Benthic pennate diatom frustules as SPF boosters

Abstract

A cosmetic composition comprising at least one sunscreen active and benthic pennate diatom frustules. A method for increasing the SPF of a sunscreen composition. A method for producing a sunscreen by providing a sunscreen active and benthic pennate diatom frustules.

Description

[Technical Field]

[0001] The present disclosure relates to compositions comprising benthic pennate diatom frustules as an SPF booster. In particular, the present invention relates to compositions comprising a sunscreen active and benthic pennate diatom frustules. [Background technology]

[0002] Sunscreens are used in cosmetics to protect the skin from the harm caused by ultraviolet rays. A common measure for determining the protection value of a sunscreen is the sun protection factor (SPF) of the sunscreen. The sun protection factor (SPF) is defined as the ratio of the amount of energy required to produce minimal erythema on sunscreen-protected skin to the amount of energy required to produce the same level of erythema on unprotected skin.

[0003] The ultraviolet rays that damage the skin can be both UVA and UVB rays.

[0004] Cosmetics with increased or enhanced SPF are important for providing better protection of the skin from harmful UV rays. Physical UV blockers and / or chemical UV absorbers are used as sunscreen active agents to provide protection from UV rays. However, some sunscreen active agents have been reported to have harmful toxic effects. Furthermore, increasing the amount of sunscreen active agents can result in less desirable cosmetic properties, such as a paste-like consistency or whitening of the skin.

[0005] SPF boosters have been developed to increase the UV protection factor of sunscreens without adding increased amounts of sunscreen actives. Or, equivalently, to allow for a reduction in the amount of sunscreen active while maintaining a similar level of UV protection, i.e., SPF. SPF boosters do not necessarily have UV protection themselves, but rather increase the SPF of cosmetic compositions containing sunscreen actives.

[0006] Patent document 1 (CODIF International) describes cosmetic compositions containing biomineral compounds, such as coccoliths and / or nonspecific diatom frustules, and claims that such compositions reduce UV-induced inflammatory biomarkers in human skin. Patent document 1 does not disclose the SPF booster or any SPF, UV blocking / screening effects of the tested biomineral compounds, but rather the anti-inflammatory effect of the cream after UV exposure.

[0007] US Patent No. 5,999,949 (Dow Global Technologies LLC) describes an SPF booster for use in alcohol-based sunscreen formulations. The SPF booster is a multi-stage polymer particle. An improved, naturally derived SPF booster with proven SPF boosting efficacy would be ideal to meet consumer expectations regarding cosmetic performance and ingredients. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] French Patent Application Publication No. 3054128 [Patent Document 2] European Patent Application Publication No. 3658107 Summary of the Invention [Problem to be solved by the invention]

[0009] Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and drawbacks in the art, singly or in any combination, and solves at least the above-mentioned problems by providing a cosmetic composition comprising at least one sunscreen active and benthic pennate diatom frustules.

[0010] A method for increasing the SPF of a sunscreen is provided.

[0011] Also provided is a method for preparing a sunscreen comprising benthic pennate diatom frustules. [Means for solving the problem]

[0012] Further advantageous embodiments are disclosed in the accompanying and dependent claims. [Brief explanation of the drawings]

[0013] The figures show the results of the experiments described in the experimental section. [Figure 1] MPF values ​​obtained with a reference SPF composition. The figure shows nine scans and the average MPF for a representative plate out of five scanned plates. [Figure 2] Figure 1 shows the MPF values ​​obtained for a control composition without benthic pennate diatoms. The figure shows nine scans and the average MPF for a representative plate out of five scanned plates. [Figure 3] Figure 1 shows the MPF values ​​obtained for a composition containing 0.1% benthic pennate diatoms. The figure shows nine scans and the average MPF for a representative plate out of five scanned plates. [Figure 4] Figure 1 shows the MPF values ​​obtained for a composition containing 0.3% benthic pennate diatoms. The figure shows nine scans and the average MPF for a representative plate out of five scanned plates. DETAILED DESCRIPTION OF THE INVENTION

[0014] Detailed Description The present disclosure relates to a cosmetic composition comprising at least one sunscreen active agent and benthic pennate diatom frustules. The benthic pennate diatom frustules enhance the sunscreen protection value (SPF) of the sunscreen agent compared to a composition that does not contain benthic pennate diatom frustules. Therefore, the benthic pennate diatom frustules are SPF boosters.

