30 minutes, 1 hour, 5 hours and 18 hours. In the Figure 7a-7f, 1 represents hair swatch treated with Comparative Composition 1 (without citric acid and ascorbic acid), 2 represents hair swatch treated with Comparative Composition 2 (without citric acid), 3 represents hair swatch treated with Comparative Composition 3 (without ascorbic acid) and 4 represents hair swatch treated with Composition 4 of the invention (containing both citric acid and ascorbic acid).

The L*(D65) for each composition at different time intervals (2 minutes, 10 minutes, 30 minutes, 1 hour, 5 hours and 18 hours) was also represented graphically in Figure 8a-8f. Figure 9 is a graph of L*(D65) against time for Comparative Compositions 1-3 and Composition 4 of the present invention. The lowering of L* values indicates darkening of hair (i.e. more black).

Comparative Composition 1 immediately darkended the hair (hair swatch 1) to give a black colour after 2 minutes of application (Figure 7a). As shown in Figure 8a, Comparative Composition 1 reduced L*(D65) value to 28.7, while L*(D65) value for the Control untreated hair swatch was 68.2. The color of the hair swatch 1 appeared slightly darker after 10 and 30 minutes of application of Comparative Composition 1 (Figures 7b and 7c). A further decrease in L*(D65) value was also observed after 10 and after 30 minutes of application of Comparative Composition 1 as shown in Figures 8b and 8c.

As shown in Figure 7d, after 1 hour of application, the color of hair swatch 1 appeared to slightly lighten from the dark color observed after 30 minutes. The L*(D65) value for Comparative Composition 1 after 1 hour also showed a slight increase (Figure 8d).

The lightening of the color of hair swatch 1 increased after 5 hours and after 18 hours (Figure 7e and 7f). As observed from Figure 8e and 8f, it can be seen that L*(D65) value for Comparative Composition 1 increased to 27.8 and 30.1. After 5 hours, the L*(D65) was near to the value after 2 minutes (28.7) of application of Comparative Composition 1. After 18 hours, the L*(D65) value further increased. This indicates that Comparative Composition 1 provided an immediate hair darkening effect after single application as the coloured complex by reaction of gallic acid with ferous sulphate was already formed. However, after 18 hours the dark color started to fade away.

Comparative Composition 2 darkended the hair to a light grey color (hair swatch 2) after 2 minutes of application (Figure 7a). As show in Figure 8a, the Comparative Composition 2 reduced L*(D65) value to 50.9 which was lower than the Control untreated hair swatch, but greater than Comparative Composition 1.

After 10 minutes, hair swatch 2 appeared to be darker in colur than that observed after 2 minutes. Figure 8b also shows that after 10 minutes, L*(D65) value for Comparative Composition 2 was 29.8 in comparision to 50.9 after 2 minutes. The hair swatch appeared slightly datker after 30 minutes of application of Comparative Composition 2 (Figure 7c). A further decrease in L*(D65) value to 25.4 was also observed after 30 minutes of application as shown in Figure 8c, this was similar to that obtained with Comparative Composition 1 after 30 minutes.

As shown in Figure 7d, after 1 hour of application, the color of hair swatch 2 appeared to lighten from the dark color observed after 30 minutes. The L*(D65) value for Comparative Composition 2 after 1 hour also showed a slight increase (Figure 8d).

As shown in Figure 7e, after 5 hours of the application, the color of hair swatch 2 appeared more dark than the color observed after 1 hour of application. The L*(D65) value for Comparative Composition 2 after 5 hours of application (Figure 8e) showed a decrease as compared to that observed after 30 minutes and after 1 hour of application.

However, after 18 hours of application, hair swatch 2 was light grey in color (Figure 7f). Figure 8f shows that L*(D65) value for Comparative Composition 2 increased to 25.7 in comparison to the value after 5 hours of application (24.4).

