Comparative Study on the Vasorelaxant Effects of Three Alkaloids-rich Extracts from Seeds of Peganum harmala L.

The effect of seed methanolic, ethyl-acetate and chloroformic extracts of Peganum harmala L. on KCl- and Noradrenaline- induced contractions of aortic strips was studied. In aortic strips with endothelium intact, contractions induced using 80 mM KCl and 10^-6 M Nor-adrenaline were dose-dependently relaxed by the extracts, a more significant effect being seen with Nor-adrenaline-induced contractions. Following mechanical damage to the aortic endothelium, the results showed that the inhibition of contraction by the three extracts was not endothelium dependent. The rank order of relaxation potency was MeOH > EtoAc> CHCl₃-extracts of Peganum harmala L. The results suggest that the relaxation effect of the three alkaloids-rich extracts may be attributed to the inhibiting of the AMP cyclic nucleotide PDE (Phosphodiesterase).