Ethnopharmacological relevance: Origanum majorana L. (Lamiaceae) is commonly used in Moroccan folk medicine to treat infantile colic, abdominal discomfort and diarrhea. Liquid stools and abdominal discomfort observed in acute infectious diarrhea are the consequences of imbalance between intestinal water secretion and absorption in the lumen, and relaxation of smooth muscle surrounding the intestinal mucosa.
Aim of the study: The objective of our study was to see if aqueous extract of Origanum majorana L. (AEOM) may exhibit an effect on those deleterious mechanisms.
Materials and methods: The effect of AEOM on electrogenic Cl- secretion and Na+ absorption, the two main mechanisms underlying water movement in the intestine, was assessed on intestinal pieces of mice intestine mounted, in vitro, in Ussing chambers. AEOM effect on muscle relaxation was measured on rat intestinal smooth muscle mounted in an isotonic transducer.
Results: 1) AEOM placed on the serosal (i.e. blood) side of the piece of jejunum entirely inhibited in a concentration-dependent manner the Forskolin-induced electrogenic chloride secretion, with an IC50 = 654 ± 8 µg/mL. 2) AEOM placed on the mucosal (i.e. luminal) side stimulated in a concentration-dependent manner an electrogenic Na+ absorption, with an IC50 = 476.9 ± 1 µg/mL. 3) AEOM (1 mg/mL) inhibition of Forskolin-induced electrogenic secretion was almost entirely prevented by prior exposure to Ca++ channels or neurotransmitters inhibitors. 4) AEOM (1 mg/mL) proabsorptive effect was greater in the ileum and progressively declined in the jejunum, distal colon and proximal colon (minimal). 5) AEOM inhibited in a concentration-dependent manner smooth muscle Carbachol or KCl induced contraction, with an IC50 = 1.64 ± 0.2 mg/mL or 1.92 ± 0.8 mg/mL, respectively.
Conclusion: the present results indicate that aqueous extract of Origanum majorana L. exhibit positive cooperative effects on the main mechanisms that are involved in acute infectious diarrhea.
Keywords: Antisecretory; Antispasmodic; Intestinal; Mice; Mucosa; Origanum majorana L.; Proabsorptive; Rat; Traditional medicine; Ussing chamber.
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