WO2013033833A1

WO2013033833A1 - Topical composition with enhanced photoprotection properties

Info

Publication number: WO2013033833A1
Application number: PCT/CA2012/000844
Authority: WO
Inventors: Anne SAVAGE FRANEY; Jaroslaw STAVIK
Original assignee: Biovision Technology Inc.
Priority date: 2011-09-09
Filing date: 2012-09-10
Publication date: 2013-03-14

Abstract

It has been determined that topical compositions comprising nanocrystalline cellulose and at least one excipient exhibit enhanced photoprotection properties. They are therefore useful as sunscreens to protect against harmful ultraviolet (UV) radiation, hi preferred embodiments, the composition is a cream comprising at least about 2 % by weight of the nanocrystalline cellulose. The length, diameter, and aspect ratio of the crystals making up the nanocrystalline cellulose, as well as the crystallinity index (CRI) also preferably fall within select bounds. In an exemplary7 embodiment, the nanocrystalline cellulose is prepared by a process involving selective oxidation of the C6 primary7 hydroxyl groups, thereby introducing carboxylrc acrd groups on the surface of the nanocrystalline cellulose and yielding the aforementioned desired crystalline properties.

Description

TOPICAL COMPOSITION WITH ENHANCED

PHOTOPROTECTION PROPERTIES

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims the benefit under 35 U.S.C. §119(e) of provisional patent application S.N. 61/573,133, filed September 9, 2011, the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] In one of its aspects, the present invention relates to a cosmetic composition with enhanced photoprotection properties. In anther of its aspects relates to a method for protecting a skin surface of a mammal. In yet another of its aspects, the present invention relates to a kit for protect a skin surface of a mammal.

BRIEF DESCRIPTION OF THE PRIOR ART

[0003] The undesirable effects of over exposure to sunlight are well known.

[0004] Such exposure can result in not only uncomfortable sunburn but in prematurely aging skin, wrinkles, loss of skin elasticity, dermatosis, and skin cancer. The most dangerous solar radiation is the ultraviolet (UV) radiation at wave lengths lower than 400 nm which includes both UV-A and UV-B radiation. In general, the UV-A radiation refers to ultraviolet light having a wave length of 320-400 nm and UV-B light refers to ultraviolet light have a wave length of 280-320 nm.

[0005] For example, exposure to ultraviolet light, primarily through exposure to the sun's rays produces a number of harmful effects including premature skin aging, loss elasticity, wrinkling, drying. Radiation can promote erythemal damage, can cause photo allergic reaction, and is implicated in skin cancer. UV-A radiation has been recognized to be involved in the genesis of solar elastosis and is the major waveband responsible for polymorphous light eruption, the most common of the idiophatic photodermatoses.(Neumann RA, Pohl-Markl H, Knobler RM., "Polymorphous light eruption: experimental reproduction of skin lesions by wholebody UVA irradiation", Photodermotology 1987; 4: 252-6)

[0006] Sunscreening is a long standing practice to attempt to protect the skin from these, and other, adverse effects of solar radiation.

[0007] Conventional sunscreen compositions are typically in the form of a liquid, either a lotion (usually a clear liquid) or a cream (usually an opaque liquid). These compositions may be either oil or water based. The water based emulsion serves mainly as an aid to disperse the active ingredients topically. The carrier water evaporates and leaves a thin film of active ingredient(s) plus excipients deposited on the skin. The film remaining on the skin contains the product which protects the skin from ultraviolet radiation - this is also referred to in the art as a "sun filter" or a "radiation filter" (these terms are used interchangeably throughout this specification). Radiation filters can be mineral based or non-mineral based.

[0008] Sun filters or radiation filters that primarily filter or absorb UV-A light are often referred to as UV-A absorbers. Similarly, sunscreen agents that primarily filter or absorb UV-B light are often referred to as UV-B absorbers.

