WO2015090871A1

WO2015090871A1 - A photoprotective personal care composition

Info

Publication number: WO2015090871A1
Application number: PCT/EP2014/075677
Authority: WO
Inventors: Shanthi APPAVOO; Lalitha Balakrishnan; Balu Kunjupillai; Praful Gulab Rao LAHORKAR; Rajkumar PERUMAL; Ashish Anant Vaidya
Original assignee: Unilever N.V.; Unilever Plc; Conopco, Inc., D/B/A Unilever
Priority date: 2013-12-20
Filing date: 2014-11-26
Publication date: 2015-06-25

Abstract

The invention relates to a photoprotective personal care composition and a method for providing enhanced stability of the UV-A sunscreen present therein. The invention more particularly relates to photostabilising a dibenzoylmethane sunscreen in a cosmetic composition by including therfein, rosmarinic acid ester.

Description

A Photoprotective Personal Care Composition Field of the invention

The invention relates to a photoprotective personal care composition that provides enhanced stability of the UV-A sunscreen present therein.

Background of the invention

Solar radiation includes ultraviolet (UV) radiation which causes various problems like reddening of the skin, localized irritation, sunburn, melanoma and formation of wrinkles. Therefore, it is desirable to protect the skin and other keratinous substrates of the human body from the harmful effects of both UV-A and UV-B radiation.

Traditionally, high amounts of organic UVA and UVB sunscreen compounds are included in personal care compositions to achieve sun protection. When UVA sunscreen of the dibenzoylmethane group is present, it is found that this is unstable when exposed to UV radiation especially when used along with a UV-B sunscreen. The present inventors have been able to obtain high stability of this UV-A sunscreen by including a rosmarinic acid ester in such compositions.

US5952391 relates to use of flavone derivatives and flavanone derivatives, in particular flavonoids for stabilizing cosmetic or dermatologically acceptable substances, the chemical formula of which includes the structural moiety of dibenzoylmethane, against the decomposition caused by UV radiation. The present invention utilises an ester of a phenolic compound and is not a flavone or flavanone derivative. JP2007-070291 relates to a sun screen composition comprising one or more of an antioxidant such as vitamin C, its derivatives and salts, vitamin Es, their derivatives and salts, dibutylhydroxytoluene and butylhydroxyanisole, and a UV sunscreen selected from one or more of a cinnamic acid, a benzophenone, a benzoic acid, a salicylic acid, a dibenzoylmethane, an anthranilic acid, an urocanic acid based compound with a basil (Ocimum basilicum) extract. It is thus an object of the present invention to provide for higher stability of the UVA sunscreen of the dibenzoylmethane group in a photoprotective personal care composition.

It is yet another object of the present invention to provide for stability of the

dibenzoylmethe group in a personal care especially when a UVB sunscreen of the cinnamic acid group is present therein.

Summary of the invention

An aspect of the present invention provides for photoprotective personal

composition comprising

(i) 0.1 to 10% by weight dibenzoylmethane or its derivative;

(ii) 0.02 to 5% by weight a rosmarinic acid ester of the formula:

where R-i is a linear or branched aliphatic hydrocarbon having 3 to 24 carbon atoms; and

(iii) a cosmetically acceptable base.

Another aspect of the present invention provides for a method of photostabilising a dibenzoylmethane sunscreen in a composition comprising 0.1 to 10% by weight dibenzoylmethane or its derivative and a cosmetically acceptable base by including therein 0.02 to 5% by weight of the composition a rosmarinic acid ester of the formula:

Where Ri is a linear or branched aliphatic hydrocarbon having 3 to 24 carbon atoms. Detailed Description of the invention

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

By "Photoprotective personal care composition" as used herein, is meant to include a composition for topical application to sun-exposed areas of the skin and/or hair of mammals, especially humans. Such a composition may be generally classified as leave-on or rinse off, and includes any product applied to a human body for also improving appearance, cleansing, odor control or general aesthetics. It is more preferably a leave-on product. The composition of the present invention can be in the form of a liquid, lotion, cream, foam, scrub, gel, or toner, or applied with an implement or via a face mask, pad or patch. Non-limiting examples of such compositions include leave-on skin lotions, creams, antiperspirants, deodorants, lipsticks, foundations, mascara, sunless tanners and sunscreen lotions. "Skin" as used herein is meant to include skin on the face and body (e.g., neck, chest, back, arms, underarms, hands, legs, buttocks and scalp) and especially to the sun exposed parts thereof. The composition of the invention is also of relevance to applications on any other keratinous substrates of the human body other than skin e.g. hair where products may be formulated with specific aim of providing photoprotection.

