Volatile Oil of Magnolia biondii Pamp. for Transnasal Administration: Its Preparation, Characterization, And Mechanism of Action in the Treatment of Allergic Rhinitis

Background: Allergic Rhinitis (AR) is a common chronic nasal condition usually caused by allergens. The immune system overreacts when the body is exposed to allergens, releasing a lot of tissue chemicals that cause congestion, more secretions, and an inflammatory reaction in the nasal mucosa. Method: In clinical practice, it remains a significant public health issue. Modern pharmacological studies have demonstrated that Magnolia Volatile Oil (MVO) has good anti-inflammatory, antibacterial, immunomodulatory, and other pharmacological effects. Previous research and literature reports have reported that MVO has good therapeutic effects on allergic rhinitis. However, due to the poor water solubility of Magnolia, its bioavailability is low. The purpose of this present work is to develop a new microemulsion formulation to improve the stability and bioavailability of MVO. Results: The droplet size, PDI, and zeta potential of Magnolia volatile oil microemulsion (MVOME) were characterized along with its physical characteristics, and these values were found to be 14.270.03 nm, 0.09410.31, and -0.35850.12 mV, respectively, demonstrating the successful formation of microemulsion. In OVA-induced AR rats, MVO-ME dramatically reduced the serum levels of TNF-α, IL-1β, and IL-6 inflammatory factors. In addition, MVO-ME significantly inhibited the expression of protein levels of PPAR-γ and P65 in the nasal mucosa of AR rats. In this regard, we hypothesized that MVO-ME may play a therapeutic role in AR by activating the PPAR signaling pathway as well as inhibiting the activation of the NF/κB signaling pathway. Conclusion: MVO-ME has systematic advantages, such as high solubility, bioavailability, etc. It is expected to be an efficient nano-drug delivery system for the clinical treatment of allergic rhinitis.