Pharmacological basis for the use of Borago officinalis in gastrointestinal, respiratory and cardiovascular disorders.

AIM OF THE STUDY In this study, we investigated the crude extract of Borago officinalis leaves (Bo.Cr) for its antispasmodic, bronchodilator, vasodilator and cardio-depressant activities to rationalize some of the traditional uses. MATERIALS AND METHODS Bo.Cr was studied using different isolated tissue preparations including rabbit jejunum, trachea, aorta, and guinea-pig atria. RESULTS Bo.Cr which was tested positive for flavonoids, coumarins, sterols and tannins produced a concentration-dependent relaxation of spontaneous and K+ (80mM)-induced contractions in isolated rabbit jejunum preparations, suggestive of Ca++ antagonist effect, which was confirmed when pretreatment of the tissue with Bo.Cr produced a rightward shift in the Ca++ concentration-response curves like that caused by verapamil. In rabbit tracheal preparations, Bo.Cr relaxed the carbachol (1microM) and K+-induced contractions. Verapamil also produced non-specific inhibitory effect. In rabbit aorta preparations, Bo.Cr exhibited vasodilator effect against phenylephrine and K+-induced contractions similar to verapamil. When tested in guinea-pig atria, Bo.Cr caused inhibition of both atrial force and rate of contractions. CONCLUSIONS These results suggest that the spasmolytic effects of Bo.Cr are mediated possibly through Ca++ antagonist mechanism, which might explain the traditional use of Borago officinalis in hyperactive gastrointestinal, respiratory and cardiovascular disorders.