Kampo medicine

Kampo medicine is a form of Japanese phytotherapy originating from traditional Chinese medicine (TCM). During the last several decades, much attention has been paid to the pharmacological effects of these medical plants and their constituents. However, in many cases, a systematic screening of Kampo remedies to determine pharmacologically relevant targets is still lacking. In this study, a broad screening of Kampo remedies was performed to look for pharmacologically relevant \(5-HT_{3A}\) and \(GABA_{A}\) receptor ligands. Several of the Kampo remedies are currently used for symptoms such as nausea, emesis, gastrointestinal motility disorders, anxiety, restlessness, or insomnia. Therefore, the pharmacological effects of 121 herbal drugs from Kampo medicine were analyzed as ethanol tinctures on heterologously expressed \(5-HT_{3A}\) and \(GABA_{A}\) receptors, due to the involvement of these receptors in such pathophysiological processes. The tinctures of \(\textit {Lindera aggregate}\) (radix) and \(\textit {Leonurus japonicas}\) (herba) were the most effective inhibitory compounds on the \(5-HT_{3A}\) receptor. Further investigation of known ingredients in these compounds led to the identification of leonurine from \(\it Leonurus\) as a new natural \(5-HT_{3A}\) receptor antagonist. Several potentiating herbs (e.g., \(\textit {Magnolia officinalis}\) (cortex), \(\textit {Syzygium aromaticum}\) (flos), and \(\textit {Panax ginseng}\) (radix)) were also identified for the \(GABA_{A}\) receptor, which are all traditionally used for their sedative or anxiolytic effects. A variety of tinctures with antagonistic effects \(\textit {Salvia miltiorrhiza}\) (radix) were also detected. Therefore, this study reveals new insights into the pharmacological action of a broad spectrum of herbal drugs from Kampo, allowing for a better understanding of their physiological effects and clinical applications