WO2022003056A1

WO2022003056A1 - Extract of hibiscus sabdariffa and use thereof for improving the barrier function and promoting the moisturization and desquamation of the skin

Info

Publication number: WO2022003056A1
Application number: PCT/EP2021/068069
Authority: WO
Inventors: Yegor DOMANOV; Saliou NGOM; Amit Tewari; Lionel PAILLAT
Original assignee: L'oreal
Priority date: 2020-06-30
Filing date: 2021-06-30
Publication date: 2022-01-06
Also published as: FR3111817A1; FR3111817B1

Abstract

The present invention relates to an extract of Hibiscus sabdariffa comprising: i. at least 26% by weight of hibiscus acid and/or salts thereof, relative to the total weight of the components of the dry extract; ii. at least 5% by weight of hydroxycitric acid and/or salts thereof, relative to the total weight of the components of the dry extract; iii. at least 10% by weight of one or more sugars, relative to the total weight of the components of the dry extract. The present invention also relates to a process of preparation of said extract, a composition comprising said extract, a cosmetic treatment process comprising the application to the skin of said composition to improve the barrier function of the skin, and 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.

Description

Title: Extract of Hibiscus sabdariffa and use thereof for improving the barrier function and promoting the moisturization and desquamation of the skin

The present invention relates to the field of active agents that are capable of improving the skin’s barrier function, for a cosmetic application, and notably an extract of Hibiscus sabdariffa comprising at least 26% by weight of hibiscus acid, at least 5% by weight of hydroxycitric acid and at least 10% by weight of one or more sugars relative to the total weight of the components of the dry extract, to a process of preparation of such extract, to a composition comprising same, to a cosmetic treatment process comprising the application of said composition, and also to the cosmetic use of said extract as a moisturizing and desquamating active agent and in the improvement of the skin’s barrier function.

The skin is the primary barrier for protecting the body from the external environment. Human skin consists of several compartments, three of which cover the whole of the body, namely a superficial compartment, which is the epidermis, the dermis and a deep compartment, which is the hypodermis.

Natural human epidermis is composed mainly of three types of cells, namely keratinocytes, which form the vast majority, melanocytes and Langerhans cells. Each of these types of cells contributes, by virtue of its intrinsic functions, towards the essential role played in the body by the skin, notably the role of protecting the body against external attacking factors, which is known as the “barrier function”.

The epidermis is conventionally divided into a basal layer of keratinocytes constituting the germinative layer of the epidermis, a “spinous” layer constituted of several layers of polyhedral cells positioned on the germinative layers, one to three “granular” layers and finally the cornified layer (or stratum corneum), constituted of a set of layers of keratinocytes at the terminal stage of their differentiation, known as corneocytes. Corneocytes are anuclear cells mainly composed of a fibrous matrix containing cytokeratins, notably cytokeratin 10, surrounded by a very strong structure 15 nm thick, known as the cornified envelope. Stacking of these corneocytes constitutes the cornified layer which is responsible for the barrier function of the epidermis. This differentiation is the result of perfectly coordinated phenomena which result in the maintenance of a constant thickness of the epidermis, thus ensuring its homeostasis. This proceeds via regulation of the number of cells that enter into the differentiation process and of the number of cells that desquamate. In the course of 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 cornified layer. Filaggrin (or filagrin), a protein present in keratohyalin granules, is produced during the final stages of differentiation of the epidermis. It participates in the organization of type I and type II keratins into balls. This protein thus enables the formation of the cytoplasmic matrix of the surface corneocytes which notably gives the skin its normal thickness, its smooth appearance and its light-reflecting properties. Furthermore, via its degradation inside the corneocytes, filaggrin provides water-soluble substances having a high osmotic power (natural moisturizing factors or NMFs) that enable maintenance of good hydration of the cornified layer of the skin and thus prevent the “dry skin” sensation. Filaggrin therefore enables maintenance of the barrier function of the epidermis and prevents drying-out of the skin.

It is thus understood that the cornified layer constitutes a veritable protective barrier against exogenous factors and endogenous water loss.

Its correct renewal and also the quality of its structure are essential for providing an effective barrier against the external environment and for limiting water losses, which are the cause of dehydration and dry skin (Velarde M.C., J. Invest. Dermatol., 2017, 137, 1206). Among the factors involved in correct regulation of the stratum corneum is the enzyme transglutaminase-1 (TGM-1 ), also known as keratinocyte transglutaminase (KTG). Its role is fully illustrated in ichthyosis, a cornification defect, associated with TGM-1 mutations (Vega V.L. and Mehta R.C., Clin. Insights, 2016, 1-2; Flerman M.L. et al. , Fluman Mutat., 2009, 30, 537).

The cohesion of the epidermis as a water barrier is provided by means of the tight junctions between keratinocytes. These tight junctions are formed from transmembrane proteins such as occludin (OCL) and claudin (CLDN-1 ) and are located in the granulous layer. Other structures, such as the zonula occludens (ZO) proteins, connect these transmembrane proteins to the cytoskeleton so as to allow the granulous cytoplasmic scaffolding (Jin S.P. et al. , J. Dermatol. Sci. , 2016, 84, 97; Velarde M.C., J. Invest. Dermatol., 2017, 137, 1206, Brandner J.M. et al., Tissue Barrier, 2015, 3, 1).

Finally, the phase of transition of the granulous layer into the cornified layer is essential for forming a skin barrier of quality, ensuring the homeostasis of the body. Among the factors involved in this transition that may be distinguished are the transglutaminases, including transglutaminase 1 (TGM-1).

