FR3111817A1 - Hibiscus sabdariffa extract and its use to improve barrier function, and promote hydration and scaling of the skin - Google Patents

Abstract

Hibiscus sabdariffa extract and its use to improve the barrier function, and promote hydration and desquamation of the skin The present invention relates to an extract of Hibiscus sabdariffa comprising:i. at least 30% by weight of hibiscus acid and/or its salts based on the total weight of the components of the dry extract;ii. at least 5% by weight of hydroxycitric acid and/or its salts based on the total weight of the components of the dry extract;iii. at least 10% by weight of one or more sugar(s) relative to the total weight of the components of the dry extract. The present invention also relates to a composition comprising said extract, a cosmetic treatment method comprising the application to the skin of said composition to improve the barrier function of the skin, and to promote hydration and desquamation of the skin, as well as the use of said extract to improve the barrier function of the skin, and as a moisturizing and desquamating active ingredient.

Description

Hibiscus sabdariffa extract and its use to improve the barrier function, and promote hydration and desquamation of the skin

The present invention relates to the field of active agents capable of improving the barrier function of the skin, for a cosmetic application and in particular an extract of Hibiscus sabdariffa comprising at least 30% by weight of hibiscus acid, at least 5% by weight of hydroxycitric acid and at least 10% by weight of one or more sugar(s) relative to the total weight of the components of the dry extract, a composition comprising it, a cosmetic treatment process comprising the application of the said composition, as well cosmetic use of said extract as a moisturizing, desquamating active ingredient and in improving the barrier function of the skin.

The skin is the body's first barrier to the external environment. Human skin is made up of several compartments, three of which cover the whole body, namely a superficial compartment, the epidermis, the dermis, and a deep compartment, the hypodermis.

The natural human epidermis is mainly composed of three types of cells which are keratinocytes, which are very predominant, melanocytes and Langerhans cells. Each of these cell types contributes by its own functions to the essential role played in the organism by the skin, in particular the role of protecting the organism from external aggressions, which is called "barrier function".

The epidermis is conventionally divided into a basal layer of keratinocytes constituting the germinal layer of the epidermis, a so-called spiny layer consisting of several layers of polyhedral cells arranged on the germinal layers, one to three so-called granular layers and finally the horny layer ( or stratum corneum), consisting of a set of layers of keratinocytes at the terminal stage of their differentiation called corneocytes. Corneocytes are anucleate cells mainly composed of a fibrous matrix containing cytokeratins, in particular cytokeratin 10, surrounded by a very resistant structure 15 nm thick, called the horny envelope. The stacking of these corneocytes constitutes the horny layer which is responsible for the barrier function of the epidermis. This differentiation is the result of perfectly coordinated phenomena which will lead to the maintenance of a constant thickness and thus ensure the homeostasis of the epidermis. This involves regulating the number of cells that enter the differentiation process and the number of cells that desquamate. During the normal desquamation process, only the most superficial corneocytes detach from the surface of the epidermis.

Other proteins, associated with keratins, play very important roles in the maturation of the stratum corneum. Filaggrin (or filagrin), a protein present in keratohyaline granules, is produced during the final stages of epidermal differentiation. It is involved in the organization into balls of type I and type II keratins. This protein thus allows the formation of the cytoplasmic matrix of the superficial corneocytes which in particular gives the skin its normal thickness, its smooth appearance and its light-reflecting properties. In addition, by its degradation inside the corneocytes, filaggrin provides water-soluble substances with high osmotic power (Natural Moisturizing Factors or NMF) which allow the maintenance of good hydration of the stratum corneum of the skin and thus avoid feelings of “dry skin”. Filaggrin therefore helps maintain the barrier function of the epidermis and prevents the skin from drying out.

It is thus understood that the stratum corneum constitutes a real protective barrier against exogenous factors and the loss of endogenous water.

Its good renewal as well as the quality of its structure are essential to ensure an effective barrier vis-à-vis the outside world and limit water loss causes of dehydration, dry skin (Velarde MC. J. Invest. Dermatol., 2017, 137, 1206). Among the actors involved in the proper regulation of the stratum corneum is the enzyme transglutaminase-1 (TGM-1), also called keratinocyte transglutaminase (TGK). Its role is well illustrated in ichthyosis, a cornification defect, associated with mutations in TGM-1 (Vega VL and Mehta RC, Clin. Insights, 2016, 1-2; Herman ML et al, Human Mutat., 2009, 30, 537).

The cohesion of the epidermis as a water barrier is ensured thanks to the tight junctions between keratinocytes. These tight junctions are made up of transmembrane proteins such as occludin (OCL), claudin (CLDN-1) and are located in the granular layer. Other structures, such as Zonula occludens (ZO) proteins, link these transmembrane proteins to the cytoskeleton to enable the granular cytoplasmic scaffolding (Jin SP et al, J. Dermatol. Sci., 2016, 84, 97; Velarde MC , J. Invest. Dermatol., 2017, 137, 1206, Brandner JM et al, Tissue Barrier, 2015, 3, 1).

Finally, the phase of transition from the granular layer to the stratum corneum is essential to the constitution of a quality skin barrier, ensuring the homeostasis of the organism. Among the actors involved in this transition, we can distinguish transglutaminases, including transglutaminase 1 (TGM-1).

Strengthening the quality of the epidermis by favoring intracellular junctions and the cohesion of the stratum corneum contributes to the maintenance of the functions of the epidermis, to good hydration.

Admittedly, active agents have already been reported for their ability to act on the barrier function of the skin, as reported in EP 1333803 B1.

In addition, among the desquamating agents known from the prior art, mention may in particular be made of α-hydroxy acids (AHAs) such as lactic acid or glycolic acid or β-hydroxy acids (BHAs) such as salicylic acid. These active agents induce, by topical application at concentrations of a few percentages, visible desquamation after a few days. Unfortunately, some peeling compounds can have side effects, such as skin discomfort.

However, with regard to the prior art, there remains however a need to reinforce, in particular in a natural way, the quality of the epidermis by favoring the intracellular junctions and the cohesion of the stratum corneum, which are a basic element allowing to maintain the functions of the epidermis, good hydration.

There also remains a need to find new pro-desquamating natural compounds, in particular not possessing the side effects mentioned above.

