Modified particles-stabilized pickering emulsion to improve the thermal stability of volatile oil: A Lingzhu pulvis case study

Essential oils have significant pharmacological activities but poor stability, especially thermal stability, and they tend to decompose and lose their pharmacological activities. Based on the concept of “combination of medicine and adjuvant” introduces particle design technology and Pickering emulsion technology. Using Lingzhu pulvis, a traditional Chinese medicine preparation with volatile oil, as a model, we aim to enhance the stability of volatile oil from Acorus gramineus (VOAG). We modify the water-insoluble precipitate of the solid particles in Lingzhu pulvis, namely the water insoluble precipitate of Bombyx batryticatus-Arisaema cum Bile extract (WIP-BBACE), using particle design technology. The modified particles stabilize the VOAG-loaded oil-in-water Pickering emulsion.

The contact angle of WIP-BBACE increased from 50.7° to 76.5°. The Pickering emulsion was optimally prepared with a stabilizer dosage of 8 mg/mL, oil-phase volume fraction of 55 %, emulsification speed of 14,000 rpm, and emulsification time of 2 min, yielding an average droplet size of 1606 nm and a zeta potential of −28.67 mV. Thermal stability studies indicated that, compared to untreated VOAG, the Pickering emulsion had lower MDA and POV levels after 1 and 3 h at 60 °C, showing significant protection of the VOAG. GC–MS analysis revealed that the composition of VOAG in the Pickering emulsion changed less after thermal treatment and remained closer to that of untreated VOAG. In artificial gastric and intestinal fluid environments, the cumulative release degrees of α-asarone were 1.36 and 1.49 times those of VOAG, and β-asarone were 1.27 and 1.35 times those of VOAG, respectively.

Particle design technology can precisely alter particle properties, making them suitable solid particles for Pickering emulsions. The Pickering emulsion prepared with modified WIP-BBACE can enhance the bioavailability, burst release capacity, and thermal stability of VOAG. This study provides a novel technological approach for stabilizing volatile oils in traditional Chinese medicine and offers theoretical support for the modernization of traditional Chinese medicine formulations.