Use of a keratin hydrolysate for improving the appearance of the skin and for preventing and / or reducing the signs of skin ageing

Abstract

The invention relates to a cosmetic, non-therapeutic, oral use of a keratin hydrolysate as an agent for improving the quality and / or appearance of the skin, said hydrolysate having a particular total amino acid profile and comprising at least 88% by weight of free amino acids relative to the total weight of the amino acids of the hydrolysate, the remainder of the amino acids of the hydrolysate being in the form of peptides having a molecular weight of less than or equal to 800 dalton, and to a corresponding cosmetic treatment method.

Description

[0001] Use of a keratin hydrolyzate to improve the appearance of the skin and to prevent and / or reduce the signs of skin aging

[0002] Field of invention

[0003] The present invention relates to the field of keratin hydrolysates and more particularly to the cosmetic use, by oral route, of a keratin hydrolysate as an agent for improving the quality and appearance of the skin and for preventing and / or reducing the signs of skin aging.

[0004] State of the art

[0005] The skin is made up of three layers: the epidermis, the dermis, and the hypodermis. The epidermis, which is in contact with the outside world, is particularly affected by external aggressions. The epidermis is covered by a hydrolipidic film and is composed of four layers: the stratum corneum, the stratum granulosum, the stratum spinosum, and the stratum basale.

[0006] The skin, and in particular the epidermis, is the human body's main protective barrier against external aggressions such as air pollution, climatic variations and UV radiation. It is therefore constantly subjected to stresses that cause its aging.

[0007] A distinction is generally made between intrinsic aging and extrinsic aging.

[0008] Intrinsic aging, also called physiological aging ("chrono-aging" in English), is the consequence of a slowdown in the renewal of keratinocytes, which are the cells of the superficial layers of the skin, particularly the epidermis. The reduction of subcutaneous adipose tissue and the appearance of fine wrinkles are the main manifestations of intrinsic aging.

[0009] Extrinsic aging ("photo-aging" in English) is characterized by a loss of skin elasticity, an alteration of the skin's barrier function and the appearance of deeper wrinkles. Extrinsic aging is mainly due to repeated exposure of the skin to the sun, it is also associated with the appearance of darker spots which generate areas of uneven appearance. This aging is also called photo-aging or actinic aging. There is always a need for new cosmetic products to improve the quality and appearance of the skin, in particular to prevent and / or reduce the signs of skin aging.

[0010] In particular, there remains a need for new products that are effective and easy to administer.

[0011] This problem has been solved by the present invention which aims at the use of a particular keratin hydrolyzate having a particularly low molecular weight.

[0012] Such a hydrolyzate, as well as its use for improving the quality and / or appearance of nails and / or hair are already known, in particular in application WO2019 / 043128. However, this patent application does not suggest the use of such a hydrolyzate for improving the appearance of the skin.

[0013] US Patent 7,579,317 B2 also describes the production of keratin derivatives and, among many medical applications, the improvement of skin health. These keratin derivatives are characterized by their high molecular weight, of the order of the molecular weight of the proteins of the raw material, and by the fact that they are S-sulfonated. They are in fact obtained by a digestion step consisting of the sulfonation of a keratin material by oxidative sulfitolysis followed by aqueous extraction. These keratin derivatives are very different from the hydrolyzate used in the present invention.

[0014] Other aspects, advantages, properties of the present invention are presented in the description and examples which follow.

[0015] Summary of the invention

[0016] The subject of the present invention is the cosmetic, non-therapeutic, oral use of a keratin hydrolyzate as an agent for improving the quality and / or appearance of the skin, said hydrolyzate comprising at least 88% by weight of free amino acids relative to the total weight of the amino acids of the hydrolyzate, the remainder of the amino acids of the hydrolyzate being in the form of peptides having a molecular mass less than or equal to 800 Dalton, said hydrolyzate having the following composition in each of the amino acids relative to the total of the amino acids: an aspartic acid content ranging from 6.0 to 9.0% by weight, preferably 7.3 to 8.2% by weight; a threonine content ranging from 4.0 to 6.0% by weight, preferably from 4.6 to 5.3% by weight; a serine content ranging from 10.0 to 15.0% by weight, preferably from 11.9 to 13.0% by weight; a glutamic acid content ranging from 9.0 to 14.0% by weight, preferably from 11.0 to 11.9% by weight;a glycine content ranging from 7.0 to 10.0% by weight, preferably from 8.4 to 9.1% by weight; an alanine content ranging from 4.0 to 6.0% by weight, preferably from 5.2 to 5.5% by weight; a valine content ranging from 6.0 to 10.0% by weight, preferably 7.8 to 8.5% by weight; a methionine content ranging from 0.0 to 0.5% by weight, preferably from 0.1 to 0.4% by weight; an isoleucine content ranging from 4.0 to 6.0% by weight, preferably from 4.1 to 4.6% by weight; a leucine content ranging from 6.0 to 9.0% by weight, preferably 6.7 to 7.7% by weight; a tyrosine content ranging from 0.0 to 0.6% by weight, preferably 0.1 to 0.5% by weight; a phenylalanine content ranging from 2.0 to 3.2% by weight, preferably 2.3 to 3.0% by weight; a lysine content ranging from 1.0 to 3.0% by weight, preferably 1.7 to 2.3% by weight, a histidine content ranging from 0.4 to 1.0% by weight, preferably 0.5 to 0.8% by weight;an arginine content ranging from 5.0 to 8.0% by weight, preferably 5.5 to 6.8% by weight; a proline content ranging from 9.0 to 14.0% by weight, preferably 9.5 to 11.8% by weight, a tryptophan content of less than 0.1%, preferably equal to 0.0% by weight and a cystine content ranging from 4.0 to 7.2% by weight, preferably 5.3 to 6.3% by weight.;

