Regulating the antioxidant activity of resveratrol through photoisomerization in different solvents: insights from experiment and DFT calculation

Exploring the impact of photoisomerization on the antioxidant activity of compounds is of great significance in fields such as medicine and daily chemical industry. Herein, the influence of photoisomerization on the antioxidant properties of resveratrol (RES) upon photoexcitation in different solvents was systematically investigated via 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging experiments and quantum chemistry computational methods. The frontier molecular orbitals and global descriptive parameters calculated using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods indicate that trans-RES exhibits higher reactivity in the S 0 state, while cis-RES shows enhanced reactivity in polar solvents under the S 1 state. Natural population analysis (NPA) charges and spin density distribution further confirm that cis-RES and trans-RES exhibit more reactive sites in the S 1 state. In addition, both theoretical and experimental results demonstrate that photoexcitation and increased solvent polarity significantly enhance the antioxidant capacity of RES. These findings highlight the modulation of antioxidant capacity by molecular configuration and environmental factors, providing fresh insights for the design and optimization of antioxidant compounds.