Ultrafast Barrierless Photoisomerization and Strong Ultraviolet Absorption of Photoproducts in Plant Sunscreens.
Sunscreens are aimed at protecting skin from solar ultraviolet (UV) irradiation. By utilizing femtosecond transient absorption spectroscopy and time-dependent density functional theory, we explain nature's selection of sinapoyl malate rather than sinapic acid as the plant sunscreen molecule. In physiological pH conditions, the two molecules are deprotonated, and their excited ππ* states are found to relax to the ground states in a few tens of picoseconds via a barrierless trans-cis photoisomerization. After the cis-photoproduct is formed, the efficacy of sinapic acid is greatly reduced. In contrast, the efficacy of sinapoyl malate is affected only slightly because the cis-product still absorbs UV light strongly. In addition, protonated sinapic acid is found to be a good potential sunscreen molecule.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences , 457 Zhongshan Road, Dalian, Liaoning 116023, China.|University of the Chinese Academy of Sciences , Beijing 10049, China.
Jian
J
Luo
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences , 457 Zhongshan Road, Dalian, Liaoning 116023, China.|University of the Chinese Academy of Sciences , Beijing 10049, China.
Yan
Y
Liu
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences , 457 Zhongshan Road, Dalian, Liaoning 116023, China.
Songqiu
S
Yang
Chaire Agro-Biotechnologies Industrielles (ABI), AgroParisTech , CEBB 3 rue des Rouges Terres, 51110 Pomacle, France.|Institut Jean-Pierre Bourgin, INRA/AgroParisTech/CNRS/Université Paris-Saclay , Route de Saint-Cyr, 78026 Versailles, France.
Amandine L
AL
Flourat
Chaire Agro-Biotechnologies Industrielles (ABI), AgroParisTech , CEBB 3 rue des Rouges Terres, 51110 Pomacle, France.|UMR GMPA, INRA/AgroParisTech/CNRS/Université Paris-Saclay , Avenue Lucien Brétignières, 78850 Thiverval-Grignon, France.|Institut Jean-Pierre Bourgin, INRA/AgroParisTech/CNRS/Université Paris-Saclay , Route de Saint-Cyr, 78026 Versailles, France.
Florent
http://orcid.org/0000-0003-4132-6210
F
Allais
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences , 457 Zhongshan Road, Dalian, Liaoning 116023, China.
Keli
http://orcid.org/0000-0001-9239-1827
K
Han