Three kinds of extracting techniques to Rhizoma Polygoni Cuspidati(RPC)were comparatively studied. The three techniques were as follows: RPC alone and Yigankang formula as a whole with RPC as a main ingredient were extracted with water

and RPC alone was extracted with alcohol. The experimental result showed that the best technique was the last one

by which the extractive rates of total anthraquinone and emodin were 96.7% and 96.1%

respectively

but after recovering alcohol

concentrating and drying

the preserved total anthraquinone and emodin were 68.9% and 65.6% respectively.