Cosmetic uses of a hydrolysate of an extraction co-product of the microalga phaeodactylum tricornutum

Abstract

The invention relates to the cosmetic or nutraceutical use of a hydrolysate of an extraction co-product of the microalga Phaeodactylum tricornutum for exfoliating the skin and / or reducing the microrelief of the skin. The invention also relates to a cosmetic skincare method comprising the topical application of a hydrolysate of an extraction co-product of the microalga P. tricornutum or of a composition comprising same for exfoliating the skin and / or reducing the microrelief of the skin.

Description

[0001] DESCRIPTION

[0002] TITLE: Cosmetic uses of a hydrolyzate of extraction co-product of the microalga Phaeodactylum tricornutum

[0003] The invention relates to the use of a hydrolyzate of Phaeodactylum tricornutum extraction co-product for exfoliating the skin and / or reducing the microrelief of the skin.

[0004] The skin is an organ made up of several layers: epidermis, dermis and hypodermis. The epidermis represents the most superficial layer and is itself made up of several layers, the stratum corneum (or stratum corneum), the clear layer (stratum lucidum), the granular layer (or stratum granulosum), the Malpighian layer and the basal lamina (stratum basale) corresponding to the deepest layer, site of keratinocyte synthesis. It is the stratum corneum which represents the most superficial part. It contains in particular the sweat glands and the cutaneous appendages (hair), but it is also the layer which accumulates dead cells, site of desquamation by definition. Desquamation is a natural mechanism generating scales, corneocyte clumps. We also speak of exfoliation. This mechanism is an integral part of cell renewal.

[0005] Mechanical solutions (peeling, scrubbing, circular massage using formulations containing synthetic or natural abrasive grains such as crushed fruit pits or seeds, sugar, seeds) to exfoliate the skin are widely used in the cosmetics field but these solutions are aggressive for the skin, they are abrasive, and can generate redness, irritation, tingling or heating. They are particularly not suitable for sensitive skin, nor for acne-prone or acne-prone skin. Few natural exfoliating ingredients are available on the cosmetics market. We can in fact mention natural fruit extracts such as kiwi extract, lemon extract, honey, or glycolic acid found in sugar cane, beetroot or grape. But the fruit acids found in these natural extracts (alphahydroxy acids AHA, betahydroxy acids BHA) are aggressive for the skin.Retinoids are also known as exfoliants but they too can be harsh on the skin.

[0006] There is therefore a need in the cosmetic field for alternative active ingredients capable of exfoliating the skin naturally, without the need for mechanical intervention, which allow the elimination of dead cells, or scales, to promote cell renewal without stripping the upper layers of the epidermis and to promote gentle and continuous exfoliation, which fruit acids do not allow.

[0007] Unexpectedly, the Applicant discovered that a hydrolyzate of Phaeodactylum tricornutum extraction co-product was effective in exfoliating the skin, as well as reducing the microrelief of the skin.

[0008] One of the advantages of the hydrolyzate according to the invention is that it is produced from a co-product of extraction of a natural microalgae, not genetically modified, without the addition of hormones or chemical compounds. It is easily produced on an industrial scale, in a sustainable manner, particularly in photobioreactors by autotrophic culture without impacting arable land.

[0009] The hydrolyzate is not irritating to the skin, nor sensitizing.

[0010] The hydrolyzate according to the invention comes from a culture of the microalga P. tricornutum. Phaeodactylum tricornutum is a diatom belonging to the genus Phaeodactylum and the family Phaeodactylaceae, present in 3 distinct morphotypes (fusiform, oval, triradiate) which are found in many oceanic regions of the world, including northern Europe, Oceania, and the Atlantic.

[0011] Extracts from P. tricornutum are already known for their use in the field of nutraceuticals. The Applicant is thus aware of an extract of P. tricornutum used in a composition as a food supplement to improve the cognitive abilities of elderly individuals or those suffering from cognitive decline.

[0012] Extracts of P. tricornutum for their cosmetic uses are also described. In this respect, application US2004136945 describes a cosmetic care method comprising the topical application of an effective amount of an extract of P. tricornutum obtained by extraction with a polar solvent to improve the firmness and elasticity of the skin and reduce wrinkles.

[0013] Application US2010092506 describes the use in a cosmetic composition of an extract of P. tricornutum as a depigmenting active agent, an agent intended to reduce or remove pigment spots on the skin or lighten the complexion or hair.

[0014] Application WO2020178213 relates to a non-therapeutic care method comprising the application of a cosmetic composition comprising a hydrophilic extract of P. tricornutum to reduce redness of sensitive skin, to relieve and to reduce inflammation of sensitive skin. Said composition is also effective in improving the skin microbiota.

[0015] However, this application does not disclose a use of a hydrolyzate of a co-product of extraction of P. tricornutum for exfoliating the skin and / or reducing the microrelief of the skin.