Reinforcing the quality of the epidermis by favouring the intracellular junctions and the cohesion of the cornified layer contributes towards maintaining the functions of the epidermis and good moisturization.

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

In addition, among the desquamating agents known from the prior art, mention may notably be made of a-hydroxy acids (AHAs) such as lactic acid or glycolic acid, or b-hydroxy acids (BHAs) such as salicylic acid. These active agents bring about, by topical application at concentrations of a few percent, desquamation that is visible after a few days. Unfortunately, certain desquamating compounds may have side effects, such as skin discomfort.

However, with regard to the prior art, the need remains, in particular naturally, to reinforce the quality of the epidermis by favouring the intracellular junctions and the cohesion of the cornified layer, which are a basic feature for maintaining the functions of the epidermis and good moisturization.

There is also a need to find novel natural pro-desquamating compounds which in particular do not have the side effects mentioned previously. Surprisingly, the inventors have in fact demonstrated the particular properties of an extract of Hibiscus sabdariffa, notably an aqueous extract obtained from the calyxes of white Hibiscus sabdariffa flowers, comprising at least 26% 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, on a model of normal human keratinocytes as a monolayer. They have also demonstrated a moisturizing effect, notably a persistent moisturizing effect, of said extract on a model of reconstructed skin and also a desquamating effect on an ex vivo skin explant. This set of properties thus advantageously makes it possible to envisage the use of an extract of Hibiscus sabdariffa, or of a composition comprising said extract, for improving the skin’s barrier function. In addition, these properties make it possible to envisage the use of said extract, or of a composition comprising said extract, as a moisturizing active agent and/or as a desquamating agent.

The prior art discloses an extract of Hibiscus sabdariffa, notably an aqueous- alcoholic extract, obtained from the calyxes of white Hibiscus sabdariffa flowers, comprising 25.43% by weight of hibiscus acid, 4.1 % by weight of hydroxycitric acid and 8.5% by weight of sugars relative to the total weight of the components of the extract, used in combination with a baobab extract for anti-ageing properties. However, as shown by Examples 4 and 5 of the present patent application, the extract known from the prior art does not have any effect either on improving the barrier function or on moisturizing the skin when compared with the extract according to the invention.

Thus, one subject of the present invention is an extract of Hibiscus sabdariffa comprising: i. at least 26% by weight of hibiscus acid and/or salts thereof, relative to the total weight of the components of the dry extract; ii. at least 5% by weight of hydroxycitric acid and/or salts thereof, relative to the total weight of the components of the dry extract; iii. at least 10% by weight of one or more sugars, relative to the total weight of the components of the dry extract.

Another subject of the present invention is a process of preparation of the extract according to the invention comprising at least the following steps : i. optionally, grinding one or more calyx(es) of white flowers of Hibiscus sabdariffa ; ii. extraction by maceration at room temperature, for example 25°C, using an aqueous solvent such as water ; iii. optionally prefiltration of the extract obtained at step ii. with a filter having a porosity ranging from 50pm to 250pm ; iv. filtration of the extract obtained at step ii. or the filtrate obtained at step iii. with a filter having porosity ranging from 0,1 pm to 10pm, preferably ranging from 0,1 pm to 5pm, more preferably ranging from 0,1 pm to 2pm, even more preferably ranging from 0,2pm to 1 ,2pm ; v. optionally drying the filtrated extract obtained at step iv. by evaporation of the aqueous solvent notably using a rotary evaporator, or by freeze-drying or by atomization.

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

Another of the subjects of the present invention concerns a cosmetic treatment process comprising the application of said composition to the skin:

- for improving the skin’s barrier function, and/or

- for preventing and/or treating roughness and/or the micro-relief and/or for improving the radiance of the complexion and/or for improving the suppleness of the skin, and/or

- for preventing and/or treating the cosmetic signs of skin dryness, and/or

- for moisturizing the skin, and/or

- for promoting desquamation of the skin.

[0020] The present invention also relates to the cosmetic use of said extract:

- for improving the skin’s barrier function, and/or

- for preventing and/or treating the cosmetic signs of skin dryness, and/or

- as a moisturizing active agent, and/or

- as a desquamating active agent. Definitions

The Hibiscus genus belongs to the Malvaceae family. Hibiscus sabdariffa originates from West Africa, India and Malaysia. It is widely distributed in the Tropics and is widely cultivated for its calyx (flowers). Hibiscus sabdariffa is also available in China, Thailand, Sudan and Mexico and in certain other countries with smaller suppliers, such as Egypt, Senegal, Tanzania, Mali and Jamaica.

Hibiscus sabdariffa more particularly exists in a white variety (white calyx) and a red variety (red calyx associated with the presence of anthocyans).

The calyxes of the white variety, popularly known as “Bissap bou weekh” in the wolof language in Senegal, are used fresh or dried as condiments in local fish- based preparations and, less frequently, in drinks.

The calyxes of the red variety are widely used in traditional medicine and find various industrial applications as sources of anthocyans (red pigments) as colorant, and of AHAs (fruit acids). The biomass used in the context of the present invention preferably consists of dried calyxes (flowers) of the white variety of hibiscus ( Hibiscus sabdariffa). This plant is a seasonal plant which can be cultivated in Senegal and particularly in the regions of Diourbel, Thies, Louga, St Louis, Fatick, Kaolack and Tambacounda during the rainy season (from July to October of each year). The calyxes are harvested when the fruit is ripe, between November and December, and are then dried in the sun and preground into particles with a size of less than or equal to 5 mm, preferably less than or equal to 2 mm.