Surprisingly, the inventors have indeed demonstrated the particular properties of an extract of Hibiscus sabdariffa, in particular aqueous extract from calyces of white flowers of Hibiscus sabdariffa, comprising at least 30% by weight of hibiscus acid, at least 5 % by weight of hydroxycitric acid and at least 10% by weight of sugars relative to the total weight of the components of the dry extract, to modify the abundance of the markers transglutaminase K, occludin, filaggrin, and cytokeratin 10, in a model of normal human keratinocytes in monolayer. They also demonstrated a hydrating effect, in particular a residual effect of said extract on a model of reconstructed skin as well as a desquamating effect on an ex vivo skin explant. All of these properties therefore advantageously make it possible to envisage the use of an extract of Hibiscus sabdariffa, or of a composition comprising said extract, to improve the barrier function of the skin. In addition, these properties make it possible to envisage the implementation of said extract or of a composition comprising said extract as a moisturizing active ingredient and/or as a desquamating agent.

It is known from the prior art an extract of Hibiscus sabdariffa, in particular hydroalcoholic obtained from calyces of white flowers of Hibiscus sabdariffa comprising 25.43% by weight of hibiscus acid, 4.1% by weight of acid hydroxycitric and 8.5% by weight of sugars based on the total weight of the extract components, used in combination with baobab extract for anti-aging properties. However, as examples 4 and 5 of the present application show, the known extract of the prior art does not have any effect either on the improvement of the barrier function or on the hydration of the skin compared to the extract according to the invention.

Thus, the subject of the present invention is an extract of Hibiscus sabdariffa comprising:
i. at least 30% by weight of hibiscus acid and/or its salts relative to the total weight of the components of the dry extract;
ii. at least 5% by weight of hydroxycitric acid and/or its salts relative to the total weight of the components of the dry extract;
iii. at least 10% by weight of one or more sugar(s) relative to the total weight of the components of the dry extract.

A subject of the present invention is also a composition comprising, in a physiologically acceptable medium, said extract.

Another of the objects of the present invention relates to a cosmetic treatment process comprising the application of said composition to the skin:
- to improve the barrier function of the skin, and/or
- to prevent and/or treat roughness or micro-relief and/or improve the radiance of the complexion and/or to improve the suppleness of the skin, and/or
- to prevent and/or treat cosmetic signs of skin dryness, and/or
- to hydrate the skin, and/or
- to promote desquamation of the skin.

The present invention also relates to the cosmetic use of said extract:
- to improve the barrier function of the skin, and/or
- to prevent and/or treat roughness or micro-relief and/or improve the radiance of the complexion and/or to improve the suppleness of the skin, and/or
- to prevent and/or treat cosmetic signs of skin dryness, and/or
- as a moisturizing active ingredient, and/or
- as a desquamating active ingredient.

Definitions

The Hibiscus genus belongs to the Malvaceae family. Hibiscus sabdariffa is native to West Africa, India and Malaysia. It has a wide distribution in the tropics and is widely cultivated for its calyx (flowers). Hibiscus sabdariffa is also available in China, Thailand, Sudan, Mexico and some other countries with smaller suppliers like Egypt, Senegal, Tanzania, Mali and Jamaica.

There is more particularly a white variety of Hibiscus sabdariffa (white calyx) and a red variety of Hibiscus sabdariffa (red calyx linked to the presence of anthocyanins).

The chalices of the white variety, popularly called “Bissap bou wèèkh” in Wolof in Senegal, are used fresh or dried as condiments in local fish preparations and in rare cases in drinks.

The calyxes of the red variety are widely used in traditional medicine and find various industrial applications as sources of anthocyanins (red pigments) as a colorant and AHAs (fruit acids).

The biomass used in the context of the present invention preferably consists of dried chalices (flowers) of the white variety of Hibiscus (Hibiscus sabdariffa). This plant is a seasonal plant that can be grown in Senegal and particularly in the regions of Diourbel, Thiès, Louga, St Louis, Fatick, Kaolack, Tambacounda during the rainy season (from July to October each year). The chalices are harvested when the fruit is ripe between November and December, then dried in the sun and pre-crushed into particles having a size less than or equal to 5 mm, preferably less than or equal to 2 mm.

We can cite in particular the biomass of calyxes of white flowers of Hibiscus sabdariffa from the regions of Diourbel or Thiès (Mbour, Mballing) in Senegal.

By "skin" is meant all of the skin of the body, and the scalp and preferably, the skin of the face, décolleté, neck, arms and forearms, or even more preferably still , the skin of the face (especially the forehead, nose, cheeks, chin), décolleté and neck.

By “prevent” or “prevention” is meant according to the invention the fact of reducing the risk of occurrence or of slowing down the occurrence of a given phenomenon.

By "treating" or "treatment" we mean any action aimed at improving the comfort and well-being of an individual, this term therefore covers both mitigation, relief and cure.

By "intended to be administered topically" is meant an application to the surface of the skin considered

Detailed description of the invention

Hibiscus sabdariffa extract

The subject of the present invention is an extract of Hibiscus sabdariffa comprising:
i. at least 30% by weight of hibiscus acid and/or its salts relative to the total weight of the components of the dry extract;
ii. at least 5% by weight of hydroxycitric acid and/or its salts relative to the total weight of the components of the dry extract;
iii. at least 10% by weight of one or more sugar(s) relative to the total weight of the components of the dry extract.

The hibiscus acid and/or its salts is (are) preferably present in a concentration of between 30% and 50% by weight, very preferably between 32% and 45% by weight, even better still between 34 and 40% by weight relative to the total weight of the components of the dry extract.

The hydroxycitric acid and/or its salts is (are) preferably present in a concentration of between 5% and 15% by weight, very preferably between 6% and 14% by weight, even more preferably between 7% and 13% by weight, even better between 8% and 12% by weight relative to the total weight of the components of the dry extract.

The sugar(s) designate monosaccharides such as glucose, fructose, arabinose, galactose, or oligosaccharides such as dissacharides such as sucrose.

Within the meaning of the present invention, the sugar(s) is (are) preferably chosen from arabinose, glucose, fructose, sucrose, and mixtures thereof.

The sugar(s) is (are) present (s) preferably in a concentration of between 10% and 30% by weight, very preferably between 10% and 20% by weight, even better between 12% and 15% by weight per relative to the total weight of the components of the dry extract.

In particular, the extract according to the invention comprises:
- arabinose in a concentration of between 0.1% and 2% by weight, preferably from 0.1% to 1% by weight relative to the total weight of the components of the dry extract, and
- glucose is present in a concentration of between 2% and 8% by weight, preferably from 4% to 8% by weight relative to the total weight of the components of the dry extract, and
- fructose is present in a concentration of between 2% and 6% by weight relative to the total weight of the components of the dry extract, and
- sucrose is present in a concentration of between 0.1% and 4% by weight, preferably from 0.5 to 3.5% by weight relative to the total weight of the components of the dry extract.