[0015] Diatoms are a type of algae that occur in both freshwater and marine environments. Diatoms contain frustules containing silicon dioxide. The frustules are the source of nanoporous silicon dioxide. Benthic diatoms are diatoms that grow attached to surfaces at the water-sediment interface, in contrast to pelagic diatoms that grow in open water. Pennate diatoms are bilaterally symmetrical diatoms, as opposed to radially symmetrical diatoms, and are defined as centric diatoms.

[0016] The light-manipulating properties of benthic pennate diatom frustules have previously been of interest in solar cell applications to increase the efficiency of solar cells (see, for example, WO 2017 / 211892 (Swedish Algae Factory AB)). However, to date, there has been no suggestion that benthic pennate diatoms could be used in cosmetic compositions as SPF boosters.

[0017] Cosmetic compositions containing fossilized diatomaceous earth frustules are known in the art. Diatomaceous earth is used in processes such as a bulking agent, opacifier, or anti-caking agent. For example, when used as an opacifier, diatomaceous earth can have a UV-absorbing effect. In contrast to fossilized diatomaceous earth, i.e., diatomaceous earth, benthic pennate diatom frustules have an SPF boost effect that is significantly greater than that expected from a similar amount of diatomaceous earth. This is demonstrated in the experimental section below, where a cosmetic composition containing only 0.1% benthic pennate diatoms has an SPF that is approximately 22% higher than a control composition that does not contain benthic pennate diatoms.

[0018] Without wishing to be bound by theory, the inventors propose that the specific structure and morphology of benthic pennate diatom frustules combine UV absorption, UV refraction, and UV conversion effects. The UV conversion effect may be the conversion of UV light from UV wavelengths to visible light (e.g., blue) through silica photoluminescence. Such SPF-boosting activity has not been demonstrated in fossilized diatom frustules. The centripetal diatom frustules of C. wailesii have been shown to emit blue light when excited with light at a wavelength of 325 nm (De Tommasi, E. et al., UV-shielding and wavelength conversion by centric diatom nanopatterned frustules. Sci Rep 8, 16285 (2018)). Because benthic pennate diatoms are less exposed to UV light in their natural environment, they are generally less likely to exhibit UV protection and have instead evolved to move downward away from UV light. (De Tommasi, E. et al., Sci Rep 8, 16285 (2018)). The present results indicate that benthic pennate diatom frustules have SPF-boosting activity that was not expected from benthic pennate diatom frustules. Therefore, it is argued that the UV conversion process may occur in the benthic pennate diatoms in this composition.

[0019] The composition may comprise at least 0.05% by weight of benthic pennate diatom frustules. The composition may comprise 0.1% by weight to about 3% by weight of benthic pennate diatom frustules. The composition may comprise about 0.05% by weight to about 1% by weight, for example, about 0.1% by weight to about 1% by weight of benthic pennate diatom frustules. The composition may comprise about 0.1% by weight to about 0.5% by weight, for example, about 0.1% by weight to about 0.3% by weight of benthic pennate diatom frustules. The benthic pennate diatom frustules are extracted from diatoms and are not fossil diatom frustules.

[0020] The composition may include an amount of benthic pennate diatom frustules that forms a monolayer when applied to a surface. The term monolayer of frustules means that there is limited, i.e., no overlap between the diatom frustules. The benthic pennate diatom frustules may self-arrange into a monolayer when provided at a sufficiently low concentration.

[0021] The frustules can be extracted from cultivated and harvested benthic pennate diatoms according to the process described in WO 2017 / 211892 (Swedish Algae Factory AB). The frustules may be extracted by a chemical extraction process in which the organic biomass of the diatoms is removed with chemical agents, leaving the frustules.

[0022] The present compositions contain at least one sunscreen active. The at least one sunscreen active can be an inorganic sunscreen active, an organic sunscreen active, or a combination thereof. The compositions can contain multiple different inorganic or organic sunscreen actives. Compositions PE1-PE3 in the experimental section contain multiple physical-blocking inorganic sunscreen actives. Combinations of different actives can provide improved sun protection across a range of ultraviolet wavelengths.

