Pickering Emulsion Stabilized by Chitosan-Modified Saigae Tataricae Cornu Particles for Improving the Oxidative Stability and In Vivo Pharmacokinetics of Acorus tatarinowii Schott Volatile Oil

Background/Objectives: Acorus tatarinowii Schott volatile oil (ATVO), a bioactive component of traditional Chinese medicine, is susceptible to light-induced oxidation and compositional changes. This study aimed to develop a chitosan-modified Saigae Tataricae Cornu particle (MSTC)-stabilized Pickering emulsion (PE) to improve the light-oxidative stability and in vivo disposition of ATVO. Methods: Saigae Tataricae Cornu particles were modified with chitosan and used to prepare an oil-in-water PE encapsulating ATVO. Particle wettability, morphology, structural interactions, emulsion type, interfacial distribution, droplet size, and zeta potential were characterized. The light-oxidative stability of ATVO was evaluated under light using peroxide value, malondialdehyde content, and gas chromatography-mass spectrometry (GC-MS) analysis. The pharmacokinetic behavior of α-asarone and β-asarone was further investigated in rats. Results: Chitosan modification increased the contact angle of Saigae Tataricae Cornu particles from 65.37° to 83.23°, indicating improved wettability and interfacial affinity. The resulting PE showed good physical stability, with a droplet size of 2.51 μm and a zeta potential of +32.00 mV. Confocal laser scanning microscopy (CLSM) confirmed that MSTC particles adsorbed at the oil–water interface and encapsulated ATVO within the oil droplets. Compared with free ATVO and the physical mixture, the PE reduced peroxide and malondialdehyde formation, slowed light-induced changes in volatile components, and better preserved major bioactive constituents. Pharmacokinetic analysis showed that the plasma concentration-time curve from 0 to t (AUC_0–t) and maximum plasma concentration (C_max) of α-asarone increased by 2.02- and 2.47-fold, respectively, whereas the effect on β-asarone was relatively limited. Conclusions: MSTC-stabilized PE provides an effective interfacial-barrier strategy for protecting ATVO against light-oxidative deterioration. This study highlights the potential of modified natural medicinal particles as green stabilizers for improving the stability, quality consistency, and delivery performance of volatile-oil-containing traditional Chinese medicine preparations.