AU2014101446A4 - Sunscreen formulations - Google Patents

Abstract

2014101446 A sunscreen formulation comprising one or more ultraviolet radiation (UVR) filtering agents, a rheology modifier and at least 35 % (w/w) plant oil, wherein at least 20 % (w/w) of the plant oil is coconut oil and the formulation is suitable for application to the skin at a rate of at least about 0.5 mg/cm 2.

Description

1 Field of the Invention [0001] The present invention relates to sunscreen formulations. In particular, the invention relates to sunscreen formulations comprising coconut oil. Background of the Invention [0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. [0003] The damaging effects of exposure to ultraviolet radiation (UVR) have been known for some time. There are both long-term and short-term consequences, with the effects ranging from being merely cosmetic to life-threatening. In particular, the effects of UVR on the skin include sunburn (erythema), wrinkles, freckles, sun spots, basal cell carcinoma and skin cancer. Indeed, in countries such as Australia, sunburn can occur in less than 10 minutes during summer between the hours of 10 am and 3pm. [0004] The UVR of particular concern can be divided into ultraviolet A radiation (UVA) and ultraviolet B radiation (UVB). UVA occurs at wavelengths in the range of 320-400 nm and tends to only penetrate the uppermost layers of skin. It contributes to the premature aging of the skin and causes fine lines and wrinkles. UVB is the more energetic of the two, occurring at wavelengths ranging from 280-320 nm. It penetrates the skin more deeply causing sunburn and potentially DNA damage. Both UVA and UVB are known to cause skin cancer. The UVR spectrum also includes ultraviolet radiation C (UVC) that occurs at a wavelength range of 100-280 nm. However, very little UVC reaches the Earth's surface, and therefore it is not considered to have a detrimental effect on the health and well-being of humans. [0005] Sunscreen have proven effective in reducing some of the damaging effects of UVR on the skin. There are two major groups of sunscreen ingredients: "chemical" sunscreening agents that absorb UVR, and "physical" sunscreening agents that block or reflect UVR. Both types are commonly referred to as "UVR filtering agents". Today's physical sunscreening agents tend to be based on metal oxides that create a physical barrier between the user and almost all UVR. On the other hand, many of the chemical sunscreening agents are aromatic, organic molecules, and often absorb a maximum amount of UVR across particular ranges of wavelengths. For example, the chemical 2 sunscreening agent butyl methoxy dibenzoylmethane (commonly referred to as Avobenzone) has an absorption peak at about 350 nm and absorbs UVR most effectively in the UVA range of 320-380 nm. Octocrylene has an absorption peak nearer to 300 nm and absorbs UVB effectively in a smaller range of about 290-310 nm. Chemical sunscreening agents that offer a broad spectrum of protection include bis ethylhexyloxyphenol methoxyphenol triazine (commonly known as Bemotrizinol) which has two absorption peaks at approximately 310 nm and 340 nm, and absorbs UVR effectively in the range of 290 nm-370 nm, covering the UVA and UVB spectrum. [0006] Typically, a sunscreen will comprise more than one UVR filtering agent. The effectiveness of a sunscreen is determined by its sun protection factor, or SPF, which is a measure of how well the sunscreen protects the user from UVB. The higher the SPF, the greater the level of protection. SPF is a relative value based on how long it would take for the user to sustain sunburn when wearing the sunscreen, versus how long it would take without the sunscreen. For instance, someone using a sunscreen with an SPF of 15 will take 15 times longer to sustain sunburn than without the sunscreen. [0007] Due to the rapidly expanding awareness of the damaging effects of the sun on the skin, the use of sunscreen has increased significantly, to the extent that, for example, a large portion of the Australian population wear some form of protective sunscreen on their skin almost every day. [0008] At the same time, the prolific use of sunscreens in some countries and the demand for higher SPF ratings had led to concerns about the safety of sunscreens containing high amounts of synthetic UVR filtering agents, such as oxybenzone (also known as Benzophenone 3, 2-Benzoyl-5-methoxyphenol, Uvinul M), especially when used routinely and/or for prolonged periods of time. In particular, as the UVR filtering agents may be absorbed through the skin, there is potential for the agents to also be absorbed into the blood. This is of particular relevance in light of recent controversies surrounding the use of oxybenzone in sunscreen formulations, as some evidence suggests this UVR filtering agent may influence hormone levels if present in the bloodstream. [0009] Indeed, the maximum concentration of UVR filtering agents permissible in sunscreen formulations is strictly regulated in countries such as Australia and U.S.A., 3 which is, at least in part, a measure taken to prevent any potential toxicity associated with using the chemicals at higher concentrations in formulations applied to the skin. [0010] Further, many sunscreens are solvent based, which can dry the skin with routine use, potentially contributing to premature aging. [0011] In light of the above-mentioned concerns, there is an increasing general demand for therapeutic and cosmetic products that contain naturally-occurring ingredients, and preferably have lower concentrations of synthetic UVR filtering agents than conventional sunscreen formulations. There is a perception that such products have, or are likely to have, less impact on the environment, less side-effects and/or greater efficacy than their wholly synthetic counterparts. [0012] Accordingly, there is a need for alternative sunscreen formulations that comprise natural UVR filtering agents that contribute to the overall SPF rating of the sunscreen formulation. Preferably, the formulations do not dry the skin. [0013] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. Summary of the Invention [0014] Many plant oils, including coconut oil, have UVR absorption properties, whilst also having other characteristics that are beneficial for the skin. [0015] The oil extracted from coconuts has been shown to have a UVR absorption capacity in the UVB range sufficient to generate a hypothetical SPF rating when measured using in vitro spectrophotometric methods (Kaur C.D. and Saraf S. In vitro sun protection factor determined of herbal oils used in cosmetics. Pharmacognosy Research, 2010 Jan-Feb; 2(1): 22-25). It is also a natural moisturiser that can prevent the skin from drying when exposed to wind, salt and water, and enhance the overall texture and appearance of the skin. However, coconut oil is solid at room temperature (standard coconut oil has a melting temperature of about 240C and hydrogenated coconut oil has a melting temperature of about 400C) At higher temperatures when the coconut oil forms a flowing liquid, it tends not to form stable, thick emulsions with commercially available UVR filtering agents. As a consequence of these properties, it 4 was assumed that it would be difficult to include coconut oil in effective amounts in sunscreening products. [0016] For example, because coconut oil is solid at room temperature, the percentage of coconut oil in the sunscreen cannot be too high as the product may not be suitable for application without heating. This is inconvenient and may discourage its use at cooler temperatures. It could also lead to processing and packaging issues during manufacture. Similarly, if the product is too thick, it may lead to improper and uneven application of the sunscreen, which could result in sunburn. It is also possible that such a product i.e. in which the coconut oil content is high, may not remain stable when temperatures fluctuate leading to melt/solidify cycles. Merely thinning the coconut oil with other components or oils does not provide the solution to the problems associated with high content coconut oil as high enough percentage of coconut oil must be maintained to effectively contribute to the SPF of the product, whilst also allowing the formation of stable emulsions between the oil mixture and any other ingredients in the sunscreen. [0017] The viscosity of sunscreen formulations is crucial to achieving an SPF rating, as standard SPF tests (such as those defined in the Australian regulatory guidelines for sunscreens, ISO 24443:2012) are based on a skin application rate of at least 2 mg/cm 2 . As such, merely adding high amounts of conventional UVR filtering agents to natural oils is not suitable for producing sunscreen products, as the very low viscosity of the resulting oil mixture makes it impossible to achieve a useful SPF rating using the required testing regimes. Further, the amounts of solid UVR filtering agents that would need to be added to the natural oils to achieve any significant thickening of the product was considered likely be in excess of the allowable limits. Many UVR filtering agents are also insoluble in oil, and it would be clear to the skilled addressee that attempts to combine these agents with natural oils would result in heterogeneous, poorly dispersed mixtures. This is particularly problematic as sunscreen formulations comprising natural oils would need to support a stable, homogenous dispersion of any UVR filtering agents added to the sunscreen to increase the SPF of the product, such that the UVR filtering agents can be applied to the skin evenly and allow for accurate and reproducible SPF testing. [0018] Some known sunscreen and beauty products rely on the scent of coconut to lead the consumer to believe that the product contains a high proportion of coconut oil.

