Research on the quality evaluation of crude drugs.

As crude drugs are natural products, their quality may vary. However, the degradation of the active ingredients in the compositional changes that occur during processing and preparation also affects the medicinal properties of the Kampo formula, which uses herbal medicines; therefore, a detailed investigation of the effects of compositional changes during preparation is required. Plant constituents vary in content depending on the year of cultivation and the plant part; however, detailed studies have rarely been reported for some crude drugs. Liquid chromatography-nuclear magnetic resonance/mass spectrometry revealed the degradation process of saponins, which are unstable components of the crude drug "Achyranthes root." The presence of diterpenes unstable with respect to drying temperature in the leaves of the crude drug "Leonurus herb" was revealed and their structures were elucidated. At the examination stage of the degradation process of perillaldehyde, the characteristic aromatic component of Perilla herb, it was elucidated that some specimens contained a small amount of perillaldehyde and that they contained more α-asarone. A trend toward lower ephedrine content was observed toward the tip of the above-ground branching of the Ephedra herb. Multivariate analysis was also introduced into the quality assessment of crude drugs and was established as a tool to identify bioactive compounds using the component diversity of crude drugs and to elucidate component differences due to the cultivation environment.