Antispasmodic effects of hydroalcoholic, aqueous, chloroform, and ethyl acetate extracts of Zaringiah on rabbit ileum smooth muscle contractions

Introduction: Zaringiah (Dracocephalum kotschyi) is an Iranian endemic herbal plant naturally growing in the Isfahan and Khorasan provinces. Hydroalcoholic extract of Zaringiah has anti-inflammatory, antispasmodic, and immunomodulatory properties. So far, the effect of Zaringiah extract on contraction induced by histamine and serotonin (۵-HT) has not been reported. The objective of this research was to investigate the antispasmodic effect of hydroalcoholic, aqueous, chloroform, and ethyl acetate extracts of Zaringiah on rabbit ileum smooth muscle contractions induced by histamine and ۵-HT. Methods: Khorasani variant of Zaringiah was used in this study. Aqueous extract was prepared by decoction, while hydroalcoholic extract was obtained by the maceration technique. Chloroform and ethyl acetate fractions were obtained using a solvent in solvent extraction technique. Rabbit isolated ileum was set up in an organ bath filled with Tyrode’s solution. The effects of the above extracts were examined on contractions induced by histamine or ۵-HT and compared with each other. Results: Hydroalcoholic extract of Zaringiah inhibited the rabbit ileum contractions induced by histamine (IC۵۰ = ۷۶ ± ۷.۷ μg/mL) and ۵-HT (IC۵۰ = ۶۰ ± ۶.۴ μg/mL), as well as spontaneous contractions (IC۵۰ = ۶۳ ± ۱۵ μg/mL). The aqueous extract, as well as chloroform and ethyl acetate fractions, concentration-dependently inhibited spontaneous, histamine, and ۵-HT induced contractions. Conclusion: There was not a significant difference among the inhibitory actions of hydroalcoholic, aqueous, chloroform, and ethyl acetate extracts of Zaringiah on rabbit ileum, indicating the distribution of active constituents in both polar and non-polar mediums.