5 However, these products generally comprise only a very small percentage of (less than 3%) or no coconut oil. Instead of coconut oil, or as a supplement to a very low percentage of coconut oil, they are often made using coconut extracts or essences, in combination with mineral oil and ethylhexyl palmitate. Neither mineral oil nor ethylhexyl palmitate are natural products, as they are petroleum derived chemicals. Further, such small percentages of coconut oil do not make a contribution to the SPF rating of these products. Despite the beneficial effects and sunscreening capacity of coconut oil, the reasons such products do not comprise effective amounts of coconut oil are likely related to the difficulty in formulating coconut oil with conventional sunscreen ingredients, as described above. [0019] It has been surprisingly found that coconut oil can be used to make fluid sunscreen formulations, wherein the coconut oil contributes to the SPF rating of the sunscreen. Further, the sunscreen can act as a natural moisturiser. It has also been found that additional UVR filtering agents can be stably and evenly dispersed in the composition. [0020] Accordingly, in a first aspect of the present invention, there is provided a sunscreen formulation comprising one or more ultra-violet radiation (UVR) filtering agents, a rheology modifier and at least 35 % (v/v) plant oil, wherein at least 20 % of the total plant oil is coconut oil. [0021] The sunscreen formulations of the invention are suitable for topical administration and may be in the form of a liquid, lotion, cream, serum, spray, ointment, gel, foam, or balm. [0022] It would be understood by the person skilled in the art that the formulation of the invention can also include preservatives, humectants, consistency factors, chelating agents, fragrance, active agents, excipients, diluents and colouring agents. [0023] The UVR filtering agent may be any compound that has the capacity to absorb, block or reflect UVR, wherein the UVR occurs at a wavelength within the range of about 280 nm to about 400 nm. It would be understood by the person skilled in the art that this wavelength range encompasses both the UVA and UVB wavelength range, and therefore encompasses the range of UVR that is reported to be the most damaging to the skin of humans.

