CH711956B1 - Cosmetic composition having anti-radical properties. - Google Patents

Abstract

The present invention relates to compositions with anti-free radical properties for topical use comprising allantoin and at least one extract from one or more plants as active principles chosen from Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis , Harpagophytum procumbens, and Ruscus aculeatus. The invention also relates to cosmetic methods, on the one hand for improving and / or preventing the signs of aging of the skin, on the other hand for improving and / or promoting skin repair, and a process for preparing said skin cosmetic compositions.

Description

Description

FIELD OF THE INVENTION The present invention relates to compositions with anti-free radical properties for topical use comprising at least one extract of one or more plants as active principles, their use on the one hand for the improvement and / or prevention of signs of aging of the skin, on the other hand to improve and / or promote skin repair, and methods of preparation of said compositions.

Context of the invention [0002] Aging is a natural phenomenon with which every individual is confronted. The most visible signs of aging appear on the face, the skin losing its tone and the first wrinkles appear.

The skin is vulnerable to attack by free radicals. These oxidizing molecules can prove to be dangerous in the event of excess and in particular play an important role in skin aging.

Free radicals, generated by the normal functioning of the human body, generally balance with antioxidant molecules. The natural antioxidant defense mechanisms of the skin involve molecules such as vitamin E, vitamin C, selenium, or enzymes. The main property of these antioxidant molecules is to trap free radicals in the body in order to maintain the balance between free radicals and antioxidant molecules.

Free radicals are also produced under the influence of external elements such as pollution, tobacco or UV rays. In some situations, the density of antioxidants decreases, while the level of free radicals increases. The natural balance between free radicals and antioxidant molecules is then disturbed creating oxidative stress. This stress makes them aggressive towards the organism, in particular vis-à-vis the fundamental elements of the skin, such as (in particular) keratinocytes, fibroblasts, as well as the production of collagen and elastin. The consequences of aggression on the skin by free radicals are manifold and the most common are its loss of resistance and elasticity.

Many solutions have been developed in an attempt to slow the appearance of these signs of aging or to repair the signs already installed.

In this context, it is important to provide compositions with anti-free radical properties to strengthen the natural defenses of the skin and help it to fight against free radicals.

Summary of the invention [0008] The invention relates to a cosmetic composition comprising:

- an aqueous phase,

- at least one extract from one or more plants as active ingredients, chosen from the group comprising Mimosa tenuiflora, Limnanthesalba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus,

- allantoin and

- at least one suitable adjuvant.

According to another object, the present invention relates to a method for preventing and / or improving the signs of skin aging, in which said cosmetic composition is applied to the skin.

The invention also relates to the use of said cosmetic composition for topical use to protect the skin against free radicals.

According to another object also, the present invention relates to a composition comprising:

- an aqueous phase,

- at least one extract from one or more plants as active ingredients, chosen from the group comprising Mimosa tenuiflora, Limnanthesalba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus,

- allantoin and

- at least one suitable adjuvant.

Another object of the invention is the use of said composition to improve and / or promote skin repair, comprising the topical application of said composition.

Another object of the invention relates to a method of manufacturing said cosmetic composition or said composition comprising the following steps:

a) prepare an aqueous solution of allantoin at least 0.1%;

CH 711 956 B1

b) mixing said aqueous solution of allantoin with an extract of one or more plants as active principles, said plants being chosen from the group comprising Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens and Ruscus aculeatus, and

c) add to the mixture b) at least one suitable adjuvant.

Another object of the invention is a kit comprising said cosmetic composition.

Brief description of the figures

Fig. 1 represents the paramagnetic resonance spectra of the electron: trapping activity of superoxide radicals in the presence or absence of the product at concentrations of 0.1; 0.25; and 5%, or of the reference molecule, the SOD at 400 IU / ml.

Fig. 2 shows the paramagnetic resonance spectra of the electron: trapping activity of hydroxyl radicals in the presence or absence of the product at concentrations of 0.03, 0.33 and 1.6% (w / v) or of the reference molecule, 10 mM mannitol (0.182%, w / v).

Fig. 3 shows the effects of the cosmetic composition and of the SOD on the RPE signal of the DMPO / superoxide radical complex.