Mention may be made in particular of the biomass of calyxes of white Hibiscus sabdariffa flowers originating from the regions of Diourbel or Thies (Mbour, Mballing) in Senegal.

The term “skin” means all of the skin of the body, and the scalp, and preferably the skin of the face, neckline, neck, arms and forearms, or even more preferably still the skin of the face (in particular of the forehead, nose, cheeks and chin), neckline and neck. According to the invention, the term “preventing” or “prevention” means reducing the risk of occurrence or slowing down the occurrence of a given phenomenon. The term “treating” or “treatment” means any action that aims to improve the comfort or the well-being of an individual; this term thus equally covers attenuating, relieving and curing.

The term “intended to be administered topically” means application to the surface of the skin under consideration.

Detailed description of the invention

Extract of Hibiscus sabdariffa

One subject of the present invention is an extract of Hibiscus sabdariffa comprising: i. at least 26% by weight of hibiscus acid and/or salts thereof, relative to the total weight of the components of the dry extract; ii. at least 5% by weight of hydroxycitric acid and/or salts thereof, relative to the total weight of the components of the dry extract; iii. at least 10% by weight of one or more sugars, relative to the total weight of the components of the dry extract. The hibiscus acid and/or the salts thereof are preferably present in a concentration of at least 30% by weight, more preferably between 30% and 50% by weight, even more preferably between 30% and 45% by weight, better still between 32% and 40% by weight, relative to the total weight of the components of the dry extract.

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

The sugar(s) denote monosaccharides such as glucose, fructose, arabinose or galactose, or oligosaccharides such as disaccharides, for instance sucrose.

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

The sugar(s) are preferably present in a concentration of between 10% and 30% by weight, very preferentially between 10% and 20% by weight, better still between 12% and 15% by weight 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 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 in a concentration of between 2% and 6% by weight relative to the total weight of the components of the dry extract, and

- sucrose 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 polyphenols relative to the total weight of the components of the dry extract, preferably between 0.3% and 2% by weight, better still between 0.4% and 0.6% by weight, relative to the total weight of the components of the dry extract.

Among the polyphenols present in said extract, mention may be made of rutin, 3- O-caffeoylquinic acid and salts thereof, 4-O-caffeoylquinic acid and salts thereof, 5-O-caffeoylquinic acid and salts thereof, and mixtures thereof.

In particular, the extract according to the invention comprises:

- rutin 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-caffeoylquinic acid and salts thereof 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-caffeoylquinic acid and salts thereof in a concentration of between 0.01% and

- 5-O-caffeoylquinic acid and salts thereof in a concentration of between 0.05% and

0.5% by weight relative to the total weight of the components of the dry extract. Advantageously, said extract also contains less than 0,1 % by weight of one or more anthocyanin(s) relative to the total weight of the components of the dry extract, preferably less than 0,01 % by weight, more preferably less than 0,001 % by weight relative to the total weight of the components of the dry extract, or even totally free of anthocyanin(s) (0%).

The anthocyanins can be chosen from cyanidine sambubioside, delphinidine sambubioside, and their mixtures.

In a preferred embodiment, the extract of Hibiscus sabdariffa according to the invention is obtained by extraction using an aqueous solvent, in particular water, preferably in a mass ratio calyx(es) of flowers, preferably white flowers, of Hibiscus sabdariffalaqueous solvent between 0.01 and 0.5, more preferentially between 0.05 and 0.3, better still between 0.07 and 0.2, optionally followed by a filtration step.

The extraction is preferably maceration at room temperature, for example 25°C, using an aqueous solvent such as water. Said extraction can be repeated at least once, preferably the extraction is repeated once.

Advantageously, the extraction is performed for an approximate time ranging from 30 minutes to 8 hours, preferably between 1 and 4 hours, more particularly between 1 and 3 hours such as 2 hours, notably with stirring, for example using an impeller or magnetic stirrer. The stirring speed may be between 100 and 300 rpm, such as 250 rpm.

Preferably, the extraction can be followed by a step of filtration, especially with a filter having a porosity ranging from 0, 1 pm to 10pm, preferably ranging from 0, 1 pm to 5pm, more preferably ranging from 0,1 pm to 2pm, even more preferably ranging from 0,2pm to 1 ,2pm.

Preferably, a step of prefiltration can be performed between the extraction and the filtration, especially with a filter having a porosity ranging from 50pm to 250pm. The extract thus obtained may be dried and is then in the form of a dry extract, for example by evaporation of the water notably using a rotary evaporator, by freeze drying or by atomization. For the purposes of the present invention, the term “dry extract” means an extract comprising less than 10% by weight of water, preferably less than 7% by weight of water, better still less than 5% or even more preferentially less than 2% by weight of water, or even totally free of water (0%).

The extract of Hibiscus sabdariffa according to the invention is preferably obtained from a variety of Hibiscus sabdariffa with white flowers, in particular from one or more white flowers of Hibiscus sabdariffa, such as one or more calyxes 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 calyxes of white flowers of Hibiscus sabdariffa which are ground, for example in the form of particles with a particle size of less than or equal to 5 mm, preferably with a particle size of less than or equal to 2 mm.

Alternatively, the present invention can concern an extract of Hibiscus sabdariffa comprising: i. at least 31 % by weight of at least one organic acid chosen from hibiscus acid and/or salts thereof and hydroxycitric acid and/or salts thereof, relative to the total weight of the components of the dry extract, preferably between 35% and 65% by weight, more preferably between 37% and 58% by weight, even more preferably between 40% and 52% by weight of organic acid chosen from hibiscus acid and/or salts thereof and hydroxycitric acid and/or salts thereof, relative to the total weight of the components of the dry extract ; ii. at least 10% by weight of one or more sugars, relative to the total weight of the components of the dry extract.

