Effects of chain length and saturation of triglycerides on cellular antioxidant activity of vegetable oil emulsions

Abstract

In this study, the cellular antioxidant activity (CAA) of α-tocopherol and γ-oryzanol was determined in two typical oil bases, namely rice bran oil base (RBOB) with long-chain unsaturated triglycerides and coconut oil base (CNOB) with medium-chain saturated triglycerides. The results showed that α-tocopherol and γ-oryzanol exhibited significantly higher CAA values in CNOB. In order to further explore the mechanism, glyceryl trioleate (GLT) and medium chain triglycerides (MCT) with similar structures to RBOB and CNOB respectively were added and compared. It was found that long-chain unsaturated triglycerides (RBOB and GLT) in emulsions exhibited lower CAA values than medium-chain saturated triglycerides (CNOB and MCT), though the former presented higher cellular uptake of minor constituents. It was speculated that unsaturated bond tended to be attacked by free radicals to initiate an oxidative chain reaction in HepG2 cells resulting in lipid peroxidation, thus depleted more antioxidants. Overall, these findings provided useful reference for further developing the production and processing of vegetable oil for better stability.