Phenotyping analysis of the Japanese Kampo medicine maoto in healthy human subjects using wide-targeted plasma metabolomics.

•Traditional herbal medicines consist of a vast number of compounds and are assumed to exert their activity by affecting various sites in the body.•Plasma metabolomics was used for phenotype analysis of the Japanese kampo medicine maoto in a human clinical study.•Maoto influenced plasma amino acids and lipid mediators.•Primary compounds in maoto such as ephedrine, prunasin, cinnamic acid, and glyccyrhetinic acid were absorbed in the bloodstream.•Alteration of branched-chain amino acid levels by maoto administration is likely caused by ephedrine and its analogues.