Process of preparation of an extract of Hibiscus sabdariffa

The present invention also relates to a process of preparation of the extract according to the invention comprising at least the following steps : i. optionally, grinding one or more calyx(es) of white flowers of Hibiscus sabdariffa ; ii. extraction by maceration at room temperature, for example 25°C, using an aqueous solvent such as water ; iii. optionally prefiltration of the extract obtained at step ii. with a filter having a porosity ranging from 50pm to 250pm ; iv. filtration of the extract obtained at step ii. or the filtrate obtained at step iii. with a filter having a porosity ranging from 0,1 pm to 10pm, preferably ranging from 0,1 pm to 5pm, more preferably ranging from 0,1 pm to 2pm, even more preferably ranging from 0,2pm to 1 ,2pm ; v. optionally drying the filtrated extract obtained at step iv. by evaporation of the aqueous solvent notably using a rotary evaporator, or by freeze-drying or by atomization.

Preferably, in the extraction step ii. the mass ratio calyx(es) of white flowers of Hibiscus sabdariffalaqueous solvent is between 0.01 and 0.5, more preferentially between 0.05 and 0.3, better still between 0.07 and 0.2.

The extraction step ii. can be repeated at least once, preferably the extraction is repeated once.

Advantageously, the extraction step ii. is performed for an approximate time ranging from 30 minutes to 8 hours, preferably between 1 and 4 hours, more particularly between 1 and 3 hours such as 2 hours, notably with stirring, for example using an impeller or magnetic stirrer. The stirring speed may be between 100 and 300 rpm, such as 250 rpm.

Preferably, step v. is performed until the water content of the extract is less than 15% by weight of water, preferably less than 12% by weight of water, better still less than 10% or even more preferentially less than 5% by weight of water, or even totally free of water (0%).

Preferably, at the end of the grinding step i. the calyx(es) of white flowers of Hibiscus sabdariffa is (are) in the form of particles with a particle size of less than or equal to 5 mm, preferably with a particle size of 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 and better still between 0.1 % and 5% by weight of dry extract relative to the total weight of the composition. The compositions, notably the cosmetic compositions, that may be used in the context of the invention generally comprise a physiologically acceptable medium.

The term “physiologically acceptable medium” means a medium that is 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 linear or branched C1-C6 monoalcohols such as ethanol, isopropanol or 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 mixtures thereof.

Preferentially, the composition according to the invention has a water content ranging from 20% to 95% by weight, better still 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, better still 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 any adjuvant normally used in the envisaged field of application.

Mention may notably be made of organic solvents, notably C1 -C6 alcohols and C2- C10 carboxylic acid esters; carbon-based and/or silicone oils, of mineral, animal and/or plant origin; water, waxes, pigments, fillers, colorants, surfactants, emulsifiers, coemulsifiers; cosmetic or dermatological active agents such as vitamin C, UV-screening agents, polymers, hydrophilic or lipophilic gelling agents, thickeners, preserving agents, fragrances, bactericides, odour absorbers and antioxidants.

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

These optional adjuvants may be present in the composition in a proportion of from 0.001 % to 80% by weight, preferably 0.01 % to 40% by weight, better still from 0.1 % to 20%, relative to the total weight of the composition. Depending on their nature, these adjuvants may 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, notably monosaccharides, oligosaccharides or 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 and better still between 0.1 % and 5% by weight, relative to the total weight of the composition.

Needless to say, a person skilled in the art will take care to select this or these optional additional ingredients and/or active agents, and/or the amount thereof, such that the advantageous properties of the extract according to the invention are not, or are not substantially, adversely affected by the envisaged addition.

The compositions according to the invention may be in any presentation form conventionally used for topical application and notably in the form of aqueous or aqueous-alcoholic solutions, oil-in-water (O/W), water-in-oil (W/O) or multiple (triple: W/O/W or O/W/O) emulsions, aqueous gels, or dispersions of a fatty phase in an aqueous phase using spherules, these spherules possibly being lipid vesicles of ionic and/or nonionic type (liposomes, niosomes or oleosomes). These compositions are prepared according to the usual methods.

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

A composition according to the invention may comprise an oily phase. A composition used according to the invention may advantageously comprise at least one liquid fatty substance other than the compounds present in the hydrolate of the invention.

The term “liquid fatty substance” means a compound with a melting point below about 30-35°C, as opposed to solid fatty substances, such as waxes, which have a melting point above about 50°C.

As oils that may be used in the composition of the invention, examples that may be mentioned include:

- hydrocarbon-based oils of animal origin;

- hydrocarbon-based oils of plant origin;

- synthetic esters and ethers, notably of fatty acids, for instance oils of formulae

RO00R2 and R’0R2 in which R’ represents a fatty acid residue including from 8 to 29 carbon atoms and R2 represents a branched or unbranched hydrocarbon- based chain containing from 3 to 30 carbon atoms;

- linear or branched hydrocarbons, of mineral or synthetic origin;

- fatty alcohols containing from 8 to 26 carbon atoms;

- fluorinated oils which are partially hydrocarbon-based and/or silicone-based;

- silicone oils;

- mixtures thereof.