[0009] European legislation currently authorizes 26 sun filters among which, there is only one mineral filter: titanium dioxide. In the United States, two mineral filters are authorized: titanium dioxide in a maximum dose of 25% and zinc oxide. Zinc oxide is authorized in Europe, but its concentration level is not limited. A large number of commercially available sunscreen composition products contain one or both of these mineral filters. The difference between these commercially available sunscreen composition products lies in the percentage of the active substance, the way they are incorporated into the final product and the size of the primary particles. Depending on the ingredient used, there is a large variation in efficacy.

[0010] Sunscreen compositions are typically rated by their sun protection factor (SPF) which is a measure of the protection from the sun afforded by the sunscreen agent or composition containing the sunscreen agent. Compositions having higher SPF values provide more protection from solar radiation. [0011] Medical organisations such as the American Cancer Society recommend the use sunscreen products. The use of sunscreens containing organic chemical compounds and inorganic particulates is controversial for various reasons. Many sunscreens do not block UV-A radiation and many ingredients are limited by domestic regulations and/or laws.

[0012] Convention sunscreen compositions contain agents which both absorb and reflect harmful ultraviolet radiation. Numerous disclosures of sunscreen compositions are available. See for example, any of the following:

• United States patent publication number US 2004/0126339 [Roszell] ;

• United States patent 5,518,712 [Stewart];

• United States patent 5,885,557 [Lentini];

• United States patent 5,916,541 [Stewart];

• United States patent 6,074,630 [Devillez et al] ;

• United States patent 6,436,376 [Hansenne et al.]; and

• International Publication Number WO 97/42933 [Stewart].

[0013] Most of the agents are petrol-based products and/or inorganic materials. These agents can be harmful to the skin and/or they are not environmentally friendly.

[0014] Despite the advance made in the art, there is room for improvement.

[0015] Specifically, it would be desirable to have a cosmetic composition such as a sunscreen composition that possessed improved photoprotection properties, for example, when compared to the using of sunscreen compositions incorporating a convention sun filter or radiation filter. It would be further desirable to have a cosmetic composition such as a sunscreen composition that was substantially completely free of petrol-based products and/or inorganic materials as the sun filter or radiation filter. SUMMARY OF THE INVENTION

[0016] It is an object of the present invention to obviate or mitigate at least one of the above- mentioned disadvantages of the prior art.

[0017] It is another object of the present invention to provide a novel topical composition for application to the skin of a mammal.

[0018] Accordingly, in one of its aspects, the present invention provides a topical composition for application to the skin of a mammal, the topical composition comprising nanocrystalline cellulose, together with at least one excipient therefor.

[0019] In another of its aspects, the present invention provides a .

[0020] Thus, the present inventors have discovered that the inclusion of nanocrystalline cellulose (also referred to throughout this specification as "NCC") in a topical composition, particularly a cosmetic composition, more particularly a sunscreen composition, confers enhanced photoprotection properties to a user of applies the composition on their skin.

BRIEF DESCRIPTION OF THE DRAWING

[0021] Embodiments of the present invention will be described with reference to the accompanying drawing, in which Figure 1 illustrates the relationship between the applied UV dose and the dose transmitted by a conventional sunscreen composition with SPF of 41.8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Unless otherwise indicated, all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about".

[0023] All parts, percentages, ratios, etc. herein are by weight unless indicated otherwise.

[0024] As used herein, the singular forms "a" or "an" or "the" are used interchangeably and intended to include the plural forms as well and fall within each meaning, unless expressly stated otherwise. Also as used herein, "at least one" is intended to mean "one or more" of the listed element. Singular word forms are intended to include plural word forms and are likewise used herein interchangeably where appropriate and fall within each meaning, unless expressly stated otherwise. Except where noted otherwise, capitalized and non-capitalized forms of all terms fall within each meaning.

[0025] An aspect of the present invention relates to the finding that the inclusion of nanocrystalline cellulose (also referred to throughout this specification as "NCC") in a topical composition, particularly a cosmetic composition, more particularly a sunscreen composition, confers enhanced photoprotection properties to a user of applies the composition on their skin.

