“…[8][9][10] It has been indicated that oxygen free radicals such as superoxide radical, hydroxyl radical, and singlet oxygen participate in enzymatic lipid peroxidation in rat liver microsomes. [27][28][29][30][31][32][33][34] We have observed that when the effects of superoxide dismutase, catalase, hydroxyl radical scavengers such as mannitol, sodium formate, and dimethylthiourea, and singlet oxygen quenchers such as histidine, diazabicyclooctane, and diphenylfuran, on enzymatic lipid peroxidation in rat liver microsomes used in the present study are examined, singlet oxygen quenchers inhibit peroxidation by more than 90%, while superoxide dismutase, catalase, and hydroxyl radical scavengers inhibit it by less than 20% (unpublished data). These results are consistent with those reported by Wright et al 34) who have proposed the involvement of singlet oxygen in the initiation of enzymatic lipid peroxidation in rat liver microsomes.…”