Antioxidants and Skin Protection (original) (raw)

Natural products have a long history of use for skincare and the improvement of the appearance and function of aged and/or damaged skin. Among them, bioactive peptides, oligosaccharides, plant polyphenols, carotenoids, vitamins, and polyunsaturated fatty acids are the most widely used ingredients. In recent decades, natural products have undergone rigorous testing, resulting in the identification of phytochemical compounds such as antioxidants with important potentials for the development of cosmetics, cosmeceuticals, and nutraceuticals. Supplementation with these products has been shown to have an effect on the signs of ageing in several human trials. In this Special Issue, up to 12 original manuscripts and a review are included, covering most of the topics related to the use of natural compounds for skincare and protection. This editorial aims to highlight the most relevant contributions of each single manuscript to the current "state of the art" and provide global significance for the use of antioxidants in skincare. Agulló-Chazarra and co-workers [1] have investigated the use of an agriculture by-product to obtain potential ingredients for the cosmetic industry. They have used sweet cherry stems, a novel by-product that has hardly been explored until now. In addition, they have developed an interesting approach, using a multistep procedure covering several aspects of antioxidant and related bioactive properties to select the best extract and propose it as an interesting ingredient for the cosmetic industry. Benincasa et al. [2] have used another raw material to develop their study; in this case, they have studied the use of olive oil by-products to obtain a pure compound, hydroxytyrosyl oleate (HtyOle), and then study its antioxidant and regenerative properties on human keratinocytes. The use of by-products from agriculture is really interesting, because it aligns with the Sustainable Development Goals of the United Nations for 2030 [3] and promotes the use and valorisation of non-previously or low-used materials for high-value applications. The photoprotective properties of natural products has been addressed by five of the original articles of this Special Issue as their central topic [4-8]. These articles show up the relevance of photoprotection not only in cosmetics but also in cancer research, as UV radiation is the main cause of some melanoma subtypes. In the first of these articles, Kuo et al. [4] focused on the role of N-(4-bromophenethyl)-caffeamide (K36H), a propolis derivative, as a protective compound against UVA-induced apoptosis. This compound has showed its antioxidant activity by reducing reactive oxygen species (ROS) generation and decreasing metalloproteinase expression, DNA damage, and inflammation. The authors has also identified the main molecular mediators of all these actions and provided a global mechanism of how K36H acts inside human keratinocyte cells. A similar approach has been used by Wu et al. in their contribution to this Special Issue [8], testing the photoprotective and anti-inflammatory properties of a sesamin derivative on human fibroblasts. Tavares and colleagues has used mouse fibroblasts, human keratinocytes, and full-thickness reconstructed human skin to demonstrate the photoprotective actions of fucoxanthin [7]. Their results show that this compound is able to reduce ROS even when used in a prototype of final formulation