SOLVENT EFFECTS ON SPF AND BROAD-SPECTRUM PROTECTION 151 used UVB fi lters in the United States include benzophenone-3, octocrylene, homosalate, and ethylhexyl salicylate (7). Because of the aforementioned bans, we only selected the “coral-safe” UVB fi lters to study. Butyl methoxydibenzoylmethane is one of the most effi cient UVA- absorbing fi lters used around the globe, and it is the only UVA-absorbing organic fi lter approved in the United States. Because no single UV fi lter is capable of providing a high SPF and broad-spectrum protection, the combination of the three fi lters was tested as well. Solvents selected by FFE included isododecane and cyclomethicone (INCI: cyclotetrasi- loxane and cyclopentasiloxane) purchased from Making Cosmetics SymMollient PDCC® (INCI: propanediol dicaprylate/caprate), Corapan TQ® (INCI: diethylhexyl 2,6-naph- thalate), and Hydrolite (INCI: pentylene glycol) provided by Symrise Crodamol SFX® (INCI: PPG-3 benzyl ether ethylhexanoate), Cromollient ESP® (INCI: tris(PPG-3 benzyl ether) citrate), and super-refi ned castor oil provided by Croda (Mill Hall, PA) Kollicream IPM® (INCI: isopropyl myristate) and Myritol 318® (INCI: caprylic/capric triglyceride) provided by BASF (Florham Park, NJ) Eastman GEM® (INCI: 2-ethylhexyl palmitate) provided by Eastman (Miami, FL) AC Olive Oil Clear® [INCI: Olea europaea (olive) fruit oil] provided by Active Concepts (Lincolnton, NC) Finsolv TN® (INCI: C12-15 alkyl benzoate) provided by Innospec (Houston, TX) Lipex Shealight® (INCI: shea butter ethyl esters) provided by AAK (Karlshamn, Sweden) mineral oil (INCI: mineral oil) purchased from The Personal Formulator (Evanston, WY) sunfl ower seed oil [INCI: Helianthus annuus (sunfl ower) seed oil] purchased from Spectrum Chemical (New Brunswick, NJ) Schercemol 318® (INCI: isopropyl isostearate) provided by Lubrizol (Wickliffe, OH) LexFeel Natural® (INCI: heptyl undecylenate) provided by INOLEX (Philadelphia, PA) Hallbrite BHB® (INCI: butyloctyl salicylate), Hallstar DIPA® (INCI: diisopropyl adipate), SolaStay S1® (INCI: ethylhexyl methoxycrylene), and Polycrylene® (INCI: poly- ester-8) provided by Hallstar (Chicago, IL) Belsil DM 10® (INCI: dimethicone) provided by Wacker Chemie (Adrian, MI) and ethanol purchased from Decon Laboratories Inc. (King of Prussia, PA). METHODOLOGY FFE™ A search was made on UL Pro spector for a list of emollients commonly used as solvents for UV fi lters. The keywords used in the search included “sunscreen solvent,” “sunscreen solubilizer,” “sunscreen photostabilizer,” and “UV fi lter solvent.” Boosters are usually defi ned as ingredients that can signifi cantly increase the SPF without meaningfully contributing to SPF. Photostabilizers are molecules that can reduce or avoid the photodegradation of UV fi lters. Solvents are liquids used to dissolve ingredients in products, provide a vehicle for formulations, and also contribute to the texture of products. The same ingredient can often fulfi ll multiple functions. For example, photostabilizers often boost the overall SPF by preventing the UV fi lter from degradation, which makes them multifunctional ingre- dients. For simplicity purposes, we called all the ingredients screened and then selected for testing solvents. The UL Prospector search re sulted in 102 solvents. The solvents were entered into FFE us- ing their canonical simplifi ed molecular-input line-entry system (SMILES). Based on the SMILES, HSPs were generated and IAG was calculated. With FFE’s own default solvents,
JOURNAL OF COSMETIC SCIENCE 152 a total of 167 solvents were ranked for each UV fi lter and the blend of UV fi lters based on the IAG. In addition, we evaluated the ingredient list of 12 commercial sunscreens to understand which solvents/potential SPF booster ingredients they included. FFE predications and fi nd- ings from commercial products helped us select 24 solvents for this project (Table I). UV FILTER–SOLVENT MIXTURES Mixtures containing a ratio of 1:9 UV fi lter:solvent (w/w) were prepared for the in vitro SPF testing. One gram of UV fi lter was measured into a beaker on an analytical balance with a readability of 0.001 g, and 9 g of solvent was added to it. The beaker was placed on a magnetic stir plate and mixed at 650 rpm for 10 min for liquid UV fi lter–solvent mixtures. Solid UV fi lter–solvent mixtures were placed on a magnetic stirrer with hot plate at 85°C for 30 min at 650 rpm. In addition, another set of mixtures was created containing the maximum allowed con- centration of each UV fi lter (i.e., 15% of homosalate, 5% ethylhexyl salicylate, and 3% of butyl methoxydibenzoylmethane) per the OTC monograph (20). These mixtures contained Table I IAG between Each Solvent and UV Filter/UV Filter Blend Calculated by FFE™ INCI name IAG with H IAG with EHS IAG with BMDM IAG with UV fi lter blend 1 Isododecane 9.78 10.0 12.14 10.08 2 Cyclotetrasiloxane and cyclopentasiloxane 11.94 11.81 14.64 12.22 3 Olea europaea (olive) fruit oil 3.26 2.92 7.97 3.61 4 C12-15 alkyl benzoate 2.47 3.04 4.63 2.65 5 Shea butter ethyl esters 5.00 5.25 7.75 5.32 6 Mineral oil 5.08 5.19 8.13 5.42 7 Helianthus annuus (sunfl ower) seed oil 2.98 2.69 6.64 3.33 8 Isopropyl isostearate 4.79 4.67 8.10 5.12 9 Dimethicone 11.70 11.60 14.41 11.99 10 Heptyl undecylenate 5.01 5.22 7.82 5.33 11 Isopropyl myristate 4.53 4.66 7.57 4.87 12 Caprylic/capric triglyceride 6.23 6.67 8.46 6.52 13 Ethanol 15.49 14.53 17.54 15.48 14 Ricinus communis (castor) oil 5.90 6.09 7.97 6.11 15 Propanediol dicaprylate/caprate 3.76 3.69 6.96 4.07 16 2-Ethylhexyl palmitate 5.97 6.25 8.55 6.28 17 Diethylhexyl 2,6-naphthalate 4.10 4.44 6.71 4.39 18 Pentylene glycol 15.01 14.14 16.66 16.8 19 PPG-3 benzyl ether ethylhexanoate 3.54 3.88 6.44 3.87 20 Tris(PPG-3 benzyl ether) citrate 3.16 2.77 6.81 3.49 21 Butyloctyl salicylate 1.46 1.54 4.98 1.79 22 Diisopropyl adipate 3.67 3.13 7.12 4.11 23 Ethylhexyl methoxycrylene 0.98 1.98 3.42 1.08 24 Polyester-8 3.17 3.49 5.68 3.41 H: homosalate, EHS: ethylhexyl salicylate, BMDM: butyl methoxydibenzoylmethane. Values in italics denote excellent quality, in-bold denote poor quality, and those without formatting denote good quality.
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