In the list of oils mentioned above, the term “hydrocarbon-based oil” means any oil mainly including carbon and hydrogen atoms, and possibly ester, ether, fluoro, carboxylic acid and/or alcohol groups. The other fatty substances that may be present in the oily phase are, for example, fatty acids including from 8 to 30 carbon atoms, waxes, silicone resins and silicone elastomers. These fatty substances may be chosen in a varied manner by a person skilled in the art in order to prepare a composition having the desired properties, for example in terms of consistency or texture.

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 may 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 and nonionic emulsifiers, used alone or as a mixture, and optionally a coemulsifier. The emulsifiers are chosen in an appropriate manner according to the emulsion to be obtained (W/O or O/W emulsion). The emulsifier and the coemulsifier 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 the W/O emulsions, examples of emulsifiers that may be mentioned include dimethicone copolyols and alkyldimethicone copolyols. A crosslinked elastomeric solid organopolysiloxane including at least one oxyalkylene group may also be used as W/O emulsion surfactant.

For the O/W emulsions, examples of emulsifiers that may be mentioned are nonionic emulsifiers. The extract according to the invention, or said composition comprising same, may be used topically in the context of a use or of a process according to the invention.

The compositions according to the invention may be applied directly to the skin or, alternatively, to cosmetic supports of occlusive or non-occlusive type, intended to be applied locally to the skin. As non-limiting examples of cosmetic supports, mention may be made notably of a patch, a wipe, a roll-on and a pen. The composition may optionally be rinsed off after having been applied to the skin.

Uses and cosmetic treatment process

According to another of its subjects, the present invention relates to a cosmetic treatment process comprising the application of the composition according to the invention to the skin:

- for improving the skin’s barrier function, and/or

- for preventing and/or treating roughness and/or micro-relief and/or for improving the radiance of the complexion and/or for improving the suppleness of the skin, and/or

- for preventing and/or treating the cosmetic signs of skin dryness, and/or - for moisturizing the skin, and/or - for promoting desquamation of the skin, notably promoting the cleansing action and the removal of dead cells at the surface of the body and/or promoting the removal of films and/or improving the staying power of the makeup and/or improving the result of treating the skin with stratum corneum colorants such as dihydroxyacetone (DHA).

The present invention also relates to the cosmetic use of the extract according to the invention:

- for improving the skin’s barrier function, and/or

- for preventing and/or treating the cosmetic signs of skin dryness, and/or

- as a moisturizing active agent, and/or

- as a desquamating active agent.

A cosmetic use of the invention thus only addresses aesthetic defects of the skin, and therefore does not exert any therapeutic effect.

The present invention is directed towards a non-therapeutic cosmetic skincare use of the extract according to the invention or of the composition comprising same, in particular a cosmetic composition comprising the extract according to the invention.

The term “care” means non-therapeutic care capable of producing an aesthetic effect without, however, preventing or correcting a pathological dysfunction of the skin.

Surface of the skin

The surface of human skin is not smooth. It has a relief reflected by fine lines, different from wrinkles, which may be observed with a magnifying glass in the case of children and by the naked eye in the case of the elderly. These fine lines or furrows criss-cross so as to form structures of polygonal shapes, namely the skin’s microrelief.

The number and depth of the furrows constituting the skin’s microrelief may be affected by many external or internal factors. Advantageously, an extract according to the invention, or a composition comprising same, may be used for preventing and/or treating impairment of the state of the skin’s surface, in particular following impairment of the skin’s barrier function.

Even more particularly, an extract according to the invention, or a composition comprising same, may be used for preventing and/or treating an impairment of the skin’s microrelief, for reducing the number of furrows in the skin’s microrelief, for smoothing out the skin’s surface, for preventing and/or treating a skin surface irregularity, in particular for preventing and/or treating a rough state of the skin, or for reducing the depth of the furrows in the skin’s microrelief. Dry skin

One of the functions of the stratum corneum is to uptake and retain the water contained in the epidermis, and any impairment of its structure and/or function, notably following or associated with impairment of the skin’s barrier function, may be reflected by modifications in the moisturization of the skin. The skin is moisturized by the water from the deep layers and by sweat. An imbalance in skin moisturization may be reflected by profound physiological and cosmetic consequences.

In physiological terms, dry skin is often associated with a decrease in the degree of skin moisturization and also a modification of the process of maturation of the stratum corneum. In sensory terms, dry skin may be characterized by a sensation of skin tautness and/or tension.

An extract according to the invention, or a composition comprising same, may particularly be suitable for preventing and/or treating dry skin and/or the cutaneous signs associated with dry skin. Irrespective of its origin, skin suffering from dryness may generally present the following signs: a rough, scaly feel, and also decreased 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 the sensations of discomfort such as the tautness associated with dry skin.

Throughout the description, including the claims, the term “comprising a” should be understood as being synonymous with “comprising at least one”, unless otherwise specified.

In addition, the term “at least one” should be understood as being synonymous with “one or more”, unless otherwise specified.

The terms “more than”, “between... and...” and “ranging from... to...” should be understood as being limits inclusive, unless otherwise specified.

The examples and figures that follow are presented as non-limiting illustrations of the invention. The compounds are, depending on the case, cited as the chemical names or as the CTFA (International Cosmetic Ingredient Dictionary and Handbook) names. Figures:

FIG.1 : Scoring scale for the “basket wave” criterion FIG. 2: Scoring scale for the SC detachment criterion

FIG. 3: Histology of the control excised skin samples, treated with the extract obtained according to Example 1 and salicylic acid at 1.5% Examples

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

The extract was prepared according to the following process: - Grinding into fine particles of the calyxes of dried white flowers of Hibiscus sabdariffa originating from Mbour, the Thies region of Senegal, in an IKA mill (particle size of 1-2 mm).

