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729 Evaluation of negative effect of blue light on human skin and potential impacts on the dermi

      Premature skin aging evidenced by a rough skin texture and wrinkles is known to be driven by external factors, mainly by sunlight and in particular UV radiation including UVB (280-320 nm) and UVA (320-400 nm). However, recent advance highlighted the role of visible light and especially the blue light part (400-500nm) in skin aging. As the blue light is the highest energetic wavelength of the visible light, it penetrates deeper into the skin and damages the skin by inducing oxidative stress and production of proteases which degrade the extracellular matrix of the dermis. We first investigated the negative effects of the blue light in human dermis through the evaluation of MMP1 by immunostaining and image analysis on living skin biopsies exposed to blue light irradiation (peak at 250 nm-85 J/cm2). We further evaluated the blue light preventive effect of a botanical extract selected for its ability to prevent UVB induced oxidative damages by promoting DNA repair system (XPC, DDB2 & POLH) to reduce DNA damages (CPD) and decreasing inflammation (IL1a, PGE2 & LDH). The ingredient was topically applied at 2 mg/cm2 for 4 days before blue light irradiation. We demonstrated that the blue light significantly increases MMP-1 level by 24%, (p<0.001). The plant extract was able to significantly decrease by 43% this MMP-1 induced level (p<0.001 versus blue light control) and could protect collagen fibers from the deleterious effect of blue light. As blue light comes from the visible light spectrum of the sun, but its exposure is accentuated by increasing use of artificial sources of light including electronic devices such as cell phone and laptop computers or LEDs from modern habits, it is important to also take into consideration the role of the blue light exposure on skin premature aging to deliver efficient antiaging skin care protection.