FR3160893A1 - COSMETIC USE OF AN EXTRACT FROM AN ALGAE OF THE GENUS CYSTOSEIRA TO REDUCE THE APPEARANCE OF VASCULAR DARK CIRCLES AND BAGS UNDER THE EYES, IMPROVE SKIN FIRMNESS AND HYDRATION IN THE EYE CONTOUR - Google Patents

Abstract

USE IN COSMETICS OF AN EXTRACT FROM AN ALGAE OF THE GENUS CYSTOSEIRA TO REDUCE THE APPEARANCE OF VASCULAR DARK CIRCLES AND BAGS UNDER THE EYES, IMPROVE SKIN FIRMNESS AND HYDRATION IN THE EYE CONTOUR The present invention relates to a cosmetic active ingredient derived from an algae of the genus Cystoseira intended to improve the quality of the skin in the region around the eye, or periorbital region, by reducing the signs of aging and fatigue such as dark circles of vascular origin and bags under the eyes and by improving skin firmness and hydration.

Description

USE IN COSMETICS OF AN EXTRACT FROM AN ALGAE OF THE GENUS CYSTOSEIRA TO REDUCE THE APPEARANCE OF VASCULAR DARK CIRCLES AND BAGS UNDER THE EYES, IMPROVE THE FIRMNESS AND HYDRATION OF THE SKIN IN THE EYE CONTOUR

CONTEXT OF THE INVENTION

The present invention relates to a cosmetic active ingredient intended to improve the quality of the skin in the eye contour region, or periorbital region, by reducing the signs of aging and fatigue such as dark circles of vascular origin and bags under the eyes and by improving skin firmness and hydration.

DESCRIPTION OF THE PRIOR ART

Reminders about the skin and its different structures

The skin, a complex and dynamic organ, is composed of three main layers: the hypodermis, the dermis, and the epidermis. Each of these layers houses a diversity of cell types that are in constant interaction, playing crucial roles in skin health and functionality.

Within the hypodermis, we mainly find adipocytes, which store lipids and play an important role in thermal insulation and mechanical protection of the body.

Fibroblasts, located in the dermis, are essential for the synthesis of extracellular matrix components, such as collagen, elastin, hyaluronic acid, thus contributing to the firmness and elasticity of the skin.

Endothelial cells, located in the blood vessels of the dermis, provide nutrition and oxygenation to skin tissues, in addition to participating in the regulation of the inflammatory response and healing.

The epidermis, the outermost layer of the skin, is primarily composed of keratinocytes, which form a protective barrier against environmental stresses and prevent moisture loss. Lacking vascularization, it receives nutrients and oxygen through diffusion from blood capillaries in the underlying dermis.

Finally, different types of immune cells scattered throughout these layers play a vital role in defending against pathogens and regulating inflammatory responses.

The eye contour, an area very sensitive to signs of aging and fatigue

The periorbital area, or eye contour, stands out as one of the thinnest and most fragile regions of the face, possessing attributes that distinguish it from other anatomical parts.

Its skin, notably more delicate, is 3 to 5 times thinner compared to the rest of the face, which makes it particularly delicate and sensitive to damage and signs of aging.

Its high vascularity, coupled with low thickness and a certain transparency, allows the blood capillaries to be visibly perceptible.

Furthermore, this area of the face is characterized by a very thin dermis and hypodermis, with a minimal presence of sebaceous and sweat glands, which predisposes it to increased dryness due to the almost total absence of a protective hydrolipidic film.

The constant mechanical stress from blinking and facial expressions further increases its sensitivity.

These characteristics make it excessively vulnerable to influences of endogenous origin (genetics, age, fatigue, stress, lack of sleep, unsuitable lifestyle habits) responsible for intrinsic or chronological aging.

In addition, factors of the exogenous cutaneous exposome of environmental origin (UV, pollutants, etc.) accentuate the effects of intrinsic aging, leading to an amplification of the signs of aging in the eye contour region.

These intrinsic and extrinsic aging processes are generally accompanied by a low-grade inflammatory state that promotes the emergence of problems such as dark circles, puffiness, dryness, loss of firmness, as well as wrinkles and fine lines.

These common cosmetic concerns are exacerbated by various factors in the exposome.

Dark circles, particularly complex due to their multifactorial nature, can be of pigmentary, structural or vascular origin.

Dark circles are characterized by their purplish-blue color and are associated with an alteration of cutaneous microcirculation, which refers to the network of small blood vessels that supply the skin.

Poor circulation and fluid accumulation in the periorbital area can also lead to puffiness. This condition is mainly due to fluid accumulation or poor lymphatic drainage, resulting in visible swelling under the eyes.

The use of an algae of the genus Cystoseira relies on its unique biological properties, offering an innovative approach in the cosmetic field to address aesthetic concerns observed in the eye contour area.

This algae was chosen for its composition rich in bioactive compounds, offering targeted benefits to improve hydration, skin firmness and reduce vascular dark circles under the eyes, thus effectively addressing the signs of aging and skin fatigue observed in the periorbital region.

Although the mechanisms underlying these problems are not completely understood, the low-grade inflammatory state and oxidative stress caused and/or accentuated by certain exposome factors could locally promote increased permeability of blood vessels in the periorbital area.

Weakened, the blood vessels, lined internally by a layer of endothelial cells, lose their optimal functioning, characterized by an increase in vascular permeability, fluid leakage, exacerbated inflammation which can stimulate the production of new vessels, a process known as angiogenesis.

Under the eyes, these phenomena cause stagnation of blood flow or stasis and extravasation of hemoglobin. This leakage of hemoglobin, as well as the release of its breakdown products, such as hemosiderin and biliverdin, cause color changes within the layers of the skin, manifesting as a bluish or purplish tint under the eyes.

The accumulation of fluids in the periorbital skin tissue leads to the formation of bags under the eyes.

In addition, the molecules released by permeable vessels are potentially pro-oxidant and maintain the inflammatory state with the chronic release of pro-inflammatory markers (cytokines, chemokines, etc.) contributing significantly to premature aging of the skin around the eyes, including photoaging due to solar radiation.

Among these pro-inflammatory factors, enzymes such as matrix metalloproteinases (MMPs), or growth factors, such as VEGF, respectively cause the degradation of the components of the extracellular matrix (collagen, elastin, hyaluronic acid, etc.) but also the formation of new vessels, making dark circles more visible and accentuating the reactivity of this area.

The interaction of different skin cell types

The synergistic interaction between different skin cell types plays a crucial role in maintaining skin health and vitality.

These cells, through their communication and cooperation, orchestrate a series of biological processes essential to skin homeostasis.

