These materials are proposed as octinoxate replacements, whose reef-friendly status has recently been called into question. In fact, as previously reported, in 2021, the State of Hawaii will ban the sale of sunscreens containing this organic UV filter. There is thus a pressing need for alternative UV filters offering safety and efficacy for users and the environment.
In this context, these authors point to p-hydroxycinnamic esters derived from naturally occurring sinapic acid via Knoevenagel–Doebner condensation. According to the article abstract, a wide library of these materials is available and they show promising UVB protection and antioxidant efficacy. Details of their synthesis and UV/antioxidant testing are disclosed in the full open access article.