title: 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.
abstract: 1. 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. 2. ME (25-100 micrograms/ml), added to RU for 20 min, caused a graded and parallel shift to the right of bradykinin (BK)-mediated contractions with an apparent pA2 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. 3. 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 pA2 values (g/ml) of 5 in both cases. 4. The purified compound sorocein A (15-60 microM) caused a parallel and graded rightward displacement of BK and ACh concentration-response curves in RU with pA2 values (molar basis) of 4.9 and 5.2. 5. Sorocein A also dose-dependently shifted to the right ACh and histamine-mediated contractions in GPI, yielding pA2 values of 5.1 and 4.8, respectively. 6. 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.
authors.affiliation: Departmento de Farmacologia, Universidade Federal de Santa Catarina, Brazil.
authors.forename: J B
authors.initials: JB
authors.lastname: Calixto
authors.forename: I
authors.initials: I
authors.lastname: Messana
authors.forename: F
authors.initials: F
authors.lastname: Della Monache
authors.forename: F
authors.initials: F
authors.lastname: Ferrari
authors.forename: T
authors.initials: T
authors.lastname: Bisognin
authors.forename: R A
authors.initials: RA
authors.lastname: Yunes
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D018377:Neurotransmitter Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D002839:Chromans; D018377:Neurotransmitter Agents; D010936:Plant Extracts; C084182:sorocein A; D010121:Oxytocin; D006632:Histamine; D000109:Acetylcholine; D001920:Bradykinin