Adipocytes, beyond their role in lipid storage, secrete factors that regulate inflammation and tissue repair, thus directly influencing the behavior of keratinocytes in the epidermis and endothelial cells of blood vessels.

With advancing age, the adipose tissue, already naturally restricted in the periorbital area, undergoes a further reduction in volume. This phenomenon contributes to sagging of the skin, favoring the emergence of wrinkles and marked furrows.

At the same time, a decrease in volume under the eyes leads to a visible hollowing, accentuating a more tired and aged appearance. This transformation of the eye contour highlights the signs of aging, significantly altering facial expression and the overall aesthetics of the face.

Additionally, with aging, subcutaneous adipose tissue becomes a source of inflammation. This chronic inflammation, or "inflamm'aging," results in the secretion of compounds, including cytokines (IL-6), and a decrease in the secretion of adipokines with anti-inflammatory properties (adiponectin), which can impact the functioning of other skin cells.

Among these, endothelial cells, responsible for the formation of blood vessels, provide a supply of nutrients and oxygen essential for the survival and function of skin cells, including keratinocytes located in the epidermis devoid of vascularization and which are essential for the establishment and maintenance of the skin barrier.

The inflammatory response in adipose tissue, through the release of pro-inflammatory compounds, contributes to the breakdown of the extracellular matrix, increased inflammation of blood vessels and loss of skin hydration, thus aggravating the visible signs of aging and fatigue, including the appearance of dark circles and puffiness in the eye area.

These complex interactions between the different cell types present in the skin underline the importance of a comprehensive approach to understanding and treating the signs of fatigue and skin aging.

By targeting these interactions and their age-related imbalances, it is possible to design more effective cosmetic treatments to preserve the youthfulness and health of the skin in the eye region, in particular by reducing the loss of firmness, skin dryness and the appearance of vascular dark circles, by countering the harmful effects of a pro-inflammatory microenvironment.

Alteration of the biological clock and skin fatigue

Disruptions to our natural biological clock, resulting from the pace of modern life, including excessive exposure to screens, lack of sleep, a sedentary lifestyle, and loss of mealtime rhythms, influence the quality of the skin, particularly that of the periorbital area.

Clinically, this can result in the accentuation of signs of fatigue, including dark circles and puffiness, and more generally, in premature aging of the skin around the eyes.

The imbalance of circadian rhythms, which refer to our biological cycles that last approximately 24 hours, affects many physiological processes and interferes with the functioning and homeostasis of skin cells, leading to the clinical signs mentioned above.

Indeed, at the cellular level, many genes and biological functions are regulated cyclically, involved in tissue regeneration and repair, the skin barrier, sebum production, protection against UV radiation, DNA repair, blood circulation and even in immune responses.

Circadian rhythm dysfunctions can lead to the loss of skin homeostasis through the deregulation of all these processes and the establishment of a chronic inflammatory state at the origin of premature aging particularly observed in the eye contour region.

Dark circles and bags under the eyes, being the most visible and striking signs of skin fatigue, turn out to be a direct reflection of the imbalance of the circadian rhythm, caused by the disruption of our natural biological clock due to the pace of modern life.

Vascular dark circles and puffiness

More or less marked, dark circles and bags contribute to the perception of age, fatigue and are associated with a state of sadness, regardless of culture.

These manifestations have a profound impact on appearance, well-being, self-esteem, and self-confidence, thus representing a major cosmetic challenge.

Their presence not only reveals a state of fatigue, but also modifies the perception we have of an individual's vitality and health, highlighting the crucial importance of maintaining a harmonious synchronization of our biological cycles to preserve not only the aesthetics of the skin but also psychological well-being.

OBJECTS OF THE INVENTION

Considered particularly unsightly, the search for solutions to reduce the signs of fatigue (dark circles, bags) and skin aging (loss of firmness, dry skin, etc.) in the eye contour area is ongoing.

Currently, aesthetic medicine solutions are generally invasive, ranging from filler injections, such as hyaluronic acid, to fat fillings ( lipofilling ), including chemical peels or microneedling .

Therefore, it has become essential to develop strategies that are absolutely non-invasive and without any surgery or side effects.

• Réduire l’état inflammatoire du microenvironnement cutané en agissant sur le tissu adipeux afin de prévenir l’inflamm’aginget ses conséquences sur les autres composants cutanés, incluant le maintien de la matrice extracellulaire ;
• Augmenter le stockage des lipides dans les adipocytes pour un effet de comblement et raffermissant naturel ;
• Limiter la production et la perméabilité excessives des vaisseaux sanguins pour réduire l’apparence des cernes vasculaires et des poches ;
• Stimuler la production de l’acide hyaluronique, pour une peau hydratée et plus ferme ;
• Réinitialiser le rythme circadien, pour le maintien de l’homéostasie cutanée et des différentes fonctions de régénérations et protection cutanées.

The present invention aims to meet these needs by proposing a new active ingredient for reducing vascular dark circles, improving skin firmness and hydration in the periorbital region, by acting directly on the underlying biological mechanisms:

• Reduce the inflammatory state of the skin microenvironment by acting on adipose tissue in order to prevent inflammaging and its consequences on other skin components, including the maintenance of the extracellular matrix;
• Increase lipid storage in adipocytes for a natural filling and firming effect;
• Limit excessive blood vessel production and permeability to reduce the appearance of vascular dark circles and puffiness;
• Stimulate the production of hyaluronic acid, for hydrated and firmer skin;
• Reset the circadian rhythm, for the maintenance of skin homeostasis and the various functions of skin regeneration and protection.

It is with this in mind that the applicant company carried out research and demonstrated that an extract obtained from an algae of the genus Cystoseira, in particular Cystoseira tamariscifolia , made it possible to meet the objectives of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is based on the unexpected discovery that an aqueous extract of phaeophyceae of the genus Cystoseira has notable effects on the skin with very interesting cosmetic properties to reduce the signs of fatigue and skin aging including the appearance of dark circles of vascular origin and bags, loss of firmness and dryness in the periorbital region, by regulating certain biological mechanisms underlying these problems.

Thus, the invention relates to the cosmetic use of an aqueous extract from an algae of the genus Cystos for the prevention or treatment of signs of fatigue and skin aging in the eye contour region, including the reduction or prevention of the appearance of vascular dark circles and bags under the eyes, the improvement of skin firmness and hydration.

Thus, according to the invention, Cystoseira extract is intended for the maintenance or treatment of tired skin or skin showing signs of premature aging, but healthy, around the eyes.

