Responses of gastrointestinal smooth muscle preparations to a muscarinic principle present in Sida veronicaefolia.

The effects of the water-soluble fraction from an alcoholic extract of Sida veronicaefolia leaves were studied on isolated guinea-pig ileum and isolated rabbit duodenum. Agonist/antagonist studies, using atropine, hexamethonium and mepyramine, suggest that the active principle may be muscarine-like. Preliminary biochemical investigations on the extract showed negative results for the presence of alkaloids, saponins and true tannins, but confirmed the presence of pseudotannins, oligosaccharides, flavonoids, choline, fructose, peptides, histidine, glycine, tyrosine, oxalic acid and phenolic acid.