EPR spin trapping and DFT studies on structure of active antioxidants in biogycerol

Spin trapping EPR spectroscopy and DFT methods were used to investigate the structure of antioxidants present in bioglycerols [glycerol fractions (GF) derived from biodiesel production]. For this purpose the reactions of GF components and their pure reference chemicals with PBN and H2O2 were examined via EPR measurements. The EPR parameters of formed PBN spin adducts indicated the α-tocopherol origin of the trapped radicals. The comparative analysis of experimental and theoretically calculated hyperfine constants for the spin adducts strongly suggests the carbon-centered nature of the radicals generated and trapped by PBN in the bioglycerol systems.

The performed investigations suggest strongly the trapping of carbon-centered radicals from α-tocopherol in the bioglycerol systems.46Research highlights► Antioxidants in bioglycerols from biodiesel production have an α-tocopherol-like structure. ► After antioxidants exhaustion the lipid components of bioglycerol form PBN spin adducts. ► DFT prediction of aiso(1H) values suggests trapping of carbon-centered α-tocopherol radical.