[0016] Thus, to the Applicant's knowledge, no prior art describes or suggests the use of a hydrolyzate of a co-product of extraction of P. tricornutum to exfoliate the skin or to reduce the microrelief of the skin.

[0017] The present invention relates firstly to the cosmetic use of a hydrolyzate of a co-product of extraction of P. tricornutum for exfoliating the skin and / or reducing the microrelief of the skin. Another subject relates to the cosmetic use of the hydrolyzate in a composition. Another subject relates to a cosmetic care method comprising the topical application of a hydrolyzate of a co-product of extraction of P. tricornutum or a cosmetic composition comprising it for exfoliating the skin and / or reducing the microrelief of the skin.

[0018] “Cosmetic use” means non-therapeutic use, i.e. non-pharmaceutical and non-dermatological; it therefore has no therapeutic purpose and is advantageously applied to all or part of healthy skin.

[0019] “Healthy skin” means any area of ​​skin that has been determined by a dermatologist to be non-pathological, i.e., an area of ​​skin that is free from injury, redness, infection, scarring, allergy, wound, disease, eczema, inflammation, acne, and / or dermatitis.

[0020] “Skin” means all or part of the face and / or body chosen from any area of ​​the arms, including the forearms, legs, thighs, back, torso, neck, décolleté, feet and / or hands. For the purposes of the invention, skin includes the scalp.

[0021] The hydrolyzate according to the invention is administered orally or applied topically, advantageously applied topically.

[0022] Here, the term "topical route" means the spraying of the hydrolyzate onto the surface of the skin or the direct local application to the skin. The hydrolyzate or the composition comprising it is topically acceptable. The term "topically acceptable" means a hydrolyzate or a composition which does not induce an allergic reaction to the skin, which is not irritating.

[0023] The term "co-product" means the residue of any extraction of the biomass of the microalga P. tricornutum capable of photosynthesis and obtained by a process making it possible to indirectly obtain the hydrolyzate according to the invention, as described in the remainder of this application. The term "co-product" will be used preferentially in the remainder of the description. The term "hydrolyzate" means any product resulting from a hydrolysis, as described in the remainder of this application.

[0024] In the present application, the term "expression" means gene expression (expression of complementary DNAs cDNA) and / or protein expression, it being understood that protein expression includes the expression of messenger RNAs (mRNA) within the meaning of the invention.

[0025] Here, "exfoliating the skin" means naturally increasing the amount of scales released from the surface of the upper layer of the epidermis. "Naturally" also means a biological action as opposed to a mechanical action, particularly of the abrasive type, such as that exerted by sea salt or silica grains.

[0026] In one embodiment of the invention, "exfoliating the skin" means increasing by at least 5%, advantageously by at least 6%, very advantageously by at least 6.5% the surface area of ​​the skin, preferably healthy, occupied by scales at the level of the upper layers of the epidermis in the presence of the hydrolyzate according to the invention, in comparison with the surface area occupied by scales without hydrolyzate according to the invention (Placebo). Advantageously, this is an increase in the surface area of ​​the upper layer of the epidermis occupied by scales after application to the forearm of a population of 35 healthy individuals, twice a day for 28 days, of a cream comprising 1.5% by weight relative to the total weight of the cream, of hydrolyzate according to the invention in comparison with a placebo cream, under the conditions described in Example 2. Still advantageously, said surface area is measured in mm 2. Very advantageously, the hydrolyzate according to the invention included in the cream is a hydrolyzate of co-product of ethanolic extraction of P. tricornutum as prepared under the conditions of example 1a). The results are presented in Table 1.

[0027] In another embodiment of the invention, "exfoliating the skin" means increasing by at least 10%, advantageously by at least 20% in the presence of the hydrolyzate according to the invention in comparison with the placebo, the desquamation index (DI) of samples of the upper layers of the epidermis, said index being defined as corresponding to the sum of twice the total surface area occupied by scales (mm 2) (A below) and the sum of the percentage of layers in relation to the thickness of each layer, the number of layers being equal to 5, according to the following formula as described by Schatz et al. (1993) [Schatz H., Kligman AM., Manning S., Stoudemayer T. (1993) Quantification of dry (xerotic) skin by image analysis of scales removed by adhesive discs (D-Squames). J. Soc. Cosmet. Chem., 44, 53-63.], under the conditions described in Example 2:

[0028] [Math 1] where A corresponds to the total surface area occupied by the scales (mm 2 ), Tn corresponds to the percentage of layers in relation to the thickness of each layer, and n corresponds to the thickness from 1 to 5.

[0029] Advantageously, the increase in the desquamation index is measured within the framework of the clinical study described above and the protocol of which is detailed in example 2, i.e. within a population of 35 individuals, advantageously healthy, i.e. not suffering from any skin pathology and having healthy skin as defined in the present invention, after application twice a day for a period of 28 days of the cream comprising 1.5% by weight relative to the total weight of the cream, of hydrolyzate according to the invention in comparison with the placebo cream.