Fig. 4 shows the effects of the cosmetic composition and of the SOD on the RPE signal of the DMPO / hydroxy radical complex.

Fig. 5 shows the effects of the cosmetic composition at time o, after 3 months and 5 months of use due to daily applications.

Detailed description of the invention The purpose of the invention described below is to propose a cosmetic composition comprising:

- an aqueous phase,

- at least one extract from one or more plants as active ingredients, chosen from the group comprising Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus,

- allantoin and

- at least one suitable adjuvant.

Preferably, the cosmetic composition according to the invention comprises as active principles between 0.01 and 50% by weight of at least one extract from one or more plants chosen from the group comprising Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus. Even more preferably, the cosmetic composition according to the invention comprises as active principles between 0.01 and 5% by weight of at least one extract from one or more plants chosen from the group comprising Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus.

Furthermore, the cosmetic composition according to the invention comprises an aqueous phase representing from 50 to 90% by weight, preferably from 60 to 80% by weight, relative to the total weight of the composition.

The cosmetic composition according to the invention also comprises allantoin. Allantoin is a nitrogenous chemical compound of organic or vegetable origin. It can be extracted from the mucus of certain gastropods or from the roots of the big comfrey and cereal seeds. Preferably, the composition comprises at least 0.1% of allantoin.

The cosmetic composition according to the invention comprises at least one adjuvant chosen from sequestering agents, antioxidants, sun filters, preservatives, fillers, dyes, perfumes, essential oils, cosmetic active agents, moisturizers, vitamins, essential fatty acids, sphingolipids, self-tanning compounds, soothing and protective agents for the skin, or mixtures thereof.

The cosmetic composition according to the invention may also contain at least one pro-penetrating and / or humectant agent, chosen from the group comprising propylene glycol, glycerin or sorbitol.

In a particular embodiment, the cosmetic composition according to the invention consists of:

Water 68.9239%

Limnanthes alba 2.0000%

CH 711 956 B1

Arnica montana 0.2000% Mimosa tenuiflora 0.6000% Calendula officinalis 0.2000% Harpagophytum procumbens 0.2000% Ruscus aculeatus 0.2000% Glycerin 5.5440% Cetaryl isononanoate 4.0000% Dicaprylyl carbonate 4.0000% Cetaryl ethylhexanoate 3.0000% Cetaryl alcohol 2.5000% Glycerin stearate 2.2000% Isopropyl myristate 2.0000% Propylene glycol 1.8940% Potassium cetyl phosphate 0.8000% Levulinic acid 0.4050% Carbo mother 0.3800% Chlorphenesin 0.2800% Allantoin 0.2000% Sodium hydroxide 0.1956% Sodium levulinate 0.0900% O-cymen-5-ol 0.0800% Citric acid 0.0280% Potassium sorbate 0.0240% Tetrasodium glutamate-diacetate 0.0235%

Sorbitol

0.0040%,% by weight, relative to the total weight of the composition.

The cosmetic composition according to the invention can be in all dosage forms normally used for topical application, in particular in the form of a cream, an oil-in-water emulsion, a water-in emulsion -oil, of a multiple emulsion, of a solution, of a suspension, of a powder, of an aqueous, hydroalcoholic or oily solution, of an aqueous or oily gel, of a liquid, pasty anhydrous product or solid, of an oil dispersion in an aqueous phase using spherules (nanospheres, nanocapsules, lipid vesicles), a transdermal device or in any other form for topical application.

In emulsions, either in "water-in-oil" form or in "oil-in-water" form, the direction of the emulsion is generally imparted by the emulsifying agent used.

Quite surprisingly, it has been found that the cosmetic composition according to the invention can be used effectively with a prolonged effect in a method for preventing and / or improving the signs of skin aging, in which said composition is applied to the skin.

As shown in Examples 3 and 4 (Fig. 5), the effects of the composition according to the invention to prevent and / or improve the signs of skin aging are visible and effective after application of the composition in the form of a cream. These visible effects are in particular protective effects linked to anti-radical properties and repairing effects of skin damage.

CH 711 956 B1 [0027] The invention also relates to the use of a cosmetic composition comprising:

- an aqueous phase,

- at least one extract from one or more plants as active ingredients, chosen from the group comprising Mimosa tenuiflora, Limnanthesalba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus,

- allantoin and

- at least one suitable adjuvant, for topical use to protect the skin against free radicals.

