The effect of cepharanthine on radiation- and Fe2+-induced lipid peroxidation was examined. Cepharanthine and α-tocopherol inhibited radiation-induced lipid peroxidation of liposomes and Fe2+-induced lipid peroxidation of mitochondria. Cepharanthine reduced the velocity of Fe2+oxidation in the presence of mitochondria but not in the absence. α-Tocopherol strongly inhibited radiation-induced peroxidation of lipid dissolved in MeOH/CHCl3/H2O (v/v, 2/1/0.8) and Fe2+-induced peroxidation of lipid dissolved in MeOH. Cepharanthine, on the other hand, only weakly inhibited lipid peroxidation in the MeOH/CHCl3/H2O system, and did not inhibit peroxidation in the MeOH system.
The change in the absorption stectrum of α-tocopherol and cepharanthine by free radicals (X irradiation) was measured. The reagents were dissolved in 95% EtOH acidified with 20mM HCl and MeOH/CHCl3/H2O (v/v, 2/1/0.8). α-Tocopherol exhibited a change in its absorption spectrum in both systems and seemed to be oxidized at a higher rate by radicals. However, cepharanthine did not exhibit a change in its absorption spectrum in acidified 95% EtOH exposed to X irradiation, and slightly exhibited a chang in its absorption spectrum in MeOH/CHCl3/H2O exposed to X irradiation. From these observations, cepharanthine seemed not to exhibit a radical-trapping ability.
