FR3072290A1 - OIL-IN-WATER EMULSION BASED ON ESSENTIAL OILS AND FORMULATED WITHOUT SURFACTANTS - Google Patents

Abstract

The present invention relates to the field of oil-in-water emulsions and more particularly proposes oil-in-water emulsions containing essential oils and formulated without surfactant or any other substitute substance.

Description

OIL-IN-WATER EMULSION BASED ON ESSENTIAL OILS AND FORMULATED WITHOUT SURFACTANT

The present invention relates to the field of oil-in-water emulsions and more particularly provides oil-in-water emulsions based on essential oils formulated without surfactant or any other substitute substance.

PRIOR ART

The preparation of emulsions without surfactant has been a subject of interest in the fields of cosmetics and pharmacopoeia for many years. Most of the solutions proposed to date relate to the use of particular substances, not classified as surfactants, but whose role in formulation is to compensate for the absence thereof. The patent US6,416,748 proposes for example the use of a crosslinked polymer of at least one ethylenically unsaturated monomer, while the patent FR2750327 proposes to use a crosslinked and neutralized poly (2-acrylamido 2-methylpropane sulfonic acid) . These solutions are thus based on the use of large molecules, which stabilize the emulsion by the structuring they impose on their environment. The patents FR2722116 and FR2720644, for their part, provide examples of the use of solid particles which ensure the dispersion of one of the two phases in the other. These particles also have the advantage of offering more advantageous product textures for the consumer. Other solutions are proposed by patents CA2295533 and FR2771293, which respectively describe the use of a cationic gel and a lipophilic agent whose HLB (hydrophilic / lipophilic balance) is less than 3. The stability of the preparations produced is then provided by the structuring that these compounds allow at the hydrophilic / lipophilic interface.

Regarding essential oil preparations in particular, there are currently three dosage forms potentially without surfactants in order to vectorize them:

- Dispersions or emulsions containing alcohol;

- Dispersions in oils;

- Emulsions containing soaps.

Direct dispersion in water or any other aqueous solution is not possible without the use of special technologies.

ADVANTAGES OF THE INVENTION

It appears from the state of the prior art that there are currently no proposals allowing the preparation of emulsified products containing no substance, of any kind, to ensure its stability. In addition, the texture of products containing essential oils offered so far is not satisfactory. It would be interesting to propose a new galenic, allowing to have products with a more pleasant texture, without oily sticky effect on application, with a soft feel and which dry quickly on the skin.

Thus, the invention relates to very simple compositions, consisting of an emulsion of an essential oil in an aqueous solution, this aqueous solution preferably being a hydrosol. Remarkably, these compositions are stable in the absence of any surfactant molecule and pleasant to use. These compositions containing only essential oils and an aqueous phase constitute a new and innovative dosage form.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to novel short and simple dosage formulations of essential oils (HE) for use in aromatherapy. These formulations constitute stable emulsions of HE in an aqueous solution without the addition of surfactant. Such emulsions can be obtained for example using the process using high frequency ultrasound, as described in patent application WO2010 / 149668.

A first object of the invention therefore relates to a composition of the oil-in-water emulsion type comprising an aqueous solution and at least one HE, this composition containing no surfactant.

Within the meaning of the invention, the compositions do not contain a surfactant, an emulsifier, or any other substance or particle intended to stabilize the preparation with respect to phase separation.

The nature of the aqueous solution used to prepare the emulsion can be diverse. It is preferably an aqueous solution containing plant extracts, in particular a hydrosol, an infusion or a maceration of plants, or a fruit water. In a preferred embodiment, the aqueous solution is a hydrosol, pure or diluted, or a mixture of hydrosols.

The amount of HE contained in the compositions must be adapted so that the finished products can be used directly, for example in topical application, without presenting a risk for the users (irritations, itching, or even burns caused by HE in overdose). Thus, the proportion of HE contained in the compositions is generally less than 3%, for example 1%, 1.5%, 2% or 2.5%. Preferably, the amount of HE will be 2%.

