Antispasmodic activity of isovanillin and isoacetovanillon in comparison with Pycnocycla spinosa Decne.exBoiss extract on rat ileum

Isovanillin and isoacetovanillon are two components found in P. spinosa Decne.exBoiss extract with no previously reported effect on ileum contractions. Spasmolytic effect of isovanillin and isoacetovanillon were examined on response to electrical field stimulation (EFS), acetylcholine (ACh) and 5-HT in strips of rat ileum. Longitudinal ileum strips were set up in an organ bath containing oxygenated Tyrode's solution. All strips that was contracted in response to EFS, acetylcholine or 5-HT showed relaxation in the presence of isovanillin (5-320 μg/ml), or isoacetovanillon (5-320 μg/ml). Isovanillin and isoacetovanillon inhibited the response to 5-HT with IC50 values of 356±50μM and 622±110μM respectively. They reduced the response to EFS without significantly affecting the acetylcholine response. P. spinosa extract (5-160 μg/ml) in a concentration dependent manner reduced the response to 5-HT, acetylcholine and EFS. This study demonstrated that isovanillin and isoacetovanillon are relaxant of ileum contractions induced by 5-HT and EFS and they have contribution to the relaxant effect of P. spinosa extract but other components are responsible for the inhibition of acetylcholine by the extract.