For the purposes of the invention, “tired skin” means skin with dark circles of vascular origin and/or bags, signs of premature aging such as a loss of firmness, a lack of hydration and dryness causing the formation of wrinkles and fine lines and sagging skin in the eye contour area.

For the purposes of the invention, “healthy skin” means skin deemed “non-pathological” by a dermatologist, i.e. not showing any infection, scar, disease or skin condition such as candidiasis, impetigo, psoriasis, eczema, acne or dermatitis, or wounds or injuries and/or other dermatoses.

By “aqueous extract” according to the invention, it is understood that the polar (hydrophilic) compounds have been solubilized and/or have been extracted in a polar solvent.

Thus, according to the invention, the extract comes from an algae of the genus Cystoseira of the Phaeophyceae class.

Phaeophyceae are algae of the Ochrophyta phylum. They are also known as "brown algae."

The inventors of the present invention have thus demonstrated using in vitro tests that an aqueous extract of an algae of the genus Cystoseira is capable of reducing inflammation of adipose tissue by inhibiting interleukin-6 (IL-6), increasing adiponectin, increasing lipid accumulation by adipocytes, limiting the formation of pseudo-tubes from endothelial cells, key components of blood vessels, decreasing vascular permeability by reducing porosity, boosting the synthesis of hyaluronic acid by keratinocytes, and resetting the expression of key genes regulating the circadian rhythm at the cellular level.

In particular, according to the invention, the prevention or treatment of signs of fatigue and skin aging in the eye contour region includes the reduction of blood vessel formation and their permeability.

The application of the extract according to the invention in fact makes it possible to prevent the leakage of hemoglobin in the periorbital region and the purplish-blue appearance of vascular circles and bags.

In particular, according to the invention, the prevention or treatment of signs of fatigue and skin aging in the eye contour region includes the reduction of wrinkles or fine lines.

The application of the extract according to the invention in fact allows the activation of the production of hyaluronic acid by keratinocytes and thus helps to combat skin dryness responsible for the appearance of wrinkles and fine lines.

In particular, according to the invention, the prevention or treatment of signs of fatigue and skin aging in the region around the eyes includes the regeneration of the epidermis.

Activation of hyaluronic acid production by keratinocytes also helps regenerate the epidermis.

In particular, according to the invention, the prevention or treatment of signs of fatigue and skin aging in the region around the eyes includes the restoration of the expression of clock genes.

The application of the extract according to the invention in fact makes it possible to restore the expression of clock genes generally altered by blue light and thus allows the maintenance of skin homeostasis.

Advantageously, the extract is derived from Cystoseira tamariscifolia, Cystoseira Barbata, Cystoseira Amantacea stricta, Cystoseira Nodicaulis, Cystoseira Usneoides, preferably Cystoseira tamariscifolia.

Advantageously, the Cystoseira extract is characterized by:

- A dry matter content greater than 5 g/L of liquid extract, preferably between 5 and 100 g/L of liquid extract, more preferably between 10 and 50 g/L of liquid extract;

- Between 0.15 and 0.5 mg of total phlorotannins per gram of liquid extract, preferably between 0.25 and 0.35;

- Between 0.5 and 5 mg of mannitol per gram of liquid extract, preferably between 1 and 4.

According to one embodiment of the invention, the extract is formulated in a composition, preferably topical, in which the quantity of extract is greater than or equal to 0.01% and less than or equal to 5% by weight, preferably between 0.1 and 3%, relative to the total weight of the composition.

Advantageously, the cosmetic composition is in the form of a cream, an oil-in-water emulsion, a water-in-oil emulsion, a multiple emulsion, a solution, a gel, a suspension, a spray or a powder.

Such a composition may of course include one or more other compounds such as colorants, film-forming agents, surfactants, perfumes, preservatives, emulsifiers, oils, UV filters, vitamins, or any other compound suitable for the cosmetic application of the composition.

The invention also relates to a cosmetic treatment method, characterized in that it consists of applying an aqueous extract from an algae of the genus Cystoseira as defined above, or a composition comprising it, to the skin around the eyes.

The preparation of the extract used in the context of the invention can be carried out as indicated below.

Seaweed can be harvested at an early stage as well as at a mature stage. These can be subjected to a partial or even total drying stage.

Preferably, the algae is harvested fresh then partially dried to ensure better reproducibility of the composition of the extract.

Any extraction method known to those skilled in the art and allowing the extraction of phlorotannins together with mannitol can be used to prepare the extract contained in the composition according to the invention. This includes in particular maceration, digestion, decoction, infusion, but also the use of techniques such as extraction by ultrasound, by microwaves or even the use of subcritical or supercritical fluids. Suitable solvents include water itself, hydroalcoholic solvents in any proportion or solvents consisting of water and a compound such as propylene glycol, butylene glycol, propanediol, glycerol in any proportion. Alcoholic solvents include in particular ethanol.

The preparation of the extracts suitable for the invention is carried out according to conventional techniques and generally involves a grinding step followed by an extraction step. The extraction methods clearly fall within the skills of those skilled in the art. Generally speaking, they use an extraction solvent which is of course chosen for its ability to extract the phlorotannins and mannitol contained in the plants in question.

This extraction solvent may be a polar solvent, in particular an aqueous solvent such as water, or a hydroglycolic solvent, i.e. a mixture of water and propylene glycol, butylene glycol or propanediol, or a hydroglyceric solvent, i.e. a water/glycerol mixture or a hydroalcoholic solvent formed by mixing water with at least one solvent such as ethanol.

Preferably, the extract is an aqueous, alcoholic, hydroglycolic, glycolic, hydroalcoholic or hydroglyceric extract.

For example, the extract according to the invention can be obtained by immersing the plant raw material in a hot solvent with a raw material/solvent mass ratio of between 1/10 and 1/100, for a period of a few hours, for example five hours. The pH can be adjusted before or after extraction in the aqueous mixture. The temperature of the solvent used can be in particular between approximately 20 and 80°C. Preferably and advantageously, the extract can be obtained by extracting the raw material using an extraction vehicle containing water and glycerin, the glycerin potentially being present in the final solvent in an amount by weight greater than that of the water. The temperature of this solvent can in particular be between approximately 20 and 80°C, preferably between 30 and 70°C, more preferably between 40 and 60°C. The extraction time can be several hours, for example between 2 and 24 hours, preferably between 2 and 8 hours, more preferably between 4 and 6 hours. The mixture can be mechanically stirred in situ at a speed between 10 and 1000 rpm. Once extracted, the solid residue of the algae is separated from the extractive solution by decantation or centrifugation. The extract is then filtered through one or more membranes of different thresholds.

