Photosensitized isomerization of resveratrol: Evaluation of energy and electron transfer pathways

Free Radic Biol Med. 2024 Jan 23:S0891-5849(24)00046-7. doi: 10.1016/j.freeradbiomed.2024.01.038. Online ahead of print.ABSTRACTResveratrol (3,5,4'-trihydroxystilbene) is a natural stilbene synthetized as trans-isomer in plants exposed to oxidative stress. In order to understand the mechanism involved during photosensitized degradation of trans-resveratrol, steady-state and time-resolved experiments were performed and compared with quantum-chemical calculations using density functional theory (DFT). Pterin (Ptr), a well-known photosensitizer, under UV-A radiation induces the oxidation of several biomolecules mainly through electron-transfer mechanisms. On the one hand, it was observed that trans-RSV participates in an energy-transfer pathway with 3Ptr* forming 3trans-RSV*, which dissipates the energy by isomerization to cis-RSV. On the other hand, RSV neutral radical (trans-RSV(-H)•) was detected in laser flash photolysis experiments, indicating an electron-transfer mechanism. The electron-transfer from 3Ptr* to trans-RSV is a barely feasible reaction, however, more favorable is the formation of trans-RSV(-H)• in a reaction between trans-RSV and Ptr radical cation (Ptr•+), which is produced during irradiation. The combination of experimental and theoretical approaches evidences the capability of trans-RSV to undergo energy-transfer (feasible by DFT calculations) and/or one-electron transfer pathways with Ptr triplet excited state. These findings reveal the mechanisms in...
Source: Free Radical Biology and Medicine - Category: Biology Authors: Source Type: research