Changes of materials that scavenge 1,1-diphenyl-2-picrylhydrazyl radicals in plasma by per-oral administration of Kampo medicine, Ninjin-yoei-to in rats

The Kampo medicine, Ninjin-yoei-to, scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in a dose-dependent fashion as did ascorbic acid and α-tocopherol. Ninjin-yoei-to, which is composed of 12 herbs, had a potent DPPH radical scavenging ability. We investigated the transition of the materials that scavenge DPPH radicals in plasma after oral administration of Ninjin-yoei-to to rats. When 1.0 gkg^-1 Ninjin-yoei-to was administered, the DPPH radical scavenging ability increased at 30 min and biphasic peaks were observed at 2 h and at 10h. From the response-time profile, kinetic parameters including values for K_a (absorption rate constant), t_max (peak concentration time), t1/2 (half-life) and MRT (mean residence time) of the radical scavenging ability in plasma could be calculated for DPPH radicals. K_a values were 0.53 ± 0.03 and 0.36 ± 0.07 h, t_max values were 2.1 ± 1.04 and 8.56 ± 2.69 h, t1/2 values were 1.60 ± 0.12 and 3.39 ± 1.72 h, and MRT values were 4.14 ± 1.59 and 8.18 ± 2.55 h, respectively. These parameters calculated from the antioxidation dynamics were considered to offer a very meaningful procedure for examining the effects of Nihjin-yoei-to.