FR3054128A1 - COSMETIC COMPOSITIONS COMPRISING BIOMINERAL COMPOUNDS AND CORRESPONDING USES FOR SKIN PROTECTION AGAINST ULTRAVIOLET RADIATION - Google Patents

Abstract

The object of the invention is to propose a cosmetic composition comprising biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, in an acceptable cosmetic medium, as well as the corresponding cosmetic uses.

Description

Holder (s): BROKERAGE AND BROADCASTING COMPANY - CODIF INTERNATIONAL Simplified joint stock company.

Extension request (s)

Agent (s): CABINET PATRICE VIDON.

COSMETIC COMPOSITIONS COMPRISING BIOMINERAL COMPOUNDS AND USES THEREOF FOR PROTECTION OF THE SKIN AGAINST ULTRAVIOLET RADIATION.

tuf) The object of the invention is to propose a cosmetic composition comprising biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, in an acceptable cosmetic medium, as well as the corresponding cosmetic uses.

FR 3 054 128 - A1

Cosmetic compositions comprising biomineral compounds and corresponding uses for protecting the skin against ultraviolet radiation

1. Field of the invention

The field of the invention is that of cosmetic compositions and corresponding cosmetic uses. More specifically, the invention relates to cosmetic compositions comprising biomineral compounds, produced in particular by microalgae belonging to the group consisting of diatoms, coccolithophorids, and their mixtures. The invention also relates to the use of these biomineral compounds, and of cosmetic compositions comprising them, for the protection of the skin against ultraviolet radiation.

2. Prior Art

Human skin has a complex structure. It is divided into four superimposed layers, which go from the most superficial layer to the deepest layer, the epidermis, the dermo-epidermal junction, the dermis and the hypodermis.

"The epidermis" is a stratified, keratinized, squamous, squamous and non-vascularized epithelium, formed with 80% of keratinocyte cells. The epidermis comprises a surface microdepression network, commonly called RmD, crossed by furrows and riddled with pilosebaceous orifices, which gives the surface of the skin a kind of microrelief. This network makes it possible in particular to increase the surface of the skin and to promote epidermal stretching. The epidermis, with an average thickness of about a tenth of a millimeter, is subdivided into at least four layers of keratinocytes, which are going from the most superficial layer to the deepest layer, the stratum corneum, the layer grainy, the spinous layer and the basal layer. The basal layer is formed by all of the keratinocytes directly in contact with the dermo-epidermal junction.

"The dermo-epidermal junction" is by definition the acellular junction zone between the dermis and the epidermis. In particular, it allows adhesion between the epidermis and the dermis, the formation of a selective physicochemical barrier between the dermis and the epidermis and provides protection by the immune system. The dermo-epidermal junction is subdivided into at least four zones, which are going from the most superficial zone to the deepest zone, the plasma membrane, the basement membrane and the fibrillar zone. In particular, it comprises numerous filaments and anchoring fibers.

"The dermis" and "the hypodermis" are richly vascular connective tissues. The dermis, of average thickness between one millimeter and two millimeters, is subdivided into two zones, which are going from the most superficial zone to the deepest zone, the papillary dermis and the reticular dermis. The dermis comprises different types of cells and in particular fibroblasts, participating in the synthesis of many proteoglycans and glycoproteins such as elastin or collagen and cells of the immune system. The dermis also includes an extracellular matrix.

It is well known that prolonged exposure of the skin to the sun, and therefore to ultraviolet (UV) radiation, in particular ultraviolet A and B radiation, can be harmful. The same goes for artificial exposure to UV radiation, for example in beauty salons. Moderate regular exposure is usually not harmful and may even be associated with certain benefits, including the production of vitamin D known as the "good mood" vitamin. However, when UV exposure is excessive, especially when the subject's skin has a high photosensitivity, it can be harmful or even dangerous. The skin naturally includes a defense mechanism against UV radiation, i.e. the presence of melanin pigments. Melanin is produced by melanocyte cells, which are located in the basal layer of the epidermis. When exposed to UV rays, the melanin already present in the skin will darken, ensuring a quick tan. In addition, new melanin will be produced, in order to strengthen the tan a few days or hours after exposure.