Advantageously, said extract also contains at least 0.3% by weight of one or more polyphenol(s) relative to the total weight of the components of the dry extract, preferably between 0.3% and 2% by weight, even better between 0.4% and 0.6% by weight relative to the total weight of the components of the dry extract.

Among the polyphenol(s) present in said extract, mention may be made of rutin, 3-O-caffeylquinic acid and its salts, 4-O-caffeylquinic acid and its salts, 5 -O-caffeylquine and its salts, and mixtures thereof.

In particular, the extract according to the invention comprises:
- rutin is present in a concentration of between 0.1% and 0.5% by weight relative to the total weight of the components of the dry extract, and
- 3-O-caffeylquinic acid and its salts is (are) present in a concentration of between 0.01% and 0.1% by weight relative to the total weight of the components of the dry extract, and
- 4-O-caffeylquinic acid and its salts is (are) present in a concentration of between 0.01% and 0.1% by weight relative to the total weight of the components of the dry extract, and
- 5-O-caffeylquinic acid and its salts is (are) present in a concentration of between 0.05% and 0.5% by weight relative to the total weight of the components of the dry extract.

In a preferred embodiment, the Hibiscus sabdariffa extract according to the invention is obtained by extraction using an aqueous solvent, in particular water, preferably at a biomass/aqueous solvent mass ratio of between 0.01 and 0.5, more preferably between 0.05 and 0.3, even better between 0.07 and 0.2, and optionally followed by a filtration step.

The extraction is preferably a maceration at ambient temperature, for example 25° C., using an aqueous solvent such as water.

Advantageously, the extraction is carried out for about a period varying from 30 min to 8 hours, preferably between 1 and 4 hours, more particularly between 1 and 3 hours such as 2 hours, in particular with stirring, for example using paddle or magnetic stirrer. The stirring speed can be between 100 and 300 revolutions per minute, such as 250 revolutions per minute.

The extract thus obtained can be dried and then be in the form of a dry extract, for example by evaporation of the water in particular using a rotary evaporator, by lyophilization, or by atomization. The term "dry extract" within the meaning of the present invention, an extract comprising less than 10% by weight of water, preferably less than 7% by weight of water, even better less than 5%, even more preferably less 2% by weight of water, or even totally free of water (0%).

The Hibiscus sabdariffa extract according to the invention is preferably obtained from a variety of Hibiscus sabdariffa with white flowers, in particular from one or more white flower(s) of Hibiscus sabdariffa , such as one or more calyx(es) of white flowers of Hibiscus sabdariffa. In a preferred embodiment of the invention, the extract of Hibiscus sabdariffa according to the invention is obtained from one or more calyx(es) of white flowers of ground Hibiscus sabdariffa(s), for example under the form of particles of size less than or equal to 5 mm, preferably of size less than or equal to 2 mm.

Composition

The present invention also relates to a composition comprising, in a physiologically acceptable medium, the extract of Hibiscus sabdariffa according to the invention.

Said extract may be present in the composition in a concentration of between 0.001% and 20% by weight of dry extract, preferably between 0.01% and 10% by weight of dry extract, even better between 0.1% and 5% by weight of dry extract relative to the total weight of the composition.

The compositions, in particular cosmetics, capable of being used in the context of the invention generally comprise a physiologically acceptable medium.

By “physiologically acceptable medium”, is meant a medium compatible with keratin materials, and in particular the skin.

More particularly, said physiologically acceptable medium may comprise water and/or one or more water-miscible organic solvents which may be chosen from monoalcohols, linear or branched, C1-C6 such as ethanol, isopropanol, tert-butanol; polyols such as glycerol, propylene glycol, hexylene glycol (or 2-methyl-2,4-pentanediol), and polyethylene glycols; polyol ethers such as dipropylene glycol monomethyl ether; and their mixtures.

Preferably, the composition according to the invention has a water content ranging from 20% to 95% by weight, even better from 40% to 90% by weight relative to the total weight of the composition.

Advantageously, the composition comprises one or more water-miscible organic solvents in a content ranging from 0.5% to 25% by weight, preferably from 5% to 20% by weight, even better from 10% to 15% by weight. relative to the total weight of the composition.

The composition according to the invention may comprise water and/or all the adjuvants usually employed in the field of application envisaged.

Mention may in particular be made of; organic solvents, especially C1-C6 alcohols and C2-C10 carboxylic acid esters; carbonaceous and/or silicone oils, of mineral, animal and/or vegetable origin; water, waxes, pigments, fillers, dyes, surfactants, emulsifiers, co-emulsifiers; cosmetic or dermatological active ingredients such as vitamin C, UV filters, polymers, hydrophilic or lipophilic gelling agents, thickeners, preservatives, perfumes, bactericides, odor absorbers, antioxidants.

In a preferred embodiment of the invention, the composition comprises, as cosmetic active ingredient, vitamin C.

These optional adjuvants may be present in the composition at a rate of 0.001% to 80% by weight, preferably 0.01% to 40% by weight, even better still from 0.1% to 20% relative to the total weight of the composition. . These adjuvants, depending on their nature, can be introduced into the fatty phase, into the aqueous phase and/or into the lipid vesicles.

The composition according to the invention may also comprise one or more additional compounds chosen from sugars, in particular monosaccharides, oligosaccharides, polysaccharides, organic acids such as AHAs and/or BHAs; said additional compounds may be identical to or different from the compounds present in the extract according to the invention.

Said additional compounds may be present in the composition according to the invention in a concentration of between 0.001% and 20% by weight, preferably between 0.01% and 10% by weight, even better between 0.1% and 5% by weight. weight relative to the total weight of the composition.

Of course, those skilled in the art will take care to choose this or these possible ingredients and/or additional active ingredients, and/or their quantity, in such a way that the advantageous properties of the extract according to the invention are not, or substantially not, altered by the proposed addition.

The compositions according to the invention can be in all the dosage forms conventionally used for topical application and in particular in the form of aqueous, hydroalcoholic solutions, oil-in-water (O/W) or water-in-oil ( W/O) or multiple (triple: W/O/W or O/W/O), aqueous gels, or dispersions of a fatty phase in an aqueous phase using spherules, these spherules possibly being lipid vesicles of the ionic and/or non-ionic type (liposomes, niosomes, oleosomes). These compositions are prepared according to the usual methods.

