Abstract: In order to establish the optimal methods for the extraction of 3 traditional Chinese medicines,the extractive yield,minimum inhibition concentration (MIC) and minimal bactericidal concentration (MBC) against Streptococcus agalactiae were used as comprehensive evaluation indexes.L₉(3⁴) orthogonal design was applied to select the optimal extraction conditions of 3 traditional Chinese medicines.The results showed that the optimal extraction conditions of 3 traditional Chinese medicines were as follows:Coptidis Rhizoma was added to 8 times of 80% ethanol,which were refluxed and extracted for 2 times with each time of 1.5 h;Radix Scutellariae were extracted with 10 times of 55% ethanol at 95 ℃,and repeated for 3 times,2 h for each time; Polygonum cuspidatum extracted 3 times at 95 ℃ with 5 times of 60% ethanol,2 h for each time.Under optimal conditions,the MICs of the extracts obtained from Coptidis Rhizoma,Radix Scutellariae and Polygonum cuspidatum against  S.agalactiae  were 26.04,5.20 mg/mL and 15.60 mg/mL,respectively and the MBCs were 26.04,6.50,31.25 mg/mL respectively.The developed extraction method was simple,rapid,accurate,reproducible and stable.

Key words: traditional Chinese medicine, extraction process, orthogonal design, extraction yield