Abstract
Callistemon citrinus is a plant of family myrtaceae that has a great medicinal importance. Traditional uses of the aerial parts of Callistemon citrinus in ethnic tribal communities are in practice, and very little are known about its importance on scientific grounds. Therefore, the crude methanolic extract of fruits of Callistemon citrinus (C.c) was screened for possible spasmolytic activity on isolated rabbit's jejunum preparations. The extract produced a relaxing effect on spontaneous contraction of rabbit's jejunum. Explaining the mode of action, the extract produced a dose dependent relaxant effect and shifted the calcium response curves to the rightward (EC50 +/- SEM = -2.05 +/- 0.05 vs. control EC50 +/- SEM = -2.5 +/- 0.05). The effect of extract was comparable with the effect of verapamil, a standard calcium channel blocker and therefore, the plant specie could be a potential target for isolation of calcium antagonist(s).