MARINE INGREDIENTS
expression and to highlight the macro- alga extract’s action to reactivate SDF-1 expression.
In senescent conditions Senescence was induced for five days in skin explants from three independent donors by a daily systemic treatment with H2O2 to evaluate its impact on SDF-1 expression and on pigmentation. Explants were also daily treated or not with the macro-alga extract at 3%. SDF-1 immunostaining was then performed to quantify its expression, as well as Fontana Masson staining on the same explants to assess the melanin content, resulting in a pigmentation index via image analysis. Senescence clearly impacts the expression of SDF-1 (down to -34%), resulting in a hyperpigmentation in the explants (+50%). The macro-alga extract significantly restores SDF-1 expression in senescent fibroblasts, by +27%, resulting in a better control of the pigmentation, down to -26%.
Under UV-exposure Another model was developed to evaluate the impact of UV-exposure on SDF-1 expression and its potential consequences in terms of hyperpigmentation. Skin explants from three independent donors were daily exposed to UV (with a representative ratio UVA/UVB=27), at 75% of MED, and topically treated or not with the macro-alga extract at 3%. SDF-1 immunostaining was then performed to quantify its expression, as well as Fontana Masson staining on the same explants to assess the melanin content, resulting in a pigmentation index via image analysis. UV-exposure clearly impacts the expression of SDF-1 (down to -48%), resulting in a hyperpigmentation in the explants (+54%). The macro-alga extract significantly restores SDF-1 expression in UV-exposed fibroblasts, by +38%, resulting in a better control of the pigmentation, down to -25%.
Unique efficacy vs. benchmark molecules To prove the unicity of the macro-alga extract, the same senescence model than before (H2O2) was applied to a pool of two donors’ skin explants, comparing the efficacy of topical treatments with the macro-alga extract at 3%, or two reference molecules:
UNTREATED 100 -18%* 80 60 +78%*** 40 20 0 Untreated
Untreated +TBP
B-LightylTM 0.005% +TBP
B-LightylTM +TBP
Figure 2: ROS inhibition under oxidative stress. Mann Whitney test: ***p<0.001, *p<0.05
hydroquinone at 2% or phenylethyl resorcinol at 0.3%. SDF-1 expression was assessed at D5 thanks to immunostaining. The macro-alga extract is the only active able to reactivate SDF-1 expression in senescent skin conditions.
Antioxidant activity and its additional benefits on pigmentation Three tests, two ex vivo and one in vitro, have been realised to analyse the macro-alga extract performance.
ROS inhibition under oxidative conditions (in vitro) Normal human epidermal keratinocytes (NHEK) were treated with increasing concentrations of the macro-alga extract (0.005% and 0.01%), then exposed to an oxidative stimulus (tert-Butylhydroperoxide (TBP) - 5mM). The intracellular ROS accumulation was then evaluated using a fluorescent probe (DCFH-DA). It results that under oxidative stress (+78% ROS production versus untreated conditions), the macro- alga extract significantly decreases ROS
UV IRRADIATION
accumulation into the keratinocytes, down to -32% at 0.01%, with a dose-dependent effect.
Reduction of oxidised proteins content (ex vivo) Cryo-sections of skin explants, submitted to the same protocol of UV-exposure than before, were labelled with a specific fluorescent probe detecting carbonyl residues. Oxidised protein content was then quantified through image analysis. It results that a significant increase of the oxidised proteins can be observed after UV irradiation (+24%), demonstrating a loss of proteasome activity. The macro-alga extract significantly decreases the oxidised proteins content, down to -40%.
Decrease of lipofuscin accumulation (ex vivo) Similar cryo-sections of skin explants were stained with a Sudan Black B solution, the specific histochemical stain for lipofuscin (an aggregate of oxidised lipids, partly responsible for pigmentation spots). Lipofuscin content was then quantified through image analysis. After UV irradiation, a significant
UV IRRADIATION + B-LIGHTYLTM 3% 0.01% -32%*
47
■Oxidised proteins Figure 3: Reduction of oxidised proteins content (ex vivo).
www.personalcaremagazine.com April 2021 PERSONAL CARE
Student’s t-test: ***p<0.001, *p<0.05
ROS production after 1h (% of untreated + TBP)
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