A Large Scale Separation of Taxanes from the Bark Extract of Taxus yunnanesis and 1H‐ and 13C‐NMR Assignments for 7‐epi‐10‐Deacetyltaxol

Abstract

AbstractA large‐scale separation of paclitaxel from semi‐purified bark extract of Taxus yunnanesis was investigated. The chromatographic behavior of paclitaxel and two dose editing analogues, cephalomannine and 7‐epi‐10‐deacetyltaxol were systematically studied on a C18 bonded phase column with different mobile phase in reverse phase mode. According to the notably different selectivity of the methanol and acetonitrile with water in the mobile phase and the most important requirement of capacity in preparative chromatography, the optimum suitably mobile phase used in a large‐scale isolation of paclitaxel and 7‐epi‐10‐deacetyltaxol on a preparative C18 column was given. Cephalomannine was eliminated by ozonolysis and after then separated throughout a normal phase silica column. The whole large‐scale process for high purity paclitaxel from the bark extract of Taxus yunnanesis consisted of a preliminary purification with Biotage FLASH 150i system based on a prepacked normal phase silica cartridge followed by using a C18 Nova‐pak™ column in Waters PrepLC™ 4000 preparative HPLC system. The structure of 7‐epi‐10‐deacetyltaxol was elucidated by 2D NMR technologies of TOCSY, DQF‐COSY, HMQC and HMBC, etc.