6 [0024] The UVR filtering agent may predominantly absorb, block or reflect UVA or UVB, or it may be a broad spectrum UVR filtering agent that absorbs, blocks or reflects UVR occurring at wavelengths that fall within both the UVA and UVB ranges. [0025] The UVR filtering agent may be a chemical sunscreening agent or a physical sunscreening agent. The choice of UVR filtering agent or agents used in the formulation would be influenced by factors such as desired SPF rating, safety and regulatory considerations, whether the agents were liquid or solid, and the capability of the UVR filtering agent(s) to be combined with the other components to form a stable formulation. Perferably, the agent(s) are evenly dispersed throughout. [0026] In preferred embodiments, the UVR filtering agent may be a commercially available UVR filtering agent selected from the group consisting of (using the Australian Approved Names (AAN)) Bemotrizinol (Bis-ethylhexyloxyphenol methoxyphenol triazine, Bemotrizinolum, Escalol S, Tinosorb S, 10%), Benzylidene camphor sulfonic acid (alpha-(2-Oxoborn-3-ylidene)toluene-4-sulphonic acid, Meroxyl SL, 6%), Butyl methoxy dibenzoylmethane (BMDM, 4-tert-butyl-4'-methoxy dibenzoylmethane, 1-(4 tert butylphenyl)-3(4-methoxyphenyl)-propane-1,3-dione, Avobenzone, 5%), Camphor benzalkonium methosulfate (N,N,N-Trimethyl-4-(oxoborn-3-ylidenemethyl)aniinium methyl sulphate, Meroxyl SO, 6%), Cinoxate (2-Ethoxyethyl para-methoxycinnamate, 6%), Diethylamino hydroxybenzoyl hexyl benzoate (Benzoic acid, 2-[4-(diethylamino)-2 hydroxybenzoyl]-hexyl ester, Uvinul A Plus, 10%), Dioxybenzone (Benzophenone 8, 3%), Disodium phenyl dibenzimidazole tetrasulfonate (1 H-Benzimidazole-4,6-disulfonic acid,2,2'-(1,4-phenylene)bis-,disodium salt, Bisimidazylate, Neo Heliopan AP, 10%), Drometrizole trisiloxane (2-(2H-Benzotriazol-2-yl)-4-methyl-6[2-methyl-3-[1,3,3,3 tetramethyl-1-[(trimethylsilyl)oxy]-disiloxanyl]-propyl-phenol, Silatrizole, Mexoryl XL, 15%), Ecamsule (Terephthalylidene dicamphor sulfonic acid, Mexoryl SX, 10%), Homosalate (Homomenthyl salicylate, 3,3,5-Trimethylcyclohexyl 2-hydroxybenzoate, 15%), Isoamyl methoxy-cinnamate (Isoamyl p-methoxycinnamate, Isoamyl-4 methoxycinnamate, Isopentenyl-4-methoxycinnamate, Amiloxate, 10%), 4 Methylbenzylidene camphor (3-(4-Methylbenzylidene)-dl-camphor, Enzacamene, 4%), Menthyl anthranilate (Menthyl 2-aminobenzoate, 5-Methyl-2-(1 -methylethyl) cyclohexanol-2-aminobenzoate, Meradimate, 5%), Methylene bis-benzo-triazolyl tetramethyl-butylphenol (2,2'-Methylene-bis-6-(2H-benzotriazol-2yl)-4-(tetramethyl butyl)-1,1,3,3-phenol, Bisoctrizole, Tinosorb M, 10%), Octocrylene (Octocrilene, 2 cyano-3,3-diphenyl acrylic acid, 2-ethyl hexyl ester, 2- Ethylhexyl-2-cyano-3,3 7 diphenylacrylate, Uvinul N, 10%), Octyl methoxy-cinnamate (Ethylhexyl methoxycinnamate, Octinoxate, Uvinul MC, 10%), Octyl salicylate (Ethylhexyl salicylate, 2-Ethylhexyl salicylate, Octisalate, 5%), Octyl triazone (Ethylhexyl triazone, 2,4,6 Trianalino-(p-Carbo-2'-ethylhexyl-1'oxy)-1,3,5-triazine, Uvinul T, 5%), Padimate 0 (Ethylhexyl dimethyl PABA, 2-Ethylhexyl 4-dimethylaminobenzoate, Octyl dimethyl PABA, 8%), PEG-25 PABA (Ethoxylated ethyl 4-aminobenzoate, PEG25 PABA, Uvinul P, 10%), Phenylbenzimidazole sulfonic acid (-Phenylbenzimidazole-5-sulfonic acid, 2 Phenyl-5-sulfobenzimidazole, Ensulizole, 4%), Polysilicone-15 (Dimethicodiethylbenzalmalonate, Diethylbezylidene malonate dimethicone, Diethylmalonylbenzylidene oxypropene dimethicone, Parsol SLX, 10%), Sulisobenzone (Benzophenone 4, 5-Benzoyl-4-hydroxy-2-methoxybenzene sulphonic acid, Uvinul MS, 10%), Sulisobenzone sodium (Benzophenone 5, 5-Benzoyl-4-hydroxy-2 methoxybenzene sulphonic acid, sodium salt, 10%), Titanium dioxide (E171, 25%), Triethanolamine salicylate (TEA-salicylate, Trolamine salicylate, 12%), Zinc oxide (Pigment white 4, no limit) (wherein the brackets included synonyms, abbreviations, trade names, and maximum concentrations allowed in Australia). [0027] The preceding list is a compilation of UVR filtering agents approved for use in Australia and this list may change over time to exclude some compounds, while new compounds may be included. It would be understood that any compounds added to the list would also be suitable UVR filtering agents for use in the present invention. [0028] The formulation may comprise at least one UVR filtering agent that is a broad spectrum UVR filter agent. In preferred embodiments, the broad spectrum UVR filtering agent is Bemotrizinol. [0029] In preferred embodiments of the invention, the formulation may comprise one of more UVR filtering agents in a concentration of less that 10 % (w/w). More preferably, the formulation may comprise one of more UVR filtering agents in a concentration of less that 5 % (w/w). In other preferred embodiments, the formulation may comprise one of more UVR filtering agents in a concentration of less that 3 % (w/w). [0030] In other embodiments of the invention, the formulation does not comprise one or more of titanium dioxide, octyl methoxy-cinnamate and oxybenzone.

