Urocanic acid as an efficient hydroxyl radical scavenger: a quantum theoretical study

摘要: The photoisomerization of urocanic acid (UCA)—which is present in human skin epidermis, where it acts as a sunscreen—from its trans isomer to cis upon exposure UV-B radiation known cause immunosuppression. In recent years, the antioxidant properties UCA (it hydroxyl radical scavenger) have also been recognized. view this, mechanisms stepwise reactions trans-UCA with up four radicals were investigated. molecular geometries different species and complexes involved (reactant, intermediate product complexes, well transition states) optimized via density functional theory gas phase. Solvation aqueous media was treated single point energy calculations using DFT polarizable continuum model. Single phase carried out second-order Moller–Plesset perturbation (MP2). AUG-cc-pVDZ basis set employed all calculations. Corrections for superposition error (BSSE) applied. Vibrational frequency analysis performed each structure ensure validity states. It found that binding first OH· involves positive barrier, while subsequent are exergonic. Transition states successfully located, even those cases barrier energies be negative. cis–trans isomerization addition comparable, meaning both processes can occur simultaneously. could serve an form efficient scavenger.