Validation of ethnopharmacological uses of Heliotropium strigosum Willd. as spasmolytic, bronchodilator and vasorelaxant remedy

Background: Heliotropium strigosum is used in traditional medicine to manage gastrointestinal pain, respiratory distress and vascular disorders. The present study was undertaken to provide scientific evidences for these folkloric uses by in vitro experimental settings. Methods: A crude methanol extract of the Heliotropium strigosum (Hs.Cr) was tested in vitro on isolated rabbit jejunum preparations to detect the possible presence of spasmolytic activity. Moreover, isolated rabbit tracheal and aorta preparations were used to ascertain the relaxant effects of the extract. Results: The Hs.Cr exhibited relaxant effects in rabbit jejunum in a concentration dependent manner (0.01-3.0 mg/ml). The Hs.Cr also relaxed K+ (80 mM)-induced spastic contractions in rabbit jejunum and shifted the Ca2+ concentration response curves towards right. The extract relaxed carbachol (1 μM)- as well as K+ (80 mM)-induced contractions in rabbit trachea at concentrations ranging from 0.01 to 10 mg/ml. Moreover, Hs.Cr. also relaxed (0.01-3.0 mg/ml) the phenylephrine (1 μM)- and K+ (80 mM)-induced contractions in isolated rabbit aorta. Conclusions: The Hs.Cr was found to exhibit spasmolytic, bronchodilator and vasorelaxant activities on isolated rabbit jejunum, trachea and aorta preparations, likely mediated through Ca2+ channel blockade. This finding may provide a scientific basis for the folkloric uses of the plant