Towards symmetry driven and nature inspired UV filter design

Abstract

In plants, sinapate esters offer crucial protection from the deleterious effects of ultraviolet radiation exposure. These esters are a promising foundation for designing UV filters, particularly for the UVA region (400 – 315 nm), where adequate photoprotection is currently lacking. Whilst sinapate esters are highly photostable due to a cis-trans (and vice versa) photoisomerization, the cis-isomer can display increased genotoxicity; an alarming concern for current cinnamate ester-based human sunscreens. To eliminate this potentiality, here we synthesize a sinapate ester with equivalent cis- and trans-isomers. We investigate its photostability through innovative ultrafast spectroscopy on a skin mimic, thus modelling the as close to true environment of sunscreen formulas. These studies are complemented by assessing endocrine disruption activity and antioxidant potential. We contest, from our results, that symmetrically functionalized sinapate esters may show exceptional promise as nature-inspired UV filters in next generation sunscreen formulations.

Sustainable Synthesis of p-Hydroxycinnamic Diacids through Proline-Mediated Knoevenagel Condensation in Ethanol: An Access to Potent Phenolic UV Filters and Radical Scavengers

“…Under these considerations, in this work, we therefore sought to develop a synthetic pathway that provides p-hydroxycinnamic diacids in high yield and at the multigram scale while being environmentally friendly. Moreover, with p-hydroxycinnamic diesters being reported as having high anti-UV and antioxidant properties [10,11,37], a specific focus has also been put on the evaluation of the radical scavenging and UV filtering capacities of the p-hydroxycinnamic diacids.…”

“…As these two possess a high structural similarity with sinapic diacid, we explored the UV potential of the p-hydroxycinnamic diacids previously obtained and benchmarked them against DES. (Figure 5) [10]. These bio-based molecules were highlighted as an exceptional promise for nature-inspired UV filters in next generation sunscreen formulations.…”

“…Spectra of the four diacids are reported in Figure 6 and their λ max were measured and are reported in Table 6. A recent work by Horbury et al focused on two sinapic acid derivatives: ethyl sinapate (ES) and diethyl sinapate (DES) ( Figure 5) [10]. These bio-based molecules were highlighted as an exceptional promise for nature-inspired UV filters in next generation sunscreen formulations.…”

“…Moreover, coumaric diacid, whose coverage is narrower than that of caffeic diacid, showed the higher absorbance intensity of the series. As described by Horbury et al for DES and ES, photostability is an important parameter when describing UV filters [10]. Indeed, an efficient UV filter must not lose its absorbance at λ max upon UV exposure.…”

“…In this context, lignin and related chemicals (e.g., lignans, phenolic acids) appear as a valuable source of sustainable aromatic building blocks [1,2]. Indeed, p-hydroxycinnamic acids and their derivatives can be readily extracted from different biomasses and be further (chemo-)enzymatically modified [3][4][5][6] to provide them with physicochemical and biological properties of interest in various fields, such as antioxidants [7][8][9] and anti-UV compounds [10][11][12]. However, p-hydroxycinnamic acids and their derivatives are not only poorly water soluble, but also they are usually present in relatively small quantities in biomass, thus greatly limiting their uses at the industrial scale.…”