Insights from computational simulations of sunscreen performance
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Presented by: Myriam Sohn
Introduction:
Computational performance simulations providing basic indeces of sun and UVA protection factors (SPF & UVA-PF) of selected UV-filter combinations became the first step of a suncare product development. This revolution was possible thanks to the development of an in-silico methodology, employing the same algorithm as in-vitro measurements, replacing measured by calculated transmittance data. The simulation uses quantitative UV spectra of all sunscreen UV-filter substances, the photointeraction properties between UV-filters, the oil/water phase repartition synergies and a model to describe the irregularity of the film distribution [1]. In this paper, we investigated the relevance and usefulness of computational simulations to predict criteria going far beyond basic SPF and UVA-PF estimations.
Methods:
First, we investigated the influence of six emollients with different polarity on the UV-filter absorbance and fed the measured emollient-dependent UV-filter spectra into the simulation tool to calculate the corresponding SPF and UVA-PF [2]. Simulations were also used to predict additional performance factors such as blue light and free radical generation protection. The light transmitted between 400 and 450nm is used for assessing the blue light protection of the corresponding filter combination. The protection against free radical generation is simulated comparably to the SPF replacing the erythemal action spectrum by the radical action spectrum. In a further experiment, the computanional model served to predict the water resistance by calculating the static and wet in-silico SPF of tested sunscreen based on in-vitro absorbance spectrum of tested sunscreen fed in the tool [3]. Finally, the impact of sunscreens on the environment can be calculated by weighting the specific environmental profile of tested UV-filter combination by the UV efficiency, obtained as the sum of calculated SPF and calculated UVA-PF divided by the total concentration [4].
Results:
The calculated SPF did not significantly differ for the tested emollients, but a slight increase of the calculated UVA-PF was observed with more polar emollients. It was also demonstrated that the estimated water-resistance based on the in-vitro absorbance spectrum of tested sunscreen is in good agreement with in vivo results. Furthermore, differences between different filter combinations on the calculated blue light protection, free radical generation protection and impact on the environment can be shown.
Discussion and Conclusion:
These experiments demonstrated the huge potential of model calculations that extend far beyond the prediction of the solely and standard SPF and UVA-PF values. In-silico methodology is a powerful tool to screen the effect of an unlimited number of UV-filter combinations on varied performance crietria without any costs and delay. It allows a selection of the most appropriate filter combination before proceedings with expensive laboratory tests.
[1] Herzog B., Osterwalder U. Simulaton of sunscreen performance. Pure Appl Chem 87 (2015) 937–951
[2] Sohn M. et al. Effect of emollients on UV fiter absorbance and sunscreen efficiency. J Photochem Photobiol B 205 (2020) 111818.1–8
[3] Sohn M. et al. In vitro water resistance testing using SPF simulation based on spectroscopic analysis of rinsed sunscreens. Int J Cosmet Sci 40 (2018) 217–225
[4] Pawlowski S. et al. EcoSun Pass: A tool to evaluate the ecofriendliness of UV filters used in sunscreen products. Int J Cosmet Sci 43 (2021) 201–210
Computational performance simulations providing basic indeces of sun and UVA protection factors (SPF & UVA-PF) of selected UV-filter combinations became the first step of a suncare product development. This revolution was possible thanks to the development of an in-silico methodology, employing the same algorithm as in-vitro measurements, replacing measured by calculated transmittance data. The simulation uses quantitative UV spectra of all sunscreen UV-filter substances, the photointeraction properties between UV-filters, the oil/water phase repartition synergies and a model to describe the irregularity of the film distribution [1]. In this paper, we investigated the relevance and usefulness of computational simulations to predict criteria going far beyond basic SPF and UVA-PF estimations.
Methods:
First, we investigated the influence of six emollients with different polarity on the UV-filter absorbance and fed the measured emollient-dependent UV-filter spectra into the simulation tool to calculate the corresponding SPF and UVA-PF [2]. Simulations were also used to predict additional performance factors such as blue light and free radical generation protection. The light transmitted between 400 and 450nm is used for assessing the blue light protection of the corresponding filter combination. The protection against free radical generation is simulated comparably to the SPF replacing the erythemal action spectrum by the radical action spectrum. In a further experiment, the computanional model served to predict the water resistance by calculating the static and wet in-silico SPF of tested sunscreen based on in-vitro absorbance spectrum of tested sunscreen fed in the tool [3]. Finally, the impact of sunscreens on the environment can be calculated by weighting the specific environmental profile of tested UV-filter combination by the UV efficiency, obtained as the sum of calculated SPF and calculated UVA-PF divided by the total concentration [4].
Results:
The calculated SPF did not significantly differ for the tested emollients, but a slight increase of the calculated UVA-PF was observed with more polar emollients. It was also demonstrated that the estimated water-resistance based on the in-vitro absorbance spectrum of tested sunscreen is in good agreement with in vivo results. Furthermore, differences between different filter combinations on the calculated blue light protection, free radical generation protection and impact on the environment can be shown.
Discussion and Conclusion:
These experiments demonstrated the huge potential of model calculations that extend far beyond the prediction of the solely and standard SPF and UVA-PF values. In-silico methodology is a powerful tool to screen the effect of an unlimited number of UV-filter combinations on varied performance crietria without any costs and delay. It allows a selection of the most appropriate filter combination before proceedings with expensive laboratory tests.
[1] Herzog B., Osterwalder U. Simulaton of sunscreen performance. Pure Appl Chem 87 (2015) 937–951
[2] Sohn M. et al. Effect of emollients on UV fiter absorbance and sunscreen efficiency. J Photochem Photobiol B 205 (2020) 111818.1–8
[3] Sohn M. et al. In vitro water resistance testing using SPF simulation based on spectroscopic analysis of rinsed sunscreens. Int J Cosmet Sci 40 (2018) 217–225
[4] Pawlowski S. et al. EcoSun Pass: A tool to evaluate the ecofriendliness of UV filters used in sunscreen products. Int J Cosmet Sci 43 (2021) 201–210