The protection conferred by melanin is partial, and does not compensate for excessive exposure to UV radiation. Thus, negative effects can be observed both in the epidermis, the dermo-epidermal junction or the dermis, in the short term, medium term or long term. Without being exhaustive, the negative effects caused by UV radiation include a loss of permanent elasticity of the skin, the appearance of fine lines and wrinkles, premature aging of the skin, sunburn, or even the appearance of skin cancer. The appearance of skin cancer is the most serious damage to the integrity of the skin, especially in the case of the appearance of malignant melanomas, which can be fatal for the subject. Note that UV radiation acts at various tissue, cellular and molecular levels. For example, it has been shown that prolonged exposure to UV radiation results in increased expression of cyclooxygenase-2 (COX3054128

2) which is a factor of inflammation of the dermis. Similarly, such exposure leads to an increase in the secretion of interleukin 8.

Many cosmetic and dermatological products protecting the skin against UV radiation, commonly known as sun creams or UV filters, are commercially available. These aim to reduce the skin's exposure to UV radiation. They include in particular compounds which will filter UV radiation. These compounds can be chemically synthesized or be mineral in nature.

Despite the availability of sunscreens on the market, it is still necessary to provide cosmetic compositions protecting the skin against ultraviolet radiation having a demonstrated or even enhanced efficacy. In addition, cosmetic compositions are sought which make it possible to limit or even suppress the increase in the secretion of cyclooxygenase-2. In addition, cosmetic compositions are sought which limit or even suppress the increase in the secretion of interleukin-8. Cosmetic compositions comprising compounds of natural origin are also sought after, in addition to or in replacement of the chemical and / or organic compounds currently used.

In addition, in addition to protecting the skin against intrinsic effects (for example aging) and extrinsic or environmental effects (for example prolonged exposure to the sun), cosmetic and dermatological products make it possible to beautify the skin, in particular by mitigating or concealing certain unsightly aspects. Among the unsightly aspects, there are especially dark circles and other signs of fatigue, spots, wrinkles and fine lines. Thus, cosmetic compositions are always sought after which make it possible to attenuate or conceal the unsightly aspects of the skin. On the one hand, cosmetic compositions are sought which make it possible to improve the texture of the skin, in particular by filling in the grooves of the surface microdepression network, fine lines, wrinkles and other crevices on the surface of the skin. This is called "smoothing effect". On the other hand, cosmetic compositions are also sought after which make it possible to accentuate the radiance of the skin and make it more luminous. We then speak of "soft focus or soft focus".

Finally, in order to avoid the application of multiple cosmetic compositions to protect the skin from such and such effects and / or to attenuate or conceal such or such unsightly aspects, the user is always looking for cosmetic compositions which are simple to apply. , efficient and versatile.

3. Objectives of the invention

The object of the invention is to provide a cosmetic composition allowing effective protection of the skin against UV radiation.

The object of the invention is to provide a cosmetic composition which limits the reduction in cell viability induced by UV radiation.

The object of the invention is to provide a cosmetic composition allowing a reduction in the expression of cyclooxygenase-2 induced by UV radiation.

The object of the invention is to provide a cosmetic composition allowing a reduction in the expression of interleukin 8 induced by UV radiation.

The object of the invention is to provide a cosmetic composition which makes it possible to attenuate or conceal the unsightly aspects of the skin, in particular dark circles and other signs of fatigue, spots, wrinkles and fine lines.

The object of the invention is to provide a cosmetic composition which makes it possible to improve the texture of the skin, in particular by filling in the grooves of the surface microdepression network, fine lines, wrinkles and other crevices on the surface of the skin.

The object of the invention is to provide a cosmetic composition which makes it possible to accentuate the radiance of the skin and make it more luminous.

Finally, the invention aims to provide a composition which both effectively protects the skin against UV radiation and attenuates or conceals the unsightly aspects of the skin.

4. Statement of the invention

The invention relates to a cosmetic composition comprising biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, and the associated cosmetic uses.

In fact, the inventors have demonstrated that the biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures have advantageous properties against UV radiation, as well as advantageous properties in terms of “smoothing effect” and “blurring effect. "

Coccoliths and frustules are biomineral compounds synthesized by certain microalgae, also called phytoplankton.

The synthesis of biomineral compounds is only possible in microalgae with metabolic pathways of biomineralization. Biomineralization can be obtained from two distinct mechanisms, namely induced biomineralization or controlled biomineralization. Induced biomineralization is a passive form of biomineralization used to obtain biomineral compounds. Controlled biomineralization is a specific metabolic pathway requiring the transport of ions in a compartment allowing their saturation to induce crystallization of the mineral around an organic protein or polysaccharide matrix. Controlled biomineralization in particular involves controlling the nucleation, growth and arrest of growth of the biomineral compound.