[0017] This amino acid profile represents the weight percentage of each amino acid (free + bound) compared to the total amino acids (free + bound).

[0018] The present invention also relates to a non-therapeutic cosmetic treatment method for improving the quality and / or appearance of the skin, comprising at least one step of administering, orally, to an individual, a keratin hydrolyzate comprising at least 88% by weight of free amino acids relative to the total weight of the amino acids in the hydrolyzate, the remainder of the amino acids in the hydrolyzate being in the form of peptides having a molecular mass less than or equal to 800 Dalton, said hydrolyzate having the following composition in each of the amino acids relative to the total amino acids: an aspartic acid content ranging from 6.0 to 9.0% by weight, preferably 7.3 to 8.2% by weight; a threonine content ranging from 4.0 to 6.0% by weight, preferably 4.6 to 5.3% by weight; a serine content ranging from 10.0 to 15.0% by weight, preferably from 11.9 to 13.0% by weight;a glutamic acid content ranging from 9.0 to 14.0% by weight, preferably from 11.0 to 11.9% by weight; a glycine content ranging from 7.0 to 10.0% by weight, preferably from 8.4 to 9.1% by weight; an alanine content ranging from 4.0 to 6.0% by weight, preferably from 5.2 to 5.5% by weight; a valine content ranging from 6.0 to 10.0% by weight, preferably 7.8 to 8.5% by weight; a methionine content ranging from 0.0 to 0.5% by weight, preferably from 0.1 to 0.4% by weight; an isoleucine content ranging from 4.0 to 6.0% by weight, preferably from 4.1 to 4.6% by weight; a leucine content ranging from 6.0 to 9.0% by weight, preferably 6.7 to 7.7% by weight; a tyrosine content ranging from 0.0 to 0.6% by weight, preferably 0.1 to 0.5% by weight; a phenylalanine content ranging from 2.0 to 3.2% by weight, preferably 2.3 to 3.0% by weight;a lysine content ranging from 1.0 to 3.0% by weight, preferably 1.7 to 2.3% by weight, a histidine content ranging from 0.4 to 1.0% by weight, preferably 0.5 to 0.8% by weight; an arginine content ranging from 5.0 to 8.0% by weight, preferably 5.5 to 6.8% by weight; a proline content ranging from 9.0 to 14.0% by weight, preferably 9.5 to 11.8% by weight, a tryptophan content of less than 0.1%, preferably equal to 0.0% by weight and a cystine content ranging from 4.0 to 7.2% by weight, preferably 5.3 to 6.3% by weight.;

[0019] The inventors have shown that, surprisingly, this hydrolyzate can confer particularly advantageous properties to the skin, notably in terms of shine, firmness and elasticity.

[0020] For the purposes of this text, "skin" means the epidermis.

[0021] The subjects to whom the hydrolyzate according to the invention was administered have skin with a younger and rested appearance.

[0022] It has also been observed that the hydrolyzate provides the skin with a good level of hydration.

[0023] In particular, the hydrolyzate according to the invention helps prevent and reduce the appearance of wrinkles and / or fine lines and leads to thicker skin. Indeed, the reduction in skin thickness is an indicator of skin aging.

[0024] Keratin derivatives known for their effects on the skin generally have a high molecular weight of the order of the molecular weight of keratin. Given their structure close to keratin, a beneficial effect for the skin could be expected. However, there was nothing to suggest that the hydrolyzate used according to the invention, whose molecular weight and free amino acid content are very different from those of native keratin, would, at low daily dosage, also have a significantly beneficial effect on the appearance of the skin.

[0025] Other characteristics and advantages of the invention will emerge from reading the detailed description which follows.

[0026] Description of the invention

[0027] According to a first aspect, the invention relates to the cosmetic, non-therapeutic, oral use of a particular keratin hydrolyzate as an agent for improving the quality and / or appearance of the skin.

[0028] According to a second aspect, the invention relates to a non-therapeutic, cosmetic treatment method for improving the quality and / or appearance of the skin comprising the oral administration to an individual of a particular keratin hydrolyzate.

[0029] The keratin hydrolyzate used according to the invention has a high level of free amino acids as well as a particular amino acid profile.

