EP2282717A1

EP2282717A1 - Crocus sativus depigmenting composition

Info

Publication number: EP2282717A1
Application number: EP09729132A
Authority: EP
Inventors: Jacques Leclere
Original assignee: Laboratoire Nuxe SA
Current assignee: Societe de Recherche Cosmetique SARL
Priority date: 2008-03-20
Filing date: 2009-03-19
Publication date: 2011-02-16
Also published as: FR2928835A1; WO2009122046A1; FR2928835B1

Abstract

The invention relates to a cosmetic and/or dermatological kaempferol composition. The composition includes a Crocus sativus extract, preferably a hydroalcoholic or hydroglycolic extract from Crocus sativus petals containing kaempferol. The invention can be used in the treatment of skin depigmentation.

Description

DEPIGMENTING COMPOSITION BASED ON CROCUS SATIVUS

The present invention relates to a novel composition based on kaempferol that can be used as an agent for depigmenting the epidermis, and more particularly an extract of Crocus sativus containing kaempferol, which can be used as a depigmenting agent or in a depigmenting composition.

Depigmentation of the skin may be desired under various circumstances, either for overall lightening of the skin, or to eliminate or reduce spots caused by local pigmentation disorders.

The skin has several integrated layers, ranging from the superficial layer, the epidermis (epithelial tissue), to the deeper layers, the dermis and the hypodermis (connective tissue), and each has specific properties allowing the whole to react and adapt to the conditions of its environment.

The pigmentation of the skin results from the presence of melanin in the epidermis and the dermis. Melanin is produced by melanocytes located mainly in the basal layer, in the presence of tyrosinase (or monophenol monooxygenase), a cupro-protein enzyme that catalyzes the conversion of tyrosine to dihydroxyphenylalanine (dopa) which is then converted to dopaquinone , then in dopachrome, to lead to melanin following a complex mechanism. This biosynthesis, or melanogenesis, is a complex process that is today relatively well known.

^• Under normal conditions, the pigmentation of the skin is uniform. However, hyperpigmentation is frequently observed, ie excessive pigmentation locally, which may manifest as freckles, senile lentigo, melasma, age spots, pigmentation due to excessive exposure to the sun, post-inflammatory hyperpigmentation due to abrasion, dermatitis, etc.

B1842WO The hyperpigmentation of the skin can be combated by means of a compound capable of degrading melanin, or of inhibiting the biosynthesis of melanin, or by using a tyrosinase inhibitor which blocks or inhibits the mechanism described above. Thus, hydroquinone and some of its derivatives may act by inhibiting tyrosinase and preventing the binding of its natural substrate, tyrosine. Thus, patent EP-A-060,092 describes the use of a hydroquinone and fatty acid ester, and US Pat. No. 4,692,261 describes a depigmenting composition containing hydroquinone, an anionic detergent and a stabilizer. Hydroquinone-based combinations are also known, such as, for example, the combination of hydroquinone and salicylic acid described in patent FR-A-2,754,253. However, hydroquinone has the disadvantage of a high toxicity causing side effects such as irritation of the skin.

Other depigmenting substances have been proposed, and for example melatonin derivatives as in FR 2,751,535, salicylic acid derivatives as in FR 2,732,594, extracts of plants of the genus Mitrapyrus such as in patent FR 2 751 874, or kojic acid esters having a lightening action on the skin, as described in FR 2,460,131. However, the acid. Kojica is unstable in solution and its use in dermatology is delicate. In addition, the salts and esters of kojic acid often have an allergenic effect. Glycyrrhiza extracts containing substances such as glabridin have also been used to inhibit the production of melanin by dermal cells by blocking the tyrosinase used in its synthesis, and depigmenting compositions containing glabridin have been proposed as in FR 2,822,067.

Despite the existing methods and compositions, there is an increased need in cosmetology to develop alternative methods for the treatment of pigmentation. and, therefore, to identify compounds having depigmenting properties, including topical compositions based on plant extracts that may have depigmenting effects. Kaempferol is a flavonoid derived from flavonol, represented by the general formula below.

Kaempferol has been isolated from plants such as tea, broccoli and several acacia flowers that owe their yellow color. It is at room temperature in the form of a yellow crystalline solid, poorly soluble in water, melting point F = 276-278 ^° C.

