Abstract
The Japanese Pharmacopoeia states that the crude drug Chotoko is composed of the hooks of Uncaria rhynchophylla Miq., U. sinensis Havil., and U. macrophylla Wall., all of which belong to the Rubiaceae family. It has been reported that the indole and oxindole type alkaloids contained in Chotoko have different pharmacological effects, and Chotoko products derived from different species are composed of different alkaloids. However, there are no reports about the factors affecting the chemical compositions of Uncaria plants. In this study, we analyzed the alkaloid contents (the rhynchophylline, geissoschizine methyl ether, and hirsutine contents) of Uncaria samples collected from a broad range of sites by HPLC after identifying their species by DNA sequence analysis. As a result, we found that the hooks and small stems of U. rhynchophylla grown in habitats with lower annual precipitation levels tended to display higher alkaloid contents. We also found that the alkaloid compositions of cultivated Uncaria plants were different from those of wild plants, even those belonging to the same species, and crude Chotoko products displayed two types of alkaloid profile, the rhynchophylline-rich type and the geissoschizine methyl ether and hirsutine-rich type.
Moreover, in order to accurately identify the botanical origin of Chotoko, we established a method involving molecular genetics techniques; i.e., DNA sequence analysis and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).
