Oxidation of low-density lipoprotein (LDL) by reactive oxygen species (ROS) and reactive nitrogen species (RNS) has been suggested to be involved in the onset of atherosclerosis. Oolong tea contains unique polyphenols including oolonghomobisflavan A (OFA). In this study, the effects of OFA on LDL oxidation by ROS and RNS were investigated in vitro. OFA suppressed formation of cholesterol ester hydroperoxides in LDL oxidized by peroxyl radical and peroxynitrite, and formation of thiobarbituric acid reactive substances in LDL oxidized by Cu. In addition, OFA inhibited fragmentation, carbonylation, and nitration of apolipoprotein B-100 (apo B-100) in the oxidized LDL, in which heparin-binding activity of apo B-100 was protected by OFA. Our results suggest that OFA exhibits antioxidant activity against both lipid peroxidation and oxidative modification of apo B-100 in LDL oxidized by ROS and RNS. Polyphenols in oolong tea may prevent atherosclerosis by reducing oxidative stress.

Abbreviationsapo; apolipoprotein, AAPH; 2,2'-azobis (2-amidinopropane) dihydrochloride, CE-OOH; cholesteryl ester hydroperoxides, DPPH; 2,2-diphenyl-1-picrylhydrazyl, HNE; 4-hydroxy-2-nonenal, HPLC; high-performance liquid chromatography, LDL; low-density lipoprotein, oxLDL; oxidized LDL, PBS; phosphate buffered saline, ROS; reactive oxygen species, SDS-PAGE; sodium dodecyl sulfatepolyacrylamide gel electrophoresis, TBARS; 2-thiobarbituric acid reactive substances, YE; yabumame bean extract. Yabumame, a legume family member, similar to hog-peanut, is an important traditional food for the Ainu people of Japan. However, its nutritional components and bioactivities are unknown. It has been suggested that low-density lipoprotein (LDL) oxidation by reactive oxygen species (ROS) may be a key factor in the onset of atherosclerosis.In this study, we evaluated the antioxidant activity of yabumame extract (YE) against LDL oxidation in vitro. vessel wall by reactive oxygen species (ROS), such as superoxide anions, hydroxyl radicals, peroxyl radicals, and peroxynitrite may be an early event in the development of atherosclerosis; however, the mechanisms of LDL oxidation in vivo remain unclear (Halliwell and Gutteridge, 2007;Peluso et al., 2012). The major targets of ROS in LDL are polyunsaturated fatty acid residues of phospholipids, cholesterol esters, and triacylglycerol (Arai, 2014). Total polyphenol content in