In the context of the present invention, free radicals are atoms or molecules which have gained or lost an electron such as the superoxide radical (or superoxide anion) and the hydroxyl radical.

Thus, the invention relates to the use of said cosmetic composition for topical use to protect the skin against the superoxide anion and the hydroxyl radical.

As shown in Example 1, the composition according to the present invention exhibits quite remarkable anti-radical properties with respect to the superoxide anion and the hydroxyl radical.

On the other hand, a composition comprising:

- an aqueous phase,

- at least one extract from one or more plants as active ingredients, chosen from the group comprising Mimosa tenuiflora, Limnanthesalba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus,

- allantoin and

- At least one suitable adjuvant can also be used to improve and / or promote skin repair, by topical application of said composition.

According to another object, the present invention relates to a process for manufacturing said cosmetic composition comprising the following steps:

a) prepare an aqueous solution of allantoin at least 0.1%;

b) mixing said aqueous solution of allantoin with an extract of one or more plants as active principles, said plants being chosen from the group comprising Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens and Ruscus aculeatus, and

c) add to the mixture b) at least one suitable adjuvant.

According to the present invention, the cosmetic composition comprises adjuvants chosen from the group comprising pro-penetrating agents, and / or humectants (such as propylene glycol, glycerin or sorbitol).

The cosmetic composition can also comprise the usual adjuvants in the cosmetic field chosen from the group comprising stabilizers, preservatives, antioxidants, solvents, perfumes, chelating agents, odor absorbers, chemical filters or minerals, mineral pigments, surfactants, polymers, silicone oils, colorants, emulsifiers, thickeners, gelling agents, water fixatives and spreading agents.

Advantageously, the content of the extract is between 0.01% and 10% by weight, preferably 0.05% and 10% by weight, even more preferably between 0.1% and 10% by weight, even more preferably between 0.5% and 5% by weight, relative to the total weight of the composition.

The present invention also relates to a kit in the form of a container such as an ampoule or a bottle containing the cosmetic composition as described above.

The invention will now be illustrated without implied limitation by the following examples 1 to 4:

Examples

Example 1

Measurement of the anti-free radical activity of the cosmetic composition The reference products, mannitol and superoxide dismutase (SOD), were supplied by SIGMA.

The cosmetic composition, the reference molecules and the reagents used were prepared in ultrapure water (Milli Q).

CH 711 956 B1 The measurement of the anti-radical activity was carried out by the electron paramagnetic resonance spectrometry technique (ROSEN G.Μ., HALPERN HJ; Spin trapping biologically generated free radicals: correlating formation with cellular injury; Methods in Enzymology. 1990; 186, 611-621).

In this method, the spin states of the single electrons of the molecules, in particular in the free radicals, are characterized. In practice, free radicals are produced in the apparatus; a probe molecule called spin trap resonates in their presence and the corresponding signal is analyzed. A radical scavenger molecule decreases the signal of the spin trap. The RPE measurements were carried out with a Brucker ECS 106 spectrometer, at ambient temperature. The spin trap used was 5.5 dimethyl-1-pyrroline-1-oxide (DMPO).

The superoxide anion was produced by the xanthine / xanthine oxidase enzyme system. The product was dissolved in ultrapure water at various concentrations. A control without product was carried out in parallel. The SOD at 400 IU / ml was tested for reference (positive control).

The hydroxyl radical was produced by photolysis (UVB) of hydrogen peroxide in aqueous solution. The product was dissolved in ultrapure water at various concentrations. A control without product was carried out in parallel. The 10 mM mannitol (i.e. 0.182 mg / ml) was tested for reference (positive control).

The intensities of the RPE signal were calculated by double integration of the lower field line. The percentages of protection of the test product were obtained from the values of the controls without the test product.

% Protection = (Sproduit - Stémoin) / (So - Stémoin) X100

Sproduit: integration of the RPE signal obtained with the test product or the reference

Stemoin: integration of the RPF signal, obtained with the witness

So: integration of the RPE signal obtained in the absence of free radicals [0046] Evaluation of the anti-free radical effect of the cosmetic composition by paramaqnetic resonance spectrometry of the electron.