Advantageously, the compositions according to the invention are in the form of a gel, or an emulsion, a powder or a paste. In addition, the composition according to the invention can be more or less fluid and have the appearance of a white or colored cream, an ointment, a milk, a lotion, a serum, a paste, a foaming gel, a scrub, a mask, a treatment, a tonic or a mousse. It can optionally be applied to the skin in the form of an aerosol. It can also be in solid form, and for example in the form of a stick.

A composition according to the invention may comprise an oily phase.

A composition used according to the invention can advantageously comprise at least one liquid fatty substance different from the compounds present in the hydrosol of the invention.

By “liquid fatty substance”, is meant a compound having a melting point lower than approximately 30-35°C, as opposed to solid fatty substances, such as waxes, which have a melting point higher than approximately 50°C.

As oils that can be used in the composition of the invention, mention may be made, for example:
- hydrocarbon oils of animal origin;
- hydrocarbon oils of vegetable origin,
- synthetic esters and ethers, in particular of fatty acids, such as the oils of formulas R'000R2 and R'0R2 in which R' represents the residue of a fatty acid comprising from 8 to 29 carbon atoms, and R2 represents a hydrocarbon chain, branched or not, containing from 3 to 30 carbon atoms;
- linear or branched hydrocarbons, of mineral or synthetic origin;
- fatty alcohols having 8 to 26 carbon atoms;
- partially hydrocarbon and/or silicone fluorinated oils;
- silicone oils;
- their mixtures.

The term “hydrocarbon oil” in the list of oils mentioned above means any oil comprising mainly carbon and hydrogen atoms, and optionally ester, ether, fluorinated, carboxylic acid and/or alcohol groups. The other fatty substances which may be present in the oily phase are, for example, fatty acids comprising from 8 to 30 carbon atoms; waxes; silicone resins; and silicone elastomers. These fatty substances can be chosen in a variety of ways by those skilled in the art in order to prepare a composition having the properties, for example of consistency or texture, desired.

According to a particular embodiment of the invention, the composition according to the invention is a water-in-oil (W/O) or oil-in-water (O/W) emulsion. The proportion of the oily phase of the emulsion can range from 5 to 90% by weight, and preferably from 5 to 60% by weight relative to the total weight of the composition. The emulsions generally contain at least one emulsifier chosen from amphoteric, anionic, cationic or nonionic emulsifiers, used alone or as a mixture, and optionally a co-emulsifier. The emulsifiers are chosen appropriately according to the emulsion to be obtained (W/O or O/W). The emulsifier and the co-emulsifier are generally present in the composition, in a proportion ranging from 0.3 to 30% by weight, and preferably from 0.5 to 20% by weight relative to the total weight of the composition.

For W/O emulsions, mention may be made, for example, of dimethicone copolyols and alkyl-dimethicone copolyols as emulsifiers. It is also possible to use, as surfactant for W/O emulsions, a crosslinked elastomeric solid organopolysiloxane comprising at least one oxyalkylene group.

For O/W emulsions, mention may be made, for example, as emulsifiers, of nonionic emulsifiers.

The extract according to the invention, or said composition comprising it, may be implemented, in the context of a use or a method according to the invention, topically.

The compositions according to the invention may be applied directly to the skin or, alternatively, to cosmetic carriers of the occlusive or non-occlusive type, intended to be applied locally to the skin. By way of non-limiting examples of cosmetic supports, mention may in particular be made of a patch, a wipe, a roll-on and a pen. The composition may or may not be rinsed off after being applied to the skin.

Uses and method of cosmetic treatment

According to another of its objects, the present invention relates to a cosmetic treatment process comprising the application of the composition according to the invention to the skin:
- to improve the barrier function of the skin, and/or
- to prevent and/or treat roughness or micro-relief and/or improve the radiance of the complexion and/or to improve the suppleness of the skin, and/or
- to prevent and/or treat cosmetic signs of skin dryness, and/or
- to hydrate the skin, and/or
- to promote desquamation of the skin, in particular to promote the cleansing action and the elimination of dead cells on the surface of the body and/or to promote the elimination of dandruff and/or to improve the hold of make-up and/or to improve the result of skin treatment with stratum corneum dyes such as dihydroxyacetone (DHA).

The present invention also relates to the cosmetic use of the extract according to the invention:
- to improve the barrier function of the skin, and/or
- to prevent and/or treat roughness or micro-relief and/or improve the radiance of the complexion and/or to improve the suppleness of the skin, and/or
- to prevent and/or treat cosmetic signs of skin dryness, and/or
- as a moisturizing active ingredient, and/or
- as a desquamating active ingredient.

A cosmetic implementation of the invention is therefore intended only for aesthetic defects of the skin, and therefore does not exert a therapeutic effect.

The present invention is aimed at a non-therapeutic cosmetic application for caring for the skin of the extract according to the invention or of the composition comprising it, in particular cosmetics comprising the extract according to the invention.

By “treatment”, is meant a non-therapeutic treatment capable of producing an aesthetic effect without however preventing or correcting a pathological dysfunction of the skin.

skin surface

The surface of human skin is not smooth. It presents a relief resulting in fine lines, distinct from wrinkles, observable with a magnifying glass in children and with the naked eye in the elderly. These fine lines or furrows intersect so as to form structures of polygonal shapes, namely the microrelief of the skin.

The number and depth of the furrows constituting the microrelief of the skin can be affected by numerous external or internal factors.

Advantageously, an extract according to the invention, or a composition comprising it, can be used to prevent and/or treat an alteration in the surface condition of the skin, in particular following an alteration in the barrier function of the skin.

More particularly still, an extract according to the invention, or a composition comprising it, can be used to prevent and/or treat an alteration of the microrelief of the skin, to reduce the number of furrows of the microrelief of the skin, to smooth the surface of the skin, to prevent and/or treat a surface irregularity of the skin, in particular to prevent and/or treat a state of roughness of the skin, or to reduce the depth of the furrows of the microrelief of the skin.

Dry skin

One of the functions of the Stratum Corneum is to capture and retain the water contained in the epidermis, and any alteration in its structure and/or its function, in particular consecutive to or associated with an alteration in the barrier function of the skin, may occur. result in changes in skin hydration.

Hydration is brought to the skin by water from deep layers and by sweat. An imbalance in skin hydration can have profound physiological and cosmetic consequences.

On a physiological level, dry skin is often associated with a drop in the level of cutaneous hydration as well as a modification of the process of maturation of the Stratum Corneum. From a sensory point of view, dry skin can be characterized by a feeling of tightness and/or cutaneous tension.

An extract according to the invention, or a composition comprising it, may be particularly suitable for preventing and/or treating dry skin and/or skin signs associated with dry skin.