[0023] The inorganic sunscreen active agent may be, for example, zinc oxide, titanium dioxide, iron oxide, zirconium oxide, or cerium oxide.The inorganic sunscreen active agent may be a nanopigment formed from a coated metal oxide as disclosed herein.Preferably, the inorganic sunscreen active agent is zinc oxide, titanium dioxide, or a mixture thereof.The inorganic sunscreen active agent may be a transparent inorganic metal oxide, such as transparent zinc oxide or transparent titanium dioxide.As known in the art, a transparent inorganic metal oxide is a metal oxide that is prepared so that it appears transparent to visible light and therefore does not appear white when applied to the skin.For clarity, the inorganic sunscreen agent may be a transparent metal oxide or an opaque metal oxide.

[0024] The sunscreen active may be an organic sunscreen active such as anthranilates, cinnamic acid derivatives, dibenzoylmethane derivatives, salicylic acid derivatives, camphor derivatives, triazine derivatives, benzophenone derivatives, β,β-diphenylacrylate derivatives, benzotriazole derivatives, benzalmalonate derivatives, benzimidazole derivatives, imidazolines, bisbenzazolyl derivatives, p-aminobenzoic acid (PABA) derivatives, methylene bis(hydroxyphenylbenzotriazole) derivatives, screening polymers and screening silicones, α-alkylstyrenes, dimers derived from 4,4-diarylbutadiene, and mixtures thereof.

[0025] Benthic pennate diatom frustules have the advantage over other known SPF boosters, such as polymer-based SPF boosters, in that they are natural, i.e., naturally occurring. Cosmetics containing natural ingredients are often preferred by consumers because they are perceived as less harmful to the body and / or the environment. Benthic pennate diatoms can be extracted from cultured diatoms grown according to the process described in International Publication No. 2017 / 211892 (Swedish Algae Factory AB). Benthic pennate diatoms can be cultivated in water containing at least a portion of wastewater from, for example, a fish farm or food processing plant. Such wastewater has an increased nitrogen content, which may be ideal for culturing diatoms. Such a production process provides both an effective SPF booster and a means of reusing the wastewater. To this end, benthic pennate diatom frustules are particularly suitable as SPF boosters in sunscreen compositions containing inorganic UV-blocking sunscreen actives, many of which are commercially available as natural or chemical-free sunscreens. As will be understood, "chemical-free" in this context refers to the absence of organic sunscreen actives, e.g., chemical absorbers such as p-aminobenzoic acid (PABA) derivatives.

[0026] Sunscreen active agents absorb radiation in the UVA and / or UVB spectrum. The UVA spectrum is the 280-320 nm region of the ultraviolet light spectrum. The UVB spectrum is the 320-400 nm region of the ultraviolet light spectrum.

[0027] The at least one sunscreen active is generally present in an amount of about 0.1% to about 75% by weight of the composition. The sunscreen active may be present in an amount of about 1% to about 40% by weight of the composition, for example, about 5% to about 25% by weight. The sunscreen active may be present in an amount of about 10% to about 15% by weight of the composition. Due to the presence of benthic pennate diatom frustules in the composition, the sunscreen active may be present in an amount less than that generally required to achieve a particular SPF in the composition.

[0028] The composition may also contain water and / or oil. The composition may be an emulsion containing water. The composition may be in the form of a water-in-oil emulsion or an oil-in-water emulsion. The water or oil may be present in an amount of about 5% to about 70% by weight of the composition.

[0029] The composition may be a powder sunscreen composition comprising benthic pennate diatom frustules. A powder or powder sunscreen composition is a composition comprising fine, non-agglomerated particles in a carrier medium. Powder sunscreen compositions are known in the art. Benthic pennate diatom frustules are particularly suitable for use in powder sunscreen compositions because the frustules are a dry powder.