Coccoliths are biomineral compounds formed from calcite (CaCCL) and a polysaccharadic matrix, and synthesized by coccolithophoridae (Haptophyta spine, class Prymnesiophyceae or Coccolithophyceae). Frustules are biomineral compounds formed from Opal A (SiO _{2. N} H ₂ O), and synthesized by diatoms (class Bacillariophyceae).

Coccolithophoridae are single cell marine microalgae of the Haptophyta phylum, of the class of Prymnesiophyceae or Coccolithophyceae and of the order Coccosphaerales or Coccolithales or Isochrysidales. These coccolithophorids are characterized by the presence on their surface of an assembly of limestone platelets commonly called coccoliths. These coccoliths therefore cover the surface of the cell. Coccoliths are biomineral compounds with a diameter of lpm to 10pm.

Diatoms are brown unicellular microalgae of the Bacillariophyta superclass. Diatoms measure from 2pm to 100pm in diameter. These diatoms are characterized by the presence on their surface of an exoskeleton commonly known as a frustule. The frustule is formed by two shells commonly called valves. It is also covered with a thin organic layer. Frustules therefore cover the surface of the cells.

The inventors have surprisingly demonstrated that coccoliths and frustules, and therefore cosmetic compositions comprising them, have protective properties for the skin against ultraviolet (UV) radiation. In particular, as demonstrated below in vitro on skin explants, coccoliths and frustules make it possible to significantly reduce the drop in cell viability induced by UV radiation. Likewise, coccoliths make it possible to limit, or even prevent, the increase in the expression of cyclooxygenase-2. In addition, coccoliths and frustules help limit or even prevent the secretion of interleukin 8.

In addition, the inventors have surprisingly demonstrated that coccoliths and frustules, and therefore the cosmetic compositions comprising them, have a higher Haze index than that of the placebo cosmetic compositions, that is to say the cosmetic compositions comprising no biomineral compounds.

In addition, the inventors have demonstrated, just as surprisingly, that coccoliths and frustules, and therefore the cosmetic compositions comprising them, have interesting aesthetic properties. In particular, as demonstrated below in vitro on skin explants, coccoliths and frustules allow filling, at the very least partial, of the surface microdepression network, characteristic of a smoothing effect on the skin. Similarly, coccoliths and frustules reduce the contrast, characteristic of a blurring effect on the skin.

In a first aspect, the present invention relates to a cosmetic composition comprising biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, and the associated cosmetic uses.

The cosmetic composition is preferably a topical composition.

The cosmetic composition can comprise biomineral compounds according to the invention present in the purified state, in the native state or their combination. By "purified state" is meant the biomineral compounds in isolated form, that is to say in the absence of the coccolithophorid or diatom cells which they cover in the native state. By "native state" is meant coccolithophorid or diatom microalgae as a whole, that is to say microalgae comprising a cell covered with coccoliths or with a frustule respectively.

Coccolithophorids and diatoms can be grown in closed photoreactors or in open culture systems. The culture medium must be composed of natural or artificial seawater comprising macroelements and microelements, present in a concentration sufficient to allow the growth of microalgae. By "macroelements" is meant in particular nitrogen, phosphorus, potassium, calcium, magnesium and carbonate. By "microelements" is meant in particular silica, iron, selenium, manganese, molybdenum, zinc, copper and cobalt in the form of salts soluble in the culture medium. The culture medium can also be aerated with air enriched with carbon dioxide, in order to potentiate photosynthesis and improve the production of coccoliths or frustules. In addition, the culture medium can also be lit by natural or artificial lighting, in particular by the use of neon lamps or LEDs, with photoperiods ranging from 12h day / 12h night to 24h day / Oh night. The coccolithophorids and the diatoms collected can be incorporated as such in the cosmetic compositions according to the invention. Such incorporation will make it possible to obtain cosmetic compositions comprising biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures present in the native state.

After harvesting coccolithophorids and diatoms, coccoliths and released frustules can be purified by any suitable technique. Coccoliths and purified diatoms can be incorporated into a cosmetic composition. Such incorporation will make it possible to obtain cosmetic compositions comprising biomineral compounds selected from the group comprising coccoliths, frustules or their mixtures present in the purified state.