Whatever the origin, skin affected by cutaneous dryness can generally present the following signs: rough to the touch and scaly appearance, as well as reduced suppleness and elasticity.

According to one embodiment, a cosmetic use of the invention may advantageously be suitable for preventing and/or treating dry or fragile skin, and winter xerosis.

According to one embodiment, a cosmetic use of the invention may advantageously be suitable for preventing and/or treating feelings of discomfort such as tightness associated with dry skin.

Throughout the description, including the claims, the expression "comprising a" must be understood as being synonymous with "comprising at least one", unless the contrary is specified.

In addition, the expression "at least one" must be understood as being synonymous with "one or more" unless the contrary is specified.

The expressions “more than”, “between … and …” and “ranging from … to …” must be understood as limits included, unless the contrary is specified.

The following examples and figures are presented by way of non-limiting illustration of the invention. The compounds are, depending on the case, cited in chemical names or in CTFA names (International Cosmetic Ingredient Dictionary and Handbook).

: Scoring scale for the “basket wave” criterion

: SC detachment criterion scoring scale

: Histology of samples of control and control excised skin, treated with the extract obtained according to example 1 and 1.5% salicylic acid

Examples

Example 1 - Preparation of an aqueous extract of calyxes of white flowers of Hibiscus sabdariffa from the region of Thiès in Senegal (according to the invention)

The extract was made according to the following process:
- Grinding of the calyxes of dried white flowers of Hibiscus sabdariffa from Mbour, Thiès region in Senegal into fine particles in an IKA grinder (1 – 2mm grain size).
- Extraction by maceration in water at room temperature (25°C regulated using a thermoregulator), by introducing 570 g of calyx powder (flowers) into 4 liters of water (corresponding to a ratio of 142.5g per 1 liter of water), and maintaining at this temperature for 2 hours, with motor stirring using a blade system at 250 rpm.
- Then, pre-filtration on a 100 µm Nitex cloth
- Then filtration on a Whatman® GF/C filter with a porosity of 1.2µm Ø 90mm
- Evaporation of water using a rotary evaporator (Buchi Rotavapor® R215, equipped with a Buchi Heating Bath B-491, as well as a Vacuubrand PC 3001 VARIO Pro vacuum pump) at 35-40 degrees up to to 1/3 of the original volume.
- Then freeze-drying of the aqueous residue for 24 hours using a Labconco FreeZone 4.5 Plus lyophilizer, coupled to a Vaccubrand RZ-6 vacuum pump in automatic start mode from -40°C in the collector.
- A dry extract of white flowers of Hibiscus sabdariffa calyxes is thus obtained in the form of a light beige powder.
- Then homogenization by grinding with a manual mortar.

A dry extract is obtained whose water content is 6.2% by weight.

Characterization

The analysis and dosage of organic acids in the dry extract thus obtained are carried out by reverse-phase HPLC equipped with a diode array detector (DAD, λ = 210 nm). The quantification is carried out using the analytical grade standards tribasic potassium hydroxycitrate monohydrate (Sigma reference 59847), (+)-Garcinia acid (Sigma reference 44282) and fumaric acid (Sigma reference 47910).

Organic acids present in the dry extract
obtained according to example 1 % (m/m) Hydroxycitric acid (g/100g) 9.47 Hibiscus acid (equivalent to garcinia acid g/100g) 36.82 Fumaric Acid (g/100g) 0.07

The analysis and assay of polyphenols (chlorogenic acids-CQA and rutin) in the extract obtained in Example 1 are carried out by reverse-phase UPLC coupled to a corona detector (CAD) and a diode array detector (DAD ). The quantification is carried out using the standard caffeic acid ethyl ester (Extrasynthesis reference 6498) and the results are expressed in caffeic acid ethyl ester equivalent.

Polyphenols present in the extract
obtained according to example 1 % (m/m) 5-caffeoylquinic acid (eq ACEE, g/100g) 0.10 4-caffeoylquinic acid (eq ACEE, g/100g) 0.05 3-caffeoylquinic acid (eq ACEE, g/100g) 0.05 Rutin 0.32

The analysis of sugars is carried out by ion exchange chromatography coupled to a gold electrode on an anion exchange column. Quantification was performed using analytical grade standards.

Sugars present in the extract obtained according to example 1 % (m/m) Arabinose (g/100g) 0.56 Glucose (g/100g) 5.9 Fructose (g/100g) 4.1 Sucrose (g/100g) 2.1

Example 2 - Preparation of an aqueous extract of calyxes of white flowers of Hibiscus sabdariffa from the Diourbel region in Senegal (according to the invention)

The extract was made according to the following process:
- Maceration of 4.09 kg of calyxes of dried white flowers of Hibiscus sabdariffa from the Diourbel region in Senegal ground to 2mm at 10%ww/ for 2 hours at 25°C in water.
- Then pre-filtration of the exhausted biomass on 195 µm nylon fabric (F1)
- Then 2nd maceration at 25°C/ 30 min in 1/2 vol water.
- and Pre-filtration on 195 µm (F2) nylon cloth.
- The F1 and F2 fractions previously obtained were combined and clarified then sterilized on a 0.2 µm cartridge.
- the sterilized solution was concentrated between 10 and 15% then shaped by atomization (160°C),

A dry extract of white flowers of Hibiscus sabdariffa calyxes is thus obtained in the form of a light beige powder with a residual water content of 5.1%.

Characterization

The analyzes carried out in Example 1 were reproduced in Example 2.

The following results were obtained:

Organic acids present in the extract
obtained according to example 2 % (m/m) Hydroxycitric acid (g/100g) 9.1 Hibiscus acid (equivalent to garcinia acid g/100g) 34.0 Fumaric Acid (g/100g) 0.15

Polyphenols present in the extract
obtained according to example 2 % (m/m) 5-caffeoylquinic acid (eq ACEE, g/100g) 0.16 4-caffeoylquinic acid (eq ACEE, g/100g) 0.06 3-caffeoylquinic acid (eq ACEE, g/100g) 0.07 Rutin 0.29

Sugars present in the extract obtained according to Example 2 % (m/m) Arabinose (g/100g) 0.7 Glucose (g/100g) 6.81 Fructose (g/100g) 4.58 Sucrose (g/100g) 1.28

Example 3 - Preparation of a hydroalcoholic extract of calyxes of white flowers of Hibiscus sabdariffa from the Thiès region in Senegal (outside the invention)

80g of calyx powder of white Hibiscus sabdariffa flowers from the Thiès region with a particle size of 2mm are macerated at room temperature in 560ml of a 50/50 (v/v) water/ethanol mixture in a mass ratio of biomass/50% ethanol of 1/7, for 2 hours with magnetic stirring at 300 rpm.

