A large-scale separation of taxol from semi-purified bark extract of Taxus
yunnanesis was investigated. The chromatographic behavior of taxol and two
close eluting analogues, cephalomannine and 7-epi-10-deacetyltaxol, was sys
tematically studied on a C-18 bonded phase column with different mobile pha
ses in reverse phase mode. According to the notably different selectivity o
f the methanol and acetonitrile with water in the mobile phase and the most
important requirement of capacity in preparative chromatography, the optim
um suitable mobile phase used in a large-scale isolation of taxol and 7-epi
-10-deacetyltaxol on a preparative C-18 column was given. Cephalomannine wa
s eliminated by ozonolysis and, then after, separated throughout a normal p
hase silica column. The whole large-scale process for high purity taxol fro
m the bark extract from Taxus yunnanesis consisted of a preliminary purific
ation with Biotage FLASH 150i system based on a prepacked normal phase sili
ca cartridge, followed by using a C-18 Nova-pak(TM) column in a Waters Prep
LC(TM) 4000 preparative HPLC system.