Bronchodilatory effect of ethanolic extract of the leaves of Nyctanthes arbortristis

BACKGROUND: Nyctanthes arbortristis has been used in traditional medicine for the treatment of asthma and cough. AIM: In this study, bronchodilatory effect of ethanolic extract of the N. arbortristis was investigated under in vitro conditions. The concentration–response curve of the tracheal smooth muscle (TSM) to histamine was recorded in presence or absence of ethanolic extract and N(ω)-nitro-l-arginine methyl ester (L-NAME). Dose–response effect of ethanolic extract on pre-constricted tissues was investigated. The ethanolic extract inhibited the histamine-induced maximum contractile responses of TSM (P < 0.001). Ethanolic extract also cause dose-dependent relaxation of TSM. These effects were reversed by L-NAME. Phytochemical analysis showed the presence of typical plant constituents. These results suggest the possible use of extract of the leaves of N. arbortristis as a bronchodilator in therapeutic treatment of asthma.