Antispasmodic and Relaxant Activity of Chelidonine, Protopine, Coptisine, and Chelidonium majus Extracts on Isolated Guinea-Pig lleum

Abstract

Two ethanolic dry extracts from the herb Chelidonium majus L. with a defined content of the main alkaloids (chelidonine, protopine, and coptisisine) and the alkaloids themselves were studied in three different antispasmodic test models on isolated ileum of guinea-pigs. In the BaCI₂-stimulated ileum, chelidonine and protopine exhibited the known papaverine-like musculotropic action, whereas coptisine (up to 3.0 × 10^-5 g/ml) was ineffective in this model. Both extracts were active with 53.5% and 49.0% relaxation at 5 × 10^-4 g/ml. The carbachol and the electric field stimulated contractions were antagonized by all three alkaloids. Coptisine showed competitive antagonist behaviour with a pA₂ value of 5.95. Chelidonine and protopine exhibited a certain degree of non-competitive antagonism. In the electric field the antagonist activities decreased in the order protopine > coptisine > chelidonine. The concentrations of the chelidonium herb extracts for 50% inhibition of the carbachol and electrical field induced spasms were in the range of 2.5 to 5 × 10^-4 g/ml.