Various properties of kaempferol have been described, in particular antioxidant properties, as well as anti-inflammatory properties by inhibiting the formation of nitric oxide NO (M. Hamalainen et al., "Mediators of inflammation" Hindawi Publ. 2007, ID45673). The patent application WO 02/49580 describes compositions for the treatment of hyperpigmentation of the skin, comprising a depigmenting agent chosen from 3,3'-thiodipropionic acid, thiazolidine-2-carboxylic acid, kaempferol- 7-glucoside, perilla oil and clofibrate and its analogues and / or derivatives. These properties are confirmed by I. Kubo et al., Bioorg. Med. Chem. , 8 (7): 1749-1755 (2000), who have shown that certain flavonols and kaempferol also possess tyrosinase inhibitory activity, derived from their ability to chelate the enzyme tyrosinase. However, kaempferol gives the compositions which contain it a yellow color which prevents its use in cosmetic or dermatological compositions intended for the depigmentation of the skin. In addition, kaempferol is very slightly soluble in water, which further limits its use in cosmetic compositions.

Studies have shown that flower petals of the genus Crocus, including the species C. sativus, contain kaempferol. Crocuses, many of which are grown as fall flowering ornamental flowers, are found in parts of Asia and southern Europe from Iran to Spain. The species Crocus sativus is known for the production of saffron obtained from the dried stigmas of the flower.

The studies carried out by the applicant have unexpectedly shown that extracts of Crocus sativus containing kaempferol derivatives have a good depigmenting activity devoid of side effects, without causing coloration of the composition, unlike kaempferol alone. Thus, while the addition of kaempferol in a composition causes a yellow coloration which renders it unusable in cosmetics, extracts of Crocus sativus can be effectively used in cosmetology and dermatology for depigmentation of the skin. In addition, the kaempferol derivatives present in the extract, more particularly the kaempferol glycosides, are soluble in water, while retaining an excellent depigmenting effect. In what follows, the term "kaempferol" is used to designate derivatives with depigmenting or lightening action, in particular glycosides.

The subject of the present invention is therefore a novel composition comprising an extract of Crocus sativus containing kaempferol, more particularly a kaempferol derivative, which can be used as a depigmenting agent in cosmetology and in dermatology.

The subject of the invention is also a novel use of an extract of Crocus sativus containing kaempferol for the preparation of a cosmetic and / or dermatological composition intended to inhibit the pigmentation of the skin. The subject of the invention is also the use of an extract of Crocus sativus as a depigmenting agent

The invention also relates to a new topical composition specially adapted for such use, comprising an extract of Crocus sativus in a concentration adapted to the desired effect.

The subject of the invention is also a method for depigmenting the skin, comprising applying to the exposed areas a composition comprising an extract of Crocus sativus containing kaempferol.

According to the present invention, the Crocus sativus extract is preferably obtained from white flower petals.

The literature in the cosmetic field evokes, depending on the case, lightening properties or depigmenting properties for the skin. In the context of the present invention, the depigmenting properties comprise, in addition to the properties making it possible to fight against hyperpigmentation, also these lightening properties.

The composition of the invention contains an extract of Crocus sativus, and it is preferably an extract of Crocus sativus petals, and more particularly of a hydroalcoholic or, preferably, a glycolic acid extract.

A hydroalcoholic extract is generally in the form of a liquid characterized by:

- dry matter about 4%

- density 0.892

- T.A. approx. 70% vol.

refractive index (at 22 ° C) 1,368

- flavonoid content 1.88%

- pH: 6.0 The extract according to the invention may represent between 0.1 to 20% by weight relative to the total weight of the composition, preferably between 2 and 10%. The content of flavonoids is expressed as a percentage of the dry matter. The hydroalcoholic extract used in the invention has the advantage of having a relatively high content of flavonoids, mainly flavonols and flavanols, and a good aptitude for storage over time, under normal conditions of temperature and humidity, preferably protected from light. It contains in particular kaempferol glycoside. It can be prepared from fresh, finely divided flowers, by. maceration with stirring for several days in ethyl alcohol, at a rate of about 100 g of flowers to 1 1 of alcohol.

