FR2640136A1 - Cosmetic composition having skin-lightening activity, based on the complex of hydroquinone [HQ] and 2,6-dimethyl- beta -cyclodextrin [DIMEB] - Google Patents

Abstract

Cosmetic composition having skin-lightening activity, comprising the complex of hydroquinone [HQ] and 2,6-dimethyl- beta -cyclodextrin [DIMEB]. The cosmetic preparations possess better stability in relation to dyeing due to oxidation of the hydroquinone, and a depigmenting effect superior to the effect produced by cosmetic preparations containing the same amount of hydroquinone. The cosmetic preparation can be a cream or a gel, for application to human skin.

Description

COSMETIC COMPOSITION WITH ECIAIRCISSANT SKIN ACTIVITY. MADE OF
HYDROQUINONE COMPLEX AND 2.6 DIMETHYL-ss-CYCLODEXTRIN.

DESCRIPTION OF THE INVENTION
Hydroquinone complex (bed) and 2.6 dimethYl-p-cyclodextrin (DIMEB).

 Numerous scientific studies concerning molecules complexed with DIMEB have shown that complexation promotes their percutaneous absorption and contributes to better regulation of their bioavailability. Therefore, better efficacy should be obtained with a lower dose.

 Other studies have shown that this type of complexation protects molecules sensitive to oxidation and or photosensitive.

(SANETO UEKAMA AND TETSUMI IRIE
Pharmaceutical Applications of Methylated Cyclodextrin Derivatives pp 393-44l in CYCLODEXTRINS IN THE INDUSTRIAL USE
Health Ed. - Paris, 1987)
The well-known efficacy of hydroquinone on the inhibition of melanogenesis means that it represents the molecule of choice for cosmetic skin lightening preparations. Unfortunately, the effective dose for the inhibition of melanogenesis is very close to the toxic dose of melanocytes with the consecutive undesirable effects.

 For all these reasons, the formation of an HQ-DIMEB complex would be entirely desirable.

The first indication of complex formation is based on the following observation
A - In a saturated aqueous solution of DIMEB (57% at 250C) we
add the crystals with hydroquinone with stirring and
shore to solubilize hydroquinone at a rate of 46.5% (the
solubility of HQ in water at 250C is 7.14%). The melan
ge is kept in solution at 40C for 8 days. We don't get
serve then no coloring of the solution which means
the absence of oxidation of hydroquinone.

Since the aqueous solution is already saturated with DIMEB,
the solubilization of HQ crystals can only be due to
the formation of a complex.

B - For the needs of our cosmetic formulation and following
te many tests, we adopted the following conditions
In 6 ml of water at room temperature, with stirring, 1.6 g of DIMEB are dissolved. Heating is started, and, still with stirring, 2.0 g of crystal HQ are added. At 450C the whole quantity of HQ is dissolved and remains in solution if the mixture returns to ambient temperature. This mixture is used for 100 g of HQ-D cream.

 A drop of this mixture, evaporated on a watch glass and observed under the microscope has characteristic crystals.

- The complexation of HQ with DIMEB is demonstrated by spec
NMR troscopy (Nuclear Magnetic Resonance). Specters
solutions A and B as well as those of the HQ and DIMEB molecules
are shown in Figures 1, 2, 3, 4 respectively.

- The ratio of HQ / DIMEB surfaces shows that it has approximately
Mixture A: 4.4 moles HQ / 1 mole DIMEB. Mix B: 6.3 moles
HQ / 1 mole DIMEB.

NMR spectra were performed in the Professor's department
M. PLAT. Therapeutic Chemistry Laboratory. PARIS-SUD UNIVERSITY
FACULTY OF PHARMACY, CiIATENAY-MALABRY.

FORMULATION EXAMPLES WITH THE EIQ-DIMEB COMPLEX
HQ-D CREAM
RAW MATERIALS
A - Glyceryl Stearate and PEG-100 Stearate 9.00
Polyoxyethylene (20) Stearyl etller 2.00
PEG - (5) - Stearyl stearate 2.00
Shea Butter 2.50
Octyl-methoxycinnamate 2.50
DL-oC-tocopherol (acetate) 0.20
Isopropyl palmitate 3.00
Polydimethylsiloxane 1500 ................. 1500 0.20 B - Demineralized water b 61.50
Propylene glycol ............................... glycol 4.00
1,1 'methylene - bis (3- (3- (hydroxymethyl) -2.4
dioxo - 5 - imidazolidinyl)) urea ............ 0.40
Sorbic acid ...............................

