The effect of 1,4-cineole, 1,8-cineole and carvacrol on electricaly evoked isolated rat ileum, urinary bladder, vas deferens and left atrium

Carvacol, 1,8-cineole and 1,4-cineole are chemicals obtained by synthesis and also they are constituents of extracts used in folk medicine.In our study, pharmacological effects of 1,4-cineole, 1,8-cineole and carvacrol on isolated rat ileum, urinary bladder, epididymal and prostatic vas deferens and left atrium preparations evoked by electric field stimulation (EFS) were investigated. Naloxone and NoARG were used for any interactions of test compounds with opioidergic and nitrergic systems.Carvacrol (10??-10?? M) was observed to inhibit contractions of all preparations, being most effective on ileum and bladder. The augmentation of inhibition of carvacrol by naloxone suggested the involvement of opioidergic system on the observed mechanism of action of carvacrol.1,8-Cineole (10??-10?³ M) decreased the EFS-induced contractions of ileum only at 10?³ M. An increase of the inhibitory effect of 1,8-cineole in the presence of naloxone on ileum at 5x10?4 M and the observation of inhibition in the presence of NoARG on left atria indicated the involvement of opioidergic and nitrergic systems on the observed mechanism of action of 1,8-cineole.1,4-Cineole (10??-10?³ M) was observed to inhibit EFS-induced contractions of ileum, urinary bladder and left atria. 1,4-Cineole inhibited contractions of epididymal part of vas deferens and left atria only in the presense of naloxone suggeting the involvement of opioidergic system on the observed mechanism of action.Most powerful inhibitory effects were observed by carvacrol and less effects by 1,8-cineole whereas 1,4-cineole was in between two of them. Most sensitive organs to the test compounds was ileum and the most insensitive was prostatic part of vas deferens which suggested that prostatic vas deferens is not a suitable test organ for these compounds. Due to structural properties of the test compounds, isopropyl group was considered as a pharmacophore. Presence of hydroxyl group augmented the observed inhibitory actions whereas loss of planarity diminished the contractile effect. In addition to the observed results of this relationship between molecular structure and pharmacological properties is reported for the first time in our study.