The total phlorotannin contents of the extracts according to the invention are evaluated by HPLC/UV (high performance liquid chromatography with ultraviolet detection) and expressed as phloroglucinol equivalent.

The mannitol content of the extracts according to the invention can be evaluated by electrophoresis or by HPLC.

The above-mentioned and other features of the invention will become more clearly apparent from the following description of exemplary embodiments.

EXAMPLES

Example 1: example of methods for extracting the aqueous extract according to the invention

Extraction example A: Hot hydroglyceric extraction (water/glycerin)

- Incorporation of 80 kg of Cystoseira Tamariscifolia in 1000 kg of a hydroglyceric mixture.

- Heating between 30 and 70°C.

- Heating and solubilization time between 2 and 24 hours.

- Separation of soluble and insoluble phases by decantation and/or centrifugation and/or filtration.

- The extract is then filtered through bags and then filtered through membranes down to 2µm.

Extraction example B: Hydroglycolic extraction and immobilization on solid support (water/glycerin)

- Incorporation of 80 kg of Cystoseira Tamariscifolia in 1000 kg of a hydroglycolic mixture.

- Heating between 30 and 70°C.

- Heating and solubilization time between 2 and 24 hours.

- Separation of soluble and insoluble phases by decantation and/or centrifugation and/or filtration.

- Selection on solid support.

- The extract is then filtered through bags and then filtered through membranes down to 2 μm.

Extraction Example C: Aqueous Extraction

- Incorporation of 80 kg of Cystoseira Tamariscifolia in 1000 kg of water.

- Heating between 30 and 70°C.

- Heating and solubilization time between 2 and 24 hours.

- Separation of soluble and insoluble phases by decantation and/or centrifugation and/or filtration.

- Selection on solid support.

- The extract is then filtered through bags and then filtered through membranes down to 2 μm.

Extraction example D: Hydroalcoholic extraction (water/ethanol)

- Incorporation of 80 kg of Cystoseira Tamariscifolia in 1000 kg of a water/ethanol mixture.

- Extraction at a temperature of 30 to 70°C between 2 and 24 hours.

- The extract is then filtered through bags and then filtered through membranes down to 2 μm. The solvents are evaporated under vacuum.

Example 2: determination of the phlorotannin and mannitol contents of an extract according to the invention

Extracts of algae belonging to the genus Cystoseira were obtained by extraction method A presented in Example 1.

The total phlorotannin contents of the extracts obtained are determined by HPLC/UV and expressed as phloroglucinol equivalent. The results obtained are presented in Table 1 below:

Species, fabric Solvent extraction Total phlorotannin content
Eq. Phloroglucinol Cystoseira Tamariscifolia Water/glycerin 0.25 mg/g liquid extract Cystoseira Barbata Water/glycerin 0.24 mg/g liquid extract Cystoseira Amantacea stricta Water/glycerin 0.23mg/g liquid extract Cystoseira Nodicaulis Water/glycerin 0.20 mg/g liquid extract Cystoseira Usneoides Water/glycerin 0.19 mg/g liquid extract

The total phlorotannin contents per gram of liquid extract are between 0.15 and 0.5 mg, preferably between 0.25 and 0.35.

The mannitol contents of the extracts obtained are determined by capillary electrophoresis. The results obtained are presented in Table 2 below:

Species, fabric Solvent extraction Mannitol content Cystoseira Tamariscifolia Water/glycerin 1.5 mg/g liquid extract Cystoseira Barbata Water/glycerin 1.2 mg/g liquid extract Cystoseira Amantacea stricta Water/glycerin 1.4 mg/g liquid extract Cystoseira Nodicaulis Water/glycerin 0.9 mg/g liquid extract Cystoseira Usneoides Water/glycerin 1.2 mg/g liquid extract

Mannitol contents per gram of liquid extract are between 0.5 and 5 mg, preferably between 1 and 4.

Extracts from different algae species of the genus Cystoseira were observed to display remarkably homogeneous phlorotannin and mannitol contents. This homogeneity demonstrates a qualitative and quantitative consistency of phlorotannin compounds and mannitol across the genus Cystoseira, which is independent of the species concerned.

Examples 3 to 5: Improvement of lipid accumulation in subcutaneous preadipocytes and inhibition of adipose tissue inflammation

The objective of the study is to evaluate the ability of the aqueous extract of Cystoseira tamariscifolia (EACT) to inhibit the inflammatory state of adipose tissue and activate the differentiation and accumulation of lipids in preadipocytes for a firming effect on the face and filling in the periorbital area.

Operating mode:

The extract used is an aqueous extract of Cystoseira tamariscifolia (EACT) obtained according to the extraction method presented in example 1 (method A).

The anti-inflammatory effects of the aqueous extract of Cystoseira tamariscifolia (EACT) were investigated, evaluating the release of the pro-inflammatory cytokine IL-6 and adiponectin, with anti-inflammatory properties, and the accumulation of lipids by cultures of preadipocytes subjected to stress or not pro-inflammatory.

Human preadipocytes isolated from the hypodermis of a woman (body mass index = 30 kg/m² and aged 33 years) were cultured for 24 hours in DMEM medium in 96-well plates.

For the study of adipogenesis, i.e. the differentiation of preadipocytes into white adipocytes, preadipocytes were incubated in a pro-adipogenic cocktail including insulin, a glucocorticoid, 3-isobutyl-1-methylxanthine (IBMX) and thiazolidinedione. Preadipocytes treated with DMEM/F12 basal medium (undifferentiated) or treated with a PPARγ antagonist (GW9662, 1 µM, M6191, Sigma) were used as negative controls for adipocyte differentiation. Culture media, including or not 0.025%, 0.05% and 0.1% aqueous extract of Cystoseira tamariscifolia (EACT) were changed every 2-3 days during the culture period (12 days).

To induce preadipocyte differentiation in a pro-inflammatory environment, cells were treated with a proadipogenic cocktail (including insulin, glucocorticoid, 3-isobutyl-1-methylxanthine (IBMX), and thiazolidinedione) and activated human macrophage (cMAb)-conditioned medium for 15 days.

Dexamethasone at 100 nM was used as an anti-inflammatory response control. During the last 24 hours of culture, cells were returned to culture medium without active ingredient to collect cellular secretions.

All conditions were carried out in three experimental replicates (n=3).

The media, including or not the aqueous extract of Cystoseira tamariscifolia (EACT) at 0.025%, 0.05% and 0.1% were changed every 2/3 days for 15 days.

After the culture period, culture media (24-hour secretion) were collected and cells were fixed with 4% paraformaldehyde before fluorescent staining experiments or other assays from culture supernatants.

