Magnolia officinalis Rehder & E. Wilson extract and its main component honokiol alleviate asthma by reducing...

Asthma is a chronic respiratory disorder whose complexity presents significant challenges for effective treatment, necessitating ongoing innovation in therapeutic approaches. Magnolia officinalis Rehder & E. Wilson, a traditional Chinese medicine, possesses anti-inflammatory and antioxidant properties, along with diverse pharmacological activities. It is commonly included in traditional formulations such as Ping Wei San and Banxia Houpo Decoction. However, research investigating the mechanisms by which Magnolia officinalis Rehder & E. Wilson alleviates asthma remains limited.

This study investigated the pharmacological activity of Magnolia officinalis Rehder & E. Wilson extract (MOE) and its main active compound, honokiol, in alleviating respiratory tract inflammation in asthmatic mice, and elucidated the underlying mechanisms.

An ovalbumin (OVA)-induced allergic asthma mouse model was established to evaluate the therapeutic efficacy of MOE by assessing pulmonary function, histopathological lung injury, and immune cell activation. Network pharmacology and molecular docking were then employed to predict the potential mechanisms of MOE. To validate these mechanisms, tumor necrosis factor (TNF)-α/interleukin-4 (IL-4)-induced BEAS-2B airway epithelial cell models were used to measure transient receptor potential vanilloid 1 (TRPV1) and thymic stromal lymphopoietin (TSLP) expression, intracellular calcium flux dynamics, and NFAT nuclear translocation. Finally, based on the identified mechanisms, the therapeutic effects of honokiol, the key bioactive compound derived from MOE, were further investigated using an in vivo model.

MOE significantly restored tidal volume (TV) and Penh (enhanced pause) levels in asthmatic mice, while suppressing mucus hypersecretion, collagen deposition, and goblet cell hyperplasia. Additionally, MOE markedly attenuated OVA-induced airway inflammatory cell infiltration, as evidenced by reduced numbers of CD45⁺, CD4⁺, MHC II⁺, CD11c⁺, F4/80⁺, Arg1⁺, and CD206⁺ cells in lung tissues, along with decreased production of IL-1β, IL-4, and TNF-α. These findings indicate that MOE exerts beneficial effects on airway hyperresponsiveness (AHR), airway remodeling, and airway inflammation. Network pharmacology and molecular docking identified TRPV1 as a pivotal target. KEGG enrichment analysis revealed the calcium signaling pathway among the top 20 enriched pathways. Further experimental validation demonstrated that MOE reduced TSLP production both in vivo and in vitro by modulating the TRPV1/NFAT pathway. Calcium flux assays showed that MOE inhibited inflammatory cytokine-mediated TRPV1-induced Ca²⁺ influx and blocked capsaicin (CAP)-triggered TRPV1 activation. Finally, honokiol alleviated asthma symptoms and inflammation by regulating the TRPV1/TSLP axis.

This study is the first to demonstrate that MOE alleviates respiratory inflammation and allergic asthma by targeting the TRPV1/NFAT/TSLP pathway, with honokiol preliminarily identified as its key bioactive component. These findings clarify the pharmacodynamic basis of MOE and propose a novel plant-derived candidate for asthma therapy.