In Vivo Pharmacological Testing of Herbal Drugs for Anti-Allergic and Anti-Asthmatic Properties

BACKGROUND: Asthma is a chronic inflammatory disease characterized by reversible airway obstruction, hyperresponsiveness, and remodeling. Asthma prevalence has increased significantly globally over the last decade, and it remains incurable to this date. AIMS AND OBJECTIVES: The present study evaluated some of the antiasthmatic medicinal plants to assess their mode of action. MATERIALS AND METHOD: Animal models for milk-induced leukocytosis, milk-induced eosinophilia, mast cell degranulation, clonidine-induced catalepsy, and active paw anaphylaxis were used to assess the pharmacological effects of Ammi visnaga, Medicago sativa, and Urtica dioica. RESULTS: Mice pretreated with diazepam, methanolic extract of M. sativa, and U. dioica exhibited significant (P < 0.05) inhibition in milk-induced leukocytosis. However, only M. sativa showed statistically significant (P < 0.05) results. All plants showed a statistically significant (P < 0.05) tendency to decrease milk-induced eosinophilia. Methanolic extracts of all plants significantly (P < 0.05) protected mast cells against degranulation by clonidine. A. visnaga and U. dioica significantly (P < 0.05) protected mice against clonidine-induced catalepsy. An acute treatment by M. sativa potentiated the catalepsy, while it significantly inhibited the catalepsy (P < 0.05) upon chronic treatment. In the allergic inflammation model, methanolic extracts of all plants under study decreased paw thickness in a statistically significant manner (P < 0.05). CONCLUSION: All the three plants in this study demonstrated anti-inflammatory and antihistaminic effects, as well as decreased paw thickness, validate anti-allergic properties. A. visnaga showed a mast cell-stabilizing effect. A. visnaga and U. dioica inhibited the histamine-mediated clonidine-induced catalepsy from mast cells which proves the antihistaminic activity of these plants.