507 A high throughput method of identifying naturally-occurring sunscreen agents

Abstract

Ultraviolet radiation (UVR) is the major environmental risk factor for the development of skin cancer. Sunscreen agents mitigate this risk by preventing UVR from inducing direct and indirect mutagenic effects within skin cells, though current sunscreen formulations may have safety or aesthetic concerns. Natural products (i.e. derived from plants, algae, and other organisms that have evolved systems for photoprotection), may provide alternative compounds to the currently used synthetic sunscreen agents. In addition to their capacity to absorb UVR, selected natural compounds may also exhibit antioxidant and anti-inflammatory properties and provide a lower environmental impact. Prior investigation of photoprotective natural products has focused on characterizing individual compounds or classes of compounds known to be of interest. To more fully explore this potential, we developed a high-throughput assay for the efficient screening of natural products. We obtained 915 natural products from the NCI Natural Products Set and MicroSource Pure Natural Products libraries. The products were plated on 384-well plates and screened using spectrophotometry for absorbance in the UV spectrum (280-400nm) before and after exposure to UV light. We identified 220 products that showed both significant UVR absorbing capacity and photostability after UVR exposure. Follow-on screening of candidate agents includes a series of cytotoxicity, phototoxicity, and free radical scavenging assays to identify the most promising safe and effective natural products for their potential use as standalone photoprotective agents, or in combination with other sunscreens or cosmetic products to boost protection against UVR-induced damage.