[0030] In particular, tyrosine is present in the keratin hydrolyzate according to the present invention in a content of less than or equal to 0.6% by weight, preferably less than or equal to 0.5% by weight and preferably less than or equal to 0.4% by weight relative to the total weight of the amino acids in the hydrolyzate. This low tyrosine content is the consequence of the implementation of a tyrosine extraction step in the process for preparing the hydrolyzate.

[0031] Advantageously, the hydrolyzate does not contain tyrosine, the only traces of this amino acid being due to the limits of the operating conditions and the equipment used during the extraction stage.

[0032] Furthermore, cysteine ​​is advantageously present in the keratin hydrolyzate according to the present invention in a content of less than or equal to 0.10%, preferably less than or equal to 0.05% by weight relative to the total weight of the amino acids of the hydrolyzate, more preferably, the hydrolyzate does not contain cysteine.

[0033] On the other hand, the hydrolyzate according to the present invention comprises cystine, more particularly L-cystine, which is a dimer of cysteine, in a significant content. Indeed, the cystine content ranges from 4.0 to 7.2% by weight, preferably 5.3 to 6.3% by weight relative to the total weight of the amino acids of the hydrolyzate.

[0034] The hydrolyzate according to the present invention comprises at least 88%, preferably at least 93% and more preferably at least 95% by weight of free amino acids relative to the total weight of the amino acids of the hydrolyzate, the remainder of the amino acids of the hydrolyzate being in the form of peptides having a molecular mass less than or equal to 800 Dalton. The average molecular weight of the hydrolyzate ranges from 140 to 160 Da.

[0035] Indeed, the hydrolyzate essentially comprises amino acids: free amino acids (at least 88% by weight relative to the total weight of amino acids) and amino acids linked to form peptides, the hydrolyzate further comprising mineral matter and water.

[0036] Advantageously, the content of amino acids also called total amino acids (free + bound) of the hydrolyzate ranges from 80% to 90% by weight relative to the total weight of the hydrolyzate.

[0037] The keratin hydrolyzate used according to the invention has the particular amino acid composition presented above, i.e. the percentage of each of the amino acids (free + bound) compared to the total amino acids (free + bound).

[0038] Advantageously, the mineral matter content of said hydrolyzate is less than or equal to 9% by weight, preferably less than 8% by weight relative to the total weight of the hydrolyzate.

[0039] The mineral content is determined after calcination of the hydrolyzate at 550°C for 4 hours.

[0040] Amino acids are measured according to the method of EC Regulation 152 / 2009.

[0041] According to this method, for the determination of the quantities of total amino acids, hydrolysis by means of an acid is previously carried out.

[0042] To determine the quantities of free and total amino acids, the amino acids are separated by chromatography (HPLC) with an ion exchange column and measured by reaction with ninhydrin and photometric detection, generally at 570 nm. Without wishing to be bound by any theory, it seems that carrying out extensive chemical hydrolysis to achieve these characteristics, in particular a molecular mass of the peptides present less than or equal to 800 Dalton, confers particular properties to the hydrolyzate with respect to the skin.

[0043] Another advantage of the hydrolyzate according to the present invention is that it is very digestible, in addition, it is recognized to be of food quality. The hydrolyzate according to the invention has a true digestibility of amino acids of at least 90%. This value is very close to the maximum possible (100%). This property allows good assimilation of the hydrolyzate and consequently better efficiency of the free amino acids.

[0044] Digestibility is measured in vivo according to the method described by Cozannet P, Primot Y., Gady C., Métayer JP, Lessire M. Skiba F., Noblet J. in “Standardized amino acid digestibility of wheat distillers' dried grains with solubles in force-fed cockerels”. British Poultry Science, Feb. 2011; 52(1 )72-81.

[0045] Process for preparing the hydrolyzate

[0046] The hydrolyzate used according to the invention is obtained by implementing a preparation process from natural keratin materials, in particular from poultry, advantageously from poultry feathers.

[0047] This natural keratin material mainly comprises high molecular weight polypeptides with a highly branched structure, making it difficult for enzymes to access and meaning that the said natural keratin material is not digestible.

[0048] Advantageously, said hydrolyzate is a hydrolyzate of poultry keratin raw material.

[0049] Poultry includes hens, chickens, turkeys, ducks, etc.

[0050] Preferably, the hydrolyzate used according to the present invention is not obtained from human keratin such as hair.

[0051] The process for preparing the keratin hydrolyzate used according to the invention implements at least one chemical hydrolysis using an acid under conditions capable of obtaining a hydrolyzate comprising at least 88% by weight of free amino acids relative to the total weight of the amino acids in the hydrolyzate, the remainder of the amino acids in the hydrolyzate being in the form of peptides having a molecular mass less than or equal to 800 Dalton.

[0052] The percentage of peptides in the hydrolyzate typically ranges from 5 to 12% by weight relative to the total weight of amino acids in the hydrolyzate.

[0053] Indeed, since the hydrolysis is partial, the percentage of peptides in the hydrolyzate is not zero, preferably it is at least 5% by weight of the total amino acids.