[0026] Nanocrystalline cellulose is known in the art - see, for example, "Chemistry and Applications of Nanocrystalline Cellulose and its Derivatives: A Nanotechnology Perspective", Peng et al., The Canadian Journal of Chemical Engineering, Volume 9999, 2011, pgs. 1-16 and the reference cited therein.

[0027] Nanocrystalline cellulose is typically derived from acid hydrolysis of native cellulose possesses different morphologies depending on the origin and hydrolysis conditions. NCCs are rigid rod-like crystals.

[0028] The NCCs useful the context of the present topical composition may be derived for natural sources. Non-limiting examples of suitable such natural sources may be selected from the group consisting of bacteria, cotton, microcrystalline cellulose (MCC), ramie, sisal, tunicate, valonia, wood and the like.

[0029] Further, the NCCs useful in the context of the present topical composition have a length in the range of from about 50 nm to about 1000 nm, preferably from about 100 nm to about 500 nm, more preferably from about 100 nm to about 350 nm, most preferably from about 100 nm to about 300 nm.

[0030] Still further, the NCCs useful in the context of the present topical composition have a diameter in the range of from about 2 nm to about 50 nm, preferably from about 2 nm to about 40 nm, more preferably from about 2 nm to about 30 nm, most preferably from about 3 nm to about 10 nm.

[0031] Still further, the NCC's useful in the context of the present topical composition have an aspect ratio (length/diameter) of least about 2, preferably in range of from about 2 to about 100, more preferably from about 5 to about 100, most preferably from about 10 to about 100.

[0032] A particularly preferred NCC in the context of the present topical composition may be produced according the the process described in International Publication Number 2011/072365 [Leung et al. (Leung)].

[0033] As described in Leung, any suitable source of cellulosic materials may be used to produce this particularly preferred NCC, for example, vegetative or non-vegetative biomasses. Non-vegetative biomasses include cellulosic materials that have undergone considerable pre- treatments, for example, cellulose from papers and microcrystalline cellulose (MCC). It is an advantage of Leung's process that NCC's may be produced in one step from vegetative biomass. Thus, the cellulosic material used to produce the particularly preferred NCC comprises vegetative biomass, more preferably raw vegetative biomass. Any suitable vegetative biomass may be used, for example, one or more of hemp material (e.g. raw hemp, pectate-lyase treated hemp), flax material (e.g. raw flax, pectate-lyase treated flax), triticale material, wood sources (e.g. wood pulp, cardboard) and agricultural residues. More preferably, the cellulosic material comprises one or more of hemp or flax material.

[0034] The particularly preferred NCC has an average diameter of less than about 7 nm with substantially all of the nanocrystals having diameters within about 0.5 nm of the average diameter and an aspect ratio (length/diameter) of 10 or greater. The average diameter is preferably less than about 5 nm. In one embodiment, the average diameter is in a range of from about 3 nm to about 7 nm, preferably in a range of from about 3 nm to about 4.9 nm. The aspect ratio is preferably in a range of from about 12 to about 60. Preferably, substantially all of the nanocrystals have diameters within about 0.3 nm of the average diameter. The particularly preferred NCC preferably has a crystallinity index (CRI) that is 5% or more greater than the CRI of the cellulosic material from which the NCCs are made. Advantageously, the CRI may be 7% or more greater than, or even 10% or more greater than, the CRI of the cellulosic material from which the NCCs are made. The CRI may be, for example, up to 20% greater, or up to 17% greater, than the CRI of the cellulosic material from which the CNCs are made. The values of 5% or more, 7% or more or 10% or more may be lower limits of a range in which the upper limit is 20% or 17%. Preferably, the surface carboxylic acid groups of the particularly preferred NCC are formed by selective oxidation of C6 primary hydroxyl groups of the NCC. Preferably, the degree of oxidation is in a range of from about 0.01 to about 0.20, more preferably in a range of from about 0.08 to about 0.19, or in a range of from about 0.05 to about 0.10, for example about 0.08.