Lipid accumulation analysis / dosage

After culture (12 days for the classical proadipogenic environment and 15 days for the pro-inflammatory proadipogenic environment), cells were fixed with 4% paraformaldehyde and then stained with AdipoRed and DAPI (4',6-Diamidino-2-Phenylindole, Dihydrochloride) at room temperature to reveal intracellular lipid droplets and nuclei, respectively.

Quantification of lipid accumulation and nuclei was performed by fluorescence signal measurements using the Spark M10 spectrophotometer (TECAN).

Biochemical analyses of IL-6 and adiponectin releases

Biochemical analyses of adiponectin (Biotechne, DY1065) were performed in the culture media of preadipocytes cultured in classical proadipogenic and pro-inflammatory environments after 12 and 15 days of culture, respectively.

Biochemical analyses of IL-6 (Biotechne, DY206) were performed only on preadipocytes cultured in a pro-inflammatory proadipogenic environment after 15 days of culture. The assessment was performed by ELISA tests using specific kits and in accordance with the suppliers' recommendations.

Results :

Examples 3: Improvement of lipid accumulation in subcutaneous preadipocytes

Table 3 below summarizes the effects of aqueous extract of Cystoseira tamariscifolia (EACT) on lipid accumulation in differentiating preadipocytes.

For statistics, values of p<0.05 are considered significant (*), (Student's t-test versus untreated classical differentiation control).

Lipid accumulation assay (% of differentiated control) under basal conditions Classical differentiation Classical differentiation + PPARγ antagonist GW9662 Classical differentiation + EACT 0.025% Classical differentiation + EACT 0.05% Classical differentiation + EACT 0.1% Average 100 58 112 113 158* Standard deviation 38 9 50 49 38

The aqueous extract of Cystoseira tamariscifolia (EACT) applied to preadipocytes at 0.1%, significantly increased lipid accumulation by (+58%) compared to classical differentiation alone, demonstrating its prodifferentiating effect on this cell type and suggesting its skin-filling capabilities due to the reduction of subcutaneous adipose tissue in the face.

Examples 4: Improvement of subcutaneous preadipocyte differentiation by stimulation of adiponectin release

Table 4 below summarizes the significant effects of aqueous extract of Cystoseira tamariscifolia (EACT) on the release of adiponectin by differentiating preadipocytes.

For statistics, values of p<0.05 are considered significant (*), (Student's t-test versus untreated classical differentiation control).

Assay of adiponectin release (% of differentiated control) under basal conditions Classical differentiation Classical differentiation + PPARγ antagonist GW9662 Classical differentiation + EACT 0.025% Classical differentiation + EACT 0.05% Classical differentiation + EACT 0.1% Average 100 26 53 63 180* Standard deviation 48 24 41 20 69

The aqueous extract of Cystoseira tamariscifolia (EACT) applied to preadipocytes at 0.1%, significantly increased the release of adiponectin by (+80%) compared to classical differentiation alone, demonstrating its prodifferentiating effect on this cell type and its anti-inflammatory properties.

Examples 5: Improvement of the inflammatory state of adipose tissue

Table 5 below summarizes the significant effects of Cystoseira tamariscifolia aqueous extract (EACT) on the release of adiponectin and IL-6, by preadipocytes during differentiation and in pro-inflammatory conditions.

Assay of adiponectin and IL6 release (% of differentiated control) under pro-inflammatory conditions) Classical differentiation + Pro-inflammatory stimulation (AcMc) Classical differentiation + Pro-inflammatory stimulation (AcMc) + PPARγ antagonist GW9662 1 µM Classical differentiation + Pro-inflammatory stimulation (AcMc) + EACT 0.025% Classical differentiation + Pro-inflammatory stimulation (AcMc) + EACT 0.05% Classical differentiation + Pro-inflammatory stimulation (AcMc) + EACT 0.1% Average Adiponectin 100 410 481* 267* 370** Adiponectin Standard Deviation 32 170 232 143 63 Average IL-6 100 57 121 75 87 IL6 Standard Deviation 13 12 60 24 24

The aqueous extract of Cystoseira tamariscifolia (EACT) applied to preadipocytes at 0.025%; 0.05% and 0.1%, significantly increased adiponectin release by +381%, 167% and 270%, respectively, compared to classical differentiation alone and in a pro-inflammatory situation, demonstrating its anti-inflammatory properties. The 0.05% extract also tends to inhibit the release of the pro-inflammatory cytokine IL-6, confirming its anti-inflammatory properties on preadipocytes stressed by a conditioned pro-inflammatory medium from activated human macrophages (AcMc).

Furthermore, the aqueous extract of Cystoseira tamariscifolia (EACT) applied to preadipocytes at 0.025%, 0.05% and 0.1%, increased lipid accumulation in differentiating preadipocytes by 85%, 18% and 75%, respectively** (**p<0.01), and despite pro-inflammatory conditions known to prevent differentiation and therefore lipid accumulation in preadipocytes.

Example 6: Reduction of pseudotube formation from co-culture of endothelial cells and dermal fibroblasts

The objective of the study is to evaluate the ability of the aqueous extract of Cystoseira tamariscifolia (EACT) to inhibit the formation of new blood vessels (pseudo-tube test) from co-cultures of endothelial cells and dermal fibroblasts and to limit their porosity in order to reduce the appearance of the vessels as well as the leakage and accumulation of hemoglobin deposits in the periorbital area, which cause the purplish-blue color of dark circles of vascular origin, puffiness and local inflammatory state.

Operating mode:

Pseudo-tube test

The pseudotube assay is a laboratory experimental method used to study the formation of new blood vessels from pre-existing vessels. For this, human dermal microvascular endothelial cells (HMVEC-d) and normal human dermal fibroblasts (NHDF) were seeded in co-culture in 96-well plates and incubated for 24 hours. The medium was then replaced with co-culture medium containing or not (control) 0.1% aqueous extract of Cystoseira tamariscifolia (EACT), or the reference (100 µM suramin). The cells were then stimulated with VEGF (100 ng/ml) to stimulate pseudotube formation. The cells were then incubated for 7 days with a renewal of treatments and stimulation after 72 hours of incubation. A non-stimulated control condition was performed in parallel. All experimental conditions were carried out in three experimental replicates (n=3).

Results :

Table 6 below summarizes the effects of aqueous extract of Cystoseira tamariscifolia (EACT) on pseudotube formation.