- Extraction by maceration in water at room temperature (25°C regulated using a heat regulator), by introducing 570 g of calyx (flowers) powder into 4 litres of water (corresponding to a ratio of 142.5 g per 1 litre of water), and maintaining at this temperature for 2 hours, with motor stirring using an impeller system at 250 rpm.

- Next, prefiltration through a 100 pm Nitex gauze.

- Next, filtration on a Whatman® GF/C filter with a porosity of 1.2 pm, 090 mm. - Evaporation of the water on a rotary evaporator (BCichi Rotavapor® R215, equipped with a BCichi B-491 heating bath, and also a Vacuubrand PC 3001 Vario Pro vacuum pump) at 35-40° down to 1/3 of the initial volume.

- Next, freeze-drying of the aqueous residue for 24 hours using a Labconco FreeZone

4.5 Plus lyophilizer, coupled to a Vacuubrand RZ-6 vacuum pump in automatic start mode from -40°C in the collector.

- A dry extract of white flowers of calyxes of Hibiscus sabdariffa is thus obtained in the form of a pale beige powder.

- Next, homogenization by grinding with a manual mortar.

A dry extract with a water content of 6.2% by weight is obtained. Characterization

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

Tablel

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

Table 2

The analysis of the sugars is performed by ion-exchange chromatography coupled with a gold electrode on an anion-exchange column. The quantification was performed using analytical grade standards.

Table 3

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

The extract was prepared according to the following process:

- Maceration of 4.09 kg of calyxes of dried white flowers of Hibiscus sabdariffa originating from the Diourbel region of Senegal, ground to 2 mm at 10%ww for 2 hours at 25°C in water.

- Next, prefiltration of the depleted biomass through a 195 pm Nylon gauze (F1).

- Next, a second maceration at 25°C/30 minutes in 1/2 volume of water. - Prefiltration through a 195 pm Nylon gauze (F2).

- The fractions F1 and F2 obtained previously were combined and clarified and then sterilized on a 0.2 pm cartridge.

- The sterilized solution was concentrated to between 10% and 15% and then placed in form by atomization (160°C).

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

Characterization

The analyses performed in Example 1 were repeated in Example 2. The following results were obtained:

Table 4

Table 5

Table 6

Example 3 - Preparation of an aqueous-alcoholic extract of calyxes of white flowers of Hibiscus sabdariffa originating from the Thies region of Senegal (outside the invention) 80 g of calyx powder of white flowers of Hibiscus sabdariffa originating from the

Thies region with a particle size of 2 mm are macerated at room temperature in 560 ml of a 50/50 (v/v) water/ethanol mixture in a biomass/50% ethanol mass ratio of 1/7, for 2 hours with magnetic stirring at 300 rpm.

The supernatant is subsequently filtered (Whatman GF/C filter) and the marc is then washed with 100 ml of 50% ethanol solution, followed by evaporating off the ethanol from the aqueous-alcoholic filtrate using a rotary evaporator and then freeze-drying for 24 hours. A dry extract of calyxes of white flowers of Hibiscus sabdariffa is thus obtained as a pale beige powder. Homogenization is then performed by grinding with a manual mortar. Characterization

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

Table 7

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

Table 8

Table 9

Example 4 - Evaluation of the efficiency of the extracts obtained in Example 1 (invention) and Example 3 (outside the invention) on modulating the barrier function

Principle:

The aim of this study is to evaluate the effects of the extracts of calyxes of white flowers of Hibiscus sabdariffa obtained according to Examples 1 and 3, on the expression of differentiation proteins and of 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 aqueous-alcoholic 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 various markers studied are: a set of keratinocyte differentiation proteins (transglutaminase K, cytokeratin 10 and filaggrin) and also a tight junction protein (occludin) in connection with reinforcement of the skin’s barrier function. Protocol (experimental conditions)

Normal human epidermal keratinocytes in monolayer were used to perform the study.

Culture and treatments:

For analysis of the TGK expression The keratinocytes were seeded in 96-well plates and cultured in culture medium for 24 hours. The medium was then replaced with test medium containing or not containing (control) the test compounds or the reference (CaCI2 at 1.5 mM), and the cells were then incubated for 72 hours. All the experimental conditions were performed in n = 3. - For the analysis of filaggrin expression

The keratinocytes were seeded in 96-well plates and cultured in culture medium for 192 hours with changing of the culture medium after 24 and 96 hours of incubation. The medium was then replaced with test medium containing or not containing (control) the test compounds or the reference (CaCI2 at 1.5 mM), and the cells were then incubated for 72 hours. All the experimental conditions were performed in n = 3.

- For the analysis of cytokeratin 10 expression

The keratinocytes were seeded in 96-well plates and cultured in culture medium for 96 hours with changing of the culture medium after 24 hours of incubation. The medium was then replaced with test medium containing or not containing (control) the test compounds or the reference (CaCI2 at 1 .5 mM), and the cells were then incubated for 72 hours. All the experimental conditions were performed in n = 3.

- For the analysis of occludin expression

The keratinocytes were seeded in 96-well plates and cultured in culture medium for 24 hours. The medium was then replaced with test medium containing or not containing (control) the test compounds or the reference (CaCI2 at 1 .5 mM), and the cells were then incubated for 144 hours with retreatment after 72 hours of incubation. All the experimental conditions were performed in n = 3. in situ immunolabelling After incubation, the culture medium was removed and the cells were rinsed, fixed and permeabilized. The cells were then labelled with the primary antibody (see the table below) directed against the protein of interest (TGK, cytokeratin 10, filaggrin and occludin). This antibody was then revealed with a secondary antibody coupled to a fluorochrome (see the table below). In parallel, the cell nuclei were stained with Hoechst 33258 (bisbenzimide).