[0054] The chemical hydrolysis of the raw material is carried out using an acid, preferably a strong acid chosen from hydrochloric, phosphoric and sulfuric acids, preferably hydrochloric acid.

[0055] Chemical hydrolysis is generally carried out for a period of time ranging from 1 hour to 8 hours, preferably 6 to 7 hours at a temperature ranging from 110 to 115°C.

[0056] According to a particular variant, chemical hydrolysis is carried out in two stages:

[0057] -a first chemical hydrolysis carried out at a temperature ranging from 60 to 80°C for a period ranging from 4 to 5 hours then

[0058] - a second chemical hydrolysis carried out at a temperature ranging from 100 to 115°C for a period ranging from 5 to 7 hours, the two hydrolyses being able to be carried out without an intermediate pause step or by carrying out an intermediate pause step of between 1 hour and 7 days.

[0059] More precisely, the first chemical hydrolysis is carried out at 72°C for 4.5 hours and the second chemical hydrolysis is carried out at 107°C for 6 hours, with an intermediate break of 24 to 80 hours being carried out between the two chemical hydrolyses.

[0060] The tyrosine extraction step is carried out using a base preferably chosen from sodium hydroxide, potassium hydroxide, preferably sodium hydroxide.

[0061] The tyrosine extraction step is a classic step, the implementation of which falls within the skills of those skilled in the art.

[0062] Unlike some keratin hydrolysates, the hydrolysate according to the present invention does not contain sulfocysteine. The chemical hydrolysis and tyrosine extraction steps may be followed by optional steps of purification of the resulting hydrolysate.

[0063] The chemical hydrolysis and tyrosine extraction steps can be followed by optional steps of concentration of the resulting hydrolyzate.

[0064] The chemical hydrolysis and tyrosine extraction steps can be followed by optional drying steps, for example by spray drying.

[0065] The purification, concentration and drying steps are classic steps whose implementation falls within the skills of a person skilled in the art.

[0066] Advantageously, the keratin hydrolyzate obtained is dried by atomization (“spray-drying” in English) in order to obtain the hydrolyzate in solid form.

[0067] Uses

[0068] As already mentioned, the present invention relates to the cosmetic use, by oral route, of the keratin hydrolyzate according to the invention as an agent for improving the quality and / or appearance of the skin.

[0069] More specifically, the present invention relates to the cosmetic use, by oral route, of keratin hydrolyzate to improve shine and confer a "healthy glow" effect, to improve firmness and / or reduce loss of elasticity of the skin. The subjects to whom the hydrolyzate was administered have younger, more rested-looking skin.

[0070] More specifically, the present invention relates to the cosmetic use, by oral route, of keratin hydrolyzate to prevent and / or reduce the signs of skin aging, in particular the appearance of wrinkles and / or fine lines.

[0071] In subjects administered the hydrolyzate, wrinkles appear less pronounced and less deep. The skin has a smoother appearance with a marked reduction in imperfections.

[0072] In subjects to whom the hydrolyzate was administered, the skin is significantly thicker, which is one of the causes of the reduction in wrinkles. The skin also has better hydration. According to a second aspect, the invention relates to a non-therapeutic cosmetic treatment method for improving the quality and / or appearance of the skin, comprising the oral administration to an individual of a particular hydrolyzate. Advantageously, the invention relates to a cosmetic treatment method for preventing and / or reducing the signs of skin aging, in particular the appearance of wrinkles and / or fine lines and / or for improving the shine and / or firmness of the skin and / or reducing the loss of elasticity of the skin.

[0073] Advantageously, the use and the method according to the invention comprise the daily administration of a quantity of hydrolyzate ranging from 0.3 to 0.7 g, preferably from 0.4 to 0.6 g of hydrolyzate and preferably 0.5 g of hydrolyzate.

[0074] Preferably, the daily administration of an amount of hydrolyzate ranging from 0.3 to 0.7 g, preferably from 0.4 to 0.6 g of hydrolyzate and preferably 0.5 g of hydrolyzate is carried out for a period ranging from at least 30 days to 100 days, preferably for a period ranging from at least 45 days to 95 days and preferably 90 days.

[0075] As can be seen from the examples, the administration of the hydrolyzate is advantageously carried out in the form of two doses per day, preferably one dose in the morning and one dose in the evening.

[0076] According to a first preferred embodiment, in the use and method according to the invention, the hydrolyzate is administered in the form of a composition comprising said hydrolyzate and at least one component chosen from the group formed by zinc or one of its salts, copper or one of its salts, B vitamins, in particular B3, B5, B6 and / or B8, vitamin D3, vitamin C, vitamin A, vitamin E, silicon, selenium, magnesium, calcium, manganese, molybdenum, iron, yeasts, plant extracts, in particular horsetail, [3-carotene, collagen, hyaluronic acid, glutathione and mixtures of these components.