Quantification of pseudotube formation (% of VEGF-stimulated control) Unstimulated control Stimulated control VEGF 100 (ng/ml) Control Suramine, pseudo-tube inhibitor VEGF + EACT 0.1% Average 7 100 42 81 Standard deviation 0 4 7 5

VEGF, tested at 100 ng/ml, strongly increased pseudotube formation (+1240%). Cystoseira tamariscifolia aqueous extract (EACT) applied at 0.1%, on HMVEC-d and NHDF co-cultures, inhibited pseudotube formation by -19% compared to the VEGF-only stimulated condition. These results demonstrate that Cystoseira tamariscifolia aqueous extract (EACT) is able to limit the formation of new vessels and potentially reduce their appearance at the periorbital level.

Example 7: Improvement of vascular permeability and function

The objective of the study is to evaluate the ability of the aqueous extract of Cystoseira tamariscifolia (EACT) to strengthen the vascular barrier and integrity.

Vascular permeability testing is commonly used to assess endothelial barrier function. The endothelial barrier, composed of endothelial cells that line blood vessels, plays a crucial role in controlling the passage of substances between the blood and surrounding tissues. This test measures the ability of molecules to cross this barrier and therefore assesses vascular integrity and functionality.

Operating mode:

Vascular permeability analysis

For the assay, HMVEC-d cells were seeded into the inserts pre-coated with fibronectin solution and incubated for 7 days, with medium replacement at 24 and 72 hours post-seeding. After this period, the medium was replaced with assay medium containing 0.5% aqueous extract of Cystoseira tamariscifolia (EACT) or a control (1 µM dexamethasone), followed by a 24-hour pre-incubation. TNF-α inducer at 1 ng/ml was then added, and the cells were incubated for an additional 24 hours. Unstimulated controls were also included. At the end of the incubation, the fluorescent tracer FITC-dextran was added to the top compartment of the insert and the cells were incubated for 20 minutes. For fluorescence measurement, a 50 µl sample from the bottom compartment of each insert was taken and these samples were diluted with PBS solution before being transferred into white flat-bottom 96-well plates. Fluorescence measurement was performed at λex 490 nm and λem 530 nm using a spectrophotometer (Synergy H1, BioTeck). All experimental conditions were performed in three experimental replicates (n=3).

Results :

Table 7 below summarizes the effects of aqueous extract of Cystoseira tamariscifolia (EACT) on vascular permeability.

Quantification of vascular permeability (% of control stimulated with TNF-α, 1 ng/ml) Unstimulated control Stimulated control VEGF 100 ng/ml) Control Dexamethasone TNF-α + EACT 0.5% Average 57 100 69 80 Standard deviation 4 8 2 2

TNF-α, tested at 1 ng/ml, increased endothelial cell permeability by +75%, demonstrated by a greater diffusion of the fluorescent signal through the insert. The aqueous extract of Cystoseira tamariscifolia (EACT) applied at 0.5% on HMVEC-d inhibited vascular permeability by -20.5% in the presence of TNF-α compared to the condition stimulated only with TNF-α. These results demonstrate that the aqueous extract of Cystoseira tamariscifolia (EACT) is able to preserve the endothelial barrier and integrity and prevent vessel leakage.

Example 8: Activation of hyaluronic acid synthesis

Hyaluronic acid plays a vital role in epidermal hydration and regeneration, helping to keep skin hydrated, firm, elastic, and promote skin repair. The objective of the study was to evaluate the ability of the aqueous extract of Cystoseira tamariscifolia (EACT) to regulate hyaluronic acid synthesis.

Operating mode:

Analysis of hyaluronic acid production by normal human epidermal keratinocytes (NHEK)

Keratinocytes were seeded in 96-well plates and cultured for 24 h before being treated for 72 h in the presence of the aqueous extract of Cystoseira tamariscifolia (EACT) applied at 1% or with retinoic acid used as a control. After 72 h of treatment, the supernatants were collected and the hyaluronic acid was measured by ELISA (R&D system).

Results :

Table 8 below summarizes the effects of aqueous extract of Cystoseira tamariscifolia (EACT) on hyaluronic acid production by NHEKs.

Quantification of hyaluronic acid release by NHEK (% of control) Control Treated Retinoic Acid (10 ^-7 M) EACT 1% Average 100 255 121* Standard deviation 2 8 2

As expected, retinoic acid tested at ^10-7 M significantly activated the production and/or release of hyaluronic acid by NHEK (+155%). The aqueous extract of Cystoseira tamariscifolia (EACT) applied at 1% on NHEK significantly stimulated by 21% the production and/or release of hyaluronic acid by NHEK. These results suggest that the aqueous extract of Cystoseira tamariscifolia (EACT) is capable of enhancing skin hydration and firmness.

Example 9: Regulation of “clock” gene expression altered by blue light

The objective of the study is to evaluate the ability of the aqueous extract of Cystoseira tamariscifolia (EACT) to restore the expression of “clock” genes altered by blue light.

At the cellular level, clock genes are essential for establishing and regulating circadian rhythms. This natural rhythm regulates biological cycles over a period of approximately 24 hours. It plays a crucial role in the regulation of several skin functions, such as the skin barrier, hydration, skin temperature, and immune response, processes essential for maintaining skin homeostasis.

To evaluate the ability of the aqueous extract of Cystoseira tamariscifolia (EACT) to restore the expression of "clock" genes, we set up a culture model of normal human keratinocytes, irradiated with blue light. Excessive exposure to blue light is indeed recognized as being involved in the alteration of the expression of these genes and the circadian rhythm.

Operating mode:

Analysis of the expression of genes coding for BMAL1, PER1, CRY2 by RT-PCR

The study was conducted on normal human keratinocytes (NHEK) seeded in 24-well plates.

After 24h, the cells were incubated with the aqueous extract of Cystoseira tamariscifolia (EACT) at a concentration of 0.3% for 24h, then subjected to blue light irradiation via a Medelisol LED lamp (Deleo SAS, irradiation dose of 50 J/cm²).

Following irradiation, cells were further incubated for 18 hours in the presence of 0.3% aqueous extract of Cystoseira tamariscifolia (EACT) before RNA extraction using TriPure® reagent following the supplier's instructions.

The quality and quantity of extracted RNA were assessed by capillary electrophoresis (Bioanalyzer 2100, Agilent Technologies) and spectrophotometry (Synergy H1, BioTek Instruments), respectively.

Complementary DNA (cDNA) was synthesized from these total RNAs in the presence of oligo(dT) and Transcriptor Reverse Transcriptase (Roche).

The adjusted cDNA quantities were then subjected to polymerase chain reaction (PCR) using the LightCycler® system (Roche Molecular System Inc.), according to the supplier's instructions.

For the analysis of differential expression of the clock genes BMAL1, PER1 and CRY2, quantitative RT-PCR was performed. The cycle threshold (Ct) values obtained were normalized to the Ct of a reference gene, ribosomal protein S28.