In the compositions of the invention, the oily phase is provided only by the HE, to the exclusion of any other vegetable oil.

In a particular embodiment, the invention relates to compositions consisting of an emulsion of one or more HE in one or more aqueous solutions, in particular in one or more hydrosols.

In another particular embodiment, the composition contains a hydrosol and an HE from the same plant. This embodiment is particularly interesting because it makes it possible to propose an integral preparation of the plant bringing together all the components extracted from the plant. Indeed, during the distillation of a plant one obtains on the one hand the HE and on the other hand the hydrosol (or distillation water) whose compositions are different, beyond the fact that the HE is a very concentrated extract compared to the hydrosol.

By way of example, there may be mentioned a composition comprising:

- one HE of rose and one hydrosol of rose, preferably 2% of HE of rose.

- one HE of peppermint and one hydrosol of peppermint, preferably 2% of HE of peppermint

- one lavender HE and one lavender hydrosol, preferably 2% lavender

- one HE of tea tree and one hydrosol of tea tree, preferably 2% of HE of tea tree.

In these compositions, hydrosol and HE may be the only ingredients.

In other embodiments, emulsions can be obtained from a mixture of aqueous solutions and / or a mixture of HE or from emulsions mixed together.

Emulsions containing aqueous solution and HE, excluding any texturing agent, are liquid. In order to facilitate handling and use, gelling agents can be added without this altering the emulsion, in particular its properties.

Thus, the compositions according to the invention can contain gelling agents, preferably of natural origin, such as xanthan gum or alginates.

The addition of gelling agents respects the naturalness and purity of the product and makes it possible to obtain a creamier and more pleasant texture when applied to the skin. The texture of the composition will depend on the amount of gelling agent added.

To obtain a lotion-type composition with a liquid appearance, the proportion of gelling agent will generally be less than 0.1%, preferably absent from the composition.

To obtain a milk-type composition, of flowing appearance but not sprayable, the proportion of gelling agent will generally be between 0.1% and 0.8% of the composition.

To obtain a gel-type composition, of non-flowing appearance, the proportion of gelling agent will generally be between 0.8% and 2% of the composition.

To obtain a composition of poultice or mask type, with a thick and creamy appearance, the proportion of gelling agent will generally be between 2% and 5% of the composition.

The texture being dependent on the temperature, these indications correspond to the appearance of the compositions at room temperature, that is to say at a temperature of approximately 20 ° C., and generally between 15 ° C. and 27 ° C.

The gelling agents are added after emulsification according to the desired texture.

On the other hand, moisturizers, preferably of natural origin, can be added to the composition, for example glycerin.

When moisturizers are added, their proportion is generally between 2% and 10% of the composition.

In general, the hydrating agents can be added before or after emulsification; however, if the agents are hydrophobic, they will be added before emulsification.

It is also possible to add, if necessary, an acidity corrector to adjust the pH of the composition as close as possible to that of the skin. This acidity corrector can be added either during the process or at the end of the process.

It should be noted that the compositions according to the invention do not contain a preservative. They are protected against microbial development due to the presence of HE in the composition.

The advantages of the compositions of the invention are numerous.

Due to their simple formulation, these compositions are natural and healthy and they present less allergen risk. The compositions can be 100% organic.

They also have other very interesting properties. The inventors have in fact shown that the activity of the active principles is preserved in emulsified compositions without surfactant and that the effectiveness of the compositions (without surfactant) is higher than that of products with surfactants, in equivalent proportion of active ingredients.

Finally, these compositions are stable. Their stability is ensured by method, in particular and preferably by means of an ultrasonic treatment whose vibration frequency is greater than or equal to 1 MHz, as described in patent WO2010 / 149668. Their stability at room temperature is observed for at least 3 months and up to more than 12 months.

The compositions according to the invention are compositions for topical use usable in humans or animals.

In a particular embodiment, the aqueous solution of the composition is water and ΙΉΕ is a mixture of HE of katafray, HE of rosemary with camphor, HE of lemon eucalyptus and HE of juniper common. An example of such a composition is described in Example 1; it has the effect of causing heating after topical application. Such a composition is in the form of a lotion preparatory to muscular effort.

