Authentication of Stephania tetrandra S. Moore (Fang Ji) and differentiation of its common adulterants using microscopy and HPLC analysis.

Stephania tetrandra S. Moore (Hang Fang Ji) is used in traditional Chinese medicine as a diuretic, an antiphlogistic, and an antirheumatic. The name "fang ji" is applied to at least four different genera of plants, including Aristolochia fangchi Y. C. Wu ex L. D. Chow and S. M. Hwang, Cocculus orbiculatus (L.) DC., Stephania tetrandra S. Moore, and Sinomenium acutum Rehder and E. H. Wilson. Due to similarity in the use of their common names, Stephania tetrandra S. Moore is often confused with Aristolochia fangchi Y. C. Wu ex L. D. Chow and S. M. Hwang, which has potentially dangerous consequences. To aid rapid and easy differentiation between the roots of these four species, so as to avoid possible contamination, detailed macroscopic and microscopic observations were made using stereo-and light-microscopy. The powdered samples were further analyzed using HPLC.