Aqueous Pyrostegia venusta (Ker Gawl.) Miers extract attenuates allergen-induced asthma in a mouse model via an antioxidant mechanism

Objective: Pyrostegia venusta (Ker-Gawl.) Miers (Bignoniaceae) is a perennial invasive vine, distributed worldwide. In folk medicine, its parts are used for the treatment of inflammatory respiratory diseases. Extracts of P. venusta have antioxidant, antimicrobial, and antinociceptive properties. The aim of this study was to evaluate the effects of two extracts (aqueous and hydroethanolic) of P. venusta in the treatment of asthma in an animal model. Methods: Balb/c mice were sensitized twice with ovalbumin (OVA) intraperitoneally (ip), one week apart, and after one week, challenged with OVA intranasally on four alternate days. Mice were treated ip with 300 mg/kg of aqueous or hydroethanolic extracts for seven consecutive days. Control groups received saline on the same days. Bronchial hyperresponsiveness, production of Th1 and Th2 cytokines, lung and airway inflammation, and antioxidant activity in lung tissue were assessed. Results: Treatment with aqueous extract significantly decreased bronchial hyperresponsiveness, measured by total and tissue resistance and elastance. The administration of hydroethanolic extract did not reduce bronchial hyperresponsiveness. In addition, both extracts significantly reduced total cell and eosinophil counts in bronchoalveolar lavage. Both extracts did not change significantly IL-4, IL-5, IL-9, IL-13, IFN-gamma, and TGF-beta levels. Of note, only the aqueous extract significantly increased the total antioxidant activity and reduced lung inflammation. Conclusion: Aqueous extract of P. venusta reduced bronchial hyperresponsiveness, lung and airway inflammation, probably via an antioxidant mechanism. These results demonstrate that P. venusta may have potential for asthma treatment.