Thus, a second object of the invention relates to the use of a composition containing an oil-in-water emulsion based on a mixture of HE of katafray, rosemary with camphor, lemon eucalyptus and common juniper as a preparatory lotion for muscular effort.

FIGURES

FIGURE 1: presents a comparison of warming on skin when applying composition A (without surfactant; curve marked with squares) with composition A-TS (with surfactant; curve marked with circles).

EXAMPLES

EXAMPLE 1 Characteristics of an oil-in-water emulsion type product comprising essential oils and devoid of surfactant

at. Composition of the product "preparation for exercise": composition A

Composition A is prepared using the process described in the application

WO2010 / 149668 and defined below:

ingredients Percentage in composition Demineralized Water 50 Rosemary to camphor hydrosol 45 xanthan 2 Katafray essential oil 0.79 Rosemary camphor essential oil 0.76 Lemon eucalyptus essential oil 0.73 Common juniper essential oil 0.72

Table 1: Ingredients of the composition "preparation for exercise"

An A-TS composition was prepared using the same process and using the same ingredients as for composition A, except that 1% of Twin 80 is added, as a surfactant.

b. Measurement of the heating effect of the product "preparation for exercise"

In order to evaluate the heating effect of composition A, it was applied to the arm of healthy subjects. The test was carried out as follows:

1) A defined area of the subject's arm was identified and cleaned (with soap, then rinsed and dried). The application surface corresponds to approximately 9 cm ² , i.e. a square of 3 cm side).

2) The temperature on the marked area was measured using an infrared thermometer.

3) 10 mg of the product to be tested were applied to the area.

4) The temperature was measured immediately, then again at regular intervals (at least every minute) for 15 min.

The protocol was repeated on three people and the data were averaged. The result is presented in Figure 1 (curve A).

The graph shows an increase in temperature during the first 5 minutes after application, to reach a maximum corresponding to an increase in temperature of 2.2 ° C. The temperature then gradually decreases, remaining still one degree higher than the temperature in the area before application.

These results show the effectiveness of composition A in inducing heating in the skin and therefore also in the muscle underlying the zone tested. Such a composition can therefore be used as a preparation product for muscular effort, by topical application to the muscles which will be used.

vs. Comparison of the efficacy of composition A with that of an A-TS composition containing surfactants

In order to evaluate the effectiveness of the formulation without surfactant, a comparative study was carried out using in parallel a product having the same components as composition A and prepared with the same process but to which surfactants were added; this composition is called composition A-TS.

FIG. 1 represents the increase in temperatures obtained after topical application of these two compositions. While composition A allows a temperature increase of more than 2 ° C (as described in the previous paragraph), composition A-TS (curve A-TS) induces a very limited rise in temperature, generally less than 0.5 ° C.

These results clearly show that composition A formulated without surfactant is more effective in causing heating, than composition A-TS comprising a surfactant, while these two compositions have the same proportion of active ingredients. A better activity of the active ingredients is therefore observed in a formulation without surfactant compared to the same dose of active ingredients in the presence of surfactant. This observation highlights the fact that a formulation without surfactant allows better bioavailability of the active ingredients.

EXAMPLE 2 Formulation of an integral gel of peppermint

A preparation of integral peppermint gel according to the invention can be obtained from the following ingredients:

ingredients Amount (%) Peppermint hydrosol 98,00 HE peppermint 2.00

Table 2: Composition of an integral gel of peppermint

The two ingredients are emulsified under high frequency vibration, as described in patent application WO2010 / 149668. The pH of the preparation is then adjusted to 7, if necessary. A texturizer can optionally be added to the emulsion in order to obtain a less liquid texture and easier to apply. It is also possible to add to this composition, without modifying the properties of interest, a preservative and an antioxidant in respective proportions making it possible to ensure the non-degradation of the product over time.

