Evaluating the Antioxidant Efficacy of Sesame Lignans Using an in Situ Triacylglycerol Model Combined with the Rancimat Method

This study established a model system to evaluate the effectiveness of sesame lignans and their derivatives in enhancing oxidative stability. Sesame triacylglycerols (STAGs) were prepared by purifying sesame oil through silica gel column chromatography to remove polar components. Oxidative stability, determined by the induction period using the Rancimat method, significantly decreased after converting sesame oil into STAGs. The efficacy of examined compounds in retarding STAGs oxidation, in descending order, was tert-butyl-hydroquinone (TBHQ), propyl gallate, butylated hydroxytoluene, butylated hydroxyanisole, sesamol, sesaminol, and y-tocopherol. Induction period of STAGs fortified with TBHQ, comparable to sesame oil, was approximately three times longer than those fortified with sesamol or sesaminol. Dominant sesame lignans, sesamin and sesamolin, and sesamolin derivatives, 7R,7'S-samin and 7R,7'R-samin, showed negligible antioxidant effects at 200 mg/kg. Dose-dependent pro-oxidant behavior was observed in samin isomers at concentrations of 400 to 1,000 mg/kg. Chemical structures of lignans and derivatives played a crucial role in determining their in situ antioxidant effects on STAGs.