This study examines the effects of methanolic extract (ME) and its main constituent, sorocein A, isolated from the roots of Sorocea bonplandii on agonist-induced contractions in the rat uterus (RU) and in the guinea pig ileum (GPI) in vitro. ME (25-100 μg/ml), added to RU for 20 min, caused a graded and parallel shift to the right of bradykinin (BK)-mediated contractions with an apparent pA 2 value (-log g/ml) of 5.0. ME caused a rightward shift of the acetylcholine (ACh) and oxytocin-induced contractions associated with a marked depression of their maximal responses. In GPI, ME produced a non-competitive antagonism against BK-induced contraction, while responses to ACh and histamine were shifted to the right in a graded fashion, yielding pA 2 values (g/ml) of 5 in both cases. The purified compound sorocein A (15-60 μM) caused a parallel and graded rightward displacement of BK and ACh concentration-response curves in RU with pA 2 values (molar basis) of 4.9 and 5.2. Sorocein A also dose-dependently shifted to the right ACh and histamine-mediated contractions in GPI, yielding pA 2 values of 5.1 and 4.8, respectively. However, sorocein A antagonized in a non-competitive manner BK-induced contraction in GPI, characterized by a graded displacement to the right of the dose-response curve and progressive depression of the maximal contraction.
Pharmacological analysis of the methanolic extract and sorocein A, a new Diels-Alder compound isolated from the roots of Sorocea bonplandii bailon in the isolated rat uterus and guinea pig ileum
MESSANA, IRENE;
1993-01-01
Abstract
This study examines the effects of methanolic extract (ME) and its main constituent, sorocein A, isolated from the roots of Sorocea bonplandii on agonist-induced contractions in the rat uterus (RU) and in the guinea pig ileum (GPI) in vitro. ME (25-100 μg/ml), added to RU for 20 min, caused a graded and parallel shift to the right of bradykinin (BK)-mediated contractions with an apparent pA 2 value (-log g/ml) of 5.0. ME caused a rightward shift of the acetylcholine (ACh) and oxytocin-induced contractions associated with a marked depression of their maximal responses. In GPI, ME produced a non-competitive antagonism against BK-induced contraction, while responses to ACh and histamine were shifted to the right in a graded fashion, yielding pA 2 values (g/ml) of 5 in both cases. The purified compound sorocein A (15-60 μM) caused a parallel and graded rightward displacement of BK and ACh concentration-response curves in RU with pA 2 values (molar basis) of 4.9 and 5.2. Sorocein A also dose-dependently shifted to the right ACh and histamine-mediated contractions in GPI, yielding pA 2 values of 5.1 and 4.8, respectively. However, sorocein A antagonized in a non-competitive manner BK-induced contraction in GPI, characterized by a graded displacement to the right of the dose-response curve and progressive depression of the maximal contraction.
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