A thermodynamic investigation of DPPH radical-scavenging mechanisms of folates

Folates are efficient antioxidants especially in reduced forms, with strong ability to scavenge diversified radicals (such as DPPH radical) and protect lipid from oxidation. However, it remains unknown how the radicals, e.g., DPPH radical, are scavenged by folates. Through theoretical calculations, it was revealed that H-atom transfer and sequential proton loss electron-transfer are more possible than electron-transfer/proton-transfer to be involved in DPPH radical-scavenging processes of folates. In addition, a quantitative structure-DPPH radical-scavenging activity relationship was established for the folates and the activity difference of oxidized and reduced folates was elucidated in terms of electronic effects of substituents.