This indicates that Comparative Composition 2 containing only ascorbic acid provided a darkening effect after 10 minutes similar to Comparative Composition 1, this delay was attributed to the anti-oxidant effect of ascorbic acid which resulted in a lesser hair darkening after 2 minutes of application of the composition, but as the ascorbic acid was completely consumed within 10 minutess, the hair darkening effect increased. However, as observed from the L*(D65) values in Figures 8a-8f, the result of hair darkening with Comparative Composition 2 was not satisfactory as the there was no consistent decerase in the L*(D65) values with time.

Comparative Composition 3 darkended the hair (hair swatch 3) to a reduced extent after 2 minutes (Figure 7a) and after 10 minutes (Figure 7b) of application of the composition than Comparative Compositions 1 and 2. The L*(D65) values after 2 minutes and after 10 minutes were 54.9 (Figure 8a) and 52.6 (Figure 8b), respectively.

After 30 minutes, hair swatch 3 appeared slightly lighter in color than after 10 minutes (Figure 7c). The L*(D65) value for Comparative Composition 3 after 30 minutes also showed a slight increase to 53.7 (Figure 8c). The colour and L*(D65) value remained almost the same after 1 hour of application (53.1) (Figure 7d and 8d).

However, after 5 hours of application, color of hair swatch 3 faded to a greater extent in comparison to colour after 1 hour. The L*(D65) value for Comparative Composition 3 after 5 hours was 61.4 i.e. near to that for the control untreated hair swatch.

After 18 hours of application, color of hair swatch 3 again darkened (Figure 7f). The L*(D65) value for Comparative Composition 3 after 18 hours decreased to 56.4 in comparison to that obtained after 5 hours. However, at the end of test period of 18 hours the L*(D65) value for Comparative Composition 3 was higher than that obtained after 2 minutes. This indicates that composition comprising only citric acid resulted in a decreased hair darkening effect. This can be attributed to the bleaching effect of citric acid.

Composition 4 of the invention showed a hair darkening effect (hair swatch 4) after 2 minutes and 10 minutes in comparison to the Control untreated hair swatch (Figure 7a and 7b). The L*(D65) value for Composition 4 after 2 minutes and 10 minutes of application was 56.9 (Figure 8a) and 55.7 (Figure 8b), respectively.

After 30 minutes, hair swatch 4 treated with Composition 4 showed a greater darkening of color than hair swatch 3 treated with Comparative Composition 3 (Figure 7c). The L*(D65) value for Composition 4 was 50.4 i.e. less than that obtained with Comparative Composition 3 after 30 minutes (53.7) (Figure 8c).

The effect of hair darkening of Composition 4 further increased after 1 hour, after 5 hours and after 18 hours of application in comparison to Comparative Composition 3 (Figures 7d-7f).

The L*(D65) value for Composition 4 was also less after 1 hour, after 5 hours and after 18 hours than Comparative Composition 3. This indicates that Composition 4 after a single application resulted in progressive hair darkening effect i.e. increase in hair darkening with time.

Whereas, Comparative composition 1, resulted in fading away of hair colour after 30 minutes of application. Comparative composuition 2, resulted in an inconsistent hair darkening and would require multiple applications in a day to get a desired result. Comparative composition 3 resulted in fading away of the hair colour after 5 hours of application.

Example 4
Naturalness index of hair darkening with the single phase composition of the present invention.
A black object is black because it absorbs all the light without reflecting any color. The percent reflectance of colour of hair swatch containing 100 white hairs and 5000 natural black hair treated with Composition 4 (H-2) of the invention was measured by Konica Minolta spectrophotometer (CM-2600d). The percent reflectance of H-2 was compared with the comparative examples described below:
H-1: a hair swatch containing 100 white hairs and 5000 natural black hair,
H-3: a hair swatch containing 5100 natural black hair,
H-4: a hair swatch containing 100 white hairs and 5000 natural black hairs, dyed black with commercial cream based dye containing p-Phenylenediamine (PPD),
H-5: a hair containing 100 white hairs and 5000 natural black hairs dyed black with commercial powder based dye containing PPD.

The decrease in percent reflectance indicates darkening of hair.