The application of the ΔΔCt method allowed the relative quantification of gene expression and the determination of the fold change (FC). The results obtained for cells treated with the aqueous extract of Cystoseira tamariscifolia (EACT) and exposed to blue light were compared, on the one hand, with those of untreated and unexposed cells (control) and, on the other hand, with cells exposed only to blue light without treatment with the aqueous extract of Cystoseira tamariscifolia (EACT).

Results

Table 9 below summarizes the effects of aqueous extract of Cystoseira tamariscifolia (EACT) on the expression of “clock” genes by NHEKs irradiated with blue light.

Gene symbol Gene name FC (Fold change) Blue light versus non-irradiated control FC (Fold change) Blue light + EACT 0.3% versus non-irradiated control FC (Fold change) Blue light + EACT 0.3% versus Blue light BMAL1 Basic helix-loop-helix ARNT like 1 2.21 ± 0.04* 1.97 ± 0.04* 0.89 ± 0.02* PER1 Circadian clock period 1 3.55 ± 0.07** 1.75 ± 0.03* 0.49 ± 0.02* CRY2 Cryptochrome circadian clock 2 2.32 ± 0.05* 1.11 ± 0.1* 0.48 ± 0.02*

Blue light significantly stimulated the expression of BMAL1, PER1 and CRY2 genes (*p<0.05;**p<0.01). Cystoseira tamariscifolia aqueous extract (EACT) significantly inhibited the overactivation of BMAL1, PER1 and CRY2 gene expression induced by blue light, by -11%, -51% and -52%, respectively (*p<0.05). These results suggest that Cystoseira tamariscifolia aqueous extract (EACT) restores the expression of “clock” genes altered by blue light and consequently maintains their synchronization essential for the establishment of circadian rhythm and skin homeostasis.

Example 10 to 13: Clinical tests demonstrating the efficacy of the aqueous extract of Cystoseira tamariscifolia (EACT) on dark circles of vascular origin, skin firmness and hydration.

To evaluate the effects of the aqueous extract of Cystoseira tamariscifolia (EACT) on signs of fatigue including vascular dark circles and aging (loss of firmness, skin dryness), a clinical trial was conducted with volunteers with visible dark circles of vascular origin. Biometrological analyses of the skin were used to assess microcirculation and colorimetry in the area under the eye, skin firmness and hydration.

Example 10: Effects on microcirculation, reduction of venous stasis in the area under the eye

The clinical trial involved 23 healthy participants, all female, with a mean age of 60±2 years.

Each volunteer used a cream on one half of their face that contained 3% of the aqueous extract of Cystoseira tamariscifolia (EACT), while on the other half of the face they applied a placebo containing no EACT.

Applications were performed twice daily for a period of 28 days.

The TiVi700® or Tissues Viability Imaging (Wheels Bridge) is a polarization spectroscopy imaging system that assesses skin microcirculation.

It was used to analyze blood flow in the very small blood vessels located just under the skin in the periocular area and associated with the formation and appearance of vascular circles.

Measurements with the TiVi700® were taken on the first day of the study (D0), before any application, and again after 28 days (D28) of twice-daily use of the product containing the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% or the placebo cream.

The percentage variation in microcirculation at D28 compared to D0 is calculated using the following formula: ((TiVi700® value at D28 - TiVi700® value at D0) / TiVi700® value at D0)*100.

Table 10 below summarizes the effects of the formulation containing 3% aqueous extract of Cystoseira tamariscifolia (EACT) and the placebo formula on the evolution of cutaneous microcirculation.

For statistics, p values <0.001 were considered highly significant. The Student t-test or Wilcoxon test were used to compare results at D28 with those at D0, depending on the data distribution.

Placebo J28 EACT 3% J28 Evolution of cutaneous microcirculation in the region under the eye (% of D0) -2.6 -3.6 Standard deviation -3.1 -2.6 p value versus J0 p = 0.0813 p = 0.0005

After 28 days of application, the 3% aqueous extract of Cystoseira tamariscifolia (EACT) significantly decreased microcirculation in the under-eye region by 3.6% compared to D0, demonstrating an improvement in blood flow and the appearance of dark circles.

The placebo did not demonstrate a significant effect.

To verify the reduction in the appearance of vascular dark circles, the measurement of the colorimetric parameter b* in the CIE Lab system was used. This is an essential indicator for assessing the appearance of dark circles under the eyes of vascular origin.

Example 11: Vascular anti-dark circle effects

The b* parameter in the CIE Lab system is essential for analyzing the color of dark circles under the eyes, indicating a bluish tint for dark circles of vascular origin.

An increase in the b* value means a reduction in this blue-purple coloration, suggesting the effectiveness of a treatment against dark circles.

CIE Lab spectrocolorimetry, a non-invasive method, was used to objectively measure these color changes, allowing a reliable assessment of the impact of 3% aqueous extract of Cystoseira tamariscifolia (EACT) on vascular circles.

The measurements carried out with the Spectrocolorimeter® were taken on the first day of the study (D0), before any application, and again after 28 days (D28) of twice-daily use of the product containing the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% or the placebo cream.

The percentage variation of parameter b* at D28 compared to D0 is calculated according to the following formula: ((Value b* at D28 - Value b* at D0) / Value b* at D0)*100.

Table 11 below summarizes the effects of the formulation containing 3% aqueous extract of Cystoseira tamariscifolia (EACT) and the placebo formula on the parameter b*.

For statistics, values of p < 0.01 are considered highly significant. Student's t test was used to compare results at D28 with those at D0.

Placebo J28 EACT 3% J28 Evolution of the parameter b* in the region under the eye (% of J0) 0.6 5.7 Standard deviation 1.7 1.9 p value versus J0 p = 0.8911 p = 0.0067

After 28 days of application, the 3% aqueous extract of Cystoseira tamariscifolia (EACT) significantly increased the b* parameter in the under-eye region by 5.7% compared to D0, demonstrating a reduction in the purplish-blue color of dark circles.

The placebo did not show any effect.

Example 12: Firming effects

The measurement of the R0 (Uf) parameter was carried out using the Cutomètre® to evaluate the effects of the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% on skin firmness after 28 days of application.

A decrease in the R0 (Uf) value indicates an increase in skin firmness.

The measurements taken with the Cutomètre® were carried out on the first day of the study (D0) before any application, and again after 28 days (D28) of twice-daily use of the product containing the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% or the placebo cream.

The percentage variation of the parameter R0 (Uf) at D28 compared to D0 is calculated according to the following formula: ((Value R0 (Uf) at D28 - Value R0 (Uf) at D0) / Value R0 (Uf) at D0)*100.

