Apigenin Derivatives Alleviate OVA-Induced Oxidative Stress in Bronchial Asthma: A Structure-Activity Relationship Study

Apigenin (API) is a flavonoid compound widely distributed in nature. The global prevalence of asthma is increasing year by year, influenced by various factors and difficult to cure completely, and new drugs and therapies are constantly emerging. Although API is a low-toxicity flavonoid compound, its poor water solubility and low bioavailability present limitations in the treatment of asthma. In this study, the structure of API was chemically modified by introducing acyl and alkyl groups while preserving its original structure. The structures were identified using FT-IR, 1H-NMR and 13C-NMR spectroscopy, yielding derivatives (A–J). To further investigate the effects of structural modifications on API’s biological activity, an ovalbumin (OVA)-induced asthma model was established in mice to evaluate the antioxidants’ activity. Hematoxylin-eosin staining was used to observe pathological changes in lung tissue, and oxidative stress-related parameters, including ROS, SOD, and MDA, were measured to assess the derivatives’ protective effects against oxidative damage. The results showed that the 10 synthetic derivatives exhibited varying degrees of oxidative stress during treatment. Compared with the model group, the API derivative treatment group significantly reduced ROS and MDA levels and increased SOD activity. Moreover, treatment with the compounds reduced the levels of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, and decreased serum IgE levels. Histopathological examination further demonstrated that the compounds alleviated inflammatory cell infiltration and tissue damage in the lungs. Structure-activity analysis indicated that, among the 10 derivatives, the tri-substituted API derivatives exhibited superior antioxidant activity compared to the di-substituted API derivatives. By modifying the chemical structure of API, its antioxidant activity in OVA-induced bronchial asthma was significantly enhanced. 5,7,4′-O-triethyl API and 5,7,4′-O-triacetyl API demonstrated therapeutic effects comparable to those of dexamethasone and show promise as lead compounds for the development of novel asthma treatments.