Myorelaxant Activity of essential oil from Origanum majorana L. on rat and rabbit.

Ethnopharmacological Relevance: Origanum majorana L. (Lamiaceae) was usually used in Moroccan folk medicine to treat infantile colic and abdominal discomfort.
Materials and Methods: The essential oil from the aerial part of the dry Origanum majorana L. (EOOM) was obtained through hydro distillation and analyzed by gas chromatography/mass spectrometry (GC/MS). The effect of EOOM on muscle relaxation was measured on rabbit and rat intestinal smooth muscle mounted in an isotonic transducer.
Results: 1) The main compounds obtained from the aqueous extract of this plant were alpha Terpineol, L-terpinen-4-ol and Beta.-Linalool. 2) EOOM inhibited in a concentration-dependent manner spontaneous contraction of rabbit jejunum, with an IC ₅₀ = 64.08 ± 2.42 μg/mL. 3) In rat intestine, EOOM induced the relaxation of the tissue in concentration-dependent manner with an IC ₅₀ = 39.70 ± 2.29 μg/mL when the tissue was pre-contracted with CCh 10 ^-6 M, and 48.70 ± 2.26 μg/mL when the tissue was pre-contracted with 25 mM KCl. 4) The relaxation effect induced by EOOM was more important than that obtained in the presence of atropine, hexamethonium, Nifedipine, L-NAME and Blue of methylene.
Conclusion: the present result indicates that essential oil of Origanum majorana L. exhibit an effect on intestinal relaxation in vitro. This effect further validates the traditional use of Origanum majorana L. to treat infantile colic and abdominal discomfort.
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