Assessment of Eight Popularly Used Plant-Derived Preparations for Their Spasmolytic Potential Using the Isolated Guinea Pig Ileum

Abstract

Aqueous extracts from eight plant species that are popularly used as spasmolytics have been evaluated for these pre-sumed activities. The species included Kalanchoë pinnata (Lam.) Pers. (Crassulaceae), Cymbopogon citratus Stapf. (Gramineae), Gossypium barbadense L. (Malvaceae), Caesalpinia pulcherrima (L.) Schwartz (Caesalpiniaceae), Tagetes erecta L. (Compositae), Bixa orellana L. (Bixaceae), Cassia alata L. (Caesalpiniaceae), and Phyllanthus amarus Schum. & Thonn. (Euphorbiaceae). Potential spasmolytic activity of the extracts was judged by their ability to reduce forces of smooth muscle contraction of a 2-cm-long piece of guinea pig ileum induced by EC50 acetylcholine (27 ± 5 µg/l) or EC50 histamine (102 ± 13 µg/l). The dried extracts were used at concentrations of 0.01, 0.1, 1, and 10 mg/ml. Incubations were carried out in Tyrode buffer kept at a temperature of 37°C and mixed with 5% CO2 in air and were monitored for 30 s with 60-s intervals. Results (means ± SD; n ≥ 3) were expressed relatively to forces of contraction due to EC50 acetylcholine or EC50 histamine alone. The extract from K. pinnata reduced the force of contraction due to histamine but not that due to acetylcholine progressively (40% to 95%) with concentrations increasing from 0.01 to 10 mg/ml. At 10 mg/ml, the C. pulcherrima and B. orellana extracts also counteracted only the histamine-induced force of contraction (by about 25% and 50%, respectively). The C. citratus extract decreased the acetylcholine-induced force of contraction by 20% to 60% at 0.1 to 10 mg/ml and that induced by histamine by 60% to 90% at 0.01 to 10 mg/ml. On the other hand, the G. barbadense extract potentiated rather than reduced forces of contraction due to both acetylcholine and histamine (1.2- to 2-fold at 0.01 to 10 mg/ml). The T. erecta extract had such an effect only on the acetylcholine-induced force of contraction (about 2-fold at 10 mg/ml). The use of the former but not the latter sample alone led to an increase in smooth muscle tone that was not reversed by atropine or chlorpheniramine. The C. alata and P. amarus extracts did not significantly modify forces of contraction due to either acetylcholine or histamine. Our results suggest that preparations from K. pinnata, C. citratus, C. pulcherrima, and B. orellana, but not from G. barbadense, T. erecta, C. alata, and P. amarus, may be useful against smooth muscle spasm. These actions were probably mediated by distinct mechanisms.