SOD and mannitol were chosen as reference molecules for the validation of the test on superoxide radicals and hydroxyl radicals respectively.

Effect on the superoxide radical In the presence of SOD at 400 IU / ml, the RPE signal of the superoxide anion is zero (FIG. 1).

The trapping effect is maximum (100%; Table 1, Fig. 3). This effect validates the test.

Table 1:

Product RPE signal % of radical protection Concentration (%, w / v) integration % of witness Witness - 2,400,000 100 0 Comp. 0.1 1,970,000 82 18 cosmé 0.25 1,250,000 52 48 tick 0.62 1,010,000 42 58 2.5 636,000 26 74 5 0 0 100 SOD 400 IU / ml 0 0 100

The control corresponds to the basal mixture contained in all the samples and used for the measurement is xanthine (10 mM) + xanthine oxidase (0.8 U / ml) + DMPO 50% (v / v).

The cosmetic composition, tested at 0.1% (w / v), has no effect on the RPE signal of the superoxide radical. At 0.25 and 0.62% (w / v), it inhibits the RPE signal by 48% and 58% respectively. The latter is completely inhibited at 5% (w / v).

Effect on the hydroxyl radical In the presence of 10 mM mannitol (ie 0.182%, w / v), the RPE signal of the oxide radical was greatly reduced (FIG. 2); trapping activity is 93% (Table 2, Fig. 4). This effect validates the test.

CH 711 956 B1 Table 2:

Product Concentration (%, w / v) RPE signal integration % of witness % of radical protection Witness - 7,460,000 100 0 Comp. 0.03 7,200,000 96 4 cosmé 0.33 3,700,000 50 50 tick 1.6 247,000 3 97 16, .6 0 0 100 Mannitol 2 (10 mM) 294,000 7 93

The control corresponds to the basal mixture contained in all the samples and used for the RPE is the H ₂ O ₂ mixture (1/50, v / v) + 800 mM DMPO in water.

The cosmetic composition, tested at 0.03% (w / v), has no effect on the RPE signal of the hydroxyl radical. At 0.33% (w / v), it inhibits the signal by 50%. At 1.6 and 16.6% (w / v), the cosmetic composition inhibits the signal by 97% and 100% respectively.

Reactive oxygen metabolites, such as the superoxide anion, the hydroxyl radical, hydrogen peroxide (H ₂ O ₂ ) and singlet oxygen are responsible for toxic reactions for the organism. Produced by the organism itself or by external aggressions, they degrade sugars, proteins, lipids and nucleic acids. The short lifetime of the radicals, around 10 ^-11 seconds for the hydroxyl radical limits the detection capacity of these chemical species.

Radicals such as the superoxide anion and the hydroxyl radical are highlighted using the electron paramagnetic resonance spectrometry technique. A spin trap like DMPO resonates in the presence of free radicals and stabilizes them in the form of complexes with a characteristic spectrum. The trapping effect of the product is directly highlighted by a reduction in the intensity of the signal emitted by the "spin trap".

Advantageously, the Applicant has demonstrated that the cosmetic composition decreases in a dose-dependent manner the RPE signal of the superoxide anion. At a concentration of 5%, the cosmetic composition has the same effect as SOD at 400 IU / ml, the reference molecule known for its power to trap superoxide radicals.

In addition, the cosmetic composition decreases in a dose-dependent manner the RPE signal of the hydroxyl radical. At a concentration of 1.6%, this effect is equivalent to that obtained with 2% mannitol, the reference molecule known for its capacity to scavenge hydroxyl radicals.

Thus, the cosmetic composition has anti-radical effects with respect to the superoxide anion and the hydroxyl radical.

Example 2 Protocol for the preparation of the cosmetic composition according to the invention:

- Preparation of a 0.2% solution of allantoin in demineralized water in a tank heated to 80 ° C.

- Between 50 and 60 ° C, addition of 0.28% chlorphenesin (% by weight, relative to the total weight of the composition) in the open tank, then stirring for 10 minutes.

