The coantioxidative effects of carboxyethyl-6-hydroxychromans and alpha-Tocopherol

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