An advantage of the present invention is that inclusion of the sunscreen stabilizer rosmarinic acid ester ensures that the UV-A sunscreen does not get degraded in the presence of UV radiation thereby providing UV-protection for long period of time to the substrate of interest.

By a photostable composition, as per this invention, is meant a composition (that includes the stabilizer rosmarinic acid ester) that exhibits at least 20% higher absolute concentration of UVA sunscreen of the dibenzoylmethane group with respect to a composition where rosmarinic acid ester is not included, after one hour of exposure to simulated solar radiation. In a preferred aspect, the compositions exhibit at least 30% higher absolute concentration of UVA sunscreen of the dibenzoylmethane group with respect to a composition where rosmarinic acid ester is not included, after one hour of exposure to simulated solar radiation. It is particularly preferred that compositions as per the invention exhibit an absolute UVA concentration of at least 60%, preferably at least 65%, further more preferably at least 70% and optimally at least 80% after one hour of irradiation. The photoprotective personal care composition as per this invention is thus targeted to preparing a photostable composition. The protocol to determine photostability are similar to the one used to measure the % photostability of Example - 8 and 9. The protocol is outlined below.

Thin film transmittance measurements were done using SPF-290S SPF meter (Optometries Corporation), 70 mm roughened PMMA plate 6 μηη roughness (from Schonberg GmbH & Co) and was used in this study. The % transmittance of the various compositions was measured using a procedure as outlined below. 2 mg/cm² of sample was applied on the PMMA plate, distributed using a syringe, and spread uniformly. Using Para film as a fingercot, the sample was spread on the PMMA plate uniformly swiping alternately, vertically and horizontally as per the protocol provided by the instrument manufacturer. The drying time for the PMMA plates was 30 minutes. After the drying time, sample plates were exposed and transmittance scan was done. This scan gives the transmittance as a function of wavelength (290 - 400 nm) for a given sample. For a single plate six different spots were scanned. The same procedure was repeated for other 3 plates. The data reported is thus an average over 18 readings. The reference transmittance scan was obtained using a blank plate with no sample on the PMMA plate with glycerine spread on it. The transmittance values were used to arrive at the SPF values using the Win SPF software provided with the instrument. Same plate was exposed to Atlas solar simulated radiations (UVA flux, 5.5 mW/cm²) using a Xenon lamp. The lamp has a radiation range from 185 nm to 2000 nm and has peak intensity between 280 nm and 1 100 nm. The % Transmittance (& SPF) was measured after 60 minutes of radiation exposure. Average absorbance at 310 & 355 nm was recorded to measure %UVA photostability.

The photoprotective personal care composition of the invention comprises UV-A sunscreen dibenzoylmethane or its derivative; a sunscreen stabliser which is the rosmarinic acid ester compound and a cosmetically acceptable base.

The composition of the invention comprises a UV- A sunscreen which is a

dibenzoylmethane or its derivatives. Preferred dibenzoylmethane derivatives are selected from 4-tert-butyl-4'-methoxydibenzoylmethane, 2-methyldibenzoylmethane, 4- methyl-dibenzoylmethane, 4-isopropyldibenzoyl-methane, 4-tert- butyldibenzoylmethane, 2,4-dimethyldibenzoylmethane, 2,5- dimethyldibenzoylmethane, 4,4'-diisopropyl-dibenzoylmethane, 2-methyl-5-isopropyl-4'- methoxydibenzoylmethane, 2-methyl-5-tert-butyl-4'-methoxy-dibenzoyl methane, 2,4- dimethyl-4'- methoxy dibenzoylmethane or 2,6-dimethyl-4-tert-butyl-4'-methoxy- dibenzoylmethane. The most preferred dibenzoylmethane derivative is 4-tert.-butyl-4'- methoxydibenzoylmethane. The composition of the invention comprises 0.1 to 10%, preferably 0.2 to 5%, further more preferably 0.4 to 3%, by weight dibenzoylmethane or a derivative thereof based on total weight of the composition and including all ranges subsumed therein.

Rosmarinic acid has the chemical formula:

The ester of rosmarinic acid has the formula

Where Ri is a linear or branched aliphatic hydrocarbon having 3 to 24 carbon atoms, preferably 5 to 20 carbon atoms, more preferably 8 to 18 carbon atoms and still more preferably 8 to 12 carbon atoms.

