Bronchodilator Phenylpropanoid Glycosides from the Seeds of Prunus mahaleb L.

Prunus mahaleb seeds were selected for phytochemical study directed by ex-vivo bronchodilator effect based on the traditional use for the treatment of respiratory problems.From the active chloroform fraction, five known phenylpropanoid glycosides: cis-melilotoside sodium salt (1), cis-methoxy-melilotoside (2), 3-(2-O--D-glucopyranosyl-4-methoxyphenyl) propanoic acid (3), trans-methoxy-melilotoside (4) and transmelilotoside (5) were identified for the first time from genus Prunus.Chemical structure of the compounds elucidated by spectroscopic techniques such as 1D, 2D NMR and HR-ESI/MS.Compounds 1, 2, 4, 5 showed promising bronchodilator effects against carbamylcholine (CCh) induced bronchospasm in isolated Guinea-pig trachea while 3 was found completely inactive.The mechanism(s) of action was studied using both CCh, low K + (25 mM) and high K + (80 mM)-mediated contractions and compound 2 was found distinctly more potent and efficacious against CCh compared to both types of K +mediated contractions where partial efficacy was observed, hence showed dual inhibition of cholinergic receptors followed by Ca 2+ channels.The anticholinergic and Ca 2+ inhibitory activities of compound 2 were further confirmed when it deflected CCh concentration response curves (CRCs) without suppression, whereas its higher doses shifted Ca 2+ CRCs similar to verapamil.The bronchodilator effect proved to be mediated via dual anticholinergic and Ca 2+ channels blocking effects.