8 [0031] The rheology modifier used in the formulations of the present invention may be any compound or composition suitable for stabilising oil-in-water and water-in-oil emulsions with an appropriate viscosity for use as a sunscreen formulation, wherein the oil comprises coconut oil. By "suitable" is meant that the components in the formulation are relatively evenly dispersed, remain active and are resistant to settling, separating, sedimenting and/or precipitating out of the formulation over time. The skilled addressee would understand that a rheology modifier is essentially a compound that, when added to fluid mixtures with low viscosity increases the viscosity of the mixture and assists in the formation and maintenance of stable emulsions. [0032] The rheology modifier may comprise inorganic or organic molecules. It is preferably an organic molecule, such as an organic polymer. Two types of organic molecules that are commonly used as rheology modifiers, are cellulosics (based on natural raw materials such as plants), and synthetic molecules. The rheology modifiers used in the present invention may be either, but are preferably plant derived organic polymers. Preferably, the rheology modifier is an organic polymer that has been hydrophobically modified. [0033] More preferably, the rheology modifier is a co-polymer comprising at least bis stearyl ethylenediamine. The skilled addressee would understand that a co-polymer is any polymer comprising more than one type of monomer, and that bis-stearyl ethylenediamine is one such monomer that would be appropriate for an organic polymer with rheology modification properties. In other preferred embodiments, the organic polymer may comprise bis-stearyl ethylenediamine monomers and neopentyl glycol monomers and/or hydrogenated dilinoleic acid monomers. [0034] The percentage of each monomer in the co-polymer, as well as the length of any organic polymer for use in the formulations of the present invention, will be dependent on the desired properties of the rheology modifier. It would be understood by the person skilled in the art that the desired properties of the rheology modifier may also be influenced by the properties of other components in the sunscreen formulation: for example, whether the formulation comprised a UVR filtering agent that was a solid or liquid, and/or whether the UVR filtering agent was oil, water or solvent soluble or miscible, may influence the choice of rheology modifier. Further to this, the total oil content in the formulation may also influence the choice of rheology modifier. The 9 choice of rheology modifier may also be influenced by the required thickness of the particular sunscreen formulation. [0035] In preferred embodiments, the rheology modifier is a bis-stearyl ethylenediamine/neopentyl glycol/stearyl hydrogenated dimer dilinoleate copolymer (commonly referred to as polyamide-8, sold under the trade names SylvaclearTMC75V and OleoCraft T M LP-20). [0036] In order for a sunscreen to be effective, it needs to adequately cover the skin and the amount of a particular formulation that is able to be evenly applied to the skin may be determined by the viscosity of the formulation. For example, it is difficult to apply significant amounts of oils to the skin of a human because of their low viscosity. Accordingly, in preferred embodiments of the present invention, the formulation is suitable for application to the skin at a rate of at least about 0.5 mg/cm 2 . More preferably, the formulation is suitable for application to the skin at a rate of at least about 1 mg/cm 2 . Even more preferably, the formulation is suitable for application to the skin at a rate of at least about 2 mg/cm 2 . The person of skill in the art would understand that the application rate of at least about 2mg/cm 2 may be significant because this is the hypothetical amount of a sunscreen formulation that preferably needs to be applied to the skin of a test subject in order to achieve an SPF rating in accordance with at least ISO 24444, E.U. and Australian in vivo testing methods. [0037] The efficacy of a particular sunscreen formulation may be expressed by the SPF, which is defined as the UVR energy required to produce a minimal erythemal dose (MED; i.e., sunburn) in skin with the sunscreen applied to it, divided by the UVR energy required to produce an MED in skin without the sunscreen. The MED is defined as the lowest time interval or dosage of UVR sufficient to produce a minimal, perceptible sunburn on skin with no sunscreen. The higher the SPF, the higher the protection from UVR afforded by the sunscreen formulation. [0038] In one or more embodiment of the present invention, the sunscreen formulation has an SPF of at least 6. Preferably, the formulation has an SPF of at least 10, and more preferably, at least 15. In other preferred embodiments, the sunscreen formulation has an SPF of at least 20, at least 25 or at least 30. In other preferred embodiments, the sunscreen formulation has an SPF of at least 40 or at least 50. The SPF may be determined in accordance with the standards defined in AS/NZS 10 2604:2012, which correlates to the true SPF of the product when applied to the skin at a rate of 2 mg/cm 2 . [0039] The plant oil in the sunscreen formulations of the present invention may be any oil derived from any oil-producing plant, and may be any mixture of any number of different plant oils, provided that 20 % (w/w) of the total oil in the sunscreen formulation is coconut oil. Accordingly, the formulation comprises at least approximately 7 % (w/w) coconut oil. In preferred embodiments, the sunscreen formulations may comprise at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 95% (w/w) plant oil. In preferred embodiments of the invention, the total plant oil may comprise at least 30%, at least 40% or at least 50% (w/w) coconut oil. [0040] The plant oils used in addition to the coconut oil may be oils that have UVR absorption abilities and/or natural moisturising properties. In preferred embodiments of the invention, in addition to the coconut oil, the total plant oil comprises at least one other plant oil selected from the group consisting of olive oil, almond oil, peppermint oil, apricot kernel oil, tulsi oil, lemon grass oil, lavender oil, sunflower seed oil, macadamia oil, hemp seed oil, jojoba oil, grape seed oil, avocado oil, raspberry seed oil, citrus oil and carrot oil. The person skilled in the art would understand that by adding other oils that may have UVR absorption abilities, this may ultimately reduce the amount UVR filtering agent(s) that need to be added to the sunscreen formulation to achieve a particular SPF rating. [0041] In preferred embodiments of the invention, in addition to the coconut oil, the total plant oil comprises at least one oil selected from the group consisting of apricot kernel oil, grape seed oil and sunflower seed oil. In further preferred embodiments, the total plant oil comprises at least one oil selected from the group consisting of apricot kernel oil, grape seed oil and sunflower seed oil at a concentration of at least 10% (w/w), or more preferably, at least 20 % (w/w). [0042] The plant oils used in the formulations of the present invention may be extracted from the plants by various methods, including, but not limited to distillation, pressing, cold-pressing, abrasion, expeller pressing, solvent extraction, maceration, refinement and supercritical carbon dioxide extraction. It would be understood that the extraction method chosen would be dependent on the type of plant and the properties of the oil being extracted. Preferably, the extraction method does not affect or only 11 minimally affects the desirable properties of the oil. For example, the extraction process used to produce the coconut oil would need to be such that the UVR absorption capabilities of the oil were sufficiently retained. Preferably, the coconut oil is produced by a pressing extraction method. More preferably, the coconut oil is produced by a cold-pressing extraction method. [0043] Preferably, the sunscreen formulations of the present invention comprise no more than 2% (w/w) mineral oil. In particularly preferred embodiments, the sunscreen formulation does not comprise mineral oil. In other preferred embodiments, the sunscreen formulations do not comprise ethylhexyl palmitate. [0044] In a second aspect of the present invention, there is provided a process for producing the sunscreen formulation according to the invention comprising the steps of heating the plant oil to at least about 450C and combining the plant oil with one or more UVR filtering agents and a rheology modifier. [0045] Preferably, the plant oil is heated to at least about 700C. More preferably, the plant oil is heated to a temperature of about 750C to 800C. The maximum temperature the plant oil may be heated to will be dependent on the equipment used and the smoke point of the oils used. For example, coconut oil has a relatively low smoke point of approximately 1750C, and any plant oil component of the present invention would preferably not be heated to above 1250C. In general, the maximum temperature to which the oils are heated would be at least 500C below the smoke point of the oil in the mixture with the lowest smoke point, to ensure the properties of the plant oil were not diminished. Preferably, the plant oil would not be heated to a temperature greater than 450C for more than four hours. [0046] The heated plant oil may be combined with the UVR filtering agent(s) and rheology modifier simultaneously, or the UVR filtering agent(s) may be added to the plant oil prior to the rheology modifier. In other embodiments, the rheology modifier may be added to the plant oil prior to the UVR filtering agent(s). [0047] While producing the formulation, the temperature may be maintained above at least 450C when the plant oil is combined with the one or more UVR filtering agents and the rheology modifier. Alternatively, the plant oil may be cooled to a temperature below 450C before being combined with the UVR filtering agent(s) and/or the rheology 12 modifier. Preferably, the mixture comprising the plant oil, UVR filtering agent(s) and rheology modifier is cooled to below 450C prior to the addition of any fragrance agent. [0048] It would be understood that conventional methods may be employed for mixing and combining the formulation to ensure a homogenous mixture is formed. That a homogenous mixture is formed may be indicated by the mixture being clear and free of any undissolved material. Preferably, the mixture would be clear and free of any undissolved material after the addition of each individual component and before any further additions to the mixture. Definitions [0049] In the context of the present application, "sunscreen formulation" means a formulation that is capable of reducing the amount of UVR absorbed by the skin of a human exposed to the sun. The formulation may be broadly classified as a therapeutic sunscreen formulation, or as a cosmetic sunscreen formulation. [0050] In the context of the present application, a "therapeutic sunscreen formulation" means a sunscreen formulation with SPF 4 or more. [0051] Therapeutic sunscreen formulations may be regulated as a therapeutic good by a relevant governing body. For example, in Australia, a therapeutic sunscreen may need to be listed on the Australian Register of Therapeutic Goods (ARTG), administrated by the Therapeutic Goods Administrationon (TGA) in accordance with the Therapeutic Goods Act 1989 and the Therapeutic Goods Regulations 1990. [0052] In the context of the present application, "cosmetic sunscreen formulations", are formulations that are applied to the skin of a human and include but are not limited to make-up products and skin care products comprising at least one sunscreeening ingredient. [0053] Cosmetic sunscreen formulations, may be regulated by laws and guidelines that relate to the safety of the product and the legitimacy of claims regarding the product's attributes, such as SPF. For example, in Australia, a cosmetic sunscreen formulation would typically need to meet the definition of a cosmetic under the requirements set forth in the Cosmetics Standard and the National Industrial Chemicals 13 Notification and Assessment Scheme (NICNAS), as enforced by the Industrial Chemicals (Notification and Assessment) Act 1989. [0054] In the context of the present invention, the term "natural" when used, for example, to describe a "natural component" or "natural moisturiser", means any compound produced by a living organism found in nature. The compound may have a pharmacological or biological activity, such as, for example, being able to absorb UVR. In general, a natural compound is free, or substantially free, of artificial ingredients. [0055] In the context of the present invention, the words "comprise", "comprising" and the like are to be construed in their inclusive, as opposed to their exclusive, sense, that is in the sense of "including, but not limited to". The phrase "does not comprise" means to be "substantially free of". For example, the formulation would not comprise any more than 0.5 % (v/v) of the particular component, or may not comprise any more than 0.1 % (v/v) of the particular component, or may not comprise any of the particular component. Brief Description of the Drawings Figure 1. Preliminary SPF report of a formulation comprising 5.5 % (w/w) UVR filtering agents and plant oil. Figure 2. Preliminary SPF report of a formulation comprising 7.5% (w/w) UVR filtering agents and plant oil. Figure 3. Preliminary SPF report of a formulation comprising 15% (w/w) UVR filtering agents and plant oil. Figure 4. Figures 4a and 4b show the FDA Protocol SPF Test Results and the International Test Method SPF Test results for an SPF 6 sunscreen formulation of the present invention, respectively. Figure 5. Figures 5a and 5b show the FDA Protocol SPF Test Results and the International Test Method SPF Test results for an SPF 10 sunscreen formulation of the present invention, respectively.

