Evaluation of antioxidative effects of sesamin on the in vivo hepatic reducing abilities by a radiofrequency ESR method.

Antioxidative effects of sesamin (a mixture of sesamin and episesamin) were evaluated in the liver, kidney and inferior vena cava of living rats using a radiofrequency ESR method. TEMPOL, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, was used as an in vivo redox probe, the half-life of which is believed to be correlated with the antioxidant status. The oral administration of sesamin (250 mg/kg rat weight) 3 h before ESR measurements shortened the half-life of TEMPOL in the liver by 10 - 15% as compared with the controls, but did not affect the other organs. This effect was maintained for at least 3 h after the administration, and then disappeared at 24 h, corresponding to the results of our preliminary pharmacokinetic studies. Changes in the reducing ability were observed only in the hepatic sites of the sesamin-treated rats. These findings suggest that sesamin exhibits effective antioxidant activity in the liver via modulation of the intracellular redox status related to TEMPOL reduction.