Pharmacological explanation for the medicinal use of Juniperus excelsa in hyperactive gastrointestinal and respiratory disorders

Crude extract of Juniperus excelsa (JeExt), which tested positive for the presence of anthraquinone, flavonoids, saponins, sterols, terpenes and tannin, exhibited a protective effect against castor oil-induced diarrhoea in mice at 100-1000 mg/kg. In rabbit jejunum preparations, JeExt (0.01-1.0 mg/mL) caused relaxation of spontaneous and K ⁺ (80 mM)-induced contractions at similar concentrations to papaverine, whereas verapamil was relatively more potent against K ⁺. JeExt (0.03-0.3 mg/mL) shifted Ca ²⁺ concentration-response curves to the right, like papaverine or verapamil. JeExt (0.003-0.01 mg/mL) caused a leftward shift of isoprenaline-induced inhibitory concentration-response curves, similar to papaverine. JeExt (1.0-30 mg/kg) caused suppression of carbachol (CCh, 100 μg/kg)-induced increase in inspiratory pressure of anaesthetized rats. In guinea-pig trachea, JeExt (0.001-3.0 mg/mL) relaxed CCh (1 μM)- and high K ⁺- induced contractions and shifted isoprenaline-induced inhibitory curves to the left. This study suggests that Juniperus excelsa possibly exhibits a combination of Ca ²⁺ antagonist and phosphodiesterase inhibitory effects, which provides a pharmacological basis for its traditional use in disorders of gut and airways hyperactivity, such as diarrhoea, colic and asthma.