14 Figure 6. Figures 6a and 6b show the Preliminary SPF Test Results and the International Test Method SPF Test results for an SPF 18 sunscreen formulation of the present invention, respectively. Detailed Description of the Invention [0056] Although the invention has been described with reference to certain embodiments detailed herein, other embodiments can achieve the same or similar results. Variations and modifications of the invention will be obvious to those skilled in the art and the invention is intended to cover all such modifications and equivalents. [0057] The present invention is further described by the following non-limiting examples. Example 1 [0058] Initial attempts to produce sunscreen formulations using natural plant oils with UVR absorption capabilities involved the addition of commercially available UVR filtering agents to oil mixtures comprising approximately 25% (w/w) coconut oil. These formulations had very low viscosity and the UVR filtering agents did not mix well with the oils, making it difficult to achieve suitable SPF ratings. Figure 1 shows the results achieved for a formulation comprising very effective UVR filtering agents, butyl methoxy dibenzoylmethane and octyl methoxy-cinnamate at concentrations routinely used in sunscreen products (0.5% and 5%, respectively) in a mixture of coconut oil, apricot kernel oil, grape seed oil and sunflower seed oil (approximately 20-25 % (w/w) each). Disappointingly, this mixture only achieved an SPF rating of 3, which was not reproducible due to the thinness of the formulation and the tendency of the UVR filtering agents to settle in the oil mixture such that they were not evenly dispersed. [0059] Figure 2 shows the results achieved for a formulation comprising UVR filtering agents at concentrations routinely used in very high SPF sunscreen products (1% butyl methoxy dibenzoylmethane, 7.5% octyl methoxy-cinnamate, 3% benzophenone-3 and 1.5 % octocrylene) in a mixture of coconut oil, apricot kernel oil, grape seed oil and sunflower seed oil (approximately 20-25 % (w/w) each). This mixture only achieved an SPF rating of 8, which was not reproducible due to the thinness of the formulation and the tendency of the UVR filtering agents to settle and clump in the oil mixture such that they were not evenly dispersed.