Disodium salt of ethylenediamine tetra acid
acetic ...................................... 0.10 Hydroxyethyl cellulose QP 300 .... ............. 0.80
C - Demineralized water ......................... 6.00
2.6 dimethyl-p-cyclodextrin (DIMI: B) ......... 1.60
Hydroquinone ................................. 2.00
D - Perfume .................................... 0.30
POE - (45) - Castor oil ................... castor 0.30
E - Sodium metabisulfite ....................... Sodium 0.40 Demineralized water E 1.00
PROCEDURE Bring the fatty phase A to 750C, add the antifoam 1500 disper
dried in hot isopropyl palmitate (750C) and mix well.

- At room temperature mix all the ingredients of the phase
aqueous B and with vigorous stirring disperse the cellulose. Continue
agitation for 30 minutes. Heat. At 750C the mixture must
be clear and transparent.

- With strong stirring, add B in A. Continue stirring pen
for 15 minutes.

 - Examine the emulsion under a microscope - Cool with slow stirring and at 500C add drop by drop.

Preparation of C: At room temperature, with stirring, set
be 2,6 dimethyl-B-cyclodextrin in solution in water. Com
start heating and still stirring, add the hydroqui-
none which must dissolve completely. Do not exceed 50 C.

- At 300C, add D. The perfume is emulsified beforehand in the
POE - (45) - castor oil (clear mixture).

- At 250C add E which must be put into solution extemporaneously.

- Continue slow agitation for 30 minutes, - This formula has been tested for its stability at 400C for 3 months.

- This formula has been tested IN VIVO for its inhibitory efficacy
melanogenesis on mouse of C3H / OUJ strain.

HQ-D GEL
RAW MATERIALS
A - Demineralized water 57.00
1,1'-methylene-bis (3- (3- (hydroxymethyl) -2,4-
dioxo-5-imidazolidinyl)) urea ................ ure 0.30
Disodium salt of ethylenediamine tetra acid
acetic 0.10
Hexylene glycol .............................. glycol 15.00
Propylene glycol ............................. glycol 12.00 Sorbic acid ............. ................. sorbic 0 rlO
Hydroxyethyl cellulose QP 300 ............... 2.80
B - Demineralized water 6.00
2.6 dimethyl-B-cyclodextrin (DIMEB) 1.60
Hydroquinone 2.00
C -Propylene glycol ............................ glycol 3.00
Butyl Hydroxy Anisol (BHA) 0.05
Mono Tertiary-Butylhydroquinone (TBHQ). 0.05
PROCEDURE: - At room temperature, mix all the ingredients of the phase
A, and, with moderate stirring, disperse the cellulose.

Continue slow agitation for 30- minutes. Heat. At 500C
the mixture should be clear and transparent.

 Maintain the temperature at 500C.

- Preparation of B: at room temperature, with stirring, solu
mobilize DIMEB in water. Start heating and always
with stirring, add the hydroquinone which must dissolve
completely.

 Do not exceed 500C.

- Phases A and B being at 500C, with slow stirring, add
drop by drop B into A. Mix well and add C.

 The gel should be clear and transparent.

IN VIVO TEST FOR THE EFFECTIVENESS OF HQ-D CREAM ON DEPIGMENTA
TION OF THE SKIN
EXPERIMENTAL PROTOCOL
ANIMAL MATERIAL
We used C3H / OUJ strain mice. They have the particularity of having a highly pigmented tail and this particularity has been used to test the depigmentation power of our preparations intended for cosmetic use.

 -The complete formula of UQ-D cream was the main object of the first study.

CONSTITUTION OF LOTS
We made up 5 lots of 5 mice each.

 At the start of the applications, the mice weighed 25 + 1 g. At the end of the applications, the mice had a weight of 27 + 1 g.

LOT - A (placebo)
In the cream for the treatment of the placebo batch, all the ingredients of the formula HQ-D have been introduced, with the exception of hy droquinone (HQ) and of 2,6 dimethyl-p-cyclodextrin (DIMEB).

LOT - B (hydroquinone)
In the cream for the treatment of the hydroquinone batch, all the ingredients of the formula HQ-D have been introduced, with the exception of 2,6 dimethyl-B-cyclodextrin (DIMEB).

LOT - C (HQ - DIMEB)
The treatment of this batch was carried out with the complete formula
HQ-D.

LOT - D (Vega)
The treatment of this batch was carried out with a lightening cream marketed for several years and to our knowledge having a hydroquinone content 2%.

LOT -'E (witnesses)
This batch received no treatment.

METHOD OF APPLICATION AND DURATION OF APPLICATION
The mice are placed in cages, in pairs or in pairs.

For application, each group is transferred to a plastic bowl, 4 times more spacious than the cage, with the bottom lined with shavings. Using the finger cots, the product to be tested is applied in excess over the entire surface of the tail; we then apply a light massage and leave the animals for 30 minutes.

Then remove the excess product with a cellulose pad and return the animals to their cages.

 The products to be tested were applied once a day, every day1 for 31 days. After sacrifice of each animal, the skin of the tail is removed over its entire length. About 1 cm from each end is removed and the remainder is divided into three for the preparation of 3 slides.