[0030] More advantageously, the hydrolyzate according to the invention included in the cream is a hydrolyzate of co-product of ethanolic extraction of P. tricornutum as prepared under the conditions of example 1a). The results are presented in Table 2 of example 2.

[0031] Very advantageously, the desquamation index is measured after sampling the epidermal superficial layers of the population concerned, at times D14 and D28 (14 days and 28 days), after application for a period of 20 seconds on the forearms of the population of a patch consisting of a transparent acetate disc and an adhesive film (D'Squame®). The samples are then advantageously analyzed via the QuantiSquam® image acquisition software, under the conditions as described in example 2, the quantity of desquamated epidermal material being higher when the light is white (Schatz et al. (1993) cited above). The results are presented in Table 2 of example 2 and in [Fig. 1]. The hydrolyzate according to the invention is effective in exfoliating the skin, it is therefore useful for increasing cell renewal of the skin, preferably healthy skin.

[0032] For the purposes of the invention, the expression "reducing the microrelief of the skin" also means a smoothing action of the skin in the presence of the hydrolyzate according to the invention. In one embodiment of the invention, this involves a reduction in the surface heterogeneity of the skin, preferably healthy, in the presence of the hydrolyzate according to the invention. Advantageously, the heterogeneity of the skin is measured in the context of the clinical study described above in a population of 35 individuals after application twice a day for a period of 28 days of a cream comprising 1.5% (w / w) of the hydrolyzate according to the invention, or of a placebo cream (without hydrolyzate).

[0033] Thus, in this embodiment, the hydrolyzate according to the invention is considered to be in an effective amount for reducing the microrelief of the skin when the reduction in the surface heterogeneity of the skin measured after 28 days of application of the cream comprising the hydrolyzate is at least 1%, preferably at least 2%, more preferably at least 2.5% in comparison with the surface heterogeneity of the skin measured at time T0 of the start of the clinical study conducted. Preferably, the hydrolyzate according to the invention included in the cream is a hydrolyzate of the co-product of ethanolic extraction of P. tricornutum as prepared under the conditions of example 1a).

[0034] Advantageously, surface heterogeneity is measured via topical application to the forearms of the population concerned at time D28 (28 days of application of the cream of interest), of a silicone resin (Silflo®), this being applied for a period of 8 minutes in order to harden. The hardened resin is then removed from the skin and represents a faithful negative replica of the area of ​​skin concerned. The replica is analyzed by image analysis using the Quantilines® software (Monaderm) (Parameter Rt), under the conditions described in the protocol of example 3.

[0035] In an alternative embodiment of the invention, "reducing the microrelief of the skin" means reducing the roughness parameter Rz of the skin, preferably healthy, of the forearms of the population described in the context of the clinical study above, in the presence of the hydrolyzate according to the invention, advantageously a hydrolyzate of ethanolic extraction co-product of P. tricornutum as prepared under the conditions of example 1a), by at least 1.5%, advantageously by at least 3% after 28 days (D8) in comparison with the parameter Rz measured on the forearms on which the cream comprising the hydrolyzate was applied at time 0 (DO). The parameter Rz makes it possible to measure the roughness of the skin via the same Quantilines® software (Monaderm), after application at time D28 of the silicone resin (Silflo®) as described above, under the conditions described in example 3.

[0036] Alternatively, "reducing the microrelief" means reducing the parameter Ra relating to the relief of the skin, preferably healthy, of the forearms of the population described in the context of the clinical study above, in the presence of the hydrolyzate according to the invention, advantageously a hydrolyzate of ethanolic extraction co-product of P. tricornutum as prepared under the conditions of example 1a), by at least 1.5%, advantageously by at least 2.5% after 28 days (D28) in comparison with said parameter measured on the forearms on which the cream comprising the hydrolyzate was applied at time 0 (DO). The Quantilines® software (Monaderm), after application at time D28 of the silicone resin (Silflo®) described above, allows the parameter Ra to be measured, under the conditions described in example 3. The results of the reduction of the parameters Rt, Rz and Ra in the presence of the hydrolyzate according to the invention are presented in example 3 and in [Fig. 2],

[0037] The microalgae P. tricornutum is cultivated under controlled conditions in suitable systems such as raceways, open ponds or closed photobioreactor systems. The photobioreactors used can be of any existing type such as horizontal tubular photobioreactors, vertical photobioreactors such as so-called "green wall panel" systems, flat or column photobioreactors. Preferably, biomass production takes place in a closed photobioreactor culture system.

[0038] Microalgae cultivation is carried out using batch, fed-batch, continuous, semi-continuous, turbidostat or chemostat cultivation methods.

[0039] The biomass obtained after cultivation can be concentrated by removing all or part of the water using chemical or physical processes such as centrifugation, filtration, flocculation, sedimentation, coupled, or not, with drying steps by freeze-drying, vacuum drying, drum drying, atomization or any process allowing the water content of the biomass to be reduced. Cell lysis processes can then be implemented such as the application of pressures, electrical flows, shear forces, the use of enzymes, or any other process allowing the destructuring of tissues, organs, cells or organelles.