[0030] The composition may contain other ingredients, such as emollients, moisturizers, lubricants, conditioning agents, surfactants, plasticizers, preservatives, fillers, active ingredients that are not sunscreen actives, fragrances, thickeners, antioxidants, vitamins, and other ingredients that are known and commonly used in cosmetic compositions.The composition may contain metal oxides in addition to the inorganic sunscreen actives.The composition may contain, for example, alumina, mica.The composition containing benthic pennate diatoms may also contain silica separately in addition to silicon oxide frustules for cosmetic use. Experimental Section

[0031] The boosting efficacy of benthic pennate diatoms for UV filter compositions was determined in an in vitro study: the sun protection factor (SPF) of a known composition was compared with the SPF of a composition containing varying concentrations of benthic pennate diatom frustules. General Description

[0032] The test product is spread onto a thin film of an appropriate synthetic substrate, and the UV absorbance through this film is measured using a spectrophotometer. The SPF is determined by first irradiating the product at four minimum erythema doses (MEDs) and then scanning the sample from 290 nm to 400 nm. During the scan, the resulting data is accumulated and saved at 1 nm intervals to determine the monochromatic protection factor (MPF) for each selected wavelength. The MPF is then used to calculate the SPF value using the solar radiation and erythema constants. Sample preparation

[0033] Benthic pennate diatom frustules were added to an existing sunscreen formulation, whereby the water content by weight was adjusted to compensate for the addition of the benthic pennate diatom frustules. The existing sunscreen formulation contained an inorganic sunscreen active.

[0034] The following compositions were prepared: [Table 1]

[0035] [Table 2]

[0036] Molded PMMA plates, 50 mm × 50 mm (reference: HEL-PMMA55 (HelioScience, France)) were used as the substrate. The foil-covered PMMA plates were removed and cleaned with an antistatic cloth. The PMMA plates were weighed. The above-mentioned compositions (PE1–PE3, SPF reference) containing various concentrations of benthic pennate diatom frustules were applied to the PMMA plates. Five plates of each of PE1–PE3 were prepared. Four plates of the reference SPF composition were prepared. Approximately 1.3 mg / cm2 of each composition was applied to the surface of the PMMA plates. The total mass of composition on each plate was 32.5 ± 0.3 mg. The compositions were spread over the plate surface with a saturated gloved finger. The coated plates were then dried in the dark for at least 30 min at the same temperature of 30.0 ± 5.0 °C and relative humidity of 50.0 ± 10.0%. The same temperature and humidity conditions were used for UV exposure and absorbance measurements.

[0037] device The irradiation source was a Solar Simulator PV Cell Test, model number 16S-300-002 (Solarlight®). The irradiation source was calibrated according to the manufacturer's specifications.

[0038] All absorbance measurements were performed using a UV spectrophotometer, SPF-290AS (Solarlight®), which was calibrated according to the manufacturer's specifications.

[0039] The UVB radiometer (SUV detector PMA2101S-UVS, Solarlight®) was calibrated against the spectroradiometry of the solar simulator output.

[0040] The dose controller / meter (DCS2.0 dose controller / meter, Solarlight®) was calibrated according to the manufacturer's specifications. UV testing of known SPF compositions

[0041] Before each test, PE1-PE3, each of the four PMMA plates treated with the reference SPF composition was tested to ensure that the instrument was maintained within expected limits. The PMMA plate with the reference composition was placed 45.7 cm from the UV beam. The time for irradiating the PMMA plate with four MEDs was determined by the dose controller. The SPF reference PMMA plate was placed in the UV spectrophotometer, and the average MPF value was recorded from nine measurements at nine different locations on the PMMA plate for each wavelength across the entire UV spectrum (290-400 nm). The in vitro SPF values ​​were compared to known in vivo references to confirm that the values ​​were within the expected range. Upper and lower limits were established for the reference composition according to ISO 24444. The in vitro SPF values ​​measured for the reference SPF composition should be within the range of 13.7-18.5.

