抄録
α-Tocopherol was reacted with the phosphatidylcholines (PCs), 1-palmitoyl-2-linoleoyl-3-sn-PC (PLPC), 1-palmitoyl-2-linolenoyl-3-sn-PC, 1-palmitoyl-2-arachidonoyl-3-sn-PC (PAPC) and 1-stearoyl-2-arachidonoyl-3-sn-PC, in the presence of the free radical initiator, 2,2′-azobis(2,4-dimethylvaleronitrile), at 37°C. The addition products of α-tocopherol with the PC peroxyl radicals were isolated and identified as 8a-(PC-dioxy)-α-tocopherones, in which the peroxyl radicals derived from each PC molecule attacked the 8a-position of the α-tocopheroxyl radical. The antioxidative efficiency of α-tocopherol against the peroxidation of PLPC and PAPC in liposomes was assessed by the formation of the reaction products of α-tocopherol. When α-tocopherol was oxidized in the presence of the water-soluble free radical initiator, 2,2′-azobis(2-amidinopropane) dihydrochloride, epoxy-α-tocopherylquinones were mainly produced together with 8a-(PC-dioxy)-α-tocopherones and α-tocopherylquinone. The yield of α-tocopherylquinone was increased by treating each sample with dilute acid which indicates the presence of tocopherone precursors other than the 8a-(PC-dioxy)-α-tocopherones. The same products were also detected from iron-dependent peroxidation, although the yields were very low.
