Mode of action of sesame lignans in protecting low-density lipoprotein against oxidative damage in vitro

We investigated the antioxidant properties of sesaminol, a major component of sesame oil, on the oxidative modification of human low-density lipoprotein (LDL) in vitro. Sesaminol inhibited the Cu2+-induced lipid peroxidation in LDL in a concentration-dependent manner with an IC50 36.0 +/- 10.0 nM. Sesaminol was a more effective scavenger than either alpha-tocopherol or probucol in reducing the peroxyl radicals derived from 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) in aqueous solution. In addition, as determined by the secondary products of lipid peroxidation identified by using immunochemical methods, sesaminol completely inhibited the formation of 4-hydroxy-nonenal (4-HNE)- and malondialdehyde (MDA)-adducts in a concentration-dependent manner. Probucol and alpha-tocopherol at the same concentration exhibited a lesser inhibitory effect. Our findings suggest that sesaminol is a potentially effective antioxidant that can protect LDL against the oxidation.