15 [0060] In an effort to produce a more viscous product to allow for an accurate measurement of the SPF rating, a comparable oil mixture was combined with 15 % (w/w) powdered UVR filtering agents (1% butyl methoxy dibenzoylmethane, 7.5% octyl methoxy-cinnamate, 3% benzophenone-3 and 1.5 % octocrylene). Unfortunately, despite a reasonable expectation that the very high amounts of UVR filtering agents in this formulation would have resulted in a formulation with an SPF in excess of 30, only an SPF rating of 6 was achieved (as shown in Figure 3). This was due to the low viscosity of the formulation and the UVR filtering agent not forming a stable, properly dispersed emulsion with the oil mixture. Example 2 [0061] In order to circumvent the issues encountered with the formulation comprising only plant oils and UVR filtering agents, formulations were made comprising the broad spectrum UVR filtering agent, Bemotrizinol (commonly referred to as Tinosorb S) in combination with equal parts coconut oil, apricot kernel oil, grape seed oil and sunflower seed oil. After many failed attempts, it was found that the addition of the rheology modifier, polyamide-8 (sold as OleoCraftTMLP-20), resulted in stable sunscreen formulations. The Tinosorb S was evenly dispersed in these formulations, and they were viscous enough to pass the required in vivo SPF rating tests. [0062] The formulations were produced by first combining all of the plant oils in a single tank and heating to 75-800C, whilst constantly stirring the tank. The plant oil mixture was maintained at a temperature between 75-80 0 C.The Tinosorb S was added and the mixture stirred for up to 15 minutes until the Tinosorb S was fully dissolved. When the plant oil and Tinosorb S mixture was completely clear and free of any undissolved solids, the rheology modifier, OleoCraftTMLP-20, was added and the mixture stirred until it was completely clear and free of any undissolved solids. [0063] This mixture was then cooled to less than 450C while being stirred with a sweep mixer. Fragrance was then added and the mixture stirred for another 30 minutes before deaerating the mixture under vacuum for approximately 30 minutes. Samples of the formulation were then taken from the top and bottom of the tank for QC testing before packaging.

