Polyphenolic sunscreens for photoprotection

Polyphenols are a class of compounds widely existing in living species ranging from plants, fungi, and bacteria to animals, and possess various interesting functions such as anti-inflammatory, immunomodulatory, anti-oxidative and anti-ultraviolet properties. Especially, excellent ultraviolet absorption and outstanding free radical scavenging ability lead to extensive development and application in sunscreens. More importantly, the unique structural and functional features of polyphenols allow further integration with other molecules towards the design and preparation of hybrid sun-protective active ingredients, which have expanded the scope of polyphenolic sunscreens. This review details the role of polyphenols as structural and functional synthons in sunscreen materials and illustrates the various sunscreen forms with typical examples. In addition, the current challenges and further perspectives of polyphenols in sunscreens have also been carefully discussed. We believe that this review will continue to stimulate further design and development of the next-generation bioinspired and robust sunscreens via the rational integration of polyphenolic materials.