Table 10

The image acquisition was performed with an INCellAnalyzer™ 2200 (GE Healthcare) high-resolution imaging system (x20 objective lens). For each well, five digitized images were produced for all the immunolabellings.

The labellings were quantified by measuring the fluorescence intensity of the proteins relative to the number of cells identified by the Hoechst stain (integration of the digital data using the Developer Toolbox 1.5 software, GE Healthcare). Results and conclusions: Effect on the expressions of the markers

Under control conditions, the markers TGK, filaggrin and cytokeratin 10 (CK10) were poorly expressed and restricted to a low number of keratinocytes. Occludin (tight junction marker) was detected only in a restricted number of cells, in the form of relatively weak, partially diffuse and mainly cytoplasmic but also membrane labelling.

Treatment of the cells with 1.5 mM calcium chloride markedly improved the overall expression of all the markers TGK, filaggrin and cytokeratin 10 and also the number of cells expressing them. In the case of filaggrin, typical punctiform labelling could be observed. For occludin, treatment of the cells with 1.5 mM calcium chloride markedly improved the membrane expression of this marker and also the number of cells expressing it. These results were expected and enabled validation of the test.

The extract according to the invention obtained in Example 1 , tested at 0.5 mg/mL had a significant stimulatory 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 occludin expression 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 aqueous-alcoholic extract outside the invention obtained in Example 3, tested at 0.167 and 0.5 mg/mL, induced a significant, strong 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 more moderately (respectively, 73% and 27% of the control). No pronounced and significant variation could be detected on the other two markers tested.

Thus, the aqueous-alcoholic extract outside the invention obtained in Example 3 either does not modify the markers followed (TGK and filaggrin) or induces a strong decrease in their expression. Aqueous-alcoholic extraction modifies the contents of the predominant components of the extract and thus the properties of the extract on the expression of the markers followed.

Table 11

[0160] ns > 0.05 not significant; ^* 0.01 to 0.05: significant; 0.001 to 0.01 : very significant; ^*** < 0.001 : extremely significant

Table 12

^*** < 0.001 : extremely significant

Example 5 - Evaluation of the efficiency of the extracts obtained in Examples 2 and 3 on moisturization Principle:

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

The principle of the test used is based on measuring the electrical capacitance of isolated human stratum corneum (SC) using a Corneometer™, which is a measuring device that was initially developed in clinical studies for determining the moisturizing potential in the upper layers of the skin (~50 pm). This capacitance depends on the mean dielectric permittivity value of the tissue. The dielectric permittivity varies greatly with the amount of water contained in the SC, since the permittivity of water (E = 81 ) is very different from that of numerous other substances contained in the skin (E <7°). This enables a fairly selective measurement. The sensor is composed of two metal (gold) electrodes in the form of a comb 1 . A thin insulating layer separates the electrodes on the end of the probe in contact with the skin. The electrical circuit power induces an electric field in the SC and an alternating electrical current (f = 1 MHz) between the two electrodes. The apparatus measures the corresponding capacitance. Measurement with a corneometer involves several advantages. In contrast with impedance measurements, the capacitance measurement is not influenced by the chemical substances or the conductivity of the products applied to the skin (salts). The depth of penetration of the electric field is very low (20-45 pm), so it is only the moisturization of the surface of the skin that is measured. The measuring time is very short (1 sec in standard mode).

This method is thus applicable to the evaluation of cosmetic products which change the water content in the SC. These are mainly hygroscopic products that are capable of penetrating into the SC so as to attract or retain water inside the SC (e.g. glycerol). The method is not applicable to products which induce moisturization via an occlusive effect (e.g. petroleum jelly, oils, etc.).

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

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

In terms of field of application, the CISC test is adapted to the evaluation of active agents with humectant properties. This test was used to evaluate the effects of the aqueous extract of the calyxes of white flowers of Hibiscus sabdariffa obtained according to Example 2 according to the invention, with regard to the aqueous-alcoholic extract of the calyxes of white flowers of Hibiscus sabdariffa obtained according to Example 3 outside the invention. The extracts were tested at 5% by weight of solids in a neutral vehicle which contains 80% of ultrapure deionized water and 20% of 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 (5% glycerol):

Relative humectant effect of the treatment (%) = ACM(treatment)-ACM(vehicle)ACM(5% glycerol)-ACM(vehicle)x100% herein ACM represents the variation of the Corneometer signal obtained on the SC before (t = 0) and after (t = 4h) application of the product (test treatment, 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.

Table 13

A very substantial humectant effect is found 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 efficiency 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 kept alive. The SC thus consists of very flat cells, corneocytes, which attach to each other via structures known as corneodesmosomes (CdM). These corneodesmosomes are distributed at the surface of the corneocytes but also on their edges where they are stronger. When these structures are modified, the surface CdMs are the first to be opened, before those of the ends. On a histological section, the highly cohesive starting SC resembles a kind of net that is stretched out: this is the “basket wave” (BW) effect. If the desquamation goes further, the corneocytes will then become completely detached. The “basket wave” and the detachment (DTC) of the corneocytes are the two parameters measured for evaluating 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 in the form of a sum of the two scores “BW” + “DTC”. The effect of a technology is compared with the skin control and with the effect of the reference, in this case 1 .5% salicylic acid. The use of viable excised human skin, kept alive for 6 days, allows four repeated daily applications.

