Traditional Japanese herbal, or Kampo medicine was developed and modified from Chinese herbal medicine. After the Japanese
government approved Kampo for clinical use, much attention has been paid to establishing scientific evidence for the effectiveness
of these medicines. Recent progress has been made in elucidating the mechanisms of action of some types of Kampo medicine, including
rikkunshito (RKT), daikenchuto, and yokukansan. In this review, we focused on identifying the target molecules and the active ingredients
Thus far, many target molecules have been implicated in the mechanism of action of Kampo medicines, such as ion channels, enzymes,
and receptors. In particular, G protein-coupled receptors are attractive candidates for explaining herbal medicine activity. This is particularly
true of RKT, which is composed of 8 independent, crude drug extracts. Recent reports have shown that RKT elicits its effects
through dual action to the G protein-coupled receptors: inhibition of serotonergic 5-HT2C and 5-HT2B receptors and activation of ghrelin
receptors via specific ingredients of RKT.
In addition, we suggest that the identification of the effective ingredients from Kampo medicines could contribute to the discovery and
development of new drugs by means of modern high-throughput drug screening technology.