Abstract
α-Tocopherol contained in human blood cells was oxidized by a photosensitized reaction in the presence of hematoporphyrin as a photosensitizer. Participation of singlet molecular oxygen, superoxide radical and hydrogen peroxide in the photooxidation was not so significant, although hematoporphyrin can generate singlet molecular oxygen on illumination. Quercetin inhibited the photooxidation of α-tocopherol. Both in the prescnce and in the absence of linoleicacid, photooxidation of α-tocopherol which was suspended in the PBS solution was also inhibited by quercetin. The rate of the photooxidation of α-tocopherol in the presence of linoleic acid was faster than that in the absence of the fatty acid. When quercetininhibited thc photooxidation of α-tocopherol contained in blood cells or suspended in PBS solution, quercetin was oxidized. The photooxidation of quercetin, which was suspended in the PBS solution, was inhibited by α-tocopherol in the absence of linoleic acid, but stimulated in the presence of the fatty acid.