[0077] According to a second preferred embodiment, in the use and method according to the invention, the hydrolyzate is administered in the form of a composition comprising said hydrolyzate and at least one of the following additional amino acids: additional cystine and / or additional arginine and / or additional proline and / or additional lysine and / or additional methionine, preferably the amount by weight of additional cystine is equal to the amount by weight of cystine in the hydrolyzate and / or the amount by weight of additional arginine is equal to the amount by weight of arginine in the hydrolyzate and / or the amount by weight of additional proline is equal to the amount by weight of proline in the hydrolyzate and / or the amount by weight of additional lysine is equal to the amount by weight of lysine in the hydrolyzate and / or the amount by weight of additional methionine ranges from 10 mg / day to 80 mg / day.

[0078] The following examples illustrate the invention without limiting its scope.

[0079] EXAMPLES

[0080] Example 1 - Compliant hydrolysates

[0081] Three hydrolysates in accordance with the invention were prepared using the same method from three different batches of feathers. Each time, the feathers were freshly collected from the applicant's partners; consequently, the nature of the feathers (chickens, turkeys, ducks, geese, etc.) may vary.

[0082] A. Preparation of hydrolysates

[0083] Each time, 4500 kg of poultry feathers are introduced into a 50,000 litre reactor / hydrolyser.

[0084] A first step of chemical hydrolysis is carried out by adding 18,000 liters of hydrochloric acid (24%), the hydrolysis is carried out at 72°C for 4.5 hours.

[0085] The resulting product is stored for 48 hours at room temperature (intermediate break).

[0086] Then a second chemical hydrolysis is carried out by heating at 105°C for 6 hours without adding acid.

[0087] The product obtained is left to cool.

[0088] Then a tyrosine extraction step is carried out by raising the pH to around 7 using sodium hydroxide.

[0089] The solution obtained is desalinated by electrodialysis then dried by atomization.

[0090] 4200 kg of hydrolyzate I are obtained in dry form.

[0091] B. Determination of the composition of hydrolysates Amino acids are determined according to the method of EC regulation 152 / 2009.

[0092] Amino acids are separated by chromatography (HPLC) with an ion exchange column and measured by reaction with ninhydrin and photometric detection at 570 nm.

[0093] The values ​​presented are expressed in grams of amino acids relative to total amino acids.

[0094] The aminogram of the total amino acids of hydrolysate I, i.e. the contents of each amino acid in relation to the total amino acids, is presented in Table 1.

[0095] Table 1

[0096] Hydrolyzate I comprises 6.6% by weight of mineral matter and 83.3% by weight of free amino acids.

[0097] The aminogram of the total amino acids of hydrolysate II, i.e. the contents of each amino acid in relation to the total amino acids, is presented in Table 2.

[0098] Table 2

[0099] Hydrolyzate II comprises 7.6% by weight of mineral matter and 80.4% by weight of free amino acids.

[0100] The aminogram of the total amino acids of hydrolysate III, i.e. the contents of each amino acid in relation to the total amino acids, is presented in Table 3.

[0101] Table 3 Hydrolyzate III comprises 7.1% by weight of mineral matter and

[0102] 83.0% by weight of free amino acids. C. Digestibility

[0103] Table 4 below presents the true digestibility coefficients of each of the amino acids in hydrolyzate I, expressed as a percentage, as well as the average true digestibility value of the total amino acids.

[0104] These values ​​were obtained according to the following protocol on caectomized roosters, which is a reference model for measuring the bioavailability of amino acids in the animal kingdom.

[0105] Experimental protocol

[0106] Digestibility measurements are carried out on adult caecectomized roosters housed in individual cages and fed outside the trial period with a standard diet.

[0107] 2 replicates of 4 caectomized roosters were used.

[0108] All animals were fasted for 24 h before ingesting a single 80 g meal consisting of 24 g of hydrolysate sample I mixed with 56 g of sugar.

[0109] All faeces (= fecal matter), including endogenous losses, are collected during the following 48 hours in two 24-hour periods to avoid fermentation and possible deterioration.

[0110] These feces, excluded from any contamination such as feathers for example, are carefully collected before being frozen (-80°C).

[0111] The feces are then oven dried, pooled and mixed into 2 pools corresponding to the 2 replicates of 4 animals used for the hydrolysate.

[0112] Both pools are analyzed.

[0113] Nutritional analyses (dry matter, crude protein (Dumas method) and amino acids) are carried out on the hydrolysate, the rooster feces as well as on endogenous losses.

[0114] These data are used to calculate the true digestibility of proteins and amino acids. For protein digestibility, due to the contamination of bird droppings with uric nitrogen, protein nitrogen is measured in feces (Terpstra method).

[0115] The true digestibility of nutrients measured as a percentage is therefore calculated using a quantitative method by the difference between the quantity of hydrolyzate ingested and the quantity of feces excreted, corrected for endogenous losses according to the following formulas:

[0116] Ingested protein hydrolysate - (protein excreted feces - endogenous protein excreted) True protein digestibility % = - x 100

[0117] Ingested protein hydrolyzate

[0118] Ingested amino acid hydrolyzate - (Amino acid excreted feces - Endogenous amino acid excreted) True digestibility Amino acid % = - x 100

[0119] Ingested amino acid hydrolyzate

[0120] The digestibility values ​​of hydrolysate I are shown in Table 4 below:

[0121] Table 4

[0122] The true digestibility of the amino acids in hydrolysate I according to the invention is very high since it is very close to the maximum possible (100%). The hydrolysate according to the invention is therefore well assimilated by the body. The same conclusion would be reached for the true digestibility of the amino acids in hydrolysates II and III.

