Pharmacological basis for the use of peach leaves in constipation

The aqueous crude extract (PPL.Cr) of peach leaves (Prunus persica) was stu died for the possible presence of gut stimulatory constituent(s) to rationa lize the folkloric use of the plant in constipation. PPL.Cr at the dose of 1-10 mg/ml caused a moderate degree of spasmogenic effect in isolated guine a-pig ileum. Pretreatment of the tissue with atropine (1 M) completely abol ished the contractile effect of the plant extract similar to that of acetyl choline which is suggestive of a cholinergic mechanism. In isolated rabbit jejunum preparations, PPL.Cr produced a week spasmogenic effect followed by relaxation of the spontaneous contractions at higher doses. Bioassay-direc ted fractionation revealed that the spasmogenic activity was separated in t he aqueous fraction, while the spasmolytic activity was concentrated in the ethyl acetate fraction. When tested against K+-induced contraction, both P PL.Cr and its ethyl acetate fraction (PPL.EtAc) caused a dose-dependent inh ibition, suggesting calcium channel blockade (CCB). The presence of CCB in peach leaves was confirmed when pretreatment of the tissue with PPL.EtAc ca used a dose-dependent rightward shift in the Ca2+ dose-response curves, sim ilar to that produced by verapamil. These data indicate that the plant cont ains spasmogenic (cholinomimetic) and spasmolytic (calcium antagonist) cons tituents, which are concentrated in the aqueous and ethyl acetate fractions , respectively. Furthermore, the laxative effect of the plant reported in t he traditional system of medicine may be partially due to the cholinergic a ction, which was dominant over the spasmolytic component. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.