Remarkably and similar to the observations of Example 1, a stable equivalent product (prepared without treatment by high frequency vibration) cannot be obtained without the addition of surfactant. In addition, a product prepared with the same protocol but also containing a surfactant will have less effectiveness.

The product according to the invention can be used directly for conventional applications of peppermint essential oil (headache, digestion, etc.). In topical use, it does not require additional dilution. In particular, no dilution in an oil is necessary. The touch of the product is completely aqueous and its application therefore leaves no unpleasant feeling of stickiness and fat.

EXAMPLE 3 Formulation of an integral lavender gel

A preparation of integral lavender gel according to the invention can be obtained from the following ingredients:

ingredients Amount (%) Fine lavender hydrosol 98,00 HE lavender aspic 2.00

Table 3: composition of an integral lavender gel

The two ingredients are emulsified under high frequency vibration, as described in patent application WO2010 / 149668. The pH of the preparation is then adjusted to 7, if necessary. A texturizer can optionally be added to the emulsion in order to obtain a less liquid texture and easier to apply. It is also possible to add to this formula, without modifying the properties of interest, a preservative and an antioxidant in respective proportions to ensure the non-degradation of the product over time.

Remarkably and similar to the observations of the preceding Examples, a stable equivalent product (prepared without treatment by high frequency vibration) cannot be obtained without the addition of surfactant. In addition, a product prepared with the same protocol but also containing a surfactant will have less effectiveness.

The product according to the invention can be used directly for conventional applications of lavender aspic essential oil (burns, insect bites, etc.). In topical use, it does not require additional dilution. In particular, no dilution in an oil is necessary. The touch of the product is completely aqueous and its application therefore leaves no unpleasant feeling of stickiness and fat.

EXAMPLE 4 Formulation of an Integral Tea Tree Gel

A preparation of integral tea tree gel according to the invention can be obtained from the following ingredients:

ingredients Amount (%) Tea tree hydrosol 98,00 HE tea tree 2.00

Table 4: Composition of an integral tea tree gel

The two ingredients are emulsified under high frequency vibration, as described in patent application WO2010 / 149668. The pH of the preparation is then adjusted to 7, if necessary. A texturizer can optionally be added to the emulsion in order to obtain a less liquid texture and easier to apply. It is also possible to add to this formula, without modifying the properties of interest, a preservative and an antioxidant in respective proportions to ensure the non-degradation of the product over time.

Remarkably and similar to the observations of the previous examples, a stable equivalent product (prepared without treatment by high frequency vibration) cannot be obtained without the addition of surfactant. In addition, a product prepared with the same protocol but also containing a surfactant will have less effectiveness.

The product according to the invention can be used directly for conventional applications of tea tree essential oil (sore throat, acne, antiseptic, etc.). In topical use, it does not require additional dilution. In particular, no dilution in an oil is necessary. The touch of the product is completely aqueous and its application therefore leaves no unpleasant feeling of stickiness and fat.

Claims (10)

1. Composition of oil-in-water emulsion type comprising an aqueous solution and at least one essential oil, characterized in that this composition does not contain a surfactant. 2. Composition according to claim 1, in which said aqueous solution is a hydrosol, a plant infusion or a fruit water. 3. Composition according to claim 2, in which the hydrosol and the essential oil come from the same plant. 4. Composition according to one of the preceding claims, further comprising a gelling agent. 5. Composition according to one of the preceding claims, in which the aqueous solution is water and the essential oils are a mixture of HE of katafray, rosemary with camphor, lemon eucalyptus and common juniper. 6. Use of a composition according to claim 5 for heating the muscles before exercise. 7. Composition according to one of claims 1 to 4 comprising between 1 and 2.5% of essential oil and a hydrosol. 8. Composition according to one of claims 1 to 4 or 7 comprising essential oil of peppermint and a hydrosol of peppermint. 9. Composition according to one of claims 1 to 4 or 7 comprising lavender essential oil and a lavender hydrosol. 10. Composition according to one of claims 1 to 4 or 7 comprising essential oil of tea tree and a hydrosol of tea tree.