The supernatant is then filtered (Whatmann GF/C filter), then washing of the marc with 100 ml of a 50% ethanol solution followed by evaporation of the ethanol from the hydroalcoholic filtrate using an evaporator rotating then freeze-drying for 24 h. We thus obtain dry extract of calyxes of white flowers of Hibiscus sabdariffa in powder of light beige color. Then, homogenization is carried out by grinding with a manual mortar.

Characterization

The analysis and determination of the organic acids in the extract thus obtained are carried out by reverse-phase HPLC equipped with a diode array detector (DAD, λ = 210 nm). The quantification is carried out using the analytical grade standards tribasic potassium hydroxycitrate monohydrate (Sigma reference 59847), (+)-Garcinia acid (Sigma reference 44282) and fumaric acid (Sigma reference 47910).

Organic acids present in the extract
obtained according to example 3 % (m/m) Hydroxycitric acid (g/100g) 4.1 Hibiscus acid (equivalent to garcinia acid g/100g) 25.43 Fumaric Acid (g/100g) <0.07

The analysis and assay of polyphenols (chlorogenic acids-CQA and rutin) in the Hibiscus extract are carried out by reverse phase UPLC coupled to a corona detector (CAD) and a diode array detector (DAD). The quantification is carried out using the standard caffeic acid ethyl ester (Extrasynthesis reference 6498) and the results are expressed in caffeic acid ethyl ester equivalent.

Polyphenols present in the extract
obtained according to example 3 % (m/m) 5-caffeoylquinic acid (eq ACEE, g/100g) 0.04 4-caffeoylquinic acid (eq ACEE, g/100g) 0.04 3-caffeoylquinic acid (eq ACEE, g/100g) 0.04 Rutin 0.07

The analysis of sugars is carried out by ion exchange chromatography coupled to a gold electrode on an anion exchange column. Quantification was performed using analytical grade standards.

Sugars present in the extract obtained according to Example 3 % (m/m) Arabinose (g/100g) 1.01 Glucose (g/100g) 4.4 Fructose (g/100g) 2.97 Sucrose (g/100g) 0.12

Example 4 - Evaluation of the efficacy of the extracts obtained in examples 1 (invention) and 3 (outside the invention) on the modulation of the barrier function

Principle:

The aim of this study is to evaluate the effects of extracts of calyxes of white flowers of Hibiscus sabdariffa obtained according to examples 1 and 3, on the expression of differentiation proteins and tight junction proteins on keratinocytes in monolayer culture. .

The aqueous extract of the calyxes of white flowers of Hibiscus sabdariffa according to the invention obtained according to example 1 was evaluated at 0.167 mg/mL and 0.5 mg/mL.

The hydroalcoholic extract of the calyxes of white flowers of Hibiscus sabdariffa outside the invention obtained according to example 3 was evaluated at 0.167 mg/mL and 0.5 mg/mL

The different markers studied are: a set of keratinocyte differentiation proteins (transglutaminase K, cytokeratin 10 and filaggrin) as well as a tight junction protein (occludin) linked to the reinforcement of the barrier function of the skin.

Protocol (experimental conditions)

Monolayer normal human epidermal keratinocytes were used to perform the study.

Cultivation and treatments:

For analysis of TGK expression

The keratinocytes were seeded in a 96-well plate and cultured in culture medium for 24 hours. The medium was then replaced with test medium containing or not (control) the test compounds or the reference (CaCl2 at 1.5 mM) and the cells were incubated for 72 hours. All the experimental conditions were carried out in n=3.

- For analysis of filaggrin expression

The keratinocytes were seeded in a 96-well plate and cultured in culture medium for 192 hours with a change of culture medium after 24 and 96 hours of incubation. The medium was then replaced with test medium containing or not (control) the test compounds or the reference (CaCl2 at 1.5 mM) and the cells were incubated for 72 hours. All the experimental conditions were carried out in n=3.

- For the analysis of the expression of cytokeratin 10

The keratinocytes were seeded in a 96-well plate and cultured in culture medium for 96 hours with a change of culture medium after 24 hours of incubation. The medium was then replaced with test medium containing or not (control) the test compounds or the reference (CaCl2 at 1.5 mM) and the cells were incubated for 72 hours. All the experimental conditions were carried out in n=3.

- For analysis of occludin expression

The keratinocytes were seeded in a 96-well plate and cultured in culture medium for 24 hours. The medium was then replaced with test medium containing or not containing (control) the compounds under test or the reference (CaCl2 at 1.5 mM) then the cells were incubated for 144 hours with retreatment after 72 hours of incubation. All the experimental conditions were carried out in n=3.

In situ immunostaining

After incubation, the culture medium was removed and the cells were rinsed, fixed and permeabilized. The cells were then labeled with the primary antibody (see Table below) directed against the protein of interest (TGK, cytokeratin 10, filaggrin and occludin). This antibody was then revealed by a secondary antibody coupled to a fluorochrome (see Table below). In parallel, the cell nuclei were stained with Hoechst 33258 (bis‐benzimide).

Protein Primary antibody Secondary antibody TGK Novus Biologicals,
ref. NB100-1844 GAR‐Alexa 488,
Molecular Probes, ref. A11008 Filaggrin Santa Cruz,
ref. sc-66192 GAM-Alexa 488,
Molecular Probes, ref. A11001 Cytokeratin 10 Santa Cruz,
ref. sc-23877 GAM-Alexa 488,
Molecular Probes, ref. A11001 Occludin Invitrogen,
ref. 33-1500 GAM-Alexa 488,
Molecular Probes, ref. A11001

Image acquisition was performed with a high-resolution imaging system, INCell Analyzer™2200 (GE Healthcare) (20x objective). For each well, 5 digitized image captures were made for all immunolabels.

The labeling was quantified by measuring the fluorescence intensity of the proteins relative to the number of cells identified by the Hoechst (integration of numerical data by the Developer Toolbox 1.5 software, GE Healthcare).

Results and Conclusions: Effect on Marker Expressions

In the control condition, the TGK, filaggrin and cytokeratin 10 (CK10) markers were weakly expressed and restricted to a low number of keratinocytes. Occludin (tight junction marker) was only detected in a limited number of cells in the form of a fairly weak, partially diffuse and mainly cytoplasmic but also membrane labeling.