Figure 10 is a graph of percent reflectance (R) against wavelength. The Figure shows that hair swatch (H-2) treated with Composition 4 had percent reflectance in between the hair swatch H-1 and H-3. The percent reflectance of H-2 was close to H-3. This indicates that that Composition 4 provided a natural hair darkening effect to the hair which is desired by the consumer than that obtained by commercial synthetic dyes containing p-Phenylenediamine.

Example 5 (Composition 5)
A water based hair darkening composition comprising the single phase composition is disclosed below:
Ingredient % wt.
Propylene Glycol 0.8
Polyethylene glycol 400 0.5
Cremophor RH 40 1.2
Gallic Acid 0.17
Pentylene glycol 1.5
Glycerin 1
D-Panthenol 0.2
Ferrous sulphate heptahydrate (FeSO4.7H2O) 0.28
Ascorbic acid 1.08
Citric acid monohydrate 1.05
Phenoxyethanol 0.3
Fragrance 0.4
Sepimax Zen 0.25
Triethanolamine (50%) 1
Belsil OW 2100 0.5
Water Q.S. to 100
pH 2.5

Example 6 (Composition 6)
An oil based hair darkening composition comprising the single phase composition is disclosed below:
Ingredient % wt.
Laureth-4 (Brij L4) 3.5
Alcohol (Ethyl Alcohol) 15
Cyclomethicone (SF1202) 10
Ferric Chloride (FeCl3) 0.08
Citric acid monohydrate 0.3
Ascorbyl palmitate 0.3
Vit. E acetate 0.4
Safflower hydrolyzed oil 10
Refined sesame oil 10
Isopropyl myristate 10
Refined Rice bran Oil 10
Octyl gallate 0.08
TBHQ (tert-Butylhydroquinone) 0.05
Fragrance 0.9
Refined coconut oil Q.S. to 100

Further, water based and oil based hair darkening composition with different amounts of polyphenol, iron salt, citric acid, ascorbic acid according to the present invention as described below, were tested for hair darkening effect.

Water based compositions
Ingredients (% wt.)
Composition 7 Composition 8 Composition 9 Composition 10 Composition 11 Composition 12
Gallic acid 0.001 1 - - 0.5 1
Tannic acid - - 0.001 1 0.5 -
Ferric chloride - - 0.001 20 - 10
Ferrous Sulphate 0.001 20 - - 20 10
Ascorbic acid
(Vitamin C) 0.001 15 0.001 15 15 15
Citric acid monohydrate 0.001 15 0.001 15 15 15
Water Q.S. to 100 Q.S. to 100 Q.S. to 100 Q.S. to 100 Q.S. to 100 Q.S. to 100
pH 2.91 2.03 2.84 2.17 2.88 2.93

Oil based compositions
Ingredients (%wt.)
Composition 13 Composition 14
Octyl Gallate 0.001 -
Propyl Gallate - 0.3
Ferric chloride 0.001 0.16
Ascorbyl palmitate 0.001 0.83
Citric acid monohydrate 0.001 2
Ethyl alcohol 1 5
Refined coconut oil Q.S. to 100 Q.S. to 100

The Compositions 5-12 were colourless and did not stain the skin.

As shown in Figure 11, hair swatch treated with Compositions 5-12 all provided a decrease in the L*(D65) value after 18 hours in comparison to the Control hair swatch. This indicates that the Compositions 5-12 provided a progressive hair darkening effect.

In view of the above data, it can be seen that a composition comprising polyphenol, iron salt, citric acid and ascorbic acid afforded compatibility between polyphenol and iron salts therby allowing both the ingredients to be present in a single composition without reacting with each other. The composition of the invention was colorless and did not stain the skin while at the same time advantageously providing a progressive darkening effect to the hair and also retaining a natural appearance of the colored hair. Thus, the composition of the invention while overcoming the disadvantages of the dual phase composition has ingredients that are safe for the skin and hair which also eliminates the toxic effects of commercial synthetic hair dyes.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.