The cosmetic composition can comprise between 0.1% and 10%, preferably between 0.5% and 3%, of said biomineral compounds in the purified state by total weight of the composition. Alternatively, the composition may comprise 1% or 2.5% of said biomineral compounds in the purified state by total weight of the composition.

The cosmetic composition also comprises an acceptable cosmetic medium. Said acceptable cosmetic medium is preferably an aqueous medium, very preferentially water.

The cosmetic composition can also comprise additional cosmetic compounds, in particular cosmetic compounds chosen from the group consisting of thickening agents, surfactants, oils, pigments, dyes, perfumes, and combinations thereof.

In a second aspect, the present invention relates to the use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for the protection of the skin against UV radiation.

The present invention also relates to the use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for the protection of the viability of skin cells during exposure to UV radiation. .

The present invention also relates to the use of biomineral compounds selected from the group consisting of coccoliths, frustules or mixtures thereof, as well as the compositions comprising them, for the protection of the skin against inflammation induced by the expression of cyclooxygenase- 2 (COX-2).

The present invention also relates to the use of biomineral compounds selected from the group consisting of coccoliths, frustules or mixtures thereof, as well as the compositions comprising them, for the protection of the skin against an increased secretion of interleukin-8 ( IL8).

The present invention also relates to the use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for improving the texture of the skin, in particular by filling the grooves of the surface microdepression network, fine lines, wrinkles and other crevices on the surface of the skin.

The present invention also relates to the use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for accentuating the radiance and / or the luminosity of the skin. .

5. Description of the figures

FIG. 1 is a graph relating to the demonstration of the protective effect of coccoliths and of diatoms against the decrease in cell viability induced by exposure to UV radiation.

FIG. 2 are photographs relating to the demonstration of the protective effect of coccoliths against the increase in the expression of cyclooxygenase-2 induced by exposure to UV radiation.

FIG. 3 is a graph relating to the demonstration of the protective effect of coccoliths and of diatoms against the synthesis of interleukin-8 induced by exposure to UV radiation.

Figure 4 is a graph showing the effect of coccoliths and diatoms on the Haze index.

Figures 5A, 5B and 5C are photographs of skin explants observed by light microscopy (magnification xl2.5) at different times.

FIGS. 6A and 6B are photographs of explants of skin observed by light microscopy (magnification x40), and FIGS. 6C and 6D represent the corresponding graphs in superimposition of gray variation as a function of distance (pixels).

Figures 7A and 7B are photographs of skin explants observed by light microscopy (x40 magnification), and Figures 7C and 7D show the graphs corresponding to the pixels as a function of the gray level.

Figures 8A, 8B and 8C are photographs of skin explants viewed by light microscopy (magnification xl2.5).

6. Description of detailed embodiments of the invention

Biocineral compounds called coccoliths (raw material)

The coccoliths are obtained as follows: the coccolithophorids are cultured in photobioreactors, then the media containing the cells and the coccoliths produced are harvested. The cells are discarded and the coccoliths are purified by a membrane technique, using a selected porosity filter.

Biomineral compounds called frustules (raw material)

The frustules are obtained as follows: the diatoms are cultured in photobioreactors, then the media containing the cells and the coccoliths produced are harvested. The cells are discarded and the frustules are purified by physical and chemical treatment (Ethanol, NaOCl).

Cosmetic compositions tested

The following formulations were prepared:

"Basic cream" or "placebo cream" including '

Compounds INCIUE % (by total weight of the composition) Demineralized Water Aqua 62.55 Propylene glycol 1.2 USP Propylene glycol 5.00 Carbopol Ultrez 10 Carbomer 0.30 Carbopol EDT 2020 Acrylates / C 10-30 alkyl Acrylate crosspolymer 0.10 Lanette N Cetearyl alcohol Sodium cetearyl sulphate 5.00 Nacol 22-98 Behenic alcohol 0.80 Crodamol GTCC / Miglyol 812 / Waglinol Triglycerides caprilic / capric 10.00 Arlamol HD Isohexadecane 14.00 Phenoxy ethanol Phenoxy ethanol 0.80 Silicone 100CS) Dimethicone 1.00

Soda (5N solution) Aqua Sodium hydroxide 0.45 "1% coccolit cream the »comprising base cream 99% and purified Coccoliths 1%;

"1% diatom frustule cream" comprising base cream 99% and purified diatom frustules 1%;

“Aqueous composition 1% coccoliths” comprising demineralized water 99% and purified coccoliths 1%;

“2.5% coccolith aqueous composition” comprising 97.5% demineralized water and 2.5% purified coccoliths;

“1% diatom aqueous composition” comprising demineralized water 99% and purified diatom frustules 1%;

“2.5% diatom aqueous composition” comprising 97.5% demineralized water and 2.5% purified diatom frustules.

