Application of ultrasound as pretreatment for extraction of podophyllotoxin from rhizomes of Podophyllum peltatum

The effect of high-power ultrasound pretreatment on the extraction of podophyllotoxin from Podophyllum peltatum was investigated. Direct sonication by an ultrasound probe horn was applied at 24 kHz and a number of factors were investigated: particle size (0.18–0.6 mm), type of solvent (0–100% aqueous ethanol), ultrasonic treatment time (2–40 min), and power of ultrasound (0–100% power intensity, maximum power: 78 W). The optimal condition of ultrasound was achieved with 0.425–0.6 mm particle size, 10 min sonication time, 35 W ultrasound power, and water as the medium. There was no obvious degradation of podophyllotoxin with ultrasound under the applied conditions, and an improvement in extractability was observed. The SEM microscopic structure change of treated samples disclosed the effect of ultrasound on the tissue cells. The increased pore volume and surface area after ultrasonic treatment also confirmed the positive effect of ultrasound pretreatment on the extraction yield of podophyllotoxin from the plant cells.

► The application of ultrasound breaks the cells and facilitates the extraction of podophyllotoxin from the rhizome particles.
► The pore volume and surface area of the particles increased after ultrasonic treatment.
► The optimal condition of ultrasound was obtained with 10 min, 32 W, water, and 0.425–0.6 mm particle size.
► No obvious degradation of podophyllotoxin with ultrasound under the applied conditions.