[0035] The NCC is present in the topical composition in an amount of at least about 2 percent by weight of the composition, preferably from about 2 to about 10 percent by weight of the composition, more preferably from about 3 to about 10 percent by weight of the composition, most preferably from about 3 to about 5 percent by weight of the composition.

[0036] A particularly preferred NCC is available from Bio Vision Tecnology Inc. under the tradename Nanocel™ (6-carboxynanocrystalline cellulose in neutral form or its sodium salt).

[0037] The topical composition of the present invention may be in the form of a cream, an ointments, a foam, a gel, a lotion, an adhesive coating coating an the like that contains a nanocrystalline cellulose, optionally a supplemental photo absorber and one or more excipients.

[0038] Preferably, a cream of the present topical composition is water-based and can contain one or more of an emollient, an emulsifier, a thickener and a preservative.

[0039] Emollients such as long chain alcohols, e.g., cetyl alcohol, stearyl alcohol and cetearyl alcohol; hydrocarbons such as petrolatum and light mineral oil; or acetylated lanolin can be included in a cream of the present topical composition. A cream can contain one or more of these emollients. The total amount of emollient in a cream of the topical composition is preferably about 5 percent to about 30 percent, and more preferably about 5 percent to about 10 percent by weight based on the total weight of the cream. [0040] Emulsifiers such as nonionic surface active agents, e.g., polysorbate 60 (available from ICI Americas), sorbitan monostearate, polyglyceryl-4 oleate, and polyoxyethylene(4)lauryl ether or trivalent cationic a cream of the present topical composition. A cream can contain one or more emulsifiers. Generally the total amount of emulsifier is preferably about 2 percent to about 14 percent, and more preferably about 2 percent to about 6 percent by weight based on the total weight of the cream.

[0041] Pharmaceutically acceptable thickeners, such as xanthum gum, guar gum, veegum gum K (available from R. T. Vanderbilt Company, Inc.), and long chain alcohols (e.g., cetyl alcohol, stearyl alcohol, cetearyl alcohol and the like) can be used. A cream can contain one or more thickeners. The total amount of thickener present is preferably about 3 percent to about 12 percent by weight based on the total weight of the cream.

[0042] Preservatives such as methylparaben, propylparaben and benzyl alcohol can be present in a cream of the invention. The appropriate amount of such preservative(s) is known to those skilled in the art.

[0043] Optionally, a cream of the present topical composition can contain a humectant such as glycerin, skin penetration enhancers such as butyl stearate and the like.

[0044] Generally, a cream consists of an oil phase and a water phase mixed together to form an emulsion - see the non-limiting examples below for specific illustrative techniques. Preferably, the amount of water present in a cream of the invention is about 45 percent to about 85 percent by weight based on the total weight of the cream. The creams of the present topical composition may be generally prepared by adding the water phase to the oil phase with both phases at a temperature of about 65°C to 75°C. The resulting emulsion is mixed with a suitable mixer apparatus to give the desired cream.

[0045] The present topical composition may also be in the form of an ointment. Such an ointment typical contains an acceptable ointment base such as petrolatum or polyethylene glycol 400 (available from Union Carbide) in combination with polyethylene glycol 3350 (available from Union Carbide) can be used. The amount of ointment base present in an ointment of the invention is preferably about 60 percent to about 95 percent by weight based on the total weight of ointment.

[0046] Optionally, an ointment of the present topical composition invention can also contain emollients, emulsifiers and thickeners. The emollients, emulsifiers, and thickeners and the preferred amounts thereof described above in connection with creams are also generally suitable for use in an ointment of the present topical composition.

[0047] Embodiments of the present invention will be described with reference to the following examples which are not intended to limit the scope of the invention and should not be used to construe the invention.