Skin explants (raw material)

The tests described below were carried out on the basis of tests carried out on skin explants obtained from an abdominal plasty performed on a Caucasian woman.

Applications of cosmetic compositions on explanted skin

For tests 1 to 9, the cosmetic compositions listed above were applied as follows: they were applied directly to the surface of the skin (20 μL / explants) using a plunger pipette and then spread with a small brush to evenly cover the suspension.

For tests 10 to 13, the cosmetic compositions “Aqueous composition 1% coccoliths” were applied as follows: they were applied directly to the surface of the skin (10 μl / explants) using a micropipette, the explants are stored for 30 minutes to allow the water to evaporate, then spread with a small brush to evenly cover the suspension.

Test 1 - Cell viability test (methodology)

The effect of the “2.5% coccolith aqueous composition” and the “2.5% diatom aqueous composition” on the cellular viability of a skin explant was tested by the MTT method. In this method, the reagent used is the tetrazolium salt MTT (3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide). The tetrazolium ring it contains is reduced, by the mitochondrial succinate dehydrogenase of active living cells, to formazan. This forms a precipitate in the purple mitochondrion. The amount of precipitate formed is proportional to the amount of living cells (but also to the metabolic activity of each cell). It is therefore sufficient after incubating the cells with MTT for a certain time at 37 ° C. (approximately three hours) to dissolve the cells, their mitochondria and therefore the purple Formazan precipitates in 100% DMSO. A simple assay of the optical density at 550 nm by spectroscopy makes it possible to know the relative quantity of living cells and metabolically active, in comparison with an untreated explant and not exposed to UV radiation (negative control) and an explant subjected to a UV radiation equivalent to 50J UVA and 500MJ UVB (positive control). The skin explants treated with the 2.5% coccolith and 2.5% diatom aqueous compositions were also subjected to UV radiation equivalent to 50J UVA and 500MJ UVB. Cell viability has been correlated with the measurement of optical density.

Test 2 - Cell viability test (results)

The results are shown in Figure 1.

The positive control has a reduction in cell vialibity of 23% compared to the negative control (untreated explant and not subjected to UV radiation).

This cell viability test demonstrates the efficacy of a cosmetic composition comprising coccoliths, the “2.5% coccolithic aqueous composition” allowing a limitation of the reduction in cell viability of the order of 21%, in comparison with with the positive control.

This cell viability test also demonstrates the effectiveness of a cosmetic composition comprising diatoms, the “2.5% diatom aqueous composition” allowing a reduction in the reduction of cell viability of the order of 13%, in comparison with 'with the positive control.

Test 3 - Cyclooxygenase-2 expression test (methodology)

Human skin explants were treated with or without the cream to be tested and then they were exposed or not to UVA + UVB irradiation. The conditions were as follows:

an untreated explant not exposed to UV radiation (negative control), an untreated explant subjected to UV radiation equivalent to 3 J / cm ² UVA and 1000 mJ / cm ² UVB (positive control 1), an non explant -treated subjected to UV radiation equivalent to 4 J / cm ² UVA and 1500 mJ / cm ² UVB (positive control 2), an explant treated with “1% coccolith cream” then subjected to UV radiation equivalent to 3 J / cm ² UVA and 1000 mJ / cm ² UVB (test 1) an explant treated with “1% coccolith cream” then subjected to UV radiation equivalent to 4 J / cm ² UVA and 1500 mJ / cm ² UVB (test 2) .

After the treatments and any irradiations, the explants were incubated for 24 hours in an incubator at 37 ° C, then fixed in 4% formaldehyde. The explants were embedded in paraffin and then fine sections were obtained using a microtome. Finally, the detection of COX-2 was carried out by immunohistochemical labeling using a rat monoclonal antibody specific for human COX-2 (supplied by the company Ventana). After a colorimetric revelation, observations were made, photographs were taken, and an image analysis was made.

