Effects of Food Constituents on Absorption and Bioaccessibility of Dietary Synthetic Phenolic Antioxidant by Caco-2 Cells.

One typical synthetic phenolic antioxidant 2,6-di-tert-butyl-hydroxytoluene (BHT) is widely used in foodstuff. Concerns are rising on the toxicity of BHT and its metabolites through dietary exposure. In this study, the effects of food macronutrients (i.e., lipid, carbohydrate, fiber, protein, and fasted (as control)) on absorption and bioaccessibility of BHT by Caco-2 cells were investigated. Food components decreased the absorption and bioaccessibility by Caco-2 cells. The highest absorption rate by Caco-2 cells was fasted state (first-order rate constant = 4.26 h-1), followed by carbohydrate (2.36 h-1), fiber (1.39 h-1), lipid (1.34 h-1), and protein (1.15 h-1). The order of bioaccessibility of BHT and its metabolites was fasted (100 ± 11.5%) > protein (83.1 ± 2.69%) > fiber (65.8 ± 2.67%) > carbohydrate (56.8 ± 1.58%) ≈ lipid (56.7 ± 0.82%). A solid-phase microextraction test together with a computational in vitro kinetic model suggested that the macronutrients may bind to BHT to reduce its free concentration and decrease the bioaccessibility. To our knowledge, this is the first study to report food influence on the absorption and bioaccessibility of BHT by Caco-2 cells. Results here can provide important implications for the safety regulation for dietary synthetic phenolic antioxidants.