Table 12 below summarizes the effects of the formulation containing 3% aqueous extract of Cystoseira tamariscifolia (EACT) and the placebo formula on the parameter b*.

For statistics, p values <0.0001 are considered highly significant. Student's t-test was used to compare results at D28 with those at D0.

Placebo J28 EACT 3% J28 Evolution of the R0 parameter (Uf) at the temple (% of J0) -10,028 -16,493 Standard deviation 1,519 1,619 p value versus J0 p < 0.0001 p < 0.0001

After 28 days of application, the formulation containing the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% significantly decreased by -16.5% the R0 parameter (Uf) in the temple region compared to D0 demonstrating a clear improvement in skin firmness.

The placebo cream also improved skin firmness, with only a -10% decrease in the R0 (Uf) parameter compared to D0. The 3% aqueous extract of Cystoseira tamariscifolia (EACT) significantly decreased the R0 (Uf) parameter compared to the placebo by -64.5% at D28 (p<0.01), demonstrating better efficacy of the cream in the presence of EACT.

Example 13: Moisturizing effects

Electrical capacitance measurement was performed using the Corneometer® to assess the effects of 3% aqueous extract of Cystoseira tamariscifolia (EACT) on skin surface hydration levels, i.e. at the stratum corneum level, after 28 days of application.

Measurements obtained with the Corneometer® are expressed in Arbitrary Units (AU) or Corneometry Units. An increase in these units indicates an improvement in the relative hydration level of the stratum corneum.

The measurements taken with the Corneometer® were carried out on the first day of the study (D0), before any application, and again after 28 days (D28) of twice-daily use of the product containing the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% or the placebo cream.

The percentage variation of the values obtained with the Corneometer® on D28 compared to D0 is calculated according to the following formula: ((Corneometer® value on D28 - Corneometer® value on D0) / Corneometer® value on D0)*100.

Table 13 below summarizes the effects of the formulation containing 3% aqueous extract of Cystoseira tamariscifolia (EACT) and the placebo formula on stratum corneum hydration.

For statistics, p values <0.0001 were considered highly significant. The Student t-test or Wilcoxon test were used to compare results at D28 with those at D0, depending on the data distribution.

Placebo J28 EACT 3% J28 Evolution of the values given by the Corneometer® at the level of the cheek (% of D0) 19,012 29,003 Standard deviation 2,819 2,312 p value versus J0 p < 0.0001 p < 0.0001

After 28 days of application, the formula containing the aqueous extract of Cystoseira tamariscifolia (EACT) at 3% significantly increased the hydration rate of the stratum corneum by 29% compared to D0, demonstrating a hydrating effect.

The placebo cream also improved stratum corneum hydration, with only a 19% increase in stratum corneum hydration compared to D0.

The 3% aqueous extract of Cystoseira tamariscifolia (EACT) significantly increased the hydration rate compared to the placebo by +53% at D28 (p<0.001), demonstrating better efficacy of the cream in the presence of EACT.

The results of clinical tests specific to Cystoseira tamariscifolia extract show a notable improvement in skin condition, confirming its potential as a key ingredient in cosmetic formulations intended to improve the signs of fatigue and premature skin aging in the eye contour area.

CONCLUSION

The invention demonstrates that Cystoseira tamariscifolia extract offers a remarkable and innovative solution to the challenges posed by skin aging in the periorbital area, notably by reducing the appearance of vascular dark circles, improving skin firmness and hydration. The results obtained through extensive studies, both in vitro and in vivo , confirm the exceptional efficacy of this extract in treating the signs of aging and fatigue in the eye contour area, thus offering a promising alternative to the invasive solutions currently available on the market.

Furthermore, this invention fits perfectly into a sustainable development approach, promoting natural resources and marine biodiversity. By exploiting the extract of Cystoseira tamariscifolia , it contributes to the emergence of environmentally friendly cosmetic products, while offering proven aesthetic benefits.

Claims (12)

Cosmetic use of an aqueous extract from an algae of the genus Cystoseira for the prevention or treatment of signs of fatigue and skin aging in the eye contour area, including the reduction or prevention of the appearance of vascular dark circles and bags under the eyes, the improvement of skin firmness and hydration. Use according to claim 1, characterized in that the prevention or treatment of signs of fatigue and skin aging in the area around the eye includes the reduction of the formation of blood vessels and their permeability. Use according to one of the preceding claims, characterized in that the prevention or treatment of signs of fatigue and skin aging in the area around the eyes includes the reduction of wrinkles or fine lines. Use according to one of the preceding claims, characterized in that the prevention or treatment of signs of fatigue and skin aging in the area around the eyes includes the regeneration of the epidermis. Use according to one of the preceding claims, characterized in that the prevention or treatment of signs of fatigue and skin aging in the region around the eye includes the restoration of the expression of clock genes. Use according to one of the preceding claims, characterized in that the extract is derived from Cystoseira tamariscifolia, Cystoseira Barbata, Cystoseira Amantacea stricta, Cystoseira Nodicaulis, Cystoseira Usneoides, preferably from Cystoseira tamariscifolia. Use according to one of the preceding claims, characterized in that the extract has:

• a dry matter content greater than 5 g/L of liquid extract, preferably between 5 and 100 g/L of liquid extract, more preferably between 10 and 50 g/L of liquid extract;
• between 0.15 and 0.5 mg of total phlorotannins per gram of liquid extract, preferably between 0.25 and 0.35;
• between 0.5 and 5 mg of mannitol per gram of liquid extract, preferably between 1 and 4.

Use according to one of the preceding claims, characterized in that the extract is in solution in a polar solvent, in particular a glycol, such as glycerol, propanediol, butanediol or propylene glycol, or a mixture of glycol and water. Use according to one of the preceding claims, characterized in that the extract is formulated in a composition, preferably topical, in which the quantity of extract is greater than or equal to 0.01% and less than or equal to 5% by weight, preferably between 0.1 and 3%, relative to the total weight of the composition. Use according to the preceding claim, characterized in that the cosmetic composition is in the form of a cream, an oil-in-water emulsion, a water-in-oil emulsion, a multiple emulsion, a solution, a gel, a suspension, a spray or a powder. Use according to one of claims 8 to 9, characterized in that the composition comprises one or more other compounds such as colorants, film-forming agents, surfactants, perfumes, preservatives, emulsifiers, oils, UV filters, vitamins, or any other compound suitable for the cosmetic application of the composition. Cosmetic treatment process, characterized in that it consists of applying an aqueous extract from an algae of the genus Cystoseira, or a composition comprising it, to the skin around the eyes.