[0048] The nano-crystalline cellulose (NCC) used for the examples obtained using the process described in International Publication Number WO 2011/072365 [Leung et al.].

[0049] The nano-cyrstalline cellulose was used in a very pure form. Thus, the nano-cellulose was washed out in demineralised water, sonicated and filtered to achieve the dersired purity. The crystallinity index of the nano-crystalline cellulose was between 65 to 72 % using X-ray analysis. The nano-crystalline cellulose contained only the crystalline part of the cellulose chain. Non-process related components elements especially were detected by the Flame Atomic Absorption Spectrometer

[0050] The properties of the nano-crystalline cellulose used in the examples had the properties reported in Table 1.

Table 1

Example 1

[0051] In this example, a lotion was prepared according to the following methodology.

[0052] In one vessel 200 g water was heated to 70°C. In another vessel, the following components were heated to 70°C: grapeseed oil (12.5 g), apricot oil (12.5 g), shea butter (10 g) and Lexemul-T™ (2.5 g).

[0053] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 2

[0054] In this example, a lotion was prepared according to the following methodology.

[0055] In one vessel 200 g water was heated to 70°C. In another vessel, the following components were heated to 70°C: grapeseed oil (12.5 g), apricot oil (12.5 g), shea butter (10 g) and Lexemul-T™ (2.5 g).

[0056] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Component Amount (g)

Jeecide Cap 5 (preservative) 2.0

Carbomer 1.0

Triethalonamine 85% 2.0

NCC (neutral form) 5.0

Example 3

[0057] In this example, a lotion was prepared according to the following methodology.

[0058] In one vessel 200 g water was heated to 70°C. In another vessel, the following components were heated to 70°C: grapeseed oil (12.5 g), apricot oil (12.5 g), shea butter (10 g) and Lexemul-T™ (2.5 g).

[0059] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 4

[0060] In this example, a cream was prepared according to the following methodology.

[0061] In one vessel 1000 g water and 50 g glycerin were mixed and heated to 70°C. In another vessel, the following components were heated to 70°C: apricot oil (125 g), Brookswax™ (40 g) and cethyl alcohol (30 g). [0062] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 5

[0063] In this example, a cream was prepared according to the following methodology.

[0064] In one vessel 1000 g water and 50 g glycerin were mixed and heated to 70°C. In another vessel, the following components were heated to 70°C: apricot oil (125 g), Brookswax™ (40 g) and cethyl alcohol (30 g).

[0065] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 6

[0066] In this example, a cream was prepared according to the following methodology.

[0067] In one vessel 1000 g water and 50 g glycerin were mixed and heated to 70°C. In another vessel, the following components were heated to 70°C: apricot oil (125 g), Brookswax™ (40 g) and cethyl alcohol (30 g). [0068] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 7

[0069] In this example, a cream was prepared according to the following methodology.

[0070] In one vessel 1000 g water and 50 g glycerin were mixed and heated to 70°C. In another vessel, the following components were heated to 70°C: apricot oil (125 g) and Brookswax™ (80 g).

[0071] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 8

[0072] In this example, a cream was prepared according to the following methodology.

[0073] In one vessel 1000 g water and 50 g glycerin were mixed and heated to 70°C. In another vessel, the following components were heated to 70°C: apricot oil (125 g) and Brookswax™ (80 g). [0074] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 9

[0075] In this example, a cream was prepared according to the following methodology.

[0076] In one vessel 1000 g water and 50 g glycerin were mixed and heated to 70°C. In another vessel, the following components were heated to 70°C: apricot oil (125 g) and Brooks wax™ (80 g).

[0077] The contents of the vessels were combined and cooled to 40°C and the following components were added:

Example 10 - Testing/Evaluation

[0078] The absorption properties of materials were analysed in terms of the barrier characteristic during exposure to UV radiation. According to the literature (Zimnicki J., Krysiack K, Kazmierska M.: Dyes as a barrier to UV radiation), in order to assess barrier properties, a so- called solar protection factor (SPF) was introduced that allows one to compare the protective capacity of various materials. It is defined as Maximum Exposure Dose ratio for unprotected skin exposure under the same conditions. [0079] The literature data (Reinet G. Sonnenschutzeigenschaften textiller Flachen und deren Verbesserung. Textilverdlung 1996) reports an extended term of SPF, the so-called UPF index, which is an index of protection against UV radiation.