The extract thus prepared can be used as it is or decolorized with activated charcoal.

According to the invention, it is advantageous to supplement the lightening and depigmenting action of kaempferol by adding to the composition substances having a depigmenting effect such as arbutin, glabridin, skullcap, vitamin C (ascorbic acid) or kojic acid, as well as their derivatives such as salts and esters, or an anti-pigmenting agent such as a saxifrage extract which reduces melanin.

Ultraviolet protection agents may also advantageously be incorporated in the compositions, and for example hydrophilic or lipophilic UV-A and UV-B sunscreens, chosen from benzophenone or a benzophenone derivative such as 2-hydroxybenzophenone. 4-methoxybenzophenone (Eusolex® 4350), or a cinnamic acid ester and more particularly octyl methoxycinnamate (Eusolex® 2292), methoxycinnamate d ¹ ethyl-2-hexyl (Parsol MCX®), or a cyano-β, β-diphenylacrylate such as octo-crylene (Eusolex® OCR) and dibenzoylmethane derivatives such as 4-isopropyl dibenzoylmethane (Eusolex 8020), t-butyl-methoxy dibenzoylmethane (Parsol 1789®), and 4-methoxy-dibenzoylmethane. It is also possible to use anti-ultraviolet screen pigments, such as, for example, dioxide titanium, zinc oxide, zirconium oxide or aluminum oxide.

The compositions in accordance with the present invention may be presented in the forms conventionally used for a topical application, that is to say in the form of an aqueous or aqueous-alcoholic solution, of a gel, lotion, emulsion (in particular cream or milk), stick for the lips, mask, ointment, serum, transdermal patches, nanocapsules or liposomes containing compatible and pharmaceutically acceptable excipients and common carriers. They can also be in the form of wipes soaked with a solution containing the extract of petals of Crocus sativus. These forms of topical administration are prepared by the known techniques, and for example, in the case of a cream, by dispersion of a fatty phase in an aqueous phase to obtain an oil-in-water emulsion, or conversely to prepare a water-in-oil emulsion. In the case of creams, it is preferred to use lamellar structure emulsions containing little or no ethoxylated products.

The topical compositions according to the invention may comprise excipients suitable for external topical administration, in particular dermatologically and cosmetologically acceptable excipients. Such excipients suitable for formulation are well known to those skilled in the art and include in particular penetrating agents such as ethoxydiphenol, phytantriol, octyl dodecanol and escin; thickeners such as natural gums and synthetic polymers; emollients and surfactants such as cetearyl octanoate, isopropyl myristate, cetearyl isononanoate, dimethicone, cyclomethicone, polyglyceryl 3-diisostearate, hydrogenated polyisobutene, cetyl alcohol, cetyl palmitate cetyl phosphate, triglycerides of capric and caprylic acid; emulsifiers such as esters sorbitan, stearic or palmitic acid derivatives, sucro-esters or glucolipids of the myristyl glucoside or stearyl glucoside type; preservatives such as phenoxyethanol, methyl parahydroxybenzoate (methylparaben), ethyl parahydroxybenzoate (ethylparaben), propyl paraben (propylparaben) and Phenonip® associating phenoxyethanol and methyl, ethyl, butyl parahydroxybenzoates and isobutyl; an antimicrobial combination of a lipoamino acid, a hydroxylated fatty acid of 8 to 12 carbon atoms and a glycerin alkyl ether; dyes; the perfumes ; etc.

Non-limiting examples of compositions according to the present invention are given below. Unless otherwise indicated, percentages and parts are by weight.

Example 1 Evaluation of the depigmenting effect

The depigmentation effect was evaluated in vitro on reconstituted epidermis (Skinethic®) in coculture with human melanocytes, after control of the cytotoxicity, as indicated below.

Keratinocytes of human origin were cultured in a defined medium MCDB 153 modified) and supplemented. The cells are cultured for 10 days at the air / liquid interface, the culture medium being changed every two days.

The epidermis thus formed on polycarbonate filters (0.63 cm ² ) were co-cultured with human melanocytes. The study was carried out between the n ^th and 17 ^th days of culture.

