Investigations on preparative thin-layer chromatographic separation of taxoids from Taxus baccata L.

Many mobile phases, including solvent systems with one and two polar modifi ers as well as some multiple development techniques and gradient elutions, were examined to select the best thin-layer chromatographic conditions on s ilica gel F-254 plates for micropreparative isolation of 10-deacetylbaccati n III (10-DAB III), baccatin III, paclitaxel, and cephalomannine from metha nolic extracts obtained from fresh and dried needles and stems of Taxus bac cata L. In case of each solvent system and development technique, R-F, k, a nd alpha values of 10-DAB In and paclitaxel were determined as well as the separation of compounds coextracted with taxoids, and the whole yew extract . The best mobile phase, benzene-chloroform-acetone-methanol (20:92.5:15:7. 5) used twice over a distance of 15 cm was applied for isolation of analyze d taxoids by preparative TLC in connection with RP-HPLC, (C-18) quantitativ e determination using two mobile phases (30% acetonitrile in water to measu re of 10-DAB III levels and 50% acetonitrile in water for baccatin III, pac litaxel, and cephalomannine).