Evaluation of Sunflower Sprout Extract as a Bioinspired Support to UV Filtration

The photochemistry of a commercial sunflower sprout extract was compared to that of pure chlorogenic acid (3-O-caffeoylquinic acid), a key photoprotective species found in the extract. Steady-state and time-resolved spectroscopy experiments revealed virtually equivalent photodynamics between aqueous solutions of the sunflower extract and chlorogenic acid, namely ∼5 picosecond nonradiative deactivation following UV photoexcitation. For chlorogenic acid, this nonradiative deactivation is achieved by relaxation through a conical intersection, mediated through rotation around the caffeoyl CC double bond. These photophysical similarities tentatively justify the use of the unpurified sprout extract for use in UV photoprotective formulations and demonstrate that the environmental complexity conferred by the presence of other phytochemical constituents in the extract does not impede the relaxation mechanism of chlorogenic acid.