The Coantioxidative Effects of Carboxyethyl-6-Hydroxychromans and α-Tocopherol

Abstract

α-Tocopherol (α-Toc) is abundant in LDL and thought to prevent the oxidation of LDL together with various water-soluble antioxidants. Recently, it was reported that α-Toc and γ-Toc metabolites, α-carboxyethyl-6-hydroxychromans (CEHC) and γ-CEHC, are water-soluble antioxidants. In this study, we investigated the interaction between α-Toc and CEHC against 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals and LDL oxidation. We administered 600 mg of α-Toc to healthy male volunteers to obtain LDL including high levels of α-Toc before antioxidant administration. The α-Toc content of their LDL was increased after consumption at 24 h (18.3 μg/mL) above the level before consumption (6.6 μg/mL). The lag time of LDL at 24 h after α-Toc consumption (α-Toc rich LDL) with α-CEHC (98.5±8.2 min) or γ-CEHC (101.3±9.0 min) was longer than that of only α-Toc-rich LDL (78.1±9.0 min). Furthermore, we examined the interaction of LDL with CEHC and α-Toc in vitro (5-20 μg/mL). The lag times of 5 and 10 μg/mL α-Toc were 65.5±18.9 min and 69.5±15.5 min, and that of 20 μg/mL α-Toc (83.5±20.2 min) was longer than the control value (55.7±14.1 min). The lag time of 20 μg/mL α-Toc with α-CEHC (98.7±25.7 min) or γ-CEHC (100.6±25.3 min) was longer than that of only α-Toc (83.5±20.2 min). These results suggest that CEHC has the potential to delay the oxidation of LDL, while enhancing the antioxidative activity of α-Toc both in vitro and ex vivo.