When Ri is a hydrocarbon with 8 carbon atoms the ester is the ethyl hexyl ester of rosmarinc acid, which is a preferred stabiliser as per the invention, it has a structure:

The rosmarinic acid ester is present in the composition in a concentration of 0.02 to 5%, preferably 0.03 to 4%, more preferably 0.03 to 3%, even more preferably 0.03 to 2%, still more preferably 0.05 to 2% or even 0.5 to 1 % by weight of the composition.

The composition preferably comprises a UV-B organic sunscreen selected from the class of cinnamic acid, salicylic acid, diphenyl acrylic acid and derivatives thereof. Illustrative non-limiting example of UV-B sunscreens which are commercially available and useful for inclusion in the composition of the invention are Octisalate™,

Homosalate™, NeoHelipan™, Octocrylene™, Oxybenzone™ or Parsol MCX™. The UV-B sunscreen is most preferably 2-ethyl-hexyl-4-methoxy cinnamate which is commercially available as Parsol MCX. The UV-B organic sunscreen is preferably included in 0.1 to 10%, more preferably 0.1 to 7 % by weight of the composition. It has been observed that presence of an organic UV-B sunscreen like 2-ethyl-hexyl-4- methoxy cinnamate causes further rapid degradation of the UV-A dibenzoylmethane sunscreen in the presence of UV radiation. The presence of the rosmarinic acid ester compound is found to be very efficacious in stabilizing the composition even when UV- B sunscreens are present.

The composition of the invention comprises a cosmetically acceptable base. The cosmetically acceptable base preferably comprises a fatty acid or a silicone compound. When the cosmetically acceptable base comprises fatty acid it is preferably present in 1 to 25% by weight of the composition. When the cosmetically acceptable bases are such as to have a product in a cream, lotion, or emulsion format, it generally comprises fatty acid. Of these formats, a more preferred format is a cream or lotion, further more preferably a cream. Vanishing cream base is one which comprises 3 to 25%, more preferably 5 to 20% fatty acid, which is a preferred format of the composition of the invention. In this, the base preferably comprises 0.1 to 10%, more preferably 0.1 to 3% soap. Ci2 to C₂o fatty acids are especially preferred in vanishing cream bases, further more preferred being C14 to Ci₈ fatty acids. In creams, the fatty acid is preferably substantially a mixture of stearic acid and palmitic acid. Soaps in the vanishing cream base include alkali metal salt of fatty acids, like sodium or potassium salts The soap is preferably the potassium salt of the fatty acid mixture. The fatty acid in vanishing cream base is often prepared using hystric acid which is substantially (generally about 90 to 95%) a mixture of stearic acid and palmitic acid (usually 55% stearic acid and 45% palmitic acid). Thus, inclusion of hystric acid and its soap to prepare the vanishing cream base is within the scope of the present invention. It is particularly preferred that the composition comprises at least 6%, preferably at least 10%, more preferably at least 12% fatty acid. The cosmetically acceptable base is usually from 10 to 99.9%, preferably from 50 to 99% by weight of the composition. Another preferred base is a lotion. Lotions generally comprise 1 to 20% fatty acid. The cosmetically acceptable base preferably includes water. Water is preferably included in 35 to 90%, more preferably 50 to 85%, further more preferably 50 to 80% by weight of the composition.

An especially suitable cosmetically acceptable base is one which comprises a water-in- oil emulsion comprising silicone oils as the continuous phase. The water in oil emulsions preferably comprise a crosslinked silicone elastomer blend.

Inclusion of silicone elastomer blend in a water-in-oil emulsion may be used as the cosmetically acceptable base for preparing the compositions of the present invention. While silicone fluids may be used, silicone elastomers which are cross-linked, are especially preferred. The creation of cross-linkages between linear polymers, such as dimethicone, converts the linear polymer into a silicone elastomer. In contrast to silicone fluid polymers, the physical properties of elastomers are typically dependent on the number of cross-linkages, rather than molecular weight. The ability of silicone elastomers to swell makes them ideal thickeners for oil phases. The elastomers have a very smooth and soft feel when applied to skin or hair. They can also be used as delivery agents for fragrances, vitamins and other additives in cosmetic compositions.