16 Example 3 [0064] An SPF 6 sunscreen formulation was produced with 2% (w/w) Tinosorb S, 3% (w/w) OleoCraftTMLP-20, and approximately 23.64 % (w/w) each of coconut oil, apricot kernel oil, grape seed oil and sunflower seed oil according to the method described in Example 2. The results of the SPF rating tests for these formulations are shown in Figure 4. Example 4 [0065] An SPF 10 sunscreen formulation was produced with 4% (w/w) Tinosorb S, 3% (w/w) OleoCraftTMLP-20, and approximately 23.25 % (w/w) each of coconut oil, apricot kernel oil, grape seed oil and sunflower seed oil according to the method described in Example 2. The results of the SPF rating tests for these formulations are shown in Figure 5. Example 5 [0066] An SPF 18 sunscreen formulation was produced with 8% (w/w) Tinosorb S, 3% (w/w) OleoCraftTMLP-20, and approximately 22.14 % (w/w) each of coconut oil, apricot kernel oil, grape seed oil and sunflower seed oil according to the method described in Example 2. The results of the SPF rating tests for these formulations are shown in Figure 6. [0067] As can be seen from the previous examples, the successful generation of the sunscreen formulations of the present invention required the inventors to find a fine balance between each of the components, such that the formulations had an appropriate viscosity and were sufficiently evenly dispersed to produce the required SPF ratings from the combined UVR absorption capabilities of the coconut oil and the UVR filtering agent, whilst also being thin enough to be suitable for even application at room temperature, and not create processing and packaging issues. This required significant ingenuity, as the outcome of combining the components to produce the sunscreen formulations was not predictable, as is evident from the failed attempts (see Example 1, above). [0068] Although the invention has been described with reference to specific examples, it will be appreciated by the skilled addressee that the invention may be embodied in many other forms.

