Bioassay-directed fractionation of the chloroform-methanol (1:1) extra
ct of Dodonaea viscose (L.) Jacq. (Sapindaceae) resulted in the isolat
ion of four active spasmolytic principles: sakuranetin (1), 6-hydroxyk
aempferyl 3,7-dimethyl ether (2) hautriwaic acid(3), and ent-15,16-epo
xy-9 alpha H-labda-13(16)14-diene-3 beta,8 alpha-diol (4). All the iso
lated compounds elicited a concentration-dependent inhibition of the s
pontaneous and electrically-induced contractions of guinea-pig ileum.
Sakuranetin and the ent-labdane inhibited the ileum contractions evoke
d by acetylcholine (Ach), histamine, and barium chloride. In addition,
both substances were capable of relaxing contractions of rat uterus i
nduced by Ca2+ in K+-depolarizing solution, displacing to the right th
e concentration-response curves to Ca2+. These results suggest that sa
kuranetin and ent-15,16-epoxy-9 alpha H-labda-13(16)14-diene-3 beta,8
alpha-diol produce an interference with calcium metabolism in smooth m
uscle cells. The spasmolytic activity exhibited by the active principl
es from D. viscosa, provides the pharmacological basis for the traditi
onal use of the plant as an antispasmodic agent.