Suitable silicone elastomer blends or gels which are commercially available and suitable for inclusion in the composition of the invention and found to provide the enhanced stability are: Dow Corning® EL-8051 IN Silicone Organic Elastomer Blend [INCI Name: Isodecyl Neopentanoate (and) Dimethicone/Bis Isobutyl PPG-20

Crosspolymer]; EL-8050 [INCI Name: Isododecane (and) Dimethicone/Bis-lsobutyl PPG 20 Crosspolymer] DC 9040, DC9041 , DC9045 (Dimethicone crosspolymer); DC 9506, 9509 (Dimethicone vinyl dimethicone crosspolymer); Shin-Etsu KSG-15, KSG- 16, KSG-17 (Dimethicone vinyl dimethicone crosspolymer). It is further preferred that the composition comprises 5 to 50% silicone elastomer by weight of the composition.

Other useful sun-protective agents e.g. inorganic sun-blocks may be preferably used in the present invention. These include, for example, zinc oxide, iron oxide, silica, such as fumed silica, or titanium dioxide. The total amount of sun block that is preferably incorporated in the composition according to the invention is from 0.1 to 5% by weight of the composition. The composition of the invention may additionally comprise a skin lightening agent. The skin lightening agent is preferably chosen from a vitamin B3 compound or its derivative e.g. niacin, nicotinic acid, niacinamide or other well known skin lightening agents e.g. aloe extract, ammonium lactate, azelaic acid, kojic acid, citrate esters, ellagic acid, glycolic acid, green tea extract, hydroquinone, lemon extract, linoleic acid, magnesium ascorbyl phosphate, vitamins like vitamin B6, vitamin B12, vitamin C, vitamin A, a dicarboxylic acid, resorcinol derivatives, hydroxycarboxylic acid like lactic acid and their salts e.g. sodium lactate, and mixtures thereof. Vitamin B3 compound or its derivative e.g. niacin, nicotinic acid, niacinamide are the more preferred skin lightening agent as per the invention, most preferred being niacinamide. Niacinamide, when used, is preferably present in an amount in the range of 0.1 to 10%, more preferably 0.2 to 5% by weight of the composition. The composition according to the invention may also comprise other diluents. The diluents act as a dispersant or carrier for other materials present in the composition, so as to facilitate their distribution when the composition is applied to the skin. Diluents other than water can include liquid or solid emollients, solvents, humectants, thickeners and powders.

The composition of the invention may comprise a conventional deodourant base as the cosmetically acceptable carrier. By a deodorant is meant a product in the stick, roll-on, or propellant medium which is used for personal deodorant benefit e.g. application in the under-arm or any other area which may or may not contain anti-perspirant actives.

Deodorant compositions can generally be in the form of firm solids, soft solids, gels, creams, and liquids and are dispensed using applicators appropriate to the physical characteristics of the composition.

The compositions of the present invention can comprise a wide range of other optional components. The CTFA Cosmetic Ingredient Handbook, Second Edition, 1992, which is incorporated by reference herein in its entirety, describes a wide variety of non- limiting cosmetic and pharmaceutical ingredients commonly used in the skin care industry, which are suitable for use in the compositions of the present invention.

Examples include: antioxidants, binders, biological additives, buffering agents, colorants, thickeners, polymers, astringents, fragrance, humectants, opacifying agents, conditioners, exfoliating agents, pH adjusters, preservatives, natural extracts, essential oils, skin sensates, skin soothing agents, and skin healing agents.

Rosmarinic acid ester may be synthetically prepared for use in the present invention. The rosmarinic acid ester may be prepared by the process comprising the steps of: (i) suspending rosmarinic acid (1 equivalent) in a suitable alcohol (chosen according to the desired ester to be prepared) at 0 C in an ice bath; (ii) adding thionyl chloride (2 equivalents) slowly to the mixture; (iii) stirring the mixture for 8 hours under N₂ gas until excess alcohol and thionyl chloride have evaporated; and (iv) purifying the crude product by column chromatography. According to yet another aspect of the present invention there is provided a method of photostabilising a dibenzoylmethane sunscreen in a composition comprising 0.1 to 10% by weight dibenzoylmethane or its derivative and a cosmetically acceptable base by including therein 0.02 to 5% by weight of the composition rosmarinic acid or an ester thereof of the formula:

Where R-i is a linear or branched aliphatic hydrocarbon having 3 to 24 carbon atoms Examples

Example E, 8-9: Photostability of compositions comprising ester of rosmarinic acid Compositions as shown in Table - 5 were prepared as shown below. They were then stored for 24 hours at room temperature (25 °C) in opaque containers in a dark storage compartment. Thereafter, the compositions were studied for photostability using the following procedure:

Thin film transmittance measurements were done using SPF-290S SPF meter (Optometries Corporation), 70 mm roughened PMMA plate 6 μηη roughness (from Schonberg GmbH & Co) and was used in this study. The % transmittance of the various compositions was measured using a procedure as outlined below. 2 mg/cm² of sample was applied on the PMMA plate, distributed using a syringe, and spread uniformly. Using Para film as a fingercot, the sample was spread on the PMMA plate uniformly swiping alternately, vertically and horizontally as per the protocol provided by the instrument manufacturer. The drying time for the PMMA plates was 30 minutes. After the drying time, sample plates were exposed and transmittance scan was done. This scan gives the transmittance as a function of wavelength (290 - 400 nm) for a given sample. For a single plate six different spots were scanned. The same procedure was repeated for other 3 plates. The data reported is thus an average over 18 readings. The reference transmittance scan was obtained using a blank plate with no sample on the PMMA plate with glycerine spread on it. The transmittance values were used to arrive at the SPF values using the Win SPF software provided with the instrument. Same plate was exposed to Atlas solar simulated radiations (UVA flux, 5.5 mW/cm²) using a Xenon lamp. The lamp has a radiation range from 185 nm to 2000 nm and has peak intensity between 280 nm and 1 100 nm. The % Transmittance (& SPF) was measured after 30, 60 and 120 minutes of UV exposure. Average absorbance at 310 & 355 nm was recorded to measure %UVA photostability as shown in Table 6.

Table- 5

Ingredient Example E, Example 8, Example 9,

wt% wt% Wt%

Hystric acid 17.00 17.00 17.00

Cetyl alcohol 0.53 0.53 0.53

Isopropyl myristate 0.75 0.75 0.75

Brij 35 3.00 3.00 3.00

Parsol 1789 1.20 1.20 1.20

Parsol MCX 2.40 2.40 -

Ethyl hexyl ester 3.00 3.00

of rosmarinic acid, wt%

Acuyln 22 1.00 1.00 1.00

Aculyn 33 0.50 0.50 0.50

Phenoxy ethanol 0.20 0.20 0.20

Glycerine 1.00 1.00 1.00

Potassium hydroxide (85%) 0.57 0.57 0.57

Dimethicone 0.5 0.5 0.5

Water To 100 To 100 To 100 Table - 6

Data in Table 5 and 6 indicates that ester of rosmarinic acid is also highly effective as a sunscreen stabilizer by the examples 8 and 9 exhibiting higher than 20% UVA concentration as compared to Example E after one hour of irradiation.

Example F, 10: Comparison of compositions comprising rosmarinic acid and rosmarinic acid ester on storage stability

The data summarized in Table-7 shows the inferior performance of rosmarinic acid when used in a composition when compared to the rosmarinic acid ester of the present invention.

Table-7

The above table indicates that a composition which is stable on storage and with desired characteristics such as colour, smoothness etc is not obtained with rosmarinic acid in the composition.

Claims

A photoprotective personal care composition comprising

(i) 0.1 to 10% by weight dibenzoylmethane or its derivative;

(ii) 0.02 to 5% by weight a rosmarinic acid ester of the formula

(iii) a cosmetically acceptable base.

2. A composition as claimed in any one of the preceding claims additionally comprising a UV-B organic sunscreen selected from the group consisting of cinnamic acid, salicylic acid, diphenyl acrylic acid and derivatives thereof.

3. A composition as claimed in claim 2 wherein said UV-B sunscreen is 2- ethyl-hexyl-4-methoxy cinnamate.

4. A composition as claimed in claims 2 or 3 wherein said UVB organic

sunscreen is present in 1 to 10% by weight of the composition.

5. A composition as claimed in any one of the preceding claims wherein said cosmetically acceptable base comprises a fatty acid or a silicone compound.

6. A composition as claimed in claim 5 comprising 1 to 25 % by weight fatty acid. A composition as claimed in any one of the preceding claims wherein the cosmetically acceptable base comprises 0.1 to 10% by weight soap.

A method of photostabilising a dibenzoylmethane sunscreen in a composition comprising 0.1 to 10% by weight dibenzoylmethane or its derivative and a cosmetically acceptable base by including therein 0.02 to 5% by weight of the composition a rosmarinic acid ester of the formula:

where Ri is a linear or branched aliphatic hydrocarbon having 3 to 24 carbon atoms.