90 SKIN PROTECTION a b c
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A Explants non irradiated and non treated : no observation of sun burn cells B Explants irradiated and non treated : observation of sun burn cells C Explants irradiated and treated by SPF 50 cream: no observation of sun burn cells D Explants irradiated and treated by placebo: presence of several sun burn cells E Explants irradiated and treated by 2.5% SA: observation of rare sun burn cells F Explants irradiated and treated by 5% SA: no observation of sun burn cells.
Figure 1: Observations of sun burn cells on human skin explants submitted to irradiation UVA+UVB. phototoxic. It contains different carotenoids:
β-carotene (0,34mg/100g), free astaxanthin (1,96mg/100g) and other carotenoids (0,27mg/100g). For ex vivo studies, SA was included in a basic Carbopol gel at various doses.
Number of sun burn cells Basic Carbopol gels with or without addition of the microalgal complex (SA 2.5% or 5%) were applied on human skin explants (30 µl/explant) for 24h (2 explants by experimental condition). Explants (from Caucasian femelle 31 years old) were irradiated (UVA 8 J/cm² + UVB 200 mJ/cm²) then treated again for 24h. The positive control is a commercially available cream SPF 50.
ROS release by blue light In vitro studies were performed on normal human fibroblasts in culture. Blue light irradiation has been applied at 453 nm with a dose 5 J / cm² after 24h treatment with SA (doses 0.025% and 0.005%) or with reference standards: Vitamin C (dose 500 µM) and vitamin E (dose 200 µM).
Elastin fibres under blue light exposure Ex vivo studies were performed on human skin explants pre-treated 24h with either placebo or basic Carbopol gel containing
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2.5% SA. They are then irradiated 3 times with blue light (453 nm- 5 J/cm²) with a treatment interval of 24h between each irradiation. This repetitive procedure appears closer to the regular daily blue light exposure.
Immunolabelling of elastin has been done with specific antibody directed against elastin and of nuclei with DAPI (Roche). Observations have been performed by fluorescence and images made with the x40 lens.
Protein carbonylation under blue light exposure Ex vivo studies were performed on human skin explants pre-treated 24h with either placebo or basic Carbopol gel containing 2.5% SA. They are then irradiated 3 times with blue light (453 nm- 5 J/cm²) with a treatment interval of 24h between each irradiation, as in the previous study. Immunolabelling of oxidised proteins has been done with specific fluorochromes (DNPH) and of nuclei with DAPI (Roche). Observations have been performed by fluorescence and images made with the x40 lens.
Results and discussion When UV rays reach the skin, they damage cells as blue light exposure but not in the same way.
Results presented here after show that the natural ingredient using microalgae (SA) was able to prevent some of the damage.
SA reduces the number of sun burn cells Sun burn cells are keratinocytes undergoing apoptosis after a UVB irradiation. Their formation appears as a consequence of UVB-induced DNA damages. Results are illustrated in Figure 1.
Sun burn cells are shown with *. Using skin explants, we demonstrate that SA formulated in a basic Carbopol gel is highly efficient against the formation of sun burn cells. At the dose of 5 % it shows a similar efficacy to the trade cream SPF 50. This result is more interesting as it is a basic formulation compared to the one of the trade cream.
SA inhibits the formation of reactive oxygen species generated by blue light The irradiation of skin cells with visible light, in doses comparable to 15–90 minutes of sunlight exposure, elicits a similar response to that induced by UV radiation in terms of inflammation, ROS production and the release of matrix-degrading enzymes.10 Blue light at different wavelengths may induce varied degrees of intracellular oxidative stress.11
be dose- and cell-type dependent.12 produced by blue light would probably be
Induced ROS levels would ROS
November 2019
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