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Research Summary Skin cells are constantly exposed to reactive oxygen species (ROS) and oxidative stress from both exogenous and endogenous sources. Among environmental factors, UV radiation is the most significant contributor to the development of skin cancer and skin aging. UV exposure primarily leads to direct DNA oxidation or the generation of free radicals, which form and decompose rapidly, but their effects can last for extended periods—ranging from hours to years.The UV-induced generation of ROS in the skin leads to oxidative stress when their formation exceeds the skin’s antioxidant defense capacity. To reduce oxidative stress, two approaches can be adopted:...

Research Summary Most vertebrates need vitamin D to develop and maintain a healthy mineralized skeleton. However, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the biologically active vitamin D metabolite, exerts a multitude of important physiological effects independent of the regulation of calcium and bone metabolism. Today, it is known that the skin has a unique role in the human body's vitamin D endocrine system. It is the only site of vitamin D photosynthesis, playing a central role in maintaining sufficient vitamin D levels. Additionally, the skin has the capacity to synthesize the biologically active vitamin D metabolite 1,25(OH)2D3 and serves as an important target...

Research Summary This study presents the association of active antioxidant substances in a multifunctional cosmetic formulation with established efficacy against signs of aging. A multifunctional cosmetic formulation containing a combination of UV filters and antioxidant substances (liposoluble vitamins A, C, and E, *Ginkgo biloba*, and *Porphyra umbilicalis* extracts) was evaluated.The formulation was subjected to a clinical efficacy study using biophysical techniques and skin image analysis (digital photography imaging systems, 20 MHz ultrasound, and reflectance confocal microscopy). The volunteers applied the formulation containing the UV filters and antioxidant substances during the day, and a version of the formulation without UV filters...

Research Summary Human skin has unique properties, one of the most apparent being its function as a physicochemical barrier. The human integument is able to resist the penetration of many molecules. However, smaller molecules, in particular, can surpass transcutaneously. They are able to pass through the corneal layer, which is thought to be the main deterrent. We argue that the molecular weight (MW) of a compound must be under 500 Daltons to allow skin absorption. Larger molecules cannot pass the corneal layer.Arguments for this "500 Dalton rule" are: 1) virtually all common contact allergens are under 500 Daltons, as larger...