17 [0069] It would be understood that the teachings of the preceding examples would be sufficient to allow the skilled addressee to generate sunscreen formulations according to the present invention with higher SPFs, up to an including SPF 30, SPF 40 and SPF 50. [0070] For example, the SPF of a sunscreen formulation of the present invention may be raised by increasing the amount of coconut oil in the formulation such that UVR absorption ability of the coconut oil had a greater contribution to the overall SPF of the formulation. Specifically, for example, a sunscreen formulation described in Examples 3, 4 or 5 may be produced with 40 % (w/w) coconut oil, which would likely result in a sunscreen formulation with a higher SPF. [0071] For example, the SPF of the sunscreen formulations of the present invention may also be raised by increasing the amount of rheology modifier such that the formulation is thicker. In other examples, the SPF of the sunscreen formulations of the present invention may also be increased by using different UVR filtering agents, such as those with higher UVR absorption abilities in the UVB range, or by increasing the amount of UVR filtering agents used.

Claims (5)

1. A sunscreen formulation comprising one or more ultraviolet radiation (UVR) filtering agents, a rheology modifier and at least 35 % (w/w) plant oil, wherein at least 20 % (w/w) of the plant oil is coconut oil.

2. The formulation of claim 1, wherein the formulation comprises at least 80 % (w/w) plant oil, wherein at least 20 % (w/w) of the plant oil is coconut oil, and the formulation is suitable for application to the skin at a rate of at least about 0.5 mg/cm 2 .

3. The formulation of claim 1 or claim 2, comprising one or more UVR filtering agents selected from the group consisting of Bemotrizinol, Benzylidene camphor sulfonic acid, Butyl methoxy dibenzoylmethane, Camphor benzalkonium methosulfate, Cinoxate, Diethylamino hydroxybenzoyl hexyl benzoate, Dioxybenzone, Disodium phenyl dibenzimidazole tetrasulfonate, Drometrizole trisiloxane, Ecamsule, Homosalate, Isoamyl methoxy-cinnamate, 4-Methylbenzylidene camphor, Menthyl anthranilate, Methylene bis-benzo-triazolyl-tetramethyl-butylphenol, Octocrylene, Octyl methoxy cinnamate, Octyl salicylate, Octyl triazone, Padimate 0, PEG-25 PABA, Phenylbenzimidazole sulfonic acid, Polysilicone-15, Sulisobenzone, Sulisobenzone sodium, Titanium dioxide, Triethanolamine salicylate and Zinc oxide.

4. A method for the prevention of sunburn comprising administering an effective amount of the sunscreen formulation according to any one of claims 1 to 3 to the skin of a human prior to exposure to sunlight.

5. A process for producing the sunscreen formulation according to any one of claims 1 to 4 comprising the steps of: heating the plant oil to at least about 45CC; combining the plant oil with one or more UVR filtering agents and a rheology modifier.