Inhibitory effect of extract of Ipomoea pes-caprae on guinea-pig ileal smooth muscle

An extract of the plant Ipomoea pes-caprae, used in Thailand as a folk remedy for treating dermatitis caused by jellyfish and Portuguese man-of-war, has been tested for antagonistic activity against histamine, acetylcholine, bradykinin and barium chloride on the isolated guinea-pig ileum. The extract reversibly inhibited the contraction induced by all the spasmogens in a concentration-dependent manner and decreased both the slope and the maximal response of the concentration response curves. It is not likely that the extract specifically interferes at the receptor level. It may be due to the direct action of the extract on the ileal smooth muscle.