Antispasmodic and anti-diarrhoeal effect of Satureja hortensis L. essential oil.

Satureja hortensis L. (Lamiaceae) is an annual herb that is used in the traditional medicine of Iran for treating stomach and intestinal disorders. The antispasmodic activity of S. hortensis essential oil (SHEO) was assessed on contractions of isolated ileum, induced by KCl and acetylcholine, and compared with the effect of atropine and dicyclomine. SHEO inhibited the response to 80 mM KCl in a concentration-dependent manner (pD(2)=1.55+/-0.09 microg/ml; this is negative log concentration of SHEO causing 50% of maximum inhibition) and attenuating the maximum inducible response of acetylcholine concentration-response curve. Effect of SHEO on KCl was similar to that of dicyclomine. Dicyclomine (3.46 and 34.6 ng/ml) also reduced the response to acetylcholine on rat isolated ileum without altering the maximum response and shifted the acetylcholine concentration-response curve to the right by 16-fold at 34.6 ng/ml (100 nM) bath concentration, while atropine only inhibited the response to acetylcholine. This study shows that SHEO is a relaxant of rat isolated ileum. In addition to antispasmodic activity in vitro, essential oil of this plant at a dose of 0.1 ml/100 g inhibited castor oil induced diarrhoea in mice. As the inhibition of contractile overactivity of the ileum is the base of the treatment of some gastrointestinal disorders such as colic, SHEO may have clinical benefits for treatment of these conditions.