58 SKIN MICROBIOME
melatonin (MT1R). Synchronight™ therefore behaves as a vegetal melatonin- like molecule, activating biological mechanisms of skin repair and defences, connected to the circadian rhythm, ultimately linked to the wellbeing. Synchronight (now referred to as
‘Gardenia fruit extract’) protects the cutaneous production of melatonin when skin is exposed to a digital stress thanks to its blue light absorbing properties. Melatonin can therefore achieve its natural role of fighting against the deleterious effects of digital pollution on premature skin ageing. But moreover, thanks to its activation by the skin microbiome into a vegetal melatonin-like molecule, Gardenia fruit extract can take an active part in skin defences and wellbeing mechanisms.
Protecting the skin from digital stress: anti-ageing efficacy In vitro tests have been realised to measure the protection of mitochondria network and cells spreading. Human dermal primary fibroblasts (57 years old donor) were treated with an equivalent of Gardenia fruit extract at 2% or left untreated. Cells were then loaded with Mitotracker green dye and seeded into a CYTOOplate™ with extra-large Y-micropatterns. After 2 hours of treatment, cells were irradiated with blue light for 1 hour at 20J/cm2
. Live imaging
analysis was performed to qualify the mitochondrial network, by measuring its characteristic metrics, and F-actin was stained to analyse the cells spreading. After exposure to blue light, the
mitochondrial network appears to be damaged. The network is less fragmented in presence of Gardenia fruit extract, demonstrating its protective effect. While blue light significantly decreases the characteristic dimensions of the mitochondrial network, Synchronight™ at 2% enables to significantly protect it, by increasing its length by +51% and reducing the number of branches by –19%. Cell spreading is also significantly affected by blue light, with a decrease down to -26% of correctly spread cells. Gardenia fruit extract at 2% is protecting significantly cells spreading (+20% cell area, +57% spread cells). Secondly, an ex vivo test was realised to
assess the reduction of oxidised proteins content. Human skin explants (35 year old donor) were cultured for 5 days in day/night cycles (12 hours of day / 12 hours of dark), with a 3 hours exposition to blue light for some of them (63,75 J/cm²). A dose equivalent to Gardenia fruit extract at 2% was topically applied on some of the explants exposed to blue light. On the last day, immunostaining of the oxidised proteins was performed and image analysis was used to quantify oxidised proteins content.
PERSONAL CARE ASIA PACIFIC Untreated Blue light
Blue light+ SynchronightTM
2%
Untreated Network lenght (um)
Nb of branches/ Total lenght
Untreated 454.1 0.464 Blue light
Blue light (-46%ooo
(-43%ooo 0.678
259.7 ) )
Blue light+ SynchronightTM
(+51%ooo 0.549
391.9 (-19%ooo
Blue light+ SynchronightTM
2% ) ) 2%
Figure 2: Protection of mitochondria network and cells spreading (in vitro), *** p<0.001 one way ANOVA test
After exposure to blue light, oxidised
proteins content significantly increases up to +93%. Gardenia fruit extract at 2% enables to significantly reduce proteins oxidation, by decreasing their content by -81%, close to basal level.
Protecting the skin from digital stress: melatonin cycle preservation Sensory neurons (derived from human induced Pluripotent Stem cells) and keratinocytes (derived from a 30 years old donor) were co-cultured under a cyclisation protocol (a drop in temperature to mimic the ‘night’ phase, together with a pause in glutamate use) during an in vitro test. At the end of D-3, a nutriment shock
was performed to synchronise the cells. At the end of D-1, a new shock was performed to initiate a new cycle on the synchronised co-culture. From this day, a
dose equivalent to Gardenia fruit extract at 4% was also added into the medium to one third of the culture samples. On D0 and D1, 30 minutes before the
‘night’ phase, two third of the co-cultured cells samples (including the ones treated with Gardenia fruit extract) were exposed to blue light (20 mJ/cm2
). The culture
supernatants were taken 30 minutes before the ‘night’ phase, then 2 hours, 5 hours and 8 hours after the shift to the “night” phase and an ELISA assay was performed to dose the amount of released melatonin. The synchronisation of the cells induces
a cyclisation of the release of melatonin after 24 hours (D1). The quantity of cutaneous melatonin is significantly increased after 2 hours, 5 hours or 8 hours in comparison to the level 30 minutes before the ‘night’ phase.
November 2020
t = 4 weeks
t= 0
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