It also reduced the enhancement of collagenase 2 mRNA expression induced by SSR exposure. Mexoryl ® SX formulations also prevented or significantly decreased to minimal, ferritin, tenascin and lysozyme expression induced by repeated UVA or SSR exposure. In the studies looking at the suppression of DTH reactions to recall antigens by the different UV spectra, the LC alterations and the cis UCA formation, Mexoryl ® SX formulations always showed a higher protective potency than sunscreen without it even when the protection against erythema was similar (products with same SPF). Pyrimidine dimer formation and p53 accumulation were significantly reduced by formulations with Mexoryl ® SX. For a same sun protection factor (SPF) the higher the UVA protection was, the higher was the PPF. Results: Mexoryl ® SX-containing formulations showed a dose-dependent level of protection against pigmentation. Prevention of the polymorphous light eruption (PMLE) in patients prone to develop this disease. Reduction of epidermal and dermal alterations induced by repeated UVA or UV solar simulated radiation (SSR) using histology or immunohistology. Protection of immune system using delayed type hypersensitivity (DTH) reactions to recall antigens, isomerization of urocanic acid (UCA), alteration of Langerhans cells (LC) density, morphology and function. Prevention of excessive pigmentation induced by UV exposure in Caucasian and Asian skins using a method that measures pigmentation protection factors (PPF).Įfficacy against DNA damage by measurement of pyrimidine dimer formation and p53 protein accumulation. Methods: The following assessments were conducted: As a consequence, to provide adequate protection, sunscreens or skin care products for daily use protective products need UVA absorbers combined with UVB ones.Īim: To assess the efficacy of sunscreens containing a broad-spectrum UVA absorber the Mexoryl ® SX or ecamsule and to compare formulations with and without it through a large number of clinical studies in human volunteers and patients. Moreover UVA is implicated in the etiology of several photodermatoses. It alters immune function, pigmentation and it is certainly responsible for a large part of photoaging changes. In preliminary studies, this approach was applied to the late-stage modifications of long peptides and the iterative synthesis of short, N-methylated peptides without the need for coupling agents.Background: UVA exposure of human skin mainly produces reactive oxygen species (ROS) leading to DNA, cell and tissue damage. The unique nature of the neutral, zwitterionic TIMs makes possible the preparation of tertiary amides via an iminium species that would not be accessible from other carbonyl derivatives and can be conducted in the presence of unprotected functional groups including acids, alcohols and thioethers. The overall transformation can be conducted either as a one-pot procedure or via isolation of the TIM. TIMs are easily prepared by acid-promoted condensation of potassium acyltrifluoroborates (KATs) and amines and are cleanly and rapidly oxidized to amides with hydrogen peroxide. As an alternative to both secondary and tertiary amides, we report their convenient synthesis by the rapid oxidation of trifluoroborate iminiums (TIMs). Although highly effective for most amide syntheses, the activation of carboxylic acids requires the use of problematic coupling reagents and is often poorly suited for challenging cases such as N-methyl amino acids.
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