Evaluation of the antioxidant capacity of lupin sprouts germinated in the presence of selenium

Abstract

Antioxidant capacity of 5 DAS (days after seeding) lupin sprouts germinated in the presence of selenate or selenite was determined by cyclic voltammetry (CV), Folin-Ciocalteu reagent (FCR) application and photochemiluminescence (PCL) methods. The hydrophilic (80% methanol) and lipophillic (hexane/methanol) extracts of 5 DAS lupin sprouts germinated in the absence of selenium (control sprouts) showed higher antioxidant capacity than ungerminated seeds. Five DAS sprouts produced in the presence of higher concentration of selenate or selenite (6–8 mg/L) showed increased total antioxidant capacity formed by both hydrophilic and lipohillic antioxidants when evaluated by CV and FCR methods. The hydrophilic extracts from sprouts produced in the presence of low concentration of selenate (2–6 mg/L) showed a significantly higher antioxidant capacity of water-soluble compounds (PCL ACW) while no changes were noted in those germinated in the presence of the highest concentration in relation to the control sprouts. In contrast, the antioxidant capacity of lipid-soluble compounds (PCL ACL) lowered significantly in relation to the control sprouts. The similar changes in antioxidant capacity of sprouts produced in the presence of selenite were found by both PCL assays. Comparison of PCL with CV and FCR reducing capacity assays has shown that these methods yielded considerably different chemical information. Moreover, the changes in total antioxidant and total reducing capacity of sprouts germinated in the presence of either selenate or selenite provided by CV and FCR assays were higher than those obtained by photochemiluminesce measurements. It can be suggested to use 6–8 mg/L of selenite rather than selenate in order to obtain a lupin sprouts with high antioxidant capacity.