UPF < 20 the material fails to meet protective properties

UPF: 21 - 30 protective properties are low

UPF: 32 - 40 medium protective properties

UPF: 41 - 50 good protective properties

UPF > 50 very good protective properties

The UPF is calculated according to the following formula:

UPF = -φ Ύ ΕλΣλΑλ

λ.Ξλ.Τλ.Αλ wherein:

Ελ = spectral intensity of radiation (W/m².nm);

8λ = spectral relative biological efficiency;

Τλ = spectral permeability of the protective items; and

Δλ = ranges of wavelength.

[0080] The results are provided in Table 2.

Table 2

4% NCC (cream) 101

5% NCC (hemp oil) 92

Standard Ti0₂ 36

Example 11

[0081] In this example, an in vitro model of sunscreen behaviour was used to compare UV protection by a test formulation containing NCC and a reference formulation not containing NCC. The model is based on absorbance spectra measured before irradiation and after each of 4 irradiation doses to provide the estimated SPF and UVA protection factor and assess photostability [Stanfield J, Osterwalder U, Herzog B. In vitro measurements of sunscreen protection. Photochem Photobiol Sci, 2010, 9:489-494; and In vitro UV Protection Method Task Force, In vitro method for the determination of the UVA protection factor and critical wavelength values of sunscreen products, Guideline, Colipa, Final Draft, March 2011]. The Diffey critical wavelength was also measured for the two formulas [Diffey BL. A method for broad spectrum classification of sunscreens. IntJCosmet Sci 16:47-52, 1994].

[0082] The test formulation consisted of:

• NCC, 2.20% (w/w), used as a 5.5% dispersion in water;

• octinoxate, 4.00% (w/w);

• avobenzone, 3% (w/w);

• isopropanol, 53.00% (w/w); and

• water, 3.78% (w/w), contained in the NCC dispersion.

[0083] The test formulation was produced according to the following methodology. Octinoxate (0.4 g) and was combined with avobenzone in isopropanol (5.3 g) and the mixture was heated to 60°C to dissolve the avobenzone. The mixture was then cooled at which point the NCC dispersion was added (4.0 g). After shaking, the material was applied to 4 PMMA plates (HD-6, Helioscreen). [0084] The reference formulation consisted of:

• octinoxate, 4.00% (w/w);

• avobenzone, 3% (w/w); and

• isopropanol, 53.00% (w/w).

[0085] The reference formulation was produced according to the following methodology. Octinoxate (0.4 g) and was combined with avobenzone in isopropanol (5.3 g) and the mixture was heated to 60°C to dissolve the avobenzone. The mixture was then cooled. After shaking, the material was applied to 4 PMMA plates (HD-6, Helioscreen).

[0086] The test formulation and the reference formulation were subjected to testing as follows.

[0087] The formulation were applied to HD-6 substrates (Helioscreen, Creil) at 1.3 mg/cm by "spotting" the formulation on each plate and rubbing with a finger tip saturated with the formulation for approximately one minute, then allowing it to equilibrate in the dark for at least 30 minutes at 35°C ± 2°. A solar simulator (Solar Light Company, Philadelphia) that complied with Colipa specifications [In vitro UV Protection Method Task Force, In vitro method for the determination of the UVA protection factor and critical wavelength values of sunscreen products, Guideline, Colipa, Final Draft, March 2011] was used to irradiate the plates with a series of 4 UV doses (11, 21, 32 and 43 J/cm²), and a calibrated UV-2000 Sunscreen Analyzer (Labsphere) was used to measure the absorbance spectrum of each plate, before UV irradiation and after each UV dose.

