Kampo formulations are widely used in the treatment of many inflammatory diseases, including ulcerative colitis. It has been reported that the herbal compound, orengedokuto (OGT), as well as one of its herbal components, a Scutellariae Radix, was able to suppress inflammation in a mouse model of DSS-induced colitis. However, there have been no studies of the effects of any other Kampo formulations that may have direct anti-inflammatory activity in this model. Furthermore, there is no available information regarding the effects of Kampo medicines that have been formulated with omission of a single specific herb.
In this study, the anti-inflammatory activity of thirteen Kampo formulations was screened in a DSS-induced murine colitis model. We observed suppression of the shortening of the colon and a decrease in MPO activity, which we believe to be due to the anti-inflammatory activity of saireito (SRT). In addition, we investigated the anti-inflammatory activity of shosaikoto (SST) and goreisan (GRS), which are the two components of SRT. Neither SST nor GRS alone showed anti-inflammatory activity in this model, indicating that the combination of these two compounds is necessary for the anti-inflammatory activity of SRT. Finally, we examined whether SRT retained its anti-inflammatory properties after various specific herbs were eliminated from the formulation. Unlike OGT, the anti-inflammatory activity of SRT was still present after removal of Scutellariae Radix from the formulation. Alternatively, SRT that lacked Bupleuri Radix did not retain any anti-inflammatory activity.
These results imply that the anti-inflammatory activity of SRT on DSS-induced murine colitis is dependent on the inclusion of Bupleuri Radix or the combination between Bupleuri Radix and other herbs.
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