- Addition of 1-2% propylene glycol

- Adding to the mixture in the tank an emulsion of meadowsweet oil (Limnanthes alba) heated to 80 ° C in the presence of various adjuvants in a 0.3% NaOH solution.

The mixture is cooled to 30 ° C. before adding an extract of several plants in hydroglycerin comprising extracts of Mimosa tenuiflora 6%, Arnica montana 2%, harpagophytum 2%, calendula 2%, of Ruscus 2%.

- The mixture is finally cooled to 25 ° C.

In a particular embodiment, the cosmetic composition according to the invention comprises:

No INCI mixed Amount (% by weight, relative to the total weight of the composition) Water 68.9239 Limnanthes alba 2.0000 Arnica montana 0.2000

CH 711 956 B1

No INCI mixed Amount (% by weight, relative to the total weight of the composition) Mimosa tenuiflora 0.6000 Calendula officinalis 0.2000 Harpagophytum procumbens 0.2000 Ruscus aculeatus 0.2000 Glycerin 5.5440 Cetaryl isononanoate 4.0000 Dicaprylyl carbonate 4.0000 Cetaryl ethylhexanoate 3.0000 Cetaryl alcohol 2.5000 Glycerin stearate 2.2000 Isopropyl myristate 2.0000 Propylene glycol 1.8940 Potassium cetyl phosphate 0.8000 Levulinic acid 0.4050 Carbo mother 0.3800 Chlorphenesin 0.2800 Allantoin 0.2000 Sodium hydroxide 0.1956 Sodium levulinate 0.0900 O-cymen-5-ol 0.0800 Citric acid 0.0280 Potassium sorbate 0.0240 Tetrasodium glutamate-diacetate 0.0235 Sorbitol 0.0040 Total% 100%

Example 3

Effectiveness of the cosmetic composition At the start of the study, each volunteer received a sample to be tested as well as the methods of use: morning and evening application to the face, neck and décolleté, apply to cleansed skin, clean and dry, making movements from the bottom of the face upwards; by emphasizing crow's feet and under eyelid wrinkles; by penetrating by massage. Each volunteer used the cosmetic composition of the invention in the form of a cream to replace their usual care cream, for 28 days.

During the study period, each subject was asked not to change their habits and cosmetic products, not to intentionally expose themselves to the sun or to perform UV sessions and not to practice care in Institute.

At the end of the study, the volunteer brought back his product and he evaluated the cosmetic qualities of the product studied.

To assess the subjective effectiveness of the anti-aging product, at the start (J1) and at the end of the study (J28), the dermatologist noted the following characteristics:

CH 711 956 B1

- Anti-wrinkle potential: from 0 to 6 (according to the BAZIN Atlas scale)

- Reshaping potential: from 0 to 5 (according to the BAZIN Atlas scale)

- Smoothing potential: from 0 to 5 (according to the BAZIN Atlas scale)

- Complexion radiance according to the CLCT method:

Color of complexion: Pink-red (from 1 to 10), olive (from 1 to 10), beige (from 1 to 10) and light pink (from 1 to 10) according to a color chart.

Brightness of the complexion: (0 = complexion not luminous; 9 = luminous complexion)

Skin clarity: (0 = not fair complexion; 9 = fair complexion)

Complexion transparency: (0 = not transparent complexion; 9 = transparent complexion)

- Skin texture:

Roughness: (0 = rough skin; 9 = smooth skin)

Softness: (0 = not soft skin; 9 = soft skin)

Hydration: (0 = dry skin; 9 = hydrated skin)

- Uniformity of complexion: score assigned on a brown spot according to the SKIN color chart To assess the effectiveness of the product, at the start (D1) and end of study (D28), the volunteer noted the following items of 0 at 9:

- Smooth skin: (0 = rough skin; 9 = smooth skin)

- Wrinkles and fine lines: (0 = many wrinkles; 9 = no wrinkles)

- Firmness of the skin: (0 = not firm skin; 9 = firm skin)

Results The evaluation of the subjective efficacy by the dermatologist revealed a statistically significant improvement in the following characteristics:

- Complexion radiance according to the CLCT method:

Skin color: olive (decrease of 12.70%)

Beige (decrease of 18.32%)

Light pink (47.62% increase)

Complexion brightness: 46.15%

Skin clarity: 40.68%

- Skin texture:

Roughness (90.48%)

Softness (90.48%)

Hydration (33.60%)

- Anti-wrinkle potential: 11.48%

- Reshaping potential: 13.04%

- Smoothing potential: 15.38% In addition, an improvement in the color of the complexion "Pink / red" (decrease of 3.70%) and "Transparency" (9.09%) was observed during this study. This made it possible to highlight an anti-aging effect of the product.