[0042] Ultraviolet testing of benthic pennate diatom composition

[0043] Each of the five PMMA plates for each of PE1-PE3 was placed 45.7 cm from the UV beam. The five plates for each of PE1-PE3 were placed in a UV spectrophotometer. Average MPF values ​​were recorded by nine measurements at nine different locations on each of the PMMA plates for each wavelength across the entire UV spectrum (290 nm to 400 nm). MPF values ​​were recorded at 1 nm intervals. Average SPF values ​​are shown in the Results section below. result

[0044] The MPF values ​​obtained for the reference SPF composition of the exemplary plate are shown in FIG. [Table 3]

[0045] The MPF values ​​obtained for an exemplary plate, PE1, are shown in FIG. [Table 4]

[0046] The MPF values ​​obtained for an exemplary plate, PE2, are shown in FIG. [Table 5]

[0047] The MPF values ​​obtained for an exemplary plate, PE3, are shown in FIG. [Table 6]

[0048] [Table 7]

[0049] Consideration

[0050] As can be seen from the results above, the compositions containing benthic pennate diatom frustules have an SPF-boosting effect compared to creams that do not contain benthic pennate diatom frustules. The compositions containing benthic pennate diatom frustules at concentrations of 0.1% (PE2) and 0.3% (PE3) have significantly higher average SPFs than the control composition (PE1).

[0051] As can be seen from the table above, the standard deviation decreased continuously with increasing abundance of benthic pennate diatoms, indicating that benthic pennate diatom frustules may have a more consistent boosting effect at increasing rates.

[0052] Additionally, it should be noted that the sunscreen active in the particular test was a mineral, present in compositions PE1-PE3 at 12%. Therefore, the addition of only 0.1% benthic pennate diatoms provided significant benefit.

[0053] Without wishing to be bound by theory, the amount of benthic pennate diatom frustules that can form a monolayer of frustules when applied as a composition may be the optimal amount for SPF boosting effect. This suggests that the boosting effect of benthic pennate diatom frustules may not necessarily be as great as a significantly increased amount in the composition, and the optimal amount that can form a monolayer when applied to a surface with the greatest SPF boosting effect may depend on the specific surface and the specific composition.

[0054] Although the present invention may be described above with reference to particular formulations or compositions, it is not intended to be limited to the specific forms set forth herein. Rather, the present invention is limited only by the appended claims.

[0055] In the claims, the term "comprises" does not exclude the presence of other elements or steps. Furthermore, although individual features may be included in different claims, these may be advantageously combined, and their inclusion in different claims does not imply that a combination of features is not feasible and / or advantageous. In addition, reference to the singular does not exclude a plurality. Terms such as "a," "an," "first," and "second" do not exclude a plurality.

Claims

1. 1. A cosmetic composition comprising: at least one sunscreen active agent, - Benthic pennate diatom frustules and A cosmetic composition comprising:

2. 10. The cosmetic composition of claim 1, wherein said composition comprises at least 0.05% (by weight) of benthic pennate diatom frustules.

3. 3. The cosmetic composition according to claim 1, wherein said composition comprises 0.05% (by weight) to 1% (by weight) of benthic pennate diatom frustules.

4. A cosmetic composition according to any one of claims 1 to 3, wherein the composition comprises from 0.05% (by weight) to 0.3% (by weight) of benthic pennate diatom frustules.

5. 5. The cosmetic composition according to any one of claims 1 to 4, wherein the sunscreen active is at least one inorganic sunscreen active selected from the list comprising titanium dioxide, zinc oxide, iron oxide, zirconium oxide, cerium oxide, or combinations thereof.

6. The cosmetic composition according to any one of claims 1 to 5, wherein said sunscreen active is at least one organic sunscreen active.

7. A cosmetic composition according to any one of claims 1 to 6 provided in an acceptable cosmetic carrier medium.

8. 8. The cosmetic composition of claim 7, wherein the acceptable cosmetic carrier medium is water or oil.

9. The cosmetic composition according to any one of claims 1 to 8, which is provided in powder form.

10. 10. The composition of any one of claims 1 to 9, wherein the frustules are extracted from cultivated and harvested benthic pennate diatoms.

11. 1. A method for increasing the SPF of a sunscreen composition, comprising: The sunscreen composition comprises: - Contains benthic pennate diatom frustules method.

12. 12. The method of claim 11, wherein the benthic pennate diatom frustules are present in an amount of 0.05% to 1% by weight of the composition.

13. 1. A method for making a sunscreen composition, comprising: - providing a sunscreen active agent in a cosmetic carrier composition; and - To provide benthic pennate diatom frustules A method comprising:

14. 14. The method of claim 13, wherein the benthic pennate diatom frustules are provided in an amount of 0.05% to 1% by weight of the composition.

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