EPIDERMIS / DERMIS SEPARATION
Sodium Bromide chemical method.

 Immerse the skin flap in a 2M aqueous solution of sodium bromide. Leave in contact for two hours at room temperature. Using pliers with rounded ends, carefully detach the epidermis from the dermis and rinse the epidermis by passing through a buffer solution pH = 7.3.

 This technique allows the separation of the epidermis and the dermis, just at the dermo-epidermal junction, without deterioration of the melanocytes.

L-DOPA - reaction
Prepare extemporaneously a solution of L-DOPA (L-3 (3 - 4 hydroxy) phenyl alanine) at 0.1 percent in a buffer (pll 7.3).

Leave in contact for about 20 minutes, protected from light.

- Immerse the epidermis in this L-DOPA solution for 30 mi
nutes at 370C.

- Renew the L-DOPA solution and leave the epidermis in contact
for two and a half hours at 37 "C.

PREPARING THE BLADES
At the end of the DOPA-reaction, rinse the epidermis by passage
in a CBS buffer solution (pH 7.3), dehydrate and degrease
by successive passages in
* 4% formaldehyde solution
* 50% ethanol
* ethanol 70%
* absolute ethanol
* toluene
Place the flap of the epidermis thus treated flat between the blade and the coverslip with a drop of polymerizing solution (EUKIT).

Place a lead weight (3x2x2) on the strip. Leave to dry for 24 hours.

MICROSCOPE READING
Under the microscope, the epidermis has strongly pigmented circular scales, regularly arranged in parallel lines and separated by non-pigmented areas. The number of melanocytes by scale was read with an enlargement factor of 150.

 For each slide, the reading was carried out on 20 different scales, ie 60 scales per mouse and 300 scales per group of animals and per product tested.

EVALUATION OF THE DEPIGMENTING ACTIVITY
Several parameters make it possible to estimate the functional capacity of melanocytes. These are - the number of melanocytes per unit area of skin, - the intermelanocytic distance, - the number of dendrites, - the length of the dendrites.

 The treatment being likely to modify the elasticity of the skin and consequently to induce errors on an estimate based on the number of melanocytes per unit of surface, we took colullte criterion the number of melanocytes per scale, which represents a well delimited entity even after treatment.

TABLE N 1
Number - of Inhibition rate of - number
melanocyte melanocytes compared
by scale to Placebo group in t
Lot - A Placebo 122.1 + 4.1
Lot - B Hydroquinone 85.4 t 5.9 30.0
Lot - C HQ - DIMEB 68.3 t 8.1 44.0
Lot - D-VEGA 82.6 + 3.5 32.3
Lot - E Witnesses 120.0 t 6.2
RESULTS AND DISCUSSION
Table 1 presents our results. We note that there was no Placebo effect, this batch having the same number of melanocytes per scale as the control batch.

 For the evaluation of the lightening power of cosmetic preparations, the number of melanocytes per shell observed in each batch is deducted from the number of melanocytes per shell in the Placebo batch and the difference expressed in percent of inhibited melanocytes.

 Quantitatively, the VEGA commercial cream produces substantially the same melanogenesis inhibiting effect as the cream prepared in our laboratories with a 2% hydroquinone content, ie 30%.

 Obviously, the complete formula HQ-D cream exerted 1 better inhibitory power on the functional capacity of melanocytes, ie 44%. This formula contains 2 z of hydroquinone complexed beforehand with 2,6 dimethyl-B-cyclodextrin.

 In this formula, as protection against indirect pigmentation, a UV-B filter, octyl methoxycinnamate is incorporated at a rate of 2.5%.

 Photos 1, 2, 3, 4 illustrate the condition of the skin after treatment of lots A, B, C, D respectively. Photo 5 was taken at the end of the treatment of the animals. The difference is visible between Placebo (A) and lots B, C, D, treated with skin lightening products.

The IN VIVO experiments were carried out in the service of
Doctor M. CESARINI. RESEARCH GROUP ON ONCOGENESIS, UL TRAVIOLETS AND HUMAN SKIN PIGMENTATION. FONDATION OPHTAL- MOLOGIQUE ADOLPHE DE ROTHSCIIILD, 25 - 29 rue Manin, PARIS.

Claims (3)

CLAIMS5 1 - Skin lightening cosmetic composition, comprising  a base containing hydroquinone and 2,6 dimethyl-9-cyclodex-  trine. 2 - Skin lightening cosmetic composition, depending on the  claim 1, characterized in that hydroquinone is  previously complexed with 2,6 dimethyl-p-cyclodextrin and  ce.complex incorporated. in a cream base. 3 - Skin lightening cosmetic composition, depending on the  claim 1, characterized in that hydroquinone is  previously complexed with 2,6 dimethyl-F-cyclodextrin  and this complex incorporated in a gel base.