[0040] The hydrolysate according to the invention is a hydrolysate of the residue, also called "co-product", this co-product corresponding to the delipidated fraction resulting from any solid-liquid extraction type process, which may be by supercritical or hypercritical or subcritical fluids, which may involve co-treatments carried out in parallel or sequentially of microwave, ultrasound, pressure, enzymatic types.

[0041] The biomass obtained after cultivation can be extracted fresh or dried before extraction. It may have been frozen. Here, the term "dry biomass" means dehydrated microalgal biomass comprising less than 15%, advantageously less than 10%, and even more advantageously less than 5% water.

[0042] The biomass may be pre-centrifuged and then filtered to remove water before extraction. Advantageously, the extraction of the biomass is a solid-liquid extraction in the presence of a solvent or solvent mixture chosen from water, acetone, hexane, ethyl acetate, methyltetrahydrofuran, 2-methyloxolane, heptane, an alcohol chosen from ethanol, methanol, isopropanol, a natural or branched oil, a glycol, a polyol, a water / alcohol mixture, water / glycol in a proportion of 99 / 1 to 1 / 99 (w / v).

[0043] The solid-liquid extraction of biomass is carried out from a quantity of biomass of 0.1 to 20% by weight, advantageously from 1% to 20%, very advantageously from 5% to 15%, and even more advantageously from 10% by weight relative to the total volume of biomass and extraction solvent.

[0044] Extraction can be carried out at a temperature ranging from 4°C to 300°C, including room temperature, i.e. a temperature of 20°C.

[0045] In one embodiment of the invention, the extraction of the biomass is carried out in water under subcritical conditions, at a temperature ranging from 100°C to 300°C, advantageously from 120°C to 250°C, still advantageously at 120°C. The extraction can be carried out at a given temperature or at successively increasing temperatures. In an advantageous embodiment of the invention, the extraction is carried out at a temperature of 120°C. In an alternative mode, it will be carried out according to a gradient of three increasing temperatures between 100°C and 200°C, such as 120°C, 140°C then 160°C or 110°C, 130°C then 150°C, or even 120°C, 145°C then 170°C.

[0046] Extraction under "subcritical conditions" means extraction in the presence of water, under conditions of temperature above 100°C and pressure below 221 bars, the water remaining in the liquid state but having a viscosity and surface tension lower than that of water at room temperature, increasing its dielectric constant. Thus, the extraction pressure is between 150 bars and 250 bars, preferably between 200 and 221 bars, advantageously in a pressurized extraction autoclave.

[0047] In another embodiment of the invention, the extraction of the biomass is carried out by supercritical CO2 extraction. In this case, said extraction may be carried out in the presence of a co-solvent chosen from ethanol, acetone, methanol or any combination thereof. Alternatively, the supercritical CO2 extraction may be carried out alone without the presence of a co-solvent and continued by an additional extraction with a polar solvent chosen from ethanol, acetone, methanol, hexane, heptane, advantageously ethanol. Advantageously, the supercritical CO2 extraction is carried out in the presence of ethanol (10%) as co-solvent. The supercritical CO2 extraction conditions are such that the pressure measured in bar is greater than 74 bar, advantageously greater than 100 bar, even more advantageously 150 bar. The temperature is above 35°C, preferably above 45°C, and preferably above 50°C.The delipidated fraction thus obtained constitutes the co-product of the extraction described above.

[0048] The term "hydrolyzate" also means any product resulting from a hydrolysis of the above delipidated fraction. Advantageously, the hydrolyzate is obtained by hot hydrolysis. Here, the term "hot hydrolysis" means hydrolysis at a temperature of at least 35°C, advantageously at least 40°C, further advantageously at least 55°C and very advantageously 60°C. The hydrolysis can be carried out under basic or acidic conditions. It is advantageously carried out under basic conditions. Here, the term "basic conditions" means hydrolysis carried out at a pH between 7.0 and 11.5, advantageously between 10 and 11, very advantageously a pH of 10.0. Advantageously, the hydrolysis is carried out at a basic pH and hot, preferably at pH 10.0 and at 60°C.

[0049] The pH is then adjusted to a value between 4.0 and 7.0, advantageously between 4.5 and 6.0. Sequential filtrations can be carried out up to a cut-off threshold of 0.22 pm or 0.1 pm, advantageously 0.22 pm. The fraction thus obtained is evaporated and then a dilution matrix can be added to the hydrolyzate, in a final concentration by weight relative to the volume of the matrix and the hydrolyzate of between 2.5% and 10%, advantageously between 5% and 10%. Advantageously, the dilution matrix is ​​chosen from propylene glycol, caprylyl glycol, butylene glycol, pentylene glycol, glycerin, and even more advantageously pentylene glycol.