[0123] Example 2 - Measurements of cosmetic activities

[0124] The examples below were carried out using a product A comprising the hydrolyzate II in accordance with the invention and a commercial keratin-based product as comparative product C.

[0125] Each capsule of Product A comprised 125 mg of keratin II hydrolysate prepared above with 205 mg of corn maltodextrin and 10 mg of magnesium stearate as excipients.

[0126] According to the available information, product C comprises a sheep wool keratin derivative with a molecular weight greater than 950 Da. The protein fraction of the keratin derivative is between 60% and 70% by weight of the total weight of the derivative and the mineral fraction represents from 30% to 40% by weight. The share of free amino acids represents less than 6% by weight of the amino acids of the keratin derivative. The protein fraction consists of 80% by weight of peptides combining from 3 to 35 amino acids. The true digestibility of product C determined according to the method described in paragraph Example 1. C above is less than 75%.

[0127] Each capsule of Product C contains 125 mg of keratin derivative, with 205 mg of corn maltodextrin and 10 mg of magnesium stearate as excipients.

[0128] The placebo consists of only 330 mg of corn maltodextrin (excipient) and 10 mg of magnesium stearate (excipient).

[0129] The study was conducted on 99 healthy subjects aged 35 to 65 years, in a double-blind, randomized, placebo-controlled trial (33 subjects received product A, 33 subjects received comparative product C, and 33 subjects received placebo). Other inclusion criteria are listed below: visible crow's feet, mild to moderate skin laxity, Fitzpatrick skin type I to IV. Products A, C, and placebo were administered orally at a dose of 4 capsules per day (2 capsules in the morning and 2 capsules in the evening) for 90 days, with interim results measured after 45 days.

[0130] The first group received a daily dose of 0.5 g of hydrolyzate II (4 capsules of product A), the second group received a daily dose of 0.5 g of keratin derivative (4 capsules of product C), the third group received 4 capsules of placebo per day.

[0131] A. Brilliance

[0132] Skin brightness was measured using a CM 700D spectrophotometer / colorimeter (Konica-Minolta).

[0133] The parameter measured was the gloss value at 8°.

[0134] The instrument emits diffuse light that reaches the skin through an opening at the end of the lighting sphere.

[0135] A sensor located at 8° relative to the vertical axis of the opening then detects the reflected light and calculates a parameter called "gloss value".

[0136] The gloss value is used in managing the brightness of the color.

[0137] The variation between skin brightness measurement at 45 days (D45) vs. brightness measurement at baseline (DO) as well as the variation between brightness measurement at 90 days (D90) vs. brightness measurement at baseline (DO) were recorded in Table 5 below:

[0138] Table 5

[0139] The hydrolyzate according to the invention (product A) allows the obtaining of a more brilliant skin than the comparative product C from 45 days, after 90 days the shine is even more marked. An additional test was carried out by administering daily 1 g of hydrolyzate II for 45 days but this test did not lead to better results than the administration of 0.5 g of hydrolyzate II for 45 days.

[0140] B. Firmness and elasticity

[0141] The measurement of skin firmness and elasticity is based on the suction / elongation method (Cutometer®MPA 580, Courage+Khazaka, electronic GmbH).

[0142] A vacuum (450 mbar) is created in the device and the skin is sucked into the probe opening for 2 seconds and released after a set time (2 seconds).

[0143] The principle of this method is illustrated in Figure 1 which shows the deformation (in 10' 3 m) as a function of time (in s).

[0144] The RO parameter corresponds to the extensibility of the skin: it is the first maximum amplitude of the curve (Uf) and represents the passive behavior of the skin when faced with a force. The RO parameter is inversely proportional to the degree of firmness of the skin. The results obtained can be expressed in absolute values ​​as an increase in skin firmness.

[0145] The R2 parameter corresponds to the gross elasticity or global elasticity: it is the ratio between the residual deformation and the maximum elongation of the skin (Ua / Uf) and it indicates the capacity of the skin to return to its initial recovery state after a stressful event.

[0146] Firmness is measured as the absolute value of the RO parameter.

[0147] The variation between skin firmness measurement at 45 days (D45) vs. firmness measurement at the start of the study (DO) as well as the variation between firmness measurement at 90 days (D90) vs. firmness measurement at the start of the study (D0) were recorded in Table 6 below: Table 6

[0148] The hydrolyzate according to the invention (product A) allows the obtaining of firmer skin than the comparative product C after 45 days of treatment.

[0149] An additional trial was conducted by administering 1 g of hydrolysate II daily for 90 days, but this trial did not lead to better results than the administration of 0.5 g of hydrolysate II for 90 days.

[0150] Elasticity is measured with the parameter R2.