Cytotoxicity study

The study was carried out in triplicate after 24 hours of contact with reconstituted epidermis (10 μl per cm ² ). Lot no. 1 consists of control epidermals receiving no product (negative controls). Lot 2 consists of the epidermis treated with the Crocus sativus extract according to the invention. Lot no. 3 consists of the positive control epidermises receiving kojic acid (2%) as a comparison depigmenting product.

The evaluation of cell viability was made by histological examination. The epidermis fixed in a 10% formaldehyde solution was embedded in paraffin blocks and vertical sections 4 μm thick were stained with hematoxylin / eosin (HES) and then photographed under an optical microscope.

It is found that the histological images, after HES staining of the epidermis treated with the Crocus sativus extract of the invention, are similar to those of the control epidermis.

These results show that the Crocus sativus extract according to the invention has no cytotoxic activity with respect to the endothelial cells of the epidermis, at the concentrations tested (0.072%).

Evaluation of the depigmenting effect

The evaluation of the activity of the Crocus sativus extract of the invention on cutaneous pigmentation was made by assaying melanin and tyrosinase.

This activity on pigmentation has been demonstrated by

• evaluation of tyrosinase activity

• Evaluation of melanin synthesis (qualitative study of intracellular melanin by spectrometry at 475 nm)

Three batches (negative control, invention, comparison) were prepared in the same manner as above. The reconstituted epidermis are the same as above.

Evaluation of intracellular melanin synthesis (qualitative study) was performed as indicated above by spectrometry at 475 nm after suspending the human skin cells and then dissolving in 1 N NaOH and dimethyl sulfoxide for 30 minutes.

The results are summarized in the table below.

These results show that the composition of the invention, based on extract of Crocus sativus causes a significant decrease in melanin. This decrease is lower here than the control with koic acid but it is significant from the tested dose of 0.07%.

Evaluation of tyrosinase activity

At the end of the incubation period, the culture medium was removed, then the epidermis was rinsed with PBS and brought into contact with Triton X-100 (Sigma, France) at 1% and then incubated for 10 minutes. The enzymatic reaction was initiated by the addition of L-dopamine (Sigma, France) to 10 mM in PBS devoid of Ca ²⁺ and Mg ²⁺ .

After incubation for 1 hour at 37 ^° C., protected from light, the tyrosinase activity was evaluated by measuring the absorption at 475 nm using a spectrophotometer.

The results are summarized in the table below.

These results show that the extract of Crocus sativus causes a significant decrease in the activity of the tyrosinase, although less important than that of kojic acid.

The depigmenting activity thus demonstrated of the Crocus sativus extract of the invention shows that this extract can be advantageously used in lightening and depigmenting cosmetic compositions, in the place of depigmenting agents such as kojic acid whose known disadvantages limit the use.

Because of its perfect safety, the Crocus sativus extract of the invention can therefore be used in depigmenting cosmetic and dermatological compositions.

In addition, the tests carried out have shown that the cosmetic compositions such as those described in the examples below do not exhibit an undesirable coloration related to the presence of kaempferol.

Example 2

Preparation of an extract of Crocus sativus.

100 g of fresh flowers (petals) finely divided are extracted with 1 1 of 70% organic ethyl alcohol (vol) by maceration with stirring for 7 days. Organic ethyl alcohol is obtained by natural fermentation of grains or fruits grown in organic farming and without additives after distillation.

After extraction, the product is passed and the residue is expressed by pressure or centrifugation according to conventional methods.

The two liquors thus obtained are joined and the amount is adjusted to 1 with water and ethyl alcohol at 70% vol. until you obtain the desired alcoholic strength.

A reddish-brown liquid extract is obtained which can be used as it is or decolorized by the addition of activated charcoal. Example 3

A depigmenting lotion comprising Crocus sativus extract obtained as described in Example 2 is prepared by mixing the components below in the order indicated. Lotus distilled water 10.0

Demineralized water q.s. 100.0

Ethyl alcohol 96% 20.0

Cucumber juice 10.0

Crocus sativus extract 10.0

Ascorbyl sulfate 1.0

Bulgarian rose water 10.0

This aqueous lotion can be applied directly to the skin, preferably twice a day, to provide a depigmenting effect is observed in most cases from the 2 ^nd to 4 ^th week of treatment.

