Ultrasound- and Negative Pressure-assisted Fractional Precipitation of Paclitaxel from Taxus chinensis

The effect of ultrasound and negative pressure on the efficiency of fractional precipitation of paclitaxel derived from Taxus chinensis was investigated. Introducing both ultrasound and negative pressure during fractional precipitation resulted in a precipitation time that was 2 times faster than the conventional ultrasound-fractional precipitation and negative pressure-fractional precipitation. In particular, using an ultrasonic power of 250 W and a negative pressure of -200 mmHg simultaneously could recover up to 98.2% of the paclitaxel within 1 min. The ultrasound/negative pressure-fractional precipitation resulted in precipitates with mean particle sizes that were 9.3, 2.3, and 2.7 times smaller than those of the conventional fractional precipitation, the negative pressure-fractional precipitation, and the ultrasound-fractional precipitation, respectively. In addition, the diffusion coefficients increased by 11.4, 2.2, and 2.6 times, and the rate constants increased by 2.9–7.0, 1.3–3.0, and 2.3–5.5 times. As the ultrasonic power and negative pressure increased, the changes of activation energy decreased, promoting faster precipitation.