[0050] In an advantageous embodiment of the invention, the hydrolyzate according to the invention is a hydrolyzate of the co-product of a solid-liquid extraction of the dry biomass of a culture of the microalga P. tricornutum. Advantageously, the extraction is carried out in the presence of a solvent chosen from ethanol, methanol, isopropanol, a natural or branched oil, a glycol, a polyol, a water / alcohol mixture, water / glycol in a proportion of 99 / 1 to 1 / 99 (w / v), still advantageously ethanol. In a particularly advantageous embodiment, the hydrolyzate according to the invention is a hydrolyzate obtained from the delipidated fraction (co-product) resulting from the solid-liquid extraction of the dry biomass of a culture of P. tricornutum in the presence of ethanol. Ethanolic extraction of biomass is carried out using a quantity of biomass of 10% by weight relative to the total volume of biomass and ethanol. The defatted fraction is rinsed with water and then filtered.It is hydrolyzed hot (60°C) at a pH of 10.0 then adjusted to a pH of 6.0 and filtered to a cut-off threshold of 0.22 pm. The hydrolyzate thus obtained is solubilized in pentylene glycol (5% pentylene glycol w / v), under the conditions as described in example 1a).

[0051] In another preferred embodiment, the hydrolyzate according to the invention is a hydrolyzate obtained from the delipidated fraction (co-product) resulting from the extraction of the dry biomass of a culture of P. tricornutum with a water / ethanol mixture in a respective proportion of 30 / 70 (v / v). Said extraction of the biomass is carried out from a quantity of biomass of 10% by weight relative to the total volume of the biomass and the ethanol. The delipidated fraction is rinsed with water and then filtered. It is hydrolyzed hot (60°C) at a pH of 10.0 and then adjusted to a pH of 6.0. It is then filtered to a cut-off threshold of 0.22 μm. The hydrolyzate obtained is solubilized in pentylene glycol (5% pentylene glycol w / v), under the conditions as described in example 1b).

[0052] In yet another advantageous embodiment of the invention, the hydrolyzate according to the invention is a hydrolyzate obtained from the delipidated fraction (co-product) resulting from the extraction of the dry biomass of a P. tricornutum culture with supercritical CO2 at a temperature of 50°C and a pressure of 150 bars in the presence of ethanol as co-solvent (10%). The delipidated fraction (co-product) is rinsed with water and then filtered. It is hydrolyzed at high temperature (60°C) at a pH of 10.0. The fraction obtained is adjusted to a pH of 6.0 and then filtered to a cut-off threshold of 0.22 pm. The hydrolyzate obtained is solubilized in pentylene glycol (5% pentylene glycol w / v), under the conditions as described in example 1c).

[0053] The hydrolyzate as prepared in examples 1a) to 1c) is in liquid form. It does not contain silica or organic silicon, in solid form, nor silicates and only contains silicon in totally soluble form, advantageously in the form of orthosilicilic acid.

[0054] The hydrolyzate according to the invention can be used alone or in a composition. In one embodiment, the hydrolyzate is used in a cosmetic composition, advantageously non-therapeutic, which comprises at least one cosmetically acceptable excipient. The excipient is advantageously chosen from natural oils such as argan oil, shea oil, jojoba oil, avocado oil, sweet almond oil, preservatives, emulsifiers, emollients, surfactants, moisturizers, thickeners, texturizing agents, conditioners, shine agents, texturizing agents, film-forming agents, pigments, colorants, perfumes, antimicrobial agents, biological additives, chelating agents, biocidal agents, astringent agents, polymers, reducing agents, pH regulating agents, humectants, conditioning agents.

[0055] The hydrolyzate according to the invention is present in the cosmetic composition at a concentration by weight relative to the total weight of the composition of between 0.1% and 5% (w / w), advantageously between 1% and 2% (w / w).

[0056] The cosmetic composition is in the form of a cream, a serum, a gel, a soap, a dermatological bar, a shower gel, an aqueous or oily solution, an oil-in-water emulsion or a water-in-oil emulsion, a mask, a lotion, an ointment, a shampoo, a conditioner, a scalp treatment, a mousse. Advantageously, the composition is in the form of a cream or a serum.

[0057] The cosmetic composition is therefore useful for exfoliating the skin and / or reducing the microrelief of the skin, preferably healthy, it is useful for increasing the cell renewal of the skin.

[0058] In another embodiment of the invention, the hydrolyzate of Phaeodactylum tricornutum extraction co-product alone or in a composition comprising it, is used in a nutraceutical composition for exfoliating the skin and / or reducing the microrelief of the skin. This composition is advantageously non-therapeutic and is intended for oral administration. The hydrolyzate or the nutraceutical composition comprising it can therefore be used as a food supplement, for nutra-cosmetic purposes. The hydrolyzate can be in liquid form or be dried to obtain a powder.

[0059] The composition may be in the form of an emulsion and then comprises at least one nutraceutically acceptable excipient chosen from vegetable oils such as olive oil, rapeseed oil, linseed oil, sunflower oil, grape seed oil, palm oil, MCT oils (Medium Chain Triglycerides) which are composed of more than 70% by weight of a mixture of caprylic acid and capric acid, advantageously chosen from coconut oil, palm oil, advantageously coconut oil, very advantageously coconut oil.