Treatment of cells with 1.5 mM calcium chloride markedly increased the overall expression of all TGK, filaggrin and cytokeratin 10 markers as well as the number of cells expressing them. In the case of filaggrin, a typical punctiform labeling could be observed. For occludin, treatment of cells with 1.5 mM calcium chloride markedly increased the membrane expression of this marker as well as the number of cells expressing it. These results were expected and made it possible to validate the trial.

The extract according to the invention obtained in Example 1, tested at 0.5 mg/mL, had a stimulating and significant effect on the expression of the four markers tested (respectively 230% of the control for TGK, 316% for filaggrin , 288% for cytokeratin 10 and 184% for occludin). At the lower concentration (0.167 mg/mL), only the expression of occludin was significantly stimulated (158% of the control).

Thus, the extract according to the invention obtained in Example 1 at 0.5 mg/mL stimulates the expression of the markers TGK, filaggrin, cytokeratin 10 and occludin

The hydroalcoholic extract outside the invention obtained in Example 3, tested at 0.167 and 0.5 mg/mL, induced a strong significant decrease in the expression of cytokeratin 10 with a concentration-dependent effect (respectively 23% and 2% of the control ). This concentration-dependent inhibitory effect was also observable on the expression of occludin but in a more moderate way (respectively 73% and 27% of the control). On the 2 other markers tested, no clear and significant variation could be detected.

Thus, the hydroalcoholic extract outside the invention obtained in Example 3 either does not modulate the markers monitored (TGK and filaggrin) or induces a strong reduction in their expression. The hydroalcoholic extraction modifies the contents of the main components of the extract and therefore the properties of the extract on the expression of the markers monitored.

Treatment TGK Filaggrin Compounds tested Concentration % witness Esm (%) P-value % witness Esm (%) P-value Witness - 100 18 * 100 14 * _CaCl2 1.5mM 816 206 - 468 39 *** Extract obtained according to example 1 according to the invention 0.167mg/ml 96 9 ns 142 21 ns 0.5mg/ml 230 33 * 316 68 * Extract obtained according to Example 3 outside the invention 0.167mg/ml 109 15 ns 87 32 ns 0.5mg/ml 134 12 ns 74 37 ns

ns >0.05 not significant; * 0.01 to 0.05: significant; ** 0.001 to 0.01: very significant; *** < 0.001: extremely significant

Treatment Cytokeratin 10 Occludin Compounds tested Concentration % witness Esm (%) P-value % witness Esm (%) P-value Witness - 100 21 * 100 3 * _CaCl2 1.5mM 319 10 *** 249 49 * Extract obtained according to example 1 according to the invention 0.167mg/ml 71 10 ns 158 11 ** 0.5mg/ml 288 19 ** 184 21 * Extract obtained according to Example 3 outside the invention 0.167mg/ml 23 8 * 73 6 * 0.5mg/ml 2 1 ** 27 4 ***

ns >0.05 not significant; * 0.01 to 0.05: significant; ** 0.001 to 0.01: very significant; *** < 0.001: extremely significant

Example 5- Evaluation of the effectiveness of the extracts obtained in examples 2 and 3 on hydration

Principle:

The Corneometry on Isolated Stratum Corneum (CISC) test was developed to select humectant active ingredients (hygroscopic molecules, such as glycerol) that penetrate easily and attract or retain water in the epidermis.

The principle of the test used is based on the measurement of the electrical capacitance of the isolated human stratum corneum (SC) using the Corneometer™ device, a measuring device originally developed in clinical studies to determine the moisturizing potential in the upper layers of the skin. (~50µm). This capacitance depends on the mean value of the dielectric permittivity of the fabric. The dielectric permittivity varies greatly with the quantity of water contained in the SC, because the permittivity of water (E=81) is very different from many other substances contained in the skin (E < 7°. This ensures a measurement quite selective The sensor consists of 2 comb-shaped metallic (gold) electrodes 1. A thin insulating layer separates the electrodes on the tip of the probe in contact with the skin.The electrical circuit power supply induces an electric field in the SC and an alternating electric current (f = 1 MHz) between the 2 electrodes.The apparatus measures the corresponding capacitance.

Corneometer measurement has several advantages. Unlike impedance measurements, capacitance measurement is not influenced by chemical substances or the conductivity of products applied to the skin (salts). The penetration depth of the electric field is very low (20 – 45 µm), so only the hydration of the skin surface is measured. The measurement time is very short (1 sec in standard mode).

This method is thus applicable to the evaluation of cosmetic products that change the water content in the SC. It is mainly hygroscopic products that are able to penetrate the SC in order to attract or retain water inside the SC (eg glycerol). The method is not applicable to products that induce hydration by an occlusive effect (eg Vaseline, oils, etc.)

In the CISC test, the test product is applied topically to the stratum corneum (SC) in a simplex vehicle or in a formula.

The difference between the capacitance measurements before and after application makes it possible to estimate its hydration potential and to position it in relation to the hydration level of the vehicle and positive control references (glycerol 5%).

In terms of scope, the CISC test is suitable for the evaluation of assets with humectant properties.

This test was used to evaluate the effects of the aqueous extract of the calyces of white flowers of Hibiscus sabdariffa obtained according to example 2 according to the invention, with regard to the hydroalcoholic extract of the calyces of white flowers of Hibiscus sabdariffa obtained according to Example 3 outside the invention.

The extracts were tested at 5% by weight dry matter in a neutral vehicle which contains 80% ultrapure deionized water and 20% n-propanol. The positive reference corresponds to a 5% glycerol solution.

Results and conclusions:

The results are expressed as a percentage relative to the moisturizing effect of the positive reference (glycerol 5%):

Relative wetting effect of treatment (%) =

∆CM(treatment)−∆CM(vehicle)∆CM(glycerol 5%)−∆CM(vehicle)∙100%

here ∆CM represents the variation of the Corneometer signal obtained on the SC before (t=0) and after (t=4h) the product application (treatment studied, reference or vehicle).

The table below shows the results for the extracts obtained according to example 2 according to the invention and according to example 3 outside the invention.

Treatment Humectant effect relative to glycerol (%) Extract obtained according to example 2 according to the invention 72.4 Extract obtained according to Example 3 outside the invention 38.7

A very significant humectant effect is observed for the extract obtained according to Example 2 according to the invention at a level comparable to that of the positive reference (glycerol: humectant effect=100%). On the other hand, the extract obtained according to example 3 outside the invention produces a much weaker effect.

