58 SUN PROTECTION
increase the physiobiological skin’s production of antioxidants by 42%, under UV(A+B), compared to without. By boosting the natural capacity of skin to produce antioxidants, through biomimetic pathways, the Haematococcus active ingredient is able to protect the skin from oxidative damages induced by external aggressions, such as UV light.
Evaluation of the ability of the Haematococcus active to act as SPF booster With the increase of consumer awareness of the risks of harmful excess exposure to UV rays, the use of cosmetic products with a high SPF is growing. SPF products are still widely used during the summer season, nevertheless, there has been a transition from a three-month consumer cycle to a year-round cycle. Following the ‘skinification’ trend,
formulations begin to blur the lines between skincare products and suncare products. Hybrid products, such as tinted moisturizers with SPF, are becoming more popular with the increase of use of SPF 24/7. To develop this kind of everyday SPF formulas, avoiding the use of a large amount of UV filters in the formula, sun protection boosters (also called ‘SPF booster’ or ‘UV booster’) have become popular to improve the effectiveness and add interesting properties for the skin to the SPF formula. Previous tests confirming that the
Haematococcus active is able to stimulate the natural production of antioxidants under UVA/UVB exposure leads to explore its effectiveness as an SPF booster using in vitro and in vivo tests. The assessment of the level of protection
of a cosmetic formulation containing sun filters, with the addition of different concentrations of the Haematococcus active, has been evaluate in order to determinate the ability of the active to boost the initial SPF by, first, an in vitro spectrophotometric method, based on ISO 24443:2021 principles, adapted for the sun protection factor “SPF”, the UVA protection factor “PF-UVA”, and the critical wavelength “CW” determination. In a second time, the measurement of the minimal erythemal dose induced by UV radiation, with different concentrations of the Haematococcus active added to a cosmetic formulation containing sun filters, has been conducted. Firstly, the placebo formula as well
as the formulas with 2% and 4% of the Haematococcus active have been irradiated to study the photostability. If the two curves overlap (before and after irradiation), the product is considered stable. The three formulae show a good stability
profile after irradiation. In particular, the formulas with 2% and 4% of the sunscreen Haematococcus active show an excellent photostability (better than placebo) meaning that the Haematococcus active is perfectly photostable and is able to stabilize the formula (Figures 8, 9 and 10). Then, the in vitro SPF and the in vitro UVA protection (PFUVA) has been determined. Starting with 2% of the Haematococcus active, the SPF is already increased by 26.3%
PERSONAL CARE March 2024 Before irradiation ■ After irradiation ■
1.6 1.4 1.2 1
0.8 0.6 0.4 0.2 0
290 297 304 311 318 325
332 339 346 353 360 367 Longueurs d'ondes / Wavelenght (nm)
374 381 388 395 Figure 8: UV absorbance spectra of the placebo sunscreen, before and after UV irradiation Before irradiation ■ After irradiation ■
1.6 1.4 1.2 1
0.8 0.6 0.4 0.2 0
290 297 304 311 318 325
332 339 346 353 360 367 Longueurs d'ondes / Wavelenght (nm)
374 381 388 395
Figure 9: UV absorbance spectra of the active sunscreen, with 2% of the Haematococcus active, before and after UV irradiation
Before irradiation ■ After irradiation ■
1.6 1.4 1.2 1
0.8 0.6 0.4 0.2 0
290 297 304 311 318 325
332 339 346 353 360 367 Longueurs d'ondes / Wavelenght (nm)
374 381 388 395
Figure 10: UV absorbance spectra of the active sunscreen, with 4% of the Haematococcus active, before and after UV irradiation
and reaches 30.4% of increase with 4% (Figure 11). These results show the ability of the active to boost SPF of a formula indicating an SPF 20. The formulation with 4% of the Haematococcus active may display an SPF 25 as well as the UVA logo, because the corrected ratio ≤ 3 is respected. All sun protection factors (SPF, Ratio SPF displayed/UVA, CW) are compliant.
Regarding the in vivo determination of the
sun protection factor (SPF) according to the ISO 24444:2019 Cosmetics — Sun protection test methods — of the sun protection factor (SPF), with 2% of the Haematococcus active, the SPF is already increased by 25% and reaches 32% of increase with 4%, compared to placebo (Figure 12).
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