Antihistaminic activity of aqueous extract of stem bark of Ailanthus excelsa Roxb.

Background: Biologically active compounds from natural sources are of interest as possible new drugs for different diseases. Over many centuries humans have been mining the bounties of nature for discovering natural products that have been used for the treatment of all human diseases. Ailanthus excelsa Roxb. (Simaroubaceae) is widely used in the Indian system of medicine as an antiasthmatic, antispasmodic, bronchodilator, anticolic pain, anticancer, antidiabetic etc. The plant was also reported for its antiasthmatic, bronchodilatory, antiallegic and many more such activities. Objective: To evaluate the antihistaminic activity of aqueous extract of stem bark of Ailanthus excelsa Roxb. Materials and Methods: We have studied the effect of aqueous extract of stem barks of A. excelsa Roxb. at a doses 100 μg/mL in the isolated goat tracheal chain preparation in vitro and 100, 200, 400 mg/kg doses orally in passive paw anaphylaxis in rat, clonidine-induced catalepsy in mice models in vivo for its antihistaminic activity. Results: Aqueous extract of stem barks of A. excelsa Roxb. significantly (***P<0.001) inhibits the percentage contraction at concentration of 100 μg/mL in goat tracheal chain preparation. A. excelsa Roxb. extract (100, 200, and 400 mg/kg oral) and dexamethasone (0.5 mg/kg, i.p.) also significantly reduced (**P<0.01) the paw volume at fourth hour and the percentage inhibition was found to be 13.98%, 28.49%, 42.47% and 46.77% respectively. The aqueous extract of stem barks of A. excelsa Roxb. (100, 200, 400 mg/kg, p.o.) and chlorpheniramine maleate (10 mg/kg, i.p.) significantly inhibited (*P<0.05, **P< 0.01) clonidine-induced catalepsy in mice at 150 min after the administration of clonidine. Conclusion: The aqueous extract of stem bark of A. excelsa Roxb. possess significant antihistaminic activity (H1-antagonist) and can be attributed to bronchodilating, anti-inflammatory, adaptogenic activity etc. Hence detailed study needs to be conducted to evaluate the phytoconstituent responsible for the above mentioned results and their clinical efficacy in the treatment of related diseases.