Absorption and photo-stability of substituted dibenzoylmethanes and chalcones as UVA filters

Abstract

There is still an international need to develop broad-spectrum sunscreen products with an adequate UVB/UVA balance, while the approved filters available in the UVA are scarce. Currently, one of the few UVA filters approved in the United States and Europe is tert-butylmethoxydibenzoylmethane (BMDM, avobenzone). However, this compound is unstable from aphotochemical point of view and cannot be used in combination with certain sunscreens. In this paper, we investigate the photochemical behavior of a set of dibenzoylmethanes and chalcones. In particular, we carry out their absorption and emission spectra, evaluate their photochemical degradation, and study their generation of free radicals and singlet oxygen photoproduction. Two compounds resultedin having the basic properties of UVA filters (2'-hydroxy-4-methoxychalcone and 2'-hydroxy-4-methoxydibenzoylmethane). Further studies are proposed, such as formulating the compounds into emulsions or other common cosmetic presentations, as well as combining them with broadly-used UVB filters. We have also considered the need to establish its toxicological profile.