Test 4 - Cyclooxygenase-2 expression test (results)

The results are shown in Figure 2.

UVA + UVB irradiation increases the expression of COX-2. This test thus demonstrates that the expression of cyclooxygenase-2 is significantly reduced in the explants treated with the “1% coccolith cream” after exposure to UV radiation equivalent to 3 J / cm ² UVA and 1000 mJ / cm ² UVB ( test 1) in comparison with the exposed untreated explants (positive control 1).

This test also demonstrates that the expression of cyclooxygenase-2 is significantly reduced in the explants treated with the “1% coccolith cream” after exposure to UV radiation equivalent to 4 mJ / cm ² UVA and 1500 mJ / cm ² UVB ( test 2) in comparison with the exposed untreated explants (positive control 2).

Test 5 - Interleukin 8 synthesis test (methodology)

Human skin explants were treated with or without the cream to be tested and then they were exposed or not to UVA + UVB irradiation. The conditions were as follows:

an untreated explant not exposed to UV radiation (negative control), an untreated explant subjected to UV radiation equivalent to 50J / cm ² UVA and 500 mJ / cm ² UVB (positive control), an explant treated with the “1% coccolith aqueous composition” then subjected to UV radiation equivalent to 50J / cm ² UVA and 500 mJ / cm ² UVB. an explant treated with the “1% diatom aqueous composition” and then subjected to UV radiation equivalent to 50J / cm ² UVA and 500 mJ / cm ² UVB.

The explants were placed at 37 ° C for 24 hours, then the explant incubation media were collected after 24 hours of incubation. Interleukin-8 (IU8) was measured in the media by the enzyme-linked immunosorbent assay (ELISA) method, literally "enzyme linked immunoabsorption assay", i.e. - enzymatic on self support). The IL-8 assay was carried out using a commercial assay kit, and following the supplier's recommendations (R&D Systems). The level of interleukin 8 synthesis was correlated with the measurement of interleukin 8 concentration (pg / mL).

Test 6 - Interleukin 8 synthesis test (results)

The results are shown in Figure 3.

The positive control shows an increase in the synthesis of interleukin 8 by 21% compared to the negative control (explant untreated and not subject to UV radiation).

This test demonstrates the effectiveness of a cosmetic composition comprising coccoliths, the aqueous composition 1% coccoliths allowing a limitation of the increase in the synthesis of interleukin 8 of the order of 6%, in comparison with control. positive.

This test demonstrates the effectiveness of a cosmetic composition comprising frustules, the “1% diatom aqueous composition” allowing a limitation of the increase in the synthesis of interleukin 8 of the order of 7%, in comparison with the positive control.

Test 7 - Haze index test (methodology)

A layer with a thickness of 10 μm is deposited on glass slides, the BTDF spectrum (for Bidirectional Transmittance Distribution Functiori) has been measured. Transmission measurement (BTDF) allows the evaluation of direct light scattering. The technical aspect consists of a collimated beam of light (without divergence) injected into the measurement system at normal incidence. A thin layer of cosmetics is placed on a glass plate placed perpendicular to the light beam. The measurement is normalized by a second measurement without cosmetics on the same glass plate. The products are applied to black plastic sample holders. A circular impression with a depth of 1mm is made. The product is then spread over the impression and leveled off with a spatula. The result is a very uniform layer, thick enough to avoid the effects of the substrate.

The effect of the "1% coccolith cream" and the "1% diatom cream" on the increase in the Haze index has been tested, in comparison with the placebo cream (negative control). The Haze index of the compositions tested was then calculated by separately evaluating the light intensity scattered and the intensity transmitted through the sample.

Test 9 - Haze index test (results)

The results are shown in Figure 4.

The placebo cream (without biomineral compound) has a Haze index of 62.29 in lumi. Fa “1% coccolith cream” and “1% diatom cream” have a significantly higher Haze index, namely a Haze index of 79.69 and

76.52. This test demonstrates the effectiveness of a cosmetic composition comprising coccoliths, frustules or their combination to diffuse UV radiation.

Test 10 - Observation of the surface microdepression network between non-treated skin and treated skin

The results are presented in Figures 5A, 5B and 5C.

