Photoprotective activity assay toward ultraviolet B in human keratinocytes

Abstract

Design and discovery of novel sunscreens are of great importance to protect the human skin toward ultraviolet-induced damages because of the incidence of skin cancers that is believed to have increased depending on the depletion of the stratospheric ozone layer. Although ultraviolet A can penetrate deep into the human skin and provoke harmful influences such as photoaging, the formation of wrinkles, and sags and bags by destruction of collagen and elastin within the dermis layer, ultraviolet B can penetrate into epidermis and the upper layers of dermis and lead to the formation of much severe dermatological problems such as acute erythema, permanent pigmentations, and carcinomas. Human keratinocyte cells that are located into the stratum germinativum layer of epidermis can be therefore employed to investigate the in vitro photoprotective capacities of the sunscreens. Although there are many different photoprotective activity detection protocols, there is no a widely acknowledged protocol to determine the in vitro photoprotective capacity of sunscreen candidates. It was therefore contemplated to suggest an assay protocol to investigate comparatively the photoprotective and destructive activities of the sunscreen candidates.