Optimization of the fractional precipitation of paclitaxel from a Taxus chinensis cell culture using response surface methodology and its isolation by consecutive high‐speed countercurrent chromatography

A consecutive preparation method for the isolation and purification of paclitaxel from the Taxus Chinensis cell culture was developed in this study. The process involved alkaline Al₂O₃ chromatography, fractional precipitation, and high‐speed countercurrent chromatography. The original cell culture materials were first extracted with methanol using ultrasound‐assisted extraction, and then the extract (the content of paclitaxel is 1.5%) was separated by alkaline Al₂O₃ column chromatography. Subsequently, fractional precipitation was used to obtain paclitaxel. In particular, response surface methodology was used to optimize the factors of fractional precipitation (methanol concentration, material‐to‐solvent ratio, and precipitating time were optimized as 48.14%, 8.85 mg/mL, and 48.71 h, respectively) and the yield of fractional precipitation product was 30.64 ± 0.60 mg (the content of paclitaxel is 89.3%, 27.37 ± 0.54 mg) from a 100 mg fraction by Al₂O₃ column separation (the content of paclitaxel is 32.4%). Then, the product was used for further isolation by high‐speed countercurrent chromatography. About 1.00 g paclitaxel (200 ± 2 mg in each loading) with a purity up to 99.61% was isolated from 1.25 g of fractional precipitation product with a solvent system of n‐hexane/ethyl acetate/methanol/water (1.2:1.8:1.5:1.5, v/v/v/v) in one run of five consecutive sample loadings without exchanging a new solvent system.