Cinnabaris modified with SiO2 nanoparticles stabilized Pickering emulsion to improve the photostability of volatile oil: A Lingzhu San case study

The pharmacological activity of volatile oils (VOs) is significant, but they can generate peroxides under light conditions, reducing the VO content and affecting their stability. This study aims to introduce Pickering emulsion technology to enhance the antioxidant activity of VOs and improve the photostability and efficacy of solid formulations. In this work, Cinnabaris was used as a stabilizer in the formulation of Lingzhu San to prepare Pickering emulsions using high-speed shearing. By controlling the duration of light exposure, the retention rate, degree of oxidation, and changes in volatile components of the volatile oil of Acorus tatarinowii Schott (AT-VO) were compared between the crude oil group and the Pickering emulsion group. Compared with the crude oil group, the Pickering emulsion group significantly improved the retention rate, reduced the degree of oxidation, and mitigated the changes in volatile components. GC-MS analysis of the quantitative and qualitative changes showed that the volatile components of the oil retained by the Pickering emulsion were closer to the untreated AT-VO in the light environment. In addition, the Pickering emulsion with water as the outer phase and oil as the inner phase retarded the formation of peroxides in the VOs and achieved the goal of maintaining the photo-stability of the VOs.