[0151] The variation between skin elasticity measurement at 45 days (D45) vs. elasticity measurement at the beginning of the study (DO) as well as the variation between elasticity measurement at 90 days (D90) vs. elasticity measurement at the beginning of the study (DO) were recorded in Table 7 below: Table 7

[0152] The hydrolyzate according to the invention (product A) allows the obtaining of more elastic skin than comparative product C from 45 days.

[0153] An additional trial was conducted by administering 1 g of hydrolysate II daily for 45 days, but this trial did not lead to better results than the administration of 0.5 g of hydrolysate II for 45 days. C. Effect on wrinkles / fine lines

[0154] The skin surface is quantitatively assessed by Primos 3D (GFMesstechnik GmbH).

[0155] Primos 3D is a non-contact in vivo skin measurement device based on structured light projection.

[0156] Combined with comprehensive 3D measurement and evaluation software, the sensor can assess the properties of the skin surface: depth, length, area (surface) of wrinkles / fine lines.

[0157] In this study, the depth, length, and area of ​​wrinkles were measured in the "crow's feet" area.

[0158] This study was conducted in comparison with placebo.

[0159] The changes between the wrinkle / line depth / length / area measurements at 45 days (D45) vs. the wrinkle / line depth / length / area measurements at baseline (DO) and the changes between the wrinkle / line depth / length / area measurements at 90 days (D90) vs. the wrinkle / line depth / length / area measurements at baseline (DO) were recorded in Table 8 below:

[0160] Table 8 The hydrolyzate according to the invention makes it possible to reduce wrinkles / fine lines from 45 days.

[0161] In addition, user opinions were collected: 80% of subjects who used the hydrolyzate according to the invention also noted that their skin was smoother, softer and better hydrated.

Claims

CLAIMS 1. Cosmetic, non-therapeutic, oral use of a keratin hydrolyzate as an agent for improving the quality and / or appearance of the skin, said hydrolyzate comprising at least 88% by weight of free amino acids relative to the total weight of the amino acids in the hydrolyzate, the remainder of the amino acids in the hydrolyzate being in the form of peptides having a molecular mass less than or equal to 800 Dalton, said hydrolyzate having the following composition in each of the amino acids relative to the total of the amino acids: an aspartic acid content ranging from 6.0 to 9.0% by weight, preferably 7.3 to 8.2% by weight; a threonine content ranging from 4.0 to 6.0% by weight, preferably 4.6 to 5.3% by weight; a serine content ranging from 10.0 to 15.0% by weight, preferably from 11.9 to 13.0% by weight; a glutamic acid content ranging from 9.0 to 14.0% by weight, preferably from 11.0 to 11.9% by weight;a glycine content ranging from 7.0 to 10.0% by weight, preferably from 8.4 to 9.1% by weight; an alanine content ranging from 4.0 to 6.0% by weight, preferably from 5.2 to 5.5% by weight; a valine content ranging from 6.0 to 10.0% by weight, preferably 7.8 to 8.5% by weight; a methionine content ranging from 0.0 to 0.5% by weight, preferably from 0.1 to 0.4% by weight; an isoleucine content ranging from 4.0 to 6.0% by weight, preferably from 4.1 to 4.6% by weight; a leucine content ranging from 6.0 to 9.0% by weight, preferably 6.7 to 7.7% by weight; a tyrosine content ranging from 0.0 to 0.6% by weight, preferably 0.1 to 0.5% by weight; a phenylalanine content ranging from 2.0 to 3.2% by weight, preferably 2.3 to 3.0% by weight; a lysine content ranging from 1.0 to 3.0% by weight, preferably 1.7 to 2.3% by weight, a histidine content ranging from 0.4 to 1.0% by weight, preferably 0.5 to 0.8% by weight;an arginine content ranging from 5.0 to 8.0% by weight, preferably 5.5 to 6.8% by weight; a proline content ranging from 9.0 to 14.0% by weight, preferably 9.5 to 11.8% by weight, a tryptophan content of less than 0.1%, preferably equal to 0.0% by weight and a cystine content ranging from 4.0 to 7.2% by weight, preferably 5.3 to 6.3% by weight.; 2. Use according to claim 1 comprising the daily administration of an amount of hydrolyzate ranging from 0.3 to 0.7 g of hydrolyzate, preferably from 0.4 to 0.6 g of hydrolyzate and more preferably 0.5 g of hydrolyzate.

3. Use according to any one of the preceding claims, characterized in that said hydrolyzate is administered in the form of a composition comprising said hydrolyzate and at least one component chosen from the group formed by zinc or one of its salts, copper or one of its salts, B vitamins, in particular B3, B5, B6 and / or B8, vitamin D3, vitamin C, vitamin A, vitamin E, silicon, selenium, magnesium, calcium, manganese, molybdenum, iron, yeasts, plant extracts, in particular horsetail, [3-carotene, collagen, hyaluronic acid, glutathione and mixtures of these components.