A first photograph (magnification xl2.5) is taken before application of the cosmetic composition on bare skin (cf. FIG. 5A - t = 0), then a second 30 minutes after application (cf. FIG. 5B - t = 30min), then a third after spreading said composition with a brush (cf. FIG. 5C). After applying the said composition (cf. FIG. 5B), a deposit was observed which was highly reflective with respect to visible light, the dispersion of which was rather heterogeneous. After spreading with a brush (cf. FIG. 5C), the composition - and therefore the reflective deposit observed - was more homogeneous.

Test 11 - Study of the filling effect

A bare skin explant was compared (cf. FIG. 6A - magnification x40, t = 30 min) and an explant of skin treated after spreading (cf. FIG. 6B - magnification x40, t = 30 min), in order to observe the filling effect - or smoothing effect - of the surface microdepression network of the cosmetic composition. The filling effect observed demonstrates an improvement in the texture of the skin, and therefore a smoothing effect. The smoothing effect is measured by image processing thanks to a study of the gray variation (cf. the corresponding graphic representations of the gray variations, FIGS. 6C and 6D). The yellow lines affixed on the photographs represent the profile analyzed. The decrease in microroughness is reflected here by a decrease in the variation of the gray level. The analysis of bare skin shows variations between 55 and 140, ie an amplitude on the order of 85. The treated skin shows variations between 65 and 135, ie an amplitude of the variation in gray.

Test 12 - Study of the blurring effect and the complexion

A bare skin explant (cf. FIG. 7A - x40 magnification, t = 30 min) and a treated skin explant after spreading (cf. FIG. 7B - x40 magnification, t = 30 min) was compared, in order to observe the blurry effect and radiance of the complexion. An analysis of the gray level distribution was also carried out. This analysis makes it possible to determine a blurring or soft-focus effect. The gray level distribution is represented as a Gaussian. The larger the Gaussian, the greater the standard deviation. The latter represents the dispersion around the average. A reduction in standard deviation is associated with a reduction in contrast and therefore a greater soft-focus effect. The application of the cosmetic composition allows a significant reduction in the width of the gaussian of about 12% which makes it possible to "measure" a slight blurring effect.

More generally, the skin appears more luminous, in particular following the application of the cosmetic composition. This observation is confirmed by the analysis of the variation of the "average value" of the Gaussian (84.7 bare skin versus 89.6 treated skin) (cf. the corresponding graphical representations of the gray variations, Figures 7C and 7D). This corresponds to overexposure of the photo and therefore the appearance of lighter pixels. This observation suggests an improvement in the condition of the complexion in the face.

Test 13 - Stability study

The comparison of the photos at t = 30 minutes (cf. figure 8A - magnification xl2.5), t = 4 hours (cf. figure 8B - magnification xl2.5) and t = 8 hours (cf. figure 8C - magnification xl2, 5) after application of the cosmetic composition does not show any significant differences. The cosmetic composition therefore has very good stability over time.

Claims (12)

1. A cosmetic composition comprising biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, and an acceptable cosmetic medium. 2. The composition according to claim 1, said composition being a topical cosmetic composition. 3. The composition according to one of the preceding claims, characterized in that said biomineral compounds are present in the purified state, in the native state or their combination. 4. The composition according to one of the preceding claims, characterized in that it comprises between 0.1% and 10% of said biomineral compounds in the purified state by total weight of said composition. 5. The composition according to one of the preceding claims, characterized in that the acceptable cosmetic medium is water. 6. The composition according to one of the preceding claims, characterized in that it comprises additional cosmetic compounds. 7. Use of biomineral compounds selected from the group comprising coccoliths, frustules or their mixtures, as well as the compositions comprising them, for the protection of the skin against UV radiation. 8. Use of biomineral compounds selected from the group consisting of coccoliths, frustules or mixtures thereof, as well as the compositions comprising them, for the protection of the viability of skin cells during exposure to UV radiation. 9. Use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for the protection of the skin against inflammation induced by the expression of cyclooxygenase-2. 10. Use of biomineral compounds selected from the group consisting of coccoliths, frustules or mixtures thereof, as well as the compositions comprising them, for the protection of the skin against increased secretion of interleukin-8. 11. Use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for improving the texture of the skin. 12. Use of biomineral compounds selected from the group consisting of coccoliths, frustules or their mixtures, as well as the compositions comprising them, for accentuating the radiance and / or the luminosity of the skin. UV test on Coccoiithes and diatoms Σ3 TO Φ CO Φ ffl> O (enbijdo ejisuea ι i iai