Example 4

Effectiveness of the cosmetic composition on fine lines A volunteer received the cosmetic composition according to the invention and its protocol of use: morning and evening application to the face, neck and décolleté, apply to clean, clean skin and dry, making movements from the bottom of the face upwards; by emphasizing crow's feet and under eyelid wrinkles; by penetrating by

CH 711 956 B1 massage. The volunteer used the cosmetic composition of the invention in the form of a cream to replace her usual care cream, for 5 months.

The photos in Figure 5 show the appearance of fine lines after 3 months and 5 months of using the cream. They show in particular a gradual attenuation of fine lines in the lower eyelid and a marked improvement in skin texture. These are the visible consequences of the tissue regenerating and rehydrating effect of the cosmetic composition according to the invention.

Indication of the source of genetic resources according to article 138 let. b LBI and article 49a LBI:

The plant extracts used were supplied by the company COSMOTEC SA (Switzerland).

Genetic resource Source of genetic resource Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, Ruscus aculeatus COSMOTEC SA (Switzerland) Claims 1. Cosmetic composition comprising: - an aqueous phase, - at least one extract from one or more plants as active ingredients, chosen from Mimosa tenuiflora, Lim

nanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus,

Claims (11)

The plant extracts used were supplied by the company COSMOTEC SA (Switzerland). Genetic resource Source of genetic resource Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, Ruscus aculeatus COSMOTEC SA (Switzerland) Claims 1. Cosmetic composition comprising: - an aqueous phase, - at least one extract from one or more plants as active ingredients, chosen from Mimosa tenuiflora, Lim nanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens, and Ruscus aculeatus, - allantoin and - at least one suitable adjuvant. 2. Cosmetic composition according to claim 1, containing as active principles between 0.01 and 50% by weight of at least one extract from one or more plants chosen from Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens , and Ruscus aculeatus relative to the total weight of the composition. 3. Cosmetic composition according to one of the preceding claims, further containing at least one pro-penetrating and / or humectant, chosen from propylene glycol, glycerin and sorbitol. 4. Cosmetic composition according to one of the preceding claims, in which the aqueous phase represents from 50 to 90% by weight, preferably from 60 to 80% by weight, relative to the total weight of the composition. 5. Cosmetic composition according to one of the preceding claims, in which said adjuvant is chosen from sequestering agents, antioxidants, sun filters, preservatives, fillers, dyes, perfumes, essential oils, cosmetic active agents, moisturizers, vitamins, essential fatty acids, sphingolipids, self-tanning compounds, soothing and protective agents for the skin, and mixtures thereof. 6. Cosmetic composition according to one of the preceding claims, supplied in the form of a cream, an oil-in-water emulsion, a water-in-oil emulsion, a multiple emulsion, a solution or a suspension. 7. Cosmetic method for preventing and / or improving the signs of skin aging, in which the cosmetic composition according to one of claims 1 to 6 is applied to the skin. 8. Cosmetic method for protecting the skin by trapping free radicals, comprising the topical application of the cosmetic composition according to one of claims 1 to 6. 9. Cosmetic method for improving and / or promoting skin repair, comprising the topical application of the cosmetic composition according to one of claims 1 to 6. 10. Method for manufacturing the cosmetic composition according to one of claims 1 to 6, comprising the following steps: a) prepare an aqueous solution of allantoin at least 0.1%; b) mixing said aqueous solution of allantoin with an extract of one or more plants as active principles, said plants being chosen from the group comprising Mimosa tenuiflora, Limnanthes alba, Arnica montana, Calendula officinalis, Harpagophytum procumbens and Ruscus aculeatus, and c) add to the mixture b) at least one suitable adjuvant. 11. Container, for example ampoule or bottle, comprising the cosmetic composition according to one of claims 1 to 6.