4. Use according to any one of the preceding claims, characterized in that said hydrolyzate is administered in the form of a composition comprising said hydrolyzate and at least one of the following additional amino acids: additional cystine and / or additional arginine and / or additional proline and / or additional lysine and / or additional methionine, preferably the amount by weight of additional cystine is equal to the amount by weight of cystine in the hydrolyzate and / or the amount by weight of additional arginine is equal to the amount by weight of arginine in the hydrolyzate and / or the amount by weight of additional proline is equal to the amount by weight of proline in the hydrolyzate and / or the amount by weight of additional lysine is equal to the amount by weight of lysine in the hydrolyzate and / or the amount by weight of additional methionine ranges from 10 mg / day to 80 mg / day.

5. Use according to any one of the preceding claims for improving the shine and / or firmness of the skin and / or reducing the loss of elasticity of the skin.

6. Use according to any one of claims 1 to 4 for preventing and / or reducing the signs of skin aging, in particular the appearance of wrinkles and / or fine lines.

7. A non-therapeutic cosmetic treatment method for improving the quality and / or appearance of the skin, comprising at least one step of administering, orally, to an individual, a keratin hydrolyzate comprising at least 88% by weight of free amino acids relative to the total weight of the amino acids in the hydrolyzate, the remainder of the amino acids in the hydrolyzate being in the form of peptides having a molecular mass less than or equal to 800 Dalton, said hydrolyzate having the following composition in each of the amino acids relative to the total amino acids: an aspartic acid content ranging from 6.0 to 9.0% by weight, preferably 7.3 to 8.2% by weight; a threonine content ranging from 4.0 to 6.0% by weight, preferably 4.6 to 5.3% by weight; a serine content ranging from 10.0 to 15.0% by weight, preferably from 11.9 to 13.0% by weight; a glutamic acid content ranging from 9.0 to 14.0% by weight, preferably from 11.0 to 11.9% by weight;a glycine content ranging from 7.0 to 10.0% by weight, preferably from 8.4 to 9.1% by weight; an alanine content ranging from 4.0 to 6.0% by weight, preferably from 5.2 to 5.5% by weight; a valine content ranging from 6.0 to 10.0% by weight, preferably 7.8 to 8.5% by weight; a methionine content ranging from 0.0 to 0.5% by weight, preferably from 0.1 to 0.4% by weight; an isoleucine content ranging from 4.0 to 6.0% by weight, preferably from 4.1 to 4.6% by weight; a leucine content ranging from 6.0 to 9.0% by weight, preferably 6.7 to 7.7% by weight; a tyrosine content ranging from 0.0 to 0.6% by weight, preferably 0.1 to 0.5% by weight; a phenylalanine content ranging from 2.0 to 3.2% by weight, preferably 2.3 to 3.0% by weight; a lysine content ranging from 1.0 to 3.0% by weight, preferably 1.7 to 2.3% by weight, a histidine content ranging from 0.4 to 1.0% by weight, preferably 0.5 to 0.8% by weight;an arginine content ranging from 5.0 to 8.0% by weight, preferably 5.5 to 6.8% by weight; a proline content ranging from 9.0 to 14.0% by weight, preferably 9.5 to 11.8% by weight, a lower tryptophan content; at 0.1%, preferably equal to 0.0% by weight and a cystine content ranging from 4.0 to 7.2% by weight, preferably 5.3 to 6.3% by weight.

8. Cosmetic treatment method according to the preceding claim comprising the daily administration of an amount of hydrolyzate ranging from 0.3 to 0.7 g, preferably from 0.4 to 0.6 g of hydrolyzate and preferably 0.5 g of hydrolyzate.

9. Cosmetic treatment method according to claim 7 or 8 wherein said hydrolyzate is administered in the form of a composition comprising said hydrolyzate and at least one component chosen from the group formed by zinc or one of its salts, copper or one of its salts, B vitamins, in particular B3, B5, B6 and / or B8, vitamin D3, vitamin C, vitamin A, vitamin E, silicon, selenium, magnesium, calcium, manganese, molybdenum, iron, yeasts, plant extracts in particular horsetail, [3-carotene, collagen, hyaluronic acid, glutathione and mixtures of these components.

10. Cosmetic treatment method according to any one of claims 7 to 9 wherein said hydrolyzate is administered in the form of a composition comprising said hydrolyzate and at least one of the following additional amino acids: additional cystine and / or additional arginine, and / or additional proline, and / or additional lysine, and / or additional methionine, preferably the amount by weight of additional cystine is equal to the amount by weight of cystine in the hydrolyzate and / or the amount by weight of additional arginine is equal to the amount by weight of arginine in the hydrolyzate, and / or the amount by weight of additional proline is equal to the amount by weight of proline in the hydrolyzate, and / or the amount by weight of additional lysine is equal to the amount by weight of lysine in the hydrolyzate and / or the amount by weight of methionine additional dose ranges from 10 mg / day to 80 mg / day.

11. Cosmetic treatment method according to any one of claims 7 to 10 for preventing and / or reducing the signs of skin aging, in particular the appearance of wrinkles and / or fine lines. and / or to improve skin brightness and / or firmness and / or reduce loss of skin elasticity.

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