Enhancement of nitroxide-reducing activity in rats after chronic administration of vitamin E, vitamin C, and idebenone examined by an in vivo electron spin resonance technique.

Rats were given vitamin E (Vit-E), idebenone (ID), or vitamin C (Vit-C) in their food for 2 or 4 weeks. After feeding, the ability of rats to reduce 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol) in terms of the half-life of Tempol was examined as a specific marker. Tempol was repeatedly injected intravenously, and its half-life was serially evaluated by an in vivo electron spin resonance (ESR) technique. The radical-reducing ability in rats was enhanced differently by Vit-E, ID, and Vit-C, i.e., slow onset of the ability after Vit-E and ID (lipid-soluble antioxidants) and fast onset after Vit-C (a water-soluble antioxidant).