Antispasmodic and antidiarrheal effects of Juniperus oxycedrus L. on the jejunum in rodents

Abstract

Functional bowel disorders (FBD) have a major potential to degrade the standards of public life. Juniperus oxycedrus L. (J. oxycedrus) (Cupressaceae) has been described as a plant used in traditional medicine as an antidiarrheal medication. The present study is the first to obtain information on the antispasmodic and antidiarrheic effects of J. oxycedrus aqueous extract through in vitro and in vivo studies. An aqueous extract of J. oxycedrus (AEJO) was extracted by decoctioning air-dried aerial sections of the plant. Antispasmodic activity was tested in an isolated jejunum segment of rats exposed to cumulative doses of drogue extract. The antidiarrheic activity was tested using diarrhea caused by castor oil, a transit study of the small intestine, and castor oil-induced enteropooling assays in mice. In the jejunum of rats, the AEJO (0.1, 0.3 and 1 mg/ml) diminished the maximum tone induced by low K⁺ (25 mM), while it exhibited a weak inhibitory effect on high K⁺ (75 mM) with an IC₅₀=0.49 ± 0.01 mg/ml and IC₅₀=2.65 ± 0.16 mg/ml, respectively. In the contractions induced by CCh (10^-6 M), AEJO diminished the maximum tone, similar to that induced by low K⁺ (25 mM). with an IC₅₀=0.45 ± 0.02 mg/ml. The inhibitory effect of AEJO on low K⁺ induced contractions was significantly diminished in the presence of glibenclamide (GB) (0.3 µM) and 4-aminopyrimidine (4-AP) (100 µM), with IC₅₀ values of 1.84 ± 0.09 mg/ml. and 1.63 ± 0.16 mg/ml, respectively). The demonstrated inhibitory effect was similar to that produced by a non-competitive antagonist acting on cholinergic receptors and calcium channels. In castor oil-induced diarrhea in mice, AEJO (100, 200, and 400 mg/kg) caused an extension of the latency time, a reduced defecation frequency, and a decrease in the amount of wet feces compared to the untreated group (distilled water). Moreover, it showed a significant anti-motility effect and reduced the amount of fluid accumulated in the intestinal lumen at all tested doses. These findings support the conventional use of Juniperus oxycedrus L. as a remedy for gastrointestinal diseases.

Keywords: Juniperus oxycedrus; antidiarrheic; antispasmodic; aqueous extract; functional bowel disorders.

Fig. 1.

Effect of the aqueous extract of Juniperus oxycedrus L. (AEJO) on the rat jejunum precontracted by low K⁺ (25 mM), high K⁺ (75 mM) and CCh (10⁻⁶ M). The values are expressed as the mean ± S.E.M., n=6.

Fig. 2.

The concentration-dependent inhibitory effect of the aqueous extract of Juniperus oxycedrus L. (AEJO) against low K⁺-induced contractions in the absence and presence of glibenclamide (Gb) (3 µM), and 4-aminopyridine (4-AP) (100 µM) in the rat jejunum preparations. Symbols represent the mean ± S.E.M., n=5.

Fig. 3.

Concentration-response curves of CCh in the presence and absence of different concentrations of the aqueous extract of Juniperus oxycedrus L. (AEJO) (0.1–1 mg/ml) or atropine (10⁻⁶ M). The values are represented as the mean ± S.E.M., n=6.

Fig. 4.

Concentration-response curves of CaCl₂ in the presence and absence of different concentrations of the aqueous extract of Juniperus oxycedrus L. (AEJO) (0.1–1 mg/ml) or verapamil (10⁻⁶ M). The values are represented as the mean ± S.E.M., n=6.

Fig. 5.

Effect of the aqueous extract of Juniperus oxycedrus L. (AEJO) on castor oil induced enteropooling in mice. The difference is statistically significant from the normal control (untreated group) at 200 mg/kg and 400 mg/kg (*P≤0.05). The values are represented as the mean ± S.E.M., n=6.