[0088] Test product absorbance spectra and the constant erythemal effective irradiance spectrum of the irradiation source were used to compute the time course of the applied and transmitted UV doses, expressed in MEDs (1 MED=20 effective mJ/cm2). As shown in Figure 1, the relationship of transmitted UV dose vs. applied UV dose was described using the following least squares curve fit equation ("Power" Trendline, Microsoft Excel® Redmond, WA): y = ax^p (1) where x represents the applied UV dose and y represents the transmitted UV dose. Equation (1) permits calculation of the SPF, since x = SPF when y = 1 MED [Stanfield J, Osterwalder U, Herzog B. In vitro measurements of sunscreen protection. Photochem Photobiol Sci, 2010, 9:489-494] Thus, the estimated SPF was given by:

SPF = (1/α)^(1/β) (2)

In equation (1) the exponent, β, serves as an index of photostability. If β is 1, the relationship between x and y is constant, and the sunscreen is photostable. If β is significantly greater than 1, the sunscreen is not photostable.

[0089] The initial SPF before irradiation is designated as SPF₀, and a more specific index of photostability is the ratio SPF/SPF₀, where SPF is the estimated SPF [Stanfield J, Osterwalder U, Herzog B. In vitro measurements of sunscreen protection. Photochem Photobiol Sci, 2010, 9:489-494].

[0090] UVA protection factors and Critical Wavelengths were computed using the Colipa method, for interpolated spectra corresponding to UVA irradiation doses of 1.2xUVAPF [In vitro UV Protection Method Task Force, In vitro method for the determination of the UVA protection factor and critical wavelength values of sunscreen products, Guideline, Colipa, Final Draft, March 201 1 ; and Diffey BL. A method for broad spectrum classification of sunscreens. Int J Cosmet Sci 16:47-52, 1994].

[0091] The test results showed that the test formulation had an estimated SPF of 4.85 whereas the reference formulation had an estimated SPF of 3.30. The test results also showed that the test formulation had a UVAPF of 2.90 whereas the reference formulation had a UVAPF of 2.39. Thus, the test formulation had significantly better SPF and UVAPF properties than the reference formulation.

[0092] While this invention has been described with reference to illustrative embodiments and examples, the description is not intended to be construed in a limiting sense. Thus, various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments.

[0093] All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

Claims

What is claimed is:

1. A topical composition for application to the skin of a mammal, the topical composition comprising nanocrystalline cellulose, together with at least one excipient therefor.

2. The topical composition defined in Claim 1, wherein the nanocrystalline cellulose is present in an amount of at least about 2 percent by weight of the composition.

3. The topical composition defined in Claim 1, wherein the nanocrystalline cellulose is present in an amount of from about 2 to about 10 percent by weight of the composition.

4. The topical composition defined in Claim 1, wherein the nanocrystalline cellulose is present in an amount of from about 3 to about 5 percent by weight of the composition.

5. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having a length in the range of from about 50 nm to about 1000 nm.

6. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having a length in the range of from about 100 nm to about 500 nm.

7. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having a length in the range of from about 100 nm to about 350 nm.

8. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having a length in the range of from about 100 nm to about 300 nm.

9. The topical composition defined in Claims 1-8, wherein the nanocryalline cellulose consists of crystals having a diameter in the range of from about 2 nm to about 50 nm.

10. The topical composition defined in Claims 1-8, wherein the nanocryalline cellulose consists of crystals having a diameter in the range of from about 2 nm to about 40 nm.

11. The topical composition defined in Claims 1-8, wherein the nanocryalline cellulose consists of crystals having a diameter in the range of from about 2 nm to about 30 nm.

12. The topical composition defined in Claims 1-8, wherein the nanocryalline cellulose consists of crystals having a diameter in the range of from about 3 nm to about 10 nm.

13. The topical composition defined in Claims 1-12, wherein the nanocryalline cellulose consists of crystals having an aspect ratio of least about 2.