[0060] The nutraceutical composition may also comprise one or more synthetic or natural antioxidants chosen from vitamin E and its derivatives, carotenoids, rosemary extract. Here, the term "vitamin E" means a tocopherol chosen from α-tocopherol, γ-tocopherol, β-tocopherol or δ-tocopherol, or a tocotrienol chosen from α-tocotrienol, β-tocotrienol, γ-tocotrienol or δ-tocotrienol. Advantageously, it is α-tocopherol.

[0061] In addition, the nutraceutical composition of the invention comprises at least one additive chosen from preservatives, colorants, flavors, disintegrating agents, lubricating agents, coating or encapsulating agents. The composition may be in powder form and is then present in the form of aqueous capsules, capsules, tablets, lozenges, liquid or loose powder. It is useful for exfoliating the skin and / or reducing the microrelief of the skin, preferably healthy skin, and for increasing cell renewal of the skin.

[0062] The hydrolyzate according to the invention is present in the nutraceutical composition at a concentration by weight relative to the total weight of the composition of between 0.1% and 5% (w / w), advantageously between 1% and 2% (w / w).

[0063] The hydrolyzate according to the invention can be combined with any other active cosmetic or nutraceutical (nutra-cosmetic) ingredient having an exfoliating effect and / or reducing the microrelief of the skin. The hydrolyzate according to the invention can also be combined with any active ingredient having an effect complementary to those of the extract, advantageously chosen from anti-aging, anti-wrinkle, skin firmness improving, regenerating active ingredients, ingredients active on sensitive skin, anti-pollution active ingredients or active ingredients on the regulation of the skin microbiota. The hydrolyzate according to the invention can also be combined with any lightening active ingredient or active ingredient on the uniformity of skin tone.

[0064] The hydrolyzate according to the invention may also be combined with one or more other algae or microalgae extracts, including an extract of Phaeodactylum tricomutum and / or an extract of Porphyridium cruentum, advantageously as an anti-aging active ingredient and protector against urban stress and UV rays, and / or an extract of the microalgae Tisochrysis lutea, in particular as an active ingredient to improve the comfort of sensitive skin.

[0065] An object of the invention also relates to a cosmetic care method, advantageously non-therapeutic, comprising the oral administration or the topical application of a hydrolyzate of a co-product of extraction of P. tricornutum or of a composition comprising it to exfoliate the skin and / or reduce the microrelief of the skin, preferably healthy. Still advantageously, the hydrolyzate is a hydrolyzate of a co-product of ethanolic extraction of Phaeodactylum tricornutum. Very advantageously, the hydrolyzate is obtained by hydrolysis of said co-product of ethanolic extraction at basic pH, advantageously at pH 10.0, and hot, preferably at a temperature of 60°C.

[0066] In an advantageous embodiment of the invention, the cosmetic care method comprises the topical application of the hydrolyzate according to the invention or of a cosmetic composition comprising it to at least one area of ​​skin, advantageously healthy skin, chosen from any area of ​​the face and / or any area of ​​the arms, including the forearms, legs, thighs, back, torso, neck, décolleté, feet and / or hands, including the scalp.

[0067] Examples are presented below with reference to the description. These examples are illustrative and do not limit the scope of the invention. The examples are an integral part of the present invention and any new feature compared to a state of the prior art from the description taken as a whole is part of the invention.

[0068] Unless otherwise stated, temperature is expressed in degrees Celsius (°C), pressure in bar, percentages are given in weight / weight (w / w). Ppm means Parts Per Million (0.01% = 100ppm).

[0069] List of figures:

[0070] [Fig. 1]: Effect of the hydrolyzate according to the invention on skin exfoliation (D0: time T0 for measuring the quantity of scales; D14 and D28: time for measuring the quantity of scales after 14 and 28 days of application of a cream comprising 1.5% (w / w) of the hydrolyzate according to the invention (Ex. 1a) or of a placebo cream) (Example 2). [Fig. 2]: Effect of the hydrolyzate according to the invention on the reduction of the microrelief of the skin (DO: time TO of measurement of the microrelief; D28 hydrolyzate: time 28 days after application of a cream comprising 1.5% (w / w) of the hydrolyzate according to the invention (Ex. la); D28 placebo: time 28 days after application of a placebo cream without hydrolyzate) (Example 3).

[0071] The extraction co-product hydrolysate is obtained from dry biomass from an autotrophic culture of a strain of P. tricornutum originating in France. Dry biomass from an autotrophic culture of the microalga P. tricornutum in a photobioreactor under controlled conditions was extracted with ethanol.

