Abstract

Some Solanum species are commonly known as “jurubeba” and have a variety of biological activities such as hypotensive, antidiarrheal, and spasmolytic actions. Solanum jabrense is a perennial shrub or tree from Solanaceae family. The hexane extract from aerial parts of S. jabrense (SJ-Hex) was assayed for possible spasmolytic effect in guinea-pig ileum. SJ-Hex inhibited the contractions induced by carbachol (IC₅₀=36.0±6.2 µg/ml) or histamine (IC₅₀=37.3±6.1 µg/ml) in a concentration dependent and equipotent manner. SJ-Hex also antagonized cumulative concentration-response curves elicited by histamine. The characterization of the blockade was evaluated by the observation that SJ-Hex shifted to the right cumulative concentration-response curves to histamine in a reversible and non-competitive manner. KCl-, carbachol- and histamine-induced tonic contractions were also inhibited (IC₅₀=51.9±11.4; 32.7±11.5, and 31.1±5.3 µg/ml) in a concentration-dependent and reversible manner, suggesting that SJ-Hex could be acting on voltage-operated Ca²⁺channels. This hypothesis was confirmed by the observation that SJ-Hex inhibited in a concentration-dependent manner CaCl₂-induced contractions in depolarizing medium. These results suggest that SJ-Hex produces spasmolytic action in guinea-pig ileum probably by inhibiting the Ca²⁺ influx through voltage-operated Ca²⁺ channels.

Key words: Solanum jabrense, Solanaceae, spasmolytic activity, Ca²⁺ channels.