DFT study of radical scavenging activity of sesame oil lignans and selected in vivo metabolites of sesamin

•The antioxidant activity of sesamin and related compounds were examined with DFT.•Non phenolic hydrogen atoms can be transferred to free radicals.•Reaction through hydrogen atom transfer affect molecular planarity.•Sesamin in vivo metabolites with catechol group are the most efficient antioxidants.•Sesamin metabolism lead to progressive loss of radical scavenging activity.