Elucidation of the Mechanism and Kinetics of Ultrasonic Extraction of Paclitaxel from Plant Cell Cultures of Taxus chinensis

Abstract

In this study, the kinetics and mechanism of ultrasonic extraction of paclitaxel from Taxus chinensis were analyzed using ultrasonic cavitation bubbles and gas bubbles. The resulting paclitaxel yields (after one-time extraction) were 62–99% at ultrasonic power of 80–380 W in ultrasonic extraction and 61–76% at gas flow rate of 0.185–1.75 L/min in extraction using gas bubbles. These results show improvements from the yield obtained using conventional extraction (58%). As the ultrasonic power and gas flow rate increased, the extraction rate constant (3.0263–6.6028 mL/mg·min at 80–380 W and 2.9679–4.1067 mL/mg·min at 0.185–1.750 L/min), effective diffusion coefficient (12.4448 × 10⁻¹³−17.5691 × 10⁻¹³ m²/s at 80–380 W and 12.0788 × 10⁻¹³−16.1050 × 10⁻¹³ m²/s at 0.185–1.750 L/min), and mass transfer coefficient (2.5196 × 10⁻⁷−2.9750 × 10⁻⁷ m/s at 80–380 W and 2.3982 × 10⁻⁷−2.6411 × 10⁻⁷ m/s at 0.185–1.750 L/min) also increased. When ultrasonic extraction was executed using degassed solution (i.e., no cavitation), the paclitaxel yield was 51%, regardless of ultrasonic power; and the extraction rate constant, effective diffusion coefficient, and mass transfer coefficient were relatively small. This investigation of the ultrasonic extraction mechanism proved that cavitation bubbles themselves play a key role in promoting cell disruption, which has been indicated as improving the recovery efficiency of paclitaxel.