The extract obtained according to Example 1 is tested at 1 % by weight of active material (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 treatment of the data.

Table 14

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 in Figure 3. The medians correspond to the sum of the BWs and of the DTC, the scoring scales for which are presented in Figures 1 and 2, obtained on the four donors used.

Table 16

The statistical analysis performed with MyStat shows:

- a significant difference between the samples treated with salicylic acid and those of the controls (weak size effect)

- a significant difference between the samples treated with the extract obtained according to Example 1 and those of the controls (weak size effect)

- 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) containing 1 % by weight of active material reduces the cohesion of the SC of excised human skin in a comparable manner to the 1.5% salicylic acid reference solution, doing so after 4 in vitro applications.

Claims

1. Extract of Hibiscus sabdariffa comprising: i. at least 26% by weight of hibiscus acid and/or salts thereof, relative to the total weight of the components of the dry extract; ii. at least 5% by weight of hydroxycitric acid and/or salts thereof, relative to the total weight of the components of the dry extract; iii. at least 10% by weight of one or more sugars, relative to the total weight of the components of the dry extract.

2. Extract of Hibiscus sabdariffa according to Claim 1 , in which hibiscus acid and/or the salts thereof are present in a concentration of at least 30% by weight, more preferably between 30% and 50% by weight, even more preferably between 30% and 45% by weight, better still between 32% and 40% by weight, relative to the total weight of the components of the dry extract.

3. Extract of Hibiscus sabdariffa according to Claim 1 or 2, in which the hydroxycitric acid and/or the salts thereof are present in a concentration of between 5% and 15% by weight, very preferentially between 6% and 14% by weight, even more preferentially between 7% and 13% by weight, better still between 8% and 12% by weight, relative to the total weight of the components of the dry extract.

4. Extract of Hibiscus sabdariffa according to any one of the preceding claims, in which the sugar(s) are chosen from arabinose, glucose, fructose, sucrose, and mixtures thereof.

5. Extract of Hibiscus sabdariffa according to any one of the preceding claims, in which the sugar(s) are present in a concentration of between 10% and 30% by weight, very preferentially between 10% and 20% by weight, better still between 12% and 15% by weight, relative to the total weight of the components of the dry extract.

6. Extract of Hibiscus sabdariffa according to any one of the preceding claims, characterized in that it also comprises at least 0.3% by weight of one or more polyphenols relative to the total weight of the components of the extract, preferably between 0.3% and 2% by weight, better still between 0.4% and 0.6% by weight, relative to the total weight of the components of the dry extract.

7. Extract of Hibiscus sabdariffa according to the preceding claim, in which the polyphenol(s) are chosen from rutin, 3-O-caffeoylquinic acid and salts thereof, 4-O-caffeoylquinic acid and salts thereof, and 5-O-caffeoylquinic acid and salts thereof.

8. Extract of Hibiscus sabdariffa according to any one of the preceding claims, characterized in that it is obtained by extraction using an aqueous solvent.

9. Extract of Hibiscus sabdariffa 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 flowers of Hibiscus sabdariffa, such as one or more calyxes of white flowers of Hibiscus sabdariffa.

10. Composition comprising, in a physiologically acceptable medium, an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9.

11. 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 and better still between 0.1% and 5% by weight of dry extract relative to the total weight of the composition.

12. Cosmetic treatment process comprising the application of a composition as defined according to either of Claims 10 and 11 to the skin, for improving the skin’s barrier function.

13. Cosmetic treatment process comprising the application of a composition as defined according to either of Claims 10 and 11 to the skin, for preventing and/or treating roughness or the microrelief and/or for improving the radiance of the complexion and/or for improving the suppleness of the skin.

14. Cosmetic treatment process comprising the application of a composition as defined according to either of Claims 10 and 11 to the skin, for preventing and/or treating the cosmetic signs of skin dryness.

15. Cosmetic treatment process comprising the application of a composition as defined according to either of Claims 10 and 11 to the skin, for moisturizing the skin.

16. Cosmetic treatment process comprising the application of a composition as defined according to either of Claims 10 and 11 to the skin, for promoting desquamation of the skin.

17. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9, for improving the skin’s barrier function.

18. 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 the microrelief and/or for improving the radiance of the complexion and/or for improving the suppleness of the skin.

19. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9, for preventing and/or treating the cosmetic signs of skin dryness.

20. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9, as a moisturizing active agent.

21. Cosmetic use of an extract of Hibiscus sabdariffa as defined according to any one of Claims 1 to 9, as a desquamating active agent.

22. Process of preparation of an extract as defined in anyone of the claims 1 to 9 comprising at least the following steps : i. optionally, grinding one or more calyx(es) of white flowers of Hibiscus sabdariffa ; ii. extraction by maceration at room temperature, for example 25°C, using an aqueous solvent such as water ; iii. optionally prefiltration of the extract obtained at step ii. with a filter having a porosity ranging from 50pm to 250pm ; iv. filtration of the extract obtained at step ii. or the filtrate obtained at step iii. with a filter having a porosity ranging from 0,1pm to 10pm, preferably ranging from 0,1pm to 5pm, more preferably ranging from 0,1pm to 2pm, even more preferably ranging from 0,2pm to 1 ,2pm ; v. optionally drying the filtrated extract obtained at step iv. by evaporation of the aqueous solvent notably using a rotary evaporator, or by freeze-drying or by atomization.