Daiokanzoto (DKT), a
Kampo medicine that includes the combination of two crude drugs (rhubarb and glycyrrhiza), is clinically effective for
constipation. The aim of this study is to clarify the influence of glycyrrhiza, three glycyrrhiza constituents (
glycyrrhizin,
liquiritin, and
liquiritin apioside), and eight
antibiotics on the
purgative action of DKT, rhubarb, or
sennoside A, a constituent of rhubarb, in mice. The
purgative actions of rhubarb and
sennoside A were significantly intensified when glycyrrhiza was co-administered orally to mice.
Liquiritin and
liquiritin apioside but not
glycyrrhizin showed significant amplification of the
purgative action in a dose-dependent manner. The
purgative actions of DKT and
sennoside A were significantly reduced by the pre-administration of
ampicillin, cefcapene pivoxil,
faropenem,
fosfomycin, or
kanamycin, but were not affected by the pre-administration of
clarithromycin or
levofloxacin. On the other hand, the
purgative action of
sennoside A was significantly reduced by the pre-administration of
minocycline, whereas that of DKT was not affected. The effect of
minocycline on the
purgative action of
sennoside A was lost when glycyrrhiza was co-administered. These results suggest that
liquiritin and
liquiritin apioside contribute as active substances for the
purgative action of DKT, and some
antibiotics reduce the
purgative action of DKT and
sennoside A. Furthermore, glycyrrhiza has the ability to recover the
purgative action of
sennoside A suppressed by
minocycline via an unknown mechanism.