[0072] (10% biomass by weight relative to the total volume of solvent and biomass). The residue or co-product of the extraction corresponding to the delipidated fraction was rinsed with water and then filtered. It was then hydrolyzed at basic pH (pH 10.0) under heat (temperature of 60°C). The fraction obtained was adjusted to a pH of 6.0 and then filtered to a cut-off threshold of 0.22 pm. Pentylene glycol (5% w / v) was added. The hydrolyzate is in liquid form. Dry biomass from an autotrophic culture of the microalga P. tricornutum in a photobioreactor under controlled conditions was extracted with a water / ethanol mixture in a proportion of 30 / 70 (v / v) (10% biomass by weight relative to the total volume of solvent and biomass). The residue or co-product of the extraction corresponding to the delipidated fraction was rinsed with water and then filtered. It was then hydrolyzed at basic pH (pH 10.0) under heat (temperature of 60°C). The fraction obtained was adjusted to a pH of 6.0 and then filtered to a cut-off threshold of 0.22 pm. Pentylene glycol (5% w / v) was added. The hydrolyzate is in liquid form. Dry biomass from an autotrophic culture of the microalga P. tricornutum in a photobioreactor under controlled conditions was extracted with supercritical CO2 in the presence of ethanol as co-solvent (10%), at a temperature of 50°C and a pressure of 150 bars. The residue or co-product of the extraction corresponding to the delipidated fraction was rinsed with water and then filtered. It was then hydrolyzed at basic pH (pH 10.0) under heat (temperature of 60°C). The fraction obtained was adjusted to a pH of 6.0 and then filtered to a cut-off threshold of 0.22 pm. Pentylene glycol (5% w / v) was added. The hydrolyzate is in liquid form.

[0073] Example 2: Exfoliation effect of a hydrolyzate according to the invention

[0074] Protocol: A clinical study was conducted on a population of 35 healthy Caucasian individuals, i.e. not suffering from a skin pathology, aged 30 to 59 years, with an average age of 49.3 years.

[0075] A cream comprising 1.5% by weight of the hydrolyzate according to the invention relative to the total weight of the cream (w / w) as prepared in Example 1a) was applied twice a day for 28 consecutive days to one forearm of the population. The same cream without hydrolyzate as a placebo was applied under the same conditions to the second forearm.

[0076] The exfoliation effect was measured by a non-invasive technique allowing the sampling of the epidermal superficial layers using a patch consisting of a transparent acetate disc and an adhesive film, named D'squame®. This disc was stuck on the surface of the skin of each of the 2 forearms of the population, the one on which the cream comprising the hydrolyzate according to the invention was applied and the one on which the placebo cream was applied. The discs were held for a period of 20 seconds on the surface using a standardized weight integrated into a pusher. The discs each allowed the sampling of 5 epidermal superficial layers noted GO, Gl, G2, G3 and G4 (G4 being the deepest layer). The discs were positioned on a black surface with standardized lighting between the different shots, under a camera to allow image acquisition.The light was reflected by the presence of the epidermal layers removed with the patches. The whiter the image, the greater the amount of desquamated epidermal material.

[0077] Two parameters were measured: the surface area occupied by the scales was measured in mm 2 via image acquisition software (QuantiSquam®) and the desquamation index (DI) was calculated according to the formula described by Schatz et al. (1993) above:

[0078] [Math 1] where A corresponds to the total surface area occupied by the scales (mm 2 ), Tn corresponds to the percentage of layers in relation to the thickness of each layer, and n corresponds to the thickness from 1 to 5. Results: the results are presented in Tables 1 (Average (AVG) of the occupied surface in mm 2 ) and 2 (Mean (AVG) of the peeling index ID) below (n=35) after 14 and 28 days of application, as well as in Figure 1.

[0079] [Table 1]

[0080] Conclusion: the cream comprising the hydrolyzate according to the invention showed its capacity to increase the average surface area occupied by scales in comparison with the placebo cream by more than 6.5% after 14 days of application in comparison with the placebo, confirming the positive exfoliation effect of the hydrolyzate according to the invention on the skin.

[0081] [Table 2]

[0082] Conclusion: the cream comprising the hydrolyzate according to the invention showed its capacity to increase the desquamation index of the skin of the population analyzed by more than 10% in comparison with the placebo cream from 14 days of application and by more than 20% after 28 days, demonstrating the positive exfoliation effect of the hydrolyzate according to the invention on the skin over time and compared with the placebo.

[0083] Example 3: Effect of reduction of the microrelief of the skin by a hydrolyzate according to the invention Protocol: the clinical study as described in the protocol of example 2 was also conducted in order to evaluate the reduction of the microrelief of the skin in the presence of the hydrolyzate according to the invention.

[0084] A cream comprising the hydrolyzate as prepared according to Example 1a) at a final concentration by weight relative to the total weight of the cream of 1.5% was applied to a first forearm of healthy skin of the 35 individuals every day twice a day for a period of 28 days. The same cream comprising water instead of the hydrolyzate was applied to the second forearm under the same conditions (Placebo).