Example 6 - Evaluation of the Efficacy of the Extract Obtained in Example 1 on Desquamation

Principle of the test:

The test consists in measuring the cohesion of the SC of excised human skin maintained in survival. The SC is therefore made up of very flat cells, the corneocytes, which attach to each other by structures called corneodesmosomes (CdM). These are distributed on the surface of the corneocytes but also on their edges where they are more resistant. When these structures are modified, the CoMs of the surface are the first to open before those of the extremities. On a histological section, the initially very cohesive SC will look like a kind of net that is stretched; this is the “basketball wave” (BW) effect. If the desquamation goes further, then the corneocytes will completely detach. The “basket wave” and the detachment (DTC) of the corneocytes are the 2 parameters measured to assess the desquamating effects of a technology. A scoring scale was established with reference products identified in clinical studies on cosmetic exfoliants. The results are expressed as the sum of the 2 “BW” + “DTC” scores. The effect of a technology is compared to the skin control and the effect of the reference, here salicylic acid at 1.5%. The use of viable excised human skin, maintained in survival for 6 days, allows four repeated daily applications.

The extract obtained according to Example 1 is tested at 1% by weight of active ingredient (relative to the content of total AHA organic acids) corresponding to 2.15% by weight of dry extract.

Protocol (experimental conditions)

The table below presents the characteristics of the protocol and the processing of the data.

Settings Terms skin model Abdominal viable skin Number of donors / study 4 Number of sample / donor / condition 3 (2x2cm) Duration of the study 6 days Application 1x/day: Thursday, Friday, Monday, Tuesday, Wednesday (not rinsed), 20mg/cm ² Controls T=0; T = 6 days or T = 9 days Reference compound 1.5% Salicylic Acid (SA) Parameter analyzed Histology (HES: 3 sections / biopsies, 5 zones per section, n=45 zones per cdt) Measurement criterion Basket wave (BW) and stratum corneum detachment (TCD) Analysis Sum of BW and DTC: medians
Descriptive statistics: spot fire
Statistics: MyStat

Results and conclusions:

The results of the effects of the extract obtained according to Example 1 and of the 1.5% salicylic acid reference solution are presented in the table below and the . The medians correspond to the sum of the BW and the DTC whose scoring scales are presented in FIGS. 1 and 2, obtained on the 4 donors used.

Witness J0 J6 control Salicylic Acid 1.5% Extract obtained according to example 1 1% in active ingredient Median 2 2 4 4 SD 1.4 1.6 1.3 1.8 not 36 36 36 36

The statistical analysis carried out with MyStat shows:
- a significant difference between the samples treated with salicylic acid and those of the controls (low effect size)
- a significant difference between the samples treated with the extract obtained according to example 1 and those of the controls (low effect size)
- no difference between the samples treated with the extract obtained according to Example 1 and those treated with salicylic acid.

In conclusion, the extract obtained according to Example 1 (according to the invention) at 1% by weight of active ingredient, decreases the cohesion of the SC of excised human skin in a manner comparable to the reference solution of salicylic acid at 1 .5%, this after 4 in vitro applications.

Claims (21)

Hibiscus sabdariffa extract comprising:
i. at least 30% by weight of hibiscus acid and/or its salts relative to the total weight of the components of the extract;
ii. at least 5% by weight of hydroxycitric acid and/or its salts relative to the total weight of the components of the extract;
iii. at least 10% by weight of one or more sugar(s) relative to the total weight of the components of the extract. Hibiscus sabdariffa extract according to claim 1, in which the hibiscus acid and/or its salts is (are) present in a concentration of between 30% and 50% by weight, very preferably between 32% and 45% by weight, even better between 34% and 40% by weight relative to the total weight of the components of the dry extract. Extract of Hibiscus sabdariffa according to Claim 1 or 2, in which the hydroxycitric acid and/or its salts is (are) present in a concentration of between 5% and 15% by weight, very preferably between 6% and 14% by weight, even more preferably between 7% and 13% by weight, even better between 8% and 12% by weight relative to the total weight of the components of the dry extract. Hibiscus sabdariffa extract according to any one of the preceding claims, in which the sugar(s) is (are) chosen from arabinose, glucose, fructose, sucrose, and mixtures thereof. Extract of Hibiscus sabdariffa according to any one of the preceding claims, in which the sugar(s) is (are) present in a concentration between 10% and 30% by weight, very preferably between 10% and 20 % by weight, even better between 12% and 15% by weight relative to the total weight of the components of the dry extract. Hibiscus sabdariffa extract according to any one of the preceding claims, characterized in that it also comprises at least 0.3% by weight of one or more polyphenol(s) relative to the total weight of the components of the extract , preferably between 0.3% and 2% by weight, even better between 0.4% and 0.6% by weight relative to the total weight of the components of the dry extract. Hibiscus sabdariffa extract according to the preceding claim, in which the polyphenol(s) is (are) chosen from rutin, 3-O-caffeylquinic acid and its salts, 4-O -caffeylquinic acid and its salts, 5-O-caffeylquinic acid and its salts. Extract of Hibiscus sabdariffa according to any one of the preceding claims, characterized in that it is obtained by extraction using an aqueous solvent. Hibiscus sabdariffa extract according to any one of the preceding claims, characterized in that it is obtained from a variety of Hibiscus sabdariffa with white flowers, in particular from one or more white flower(s). s) of Hibiscus sabdariffa, such as one or more calyx(es) of white flowers of Hibiscus sabdariffa. Composition comprising, in a physiologically acceptable medium, an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9. Composition according to the preceding claim, in which the extract is present in a concentration of between 0.001% and 20% by weight of dry extract, preferably between 0.01% and 10% by weight of dry extract, even better between 0.1% and 5% by weight of dry extract relative to the total weight of the composition. Cosmetic treatment process comprising the application of a composition as defined according to any one of Claims 10 or 11 to the skin, to improve the barrier function of the skin. Cosmetic treatment process comprising the application of a composition as defined according to any one of Claims 10 or 11 to the skin, to prevent and/or treat roughness or micro-relief and/or improve the radiance of the complexion and/or to improve the suppleness of the skin. Cosmetic treatment process comprising the application of a composition as defined according to any one of Claims 10 or 11 to the skin, to prevent and/or treat the cosmetic signs of skin dryness. Cosmetic treatment process comprising the application of a composition as defined according to any one of claims 10 or 11 to the skin, to moisturize the skin. Cosmetic treatment process comprising the application of a composition as defined according to any one of Claims 10 or 11 to the skin, to promote desquamation of the skin. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9 for improving the barrier function of the skin. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9 for preventing and/or treating roughness or micro-relief and/or improving the radiance of the complexion and/or for improving the suppleness of the skin. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9 for preventing and/or treating cosmetic signs of skin dryness. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9 as a moisturizing active ingredient. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9 as a desquamating active