Inhibitory effect of Rosa damascena Mill flower essential oil, geraniol and citronellol on rat ileum contraction.

Flower of Rosa damascena Mill is widely used in Iran for gastrointestinal (GI) disorders. However, its pharmacological action on ileum contraction has not been studied. In this research we have investigated ileum motility effect of essential oil of flower petals of R. damascena growing in Kashan, Iran, and two of its constituents. The essential oils obtained by hydrodistillation were investigated by a combination of GC and GC/MS. More than 34 compounds have been identified. The main constituents of the essential oil were β-citronellol (23%), nonadecane (16%), geraniol (16%) and heneicosane (5%). A portion of rat isolated ileum was suspended under 1g tension in Tyrode's solution at 37°C and gassed with O2. Effect of the R. damascena essential oil (2.5-160 μg/ml), geraniol (0.2-3.2 μg/ml) and citronellol (0.8-6.4 μg/ml) were studied on ileum contractions induced by KCl, acetylcholine (ACh) and electrical field stimulation (EFS) and compared with standard drugs atropine and loperamide. The contractile response of EFS was mediated mainly through the intramural nerve plexuses, because its response was inhibited by loperamide and partially reduced by atropine. The essential oil concentration dependently inhibited the response to KCl (IC50=67 ± 8.4μg/ml) and EFS (IC50=47 ± 10.6 μg/ml). Geraniol (IC50=1.7 ± 0.15 μg/ml for KCl) and citronellol (IC50=2.9 ± 0.3 μg/ml for KCl) also had inhibitory effect of ileum contraction and both were more potent than the essential oil. It was concluded that R. damascena essential oil mainly had an inhibitory effect on ileum contractions and geraniol and citronellol had a major role in inhibitory effect of the essential.