Natural Antioxidants: Multiple Mechanisms to Protect Skin From Solar Radiation

Abstract

Human skin exposed to solar ultraviolet radiation (UVR) results in a dramatic increase in the production of reactive oxygen species (ROS). The sudden increase in ROS shifts the natural balance toward a pro-oxidative state, resulting in oxidative stress. The detrimental effects of oxidative stress occur through multiple mechanisms that involve alterations to proteins and lipids, induction of inflammation, immunosuppression, DNA damage, and activation of signaling pathways that affect gene transcription, cell cycle, proliferation, and apoptosis. All of these alterations promote carcinogenesis and therefore, regulation of ROS levels is critical to the maintenance of normal skin homeostasis. Several botanical products have been found to exhibit potent antioxidant capacity and the ability to counteract UV-induced insults to the skin. These natural products exert their beneficial effects through multiple pathways, including some known to be negatively affected by solar UVR. Aging of the skin is also accelerated by UVR exposure, in particular UVA rays that penetrate deep into the epidermis and the dermis where it causes the degradation of collagen and elastin fibers via oxidative stress and activation of matrix metalloproteinases (MMPs). Because natural compounds are capable of attenuating some of the UV-induced aging effects in the skin, increased attention has been generated in the area of cosmetic sciences. The focus of this review is to cover the most prominent phytoproducts with potential to mitigate the deleterious effects of solar UVR and suitability for use in topical application.

Transepidermal UV radiation of scalp skin ex vivo induces hair follicle damage that is alleviated by the topical treatment with caffeine

“…HFs, to sunlight and promises important new insights on how topically administered cosmeceuticals impacts on these. In line with previous results in vivo , UV radiation induces skin cytotoxicity, and epidermal damage in our model. In addition, in our model, in concurrence to previous reports , caffeine protects/reverses most of such effects.…”

“…UVR triggers skin cytotoxicity and epidermal damage . To confirm the clinical relevance of our improved ex vivo model, skin and epidermal UV‐mediated responses were analysed.…”

“…Since UV‐mediated oxidative stress also contributes to skin cytotoxicity , we studied whether UVR penetrating the skin causes HF cytotoxicity and dystrophy by evaluation of melanin clumping in the HF bulb . A significant increase in melanin clumping was observed in the hair bulbs on day 3 after low UV irradiation (Figure c,d).…”

“…Solar ultraviolet (UV) radiation encompasses three sub‐categories of rays of different wavelengths: long wave UVA (320–400 nm), medium wave UVB (280–320 nm), and short wave UVC (100–280 nm). As more than 99% of UVC is absorbed by the ozone layer, only UVA and UVB reach the earth′s surface and impact on biological and pathological processes, especially within the organism's integuments . Although UVA penetrates into the dermis, UVB is almost completely absorbed by the epidermis .…”

“…En outre, il a diminu e la prolif eration et favoris e l'apoptose de la gaine externe de la racine (ORS) du FP et des k eratinocytes de la matrice des cheveux (MC), a stimul e le d eveloppement de la phase catag ene, a r egul e de mani ere diff erentielle l'expression des facteurs de Introduction Solar ultraviolet (UV) radiation encompasses three sub-categories of rays of different wavelengths: long wave UVA (320-400 nm), medium wave UVB (280-320 nm), and short wave UVC (100-280 nm). As more than 99% of UVC is absorbed by the ozone layer, only UVA and UVB reach the earth 0 s surface and impact on biological and pathological processes, especially within the organism's integuments (1)(2)(3). Although UVA penetrates into the dermis, UVB is almost completely absorbed by the epidermis (2,4,5).…”