[0085] A silicone resin (Siflo®) was applied to the forearms at time TO (DO), after 28 days (D28) of application of the cream (or placebo cream) and maintained on the skin area for a period of 8 minutes to collect the negative imprint of the analyzed skin area. Once dried, three parameters (Rt, Rz, Ra) were analyzed using Quantilines® software (Cosderma). The Rt parameter corresponds to the surface heterogeneity, Rz reflects the skin roughness and Ra reflects the skin relief.

[0086] Results: The results are presented in Table 3 below (average % variation of the parameters Rt, Rz and Ra between DO and D28 after application of a cream comprising 1.5% (w / w) of the hydrolyzate according to example 1a) (n= 35) and in Figure 2.

[0087] [Table 3]

[0088] Conclusion: The cream comprising 1.5% (w / w) of the hydrolyzate according to example 1a) made it possible to reduce the heterogeneity of the skin of the forearms of the population studied, as well as to reduce its roughness and relief, after 28 days of application, demonstrating the effectiveness of the hydrolyzate on the overall reduction of the microrelief of the skin.

[0089] Example 4: Examples of cosmetic formulations comprising the hydrolyzate according to the invention

[0090] The different phases making up the formulations described in Table 5 below are mixed according to methods known to those skilled in the art. The percentages are expressed by weight relative to the total weight of the cream (w / w).

[0091] Example 4a) Cream comprising the hydrolyzate according to the invention

[0092] At room temperature, phase B is hydrated and then mixed for 5 minutes. Sodium hydroxide is added to neutralize the pH (up to 5.5). Phase D is added to the aqueous phase and then the whole is mixed to form an emulsion (at room temperature, 5 minutes). Phases E, F, G and H are added and then the pH is adjusted to a pH between 4.5 and 5.5. [Table 4]

[0093] Example 4b) Mask comprising the hydrolyzate according to the invention

[0094] At room temperature, phase B is pre-mixed with phase A for 5 minutes. Phase C is then added (5 minutes). Phases D and E are added one by one with gentle stirring. Phase F is pre-mixed and then added when the mixture is completely homogenized. Phase C is then added and the pH is adjusted to a pH between 4.5 and

[0095] 5.5.

[0096] [Table 5]

Claims

Claims 1. Cosmetic use of a hydrolyzate of Phaeodactylum tricornutum extraction co-product to exfoliate the skin and / or reduce the microrelief of the skin.

2. Use according to claim 2 by topical route.

3. Use according to claim 1 or 2 in a cosmetic composition comprising at least one cosmetically acceptable excipient, such that the hydrolyzate is present in the composition in a concentration of between 0.1% and 5%, advantageously between 1% and 2% by weight relative to the total weight of the composition.

4. Use according to any one of claims 1 to 3 in the form of a cream, a serum, a gel, a soap, a dermatological bar, a shower gel, an aqueous or oily solution, an oil-in-water emulsion or a water-in-oil emulsion, a mask, a lotion, an ointment, a shampoo, a conditioner, a scalp treatment, a mousse.

5. Nutraceutical use of a hydrolyzate of Phaeodactylum tricornutum extraction co-product alone or in a composition comprising it for exfoliating the skin and / or reducing the microrelief of the skin.

6. Use according to any one of claims 1 to 5 for increasing skin cell renewal.

7. Use according to any one of claims 1 to 6 such that the hydrolyzate is a hydrolyzate of co-product of extraction of Phaeodactylum tricornutum with supercritical CO2 or of an extraction in the presence of a solvent chosen from ethanol, methanol, isopropanol, a natural or branched oil, a glycol, a polyol, a water / alcohol mixture, water / glycol in a proportion of 99 / 1 to 1 / 99 (w / v).

8. Use according to claim 7 such that the hydrolyzate is a hydrolyzate of co-product of ethanolic extraction of Phaeodactylum tricornutum.

9. Use according to any one of claims 1 to 8 such that the hydrolyzate is obtained by hydrolysis at basic pH under hot conditions.

10. Use according to any one of claims 5 to 9 such that the hydrolyzate is present in the composition in a concentration of between 0.1% and 5%, advantageously between 1% and 2% by weight relative to the total weight of the composition.

11. Cosmetic care method characterized in that it comprises the oral administration or the topical application of a hydrolyzate of Phaeodactylum tricomutum extraction co-product or a composition comprising it to exfoliate the skin and / or reduce the microrelief of the skin.

12. Method according to claim 11 comprising the topical application of the hydrolyzate of Phaeodactylum tricornutum extraction co-product or a cosmetic composition comprising it on at least one area of ​​skin chosen from any area of ​​the face and / or any area of ​​the arms, including the forearms, legs, thighs, back, torso, neck, décolleté, feet and / or hands, including the scalp.

13. Process according to claim 11 or 12 such that the hydrolyzate is a hydrolyzate of co-product of ethanolic extraction of Phaeodactylum tricomutum.

14. Process according to any one of claims 11 to 13 such that the hydrolyzate is obtained by hydrolysis at basic pH under hot conditions.

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