174 SKIN PROTECTION
whereas UVA penetrate the dermis and are responsible for extrinsic skin ageing. In order to protect the skin, formulators use, in finished cosmetic products, sunscreens that play the role of a ‘screen’ against the rays. The Sun Protection Factor (SPF) and the UVA
Protection Index (PF UVA) are indicators which reflect the ability of photoprotective filters and active agents, to protect the skin from UV rays by preventing their penetration. Photo stability indicates the potential of the formula to be stable under UV exposure. If the product is photo unstable, it could not be active anymore or become phototoxic. Moreover, sunscreen formulations using photo unstable filters systems may have a high potential of UV- inducible free radical production. An approximate SPF 20 formula12
70 60 50 40 30 20 10 0
+14%
+11% +43% +1% +24%
SPF Basal state
PF UVA Basal state
Figure 9: Anti-solar efficacy evaluation. containing
chemical sunscreens was used as a positive control. The ingredient was tested at 10% to evaluate SPF and PF-UVA before and after formula irradiation, allowing the determination of photo stability (Fig 9). The results have shown that Crocus sativus flower extract boosts the antisolar activity by increasing the SPF by 43%, the PF-UVA by 24% and the photo stability by 14%, after irradiation of the formula. Crocus sativus flower extract boosts anti-
solar property of cosmetic formulation made from chemical sunscreens and helps to photo stabilise it. Both biological skin activities and formulas are protected from the UV and its harmful impact.
Conclusion To conclude, Crocus sativus flower extract has proven its global photoprotective effect (Fig 10). Chronobiology protector, it preserves the circadian rhythm. Indeed, it restores the
rhythmicity of genes studied closer to physiological pattern expression. Its effect is global with an action on many actors of circadian clock modulation. This capacity could be interesting to fight signs of tiredness, jetlag, or more simply deregulation of the circadian rhythm after UV exposure. Furthermore, its antioxidant capacity allows
to protect skin from damages caused by UV and other resulting negative effects. The photoprotective power of Crocus sativus flower is proved in different biological targets: the stimulation of the barrier function through the transglutaminase-1 and the reduction of sunburn cells. These processes could be considered as skin’s defence mechanisms which protect the skin in its deep layers and even at the heart of cells. Finally, this plant extract boosts different solar parameters such as the SPF as well as improvement of sun care formulas’ photo stability.
By combining its two activities, Crocus
sativus flower extract protects both skin and formula: A complete extract for a complete photoprotection!
References 1 Pittayapruek P, Meephansan J, Prapapan O, Komine M, Ohtsuki M. Role of Matrix Metalloproteinases in Photoaging and Photocarcinogenesis. Int J Mol Sci 2016;17(6).
2 Geyfman M, Andersen B. How the skin can tell time. J Invest Dermatol 2009;129(5):1063-6.
3 Le Fur I, Reinberg A, Lopez S, Morizot F, Mechkouri M, Tschachler E. Analysis of circadian and ultradian rhythms of skin surface properties of face and forearm of healthy women. J Invest Dermatol 2001;117(3):718-24.
4 Matsui MS, Pelle E, Dong K, Pernodet N. Biological Rhythms in the Skin. Int J Mol Sci 2016;17(6).
5 Hardman JA, Tobin DJ, Haslam IS, Farjo N, Farjo B, Al-Nuaimi Y, et al. The peripheral clock regulates human pigmentation. J Invest Dermatol 2015;135(4):1053-64.
6 Matsunaga N, Itcho K, Hamamura K, Ikeda E, Ikeyama H, Furuichi Y, et al. 24-hour rhythm of aquaporin-3 function in the epidermis is regulated by molecular clocks. J Invest Dermatol 2014;134(6):1636-44.
7 Poljšak B, Dahmane R. Free Radicals and Extrinsic Skin Aging. Dermatology Research and Practice 2012;2012:135206.
8 Sharma OP, Bhat TK. DPPH antioxidant assay revisited. Food Chemistry 2009;113(4):1202-5.
9 Takagi Y, Nakagawa H, Kondo H, Takema Y, Imokawa G. Decreased levels of covalently bound ceramide are associated with ultraviolet B-induced perturbation of the skin barrier. J Invest Dermatol 2004;123(6):1102-9.
10 Eckert RL, Sturniolo MT, Broome AM, Ruse M, Rorke EA. Transglutaminase function in epidermis. J Invest Dermatol 2005;124(3):481-92.
11 Ziegler A, Jonason AS, Leffellt DJ, Simon JA, Sharma HW, Kimmelman J, et al. Sunburn and p53 in the onset of skin cancer. Nature 1994; 372(6508):773.
Figure 10: Schematic representation of Crocus sativus flower extract in the skin. PERSONAL CARE EUROPE
12 Feng F, Zlotnik D, Zhang Eileen. Photostabilisation: for safe, pleasant sunscreens. Personal Care Europe 2018;12(5);53-58.
April 2019 PC
PF UVA
SPF
Photo stability Positive control CS extract at 10%
UV irradiation
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