14. The topical composition defined in Claims 1-12, wherein the nanocryalline cellulose consists of crystals having an aspect ratio in the range of from about 2 to about 100.

15. The topical composition defined in Claims 1-12, wherein the nanocryalline cellulose consists of crystals having an aspect ratio in the range of from about 5 to about 100.

16. The topical composition defined in Claims 1-12, wherein the nanocryalline cellulose consists of crystals having an aspect ratio in the range of from about 10 to about 100.

17. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having an average diameter of less than about 7 nm.

18. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having an average diameter of less than about 5 nm.

19. The topical composition defined in Claims 1-4, wherein the nanocryalline cellulose consists of crystals having an average diameter in the range of from about 3 to about 4.9 nm.

20. The topical composition defined in Claims 17-19, wherein the nanocryalline cellulose consists of crystals having a diameter within about 0.5 nm of the average diameter.

21. The topical composition defined in Claims 17-19, wherein the nanocryalline cellulose consists of crystals having a diameter within about 0.3 nm of the average diameter.

22. The topical composition defined in Claims 17-21, wherein the nanocryalline cellulose consists of crystals having an aspect ratio at least 10.

23. The topical composition defined in Claims 17-21, wherein the nanocryalline cellulose consists of crystals having an aspect ratio in the range of from about 12 to about 60.

24. The topical composition defined in Claims 17-21, wherein the nanocryalline cellulose has a crystallinity index (CRI) that is 5% or more greater than the CRI of a cellulosic material from which the nanocrystalline cellulose material is derived.

25. The topical composition defined in Claims 17-21, wherein the nanocryalline cellulose has a crystallinity index (CRI) that is 7% or more greater than the CRI of a cellulosic material from which the nanocrystalline cellulose material is derived.

26. The topical composition defined in Claims 17-21, wherein the nanocryalline cellulose has a crystallinity index (CRI) that is 10% or more greater than the CRI of a cellulosic material from which the nanocrystalline cellulose material is derived.

27. The topical composition defined in Claims 24-26, wherein the nanocryalline cellulose has a crystallinity index (CRI) that is up to about 20% greater than the CRI of a cellulosic material from which the nanocrystalline cellulose material is derived.

28. The topical composition defined in Claims 24-26, wherein the nanocryalline cellulose has a crystallinity index (CRI) that is up to about 17% greater than the CRI of a cellulosic material from which the nanocrystalline cellulose material is derived.

29. The topical composition defined in Claims 1-28, wherein the nanocryalline cellulose comprises carboxylic acid groups on a surface thereof.

30. The topical composition defined in Claim 29, wherein the carboxylic acid groups are produced by selective oxidation of C6 primary hydroxyl groups of the nanocrystalline cellulose.

31. The topical composition defined in Claim 29, wherein the nanocryalline cellulose comprises a degree of oxidation is in the range of from about 0.01 to about 0.20.

32. The topical composition defined in Claim 29, wherein the nanocryalline cellulose comprises a degree of oxidation is in the range of from about 0.08 to about 0.19.

33. The topical composition defined in Claim 29, wherein the nanocryalline cellulose comprises a degree of oxidation is in the range of from about 0.05 to about 0.10.

34. The topical composition defined in Claim 29, wherein the nanocryalline cellulose comprises a degree of oxidation is about 0.08.

35. The topical composition defined in Claims 1-34, in the form of a cream composition.

36. The topical composition defined in Claim 35, wherein the cream composition comprises water and one or more of an emollient, an emulsifier, a thickener and a preservative.

37. Use of the topical composition defined in Claims 1-36 to protect the skin of a mammal from exposure to ultraviolet radiation.

38. Use of the topical composition defined in Claims 1-36 to protect the skin of a mammal from exposure to sunlight.

39. A kit comprising container having disposed therein the topical composition defined in Claims 1-36, the kit further comprising instructions to apply the topical composition to the skin of a mammal.