Avaliação da atividade espasmolítica das partes aéreas e das raízes de Solanum paniculatum L.: um estudo comparativo.

Abstract

Solanum paniculatum L. popularly known as "jurubeba - verdadeira." Recently been demonstrated spasmolytic and antidiarrheal activities for the crude ethanol ic extract of the aerial parts of this species. Therefore , the aim of this work was to investigate and compare possible spasmolytic activity of ethanol ic extracts extracted of the aerial parts ( SP - EtOH PA ) and roots ( SP - EtOH R ) of Solanum paniculatum in smooth muscle models and elucidate action mechanism of the extract to present the better spasmolytic effect in one of the tested organs . Rat aorta: SP - EtOH PA and SP - EtOH R (243 and 729 μg/mL , n = 3) relaxed organ to pre - contracted with phenylephrine (3 x 10 - 7 M) in the presence ( E max = 59.3 ± 7.1 and 57. 0 ± 3.2%, respectively) or absence (E max = 58.3 ± 6.7 and 66.3 ± 4.1% respectively) functional endothelium. Guinea pig trachea: SP - EtOH PA and SP - EtOH R (243 and 729 μg/mL , n = 3) relaxed organ pre contracted with carbachol (CCh, 10 - 6 M) in the pre sence (E max = 56.8 ± 2.7 and 52. 7 ± 2.9% , respectively) or absence (E max = 30.0 ± 1.5 and 73.6 ± 9.2%, respectively) of the functional epithelium. Rat uterus: SP - EtOH PA ( 243 and 729 μg/mL, n = 3) had no significantly tocolytic effect front of phasic contractions ind uced by 10 - 2 UI/mL of oxytocin (E max = 6.3 ± 3.5%) and 10 - 5 M CCh (E max = 0.3 ± 0.3%), while SP - EtOH R (243 and 729 mg/ mL) inhibited in a significant way the phasic contractions induced by oxytocin ( 10 - 2 UI/mL ) or CCh ( 10 - 5 M ) (E max = 40.2 ± 10.2 and 47.0 ± 8.9%, respectively). Guinea pig ileum : SP - EtOH R (243 and 729 μg/mL , n = 3) inhibited significantly the phasic contractions induced by CCh (E max = 65.3 ± 8.5 %) or histamine ( 10 - 6 M , E max = 58.8 ± 3.9%). Clementino - Neto (2012) related that SP - EtOH PA showed spasmolytic effect front of the phasic contractions induced by CCh (E max = 81.2 ± 5.4%) and histamine (E max = 93.9 ± 1.2%). Thus, So we decided to characterize the action mechanism of SP - EtOH PA on this o rgan that proved to be more effective. SP - EtOH PA (0.1 to 729 μg/mL , n = 5) relaxed the ileum in a significant and concentration - dependent manner wi th 40 mM KCl (EC 50 = 47.5 ± 4.4 μg/mL ), 10 - 6 M CCh (EC50 = 49.9 ± 7.3 μg/mL ) or 10 - 6 M histamine (EC 50 = 65.0 ± 5.3 μg/mL ) and 1.3 times more potent to KCl when compared to histamine. How the common pathway of signaling of these contractile agents are the voltage - gated Ca 2+ channels (Ca V ), we investigated their involvement in mechanism of action of SP - EtOH PA , n = 5 . The control cumulative curves of CaCl 2 were diverted to the right a non - parallel form and reduction of the E max to 100% fo 27.7 ± 3.0% and EC 50 of CaCl 2 value increased from 1.4 ± 0.1 x 10 - 3 M to 6.5 ± 0.7 x 10 - 3 M at the highest concentration of the extract (729 μg/mL ) , but without concentration dependence , suggesting the ex tract could act indirectly on Ca V . As Ca V are modulated by K + channels, we investigated the involvement of these channels (n = 5). The relaxing potency of SP - EtOH PA (EC 50 = 65.0 ± 5.3 μg/mL ) was reduced in the presence of CsCl , a nonspecific blocker of K + channels (EC 50 = 89.0 ± 3.0 μg/mL ) , suggesting the upregulation of these channels, leading to hyperpolarization the membrane with consequent blocking of Ca V and relaxation of intestinal smooth muscle.