Example 4

A lightening essence is prepared using the three phases A, B and C, the composition of which is given below. Phases A and C are prepared at room temperature while phase B is prepared by heating until a clear solution is obtained.

Phase A

Demineralized water q.s. 100.00

Trisodium EDTA 0.10

Benzophenone 5 0.05

Ethyl alcohol 96% 10.00

Levulinic acid 0.50

Caprylyl glycine 0.30

Butylene glycol 5.00

Xanthan Gum 0.04

Ascorbyl magnesium phosphate 0.40 Phase B

Demineralized water q.s. 10.00

Butylene glycol 3.00

Glycerin 9.00

PEG 60 hydrogenated castor oil 0.20

Polyglyceryl di-isostearate-2 0.10

Tocopherol 0.10

Shea Butter 0.05

0.05 potash

Phase C

Extract of saxifrage 0,50

Skullcap extract 1.00

Crocus sativus extract 2.00

Concentrated rosé water 5.00 Phase C, once homogenized, is added to phase B, the mixture is stirred until a homogeneous mixture, then phase A is added with stirring.

Example 5

A depigmenting cream is prepared by mixing the four phases whose compositions are given below.

Phase A

Demineralized water q.s. 100.00

Phytic acid 0.10

Dehydroacetic acid 0.10

Benzyl alcohol 0.60

Carboxy vinyl polymer 0.10

Butylene glycol 3.00

Phase B

Myristyl glucoside 1.50

Stearyl glucoside 2.50

Behenyl alcohol 1.20

Marula oil 3,00 Capric / caprylic triglyceride 3.00

Phase C

0.03 potassium hydroxide

Demineralized water 3.00

Phase D

Arbutin 2.00

Crocus sativus extract 2.00

Ascorbyl sucrose 0.50

Ethyl alcohol 96% 10.00

Isoprene glycol 5.00 The components of phase A are mixed at approximately 70 ^° C., then phase B is added with stirring at room temperature, and the mixture, after homogenization, is added with phase C at 60 ^° C. then phase D after having thoroughly mixed.

Example 6

A lightening cream is prepared by mixing the 6 phases, the compositions of which are described below.

Phase A

Perhydroqualene 5.00

Capric / caprylic triglyceride 4.00

Hydrogenated coconut oil 3,00

Cetostearyl alcohol 0,70

Jojoba Oil 1.50

Macadamia Oil 1.00

PEG 20 Sorbitan stearate 3.50

Sorbitan stearate 2.50

Dimethicone 0.75

Ascorbyl Palmitate 0.15 Phase B

Demineralized water q.s. 100.00

Dehydroacetic acid 0.15

Benzyl alcohol 0.60

Trisodium EDTA 0.10

Butylene glycol 5.00

Phase C

Carbopol 0.12

Demineralized water 10.00

Phase D

0.05 potassium hydroxide

Demineralized water 3.00

Phase E

Cocoa polyphenols 0,10

Crocus sativus extract 5.00

Demineralized water 5.00

Phase F

Fragrance 0.15 The components of phase A are mixed at approximately 80 ° C., and phase B, the components of which are mixed at 75 ^° C., the phase C at 70 ^° C., the phase D at 60 ° C., are added thereto. then phase E at 40 ^° C., and finally the perfumes are added at about 35 ^° C., to obtain a lightening cream.

Claims

1. Composition for topical use depigmenting effect, characterized in that it comprises an extract of Crocus sativus containing kaempferol.

2. Composition according to claim 1, characterized in that it comprises an extract of petals of Crocus sativus.

3. Composition according to any one of claims 1 and 2, characterized in that it comprises a hydroalcoholic or hydroglycolic extract of Crocus sativus.

4. Composition according to claim 3, characterized in that the hydroalcoholic extract is in the form of a liquid characterized by:

- dry matter about 4%

- density 0.892

- T.A. approx. 70% vol.

refractive index (at 22 ° C) 1,368

- flavonoid content 1.88%

- pH: 6, 0

5. Composition according to any one of the preceding claims, characterized in that the extract represents between 0.1 and 20% by weight relative to the total weight of the composition.

6. Use of a Crocus sativus extract containing kaempferol for the preparation of a cosmetic composition for inhibiting skin pigmentation.