Some Gastrointestinal Effects of the Aqueous Root Extract of <i>Plumbago Zeylanica</i> (Lead Wort)

Abstract

The effects of the aqueous root extract of Plumbago zeylanica (PLZ, family, Plumbaginaceae) on the gastrointestinal tract (GIT) function was evaluated in normal intestinal transit and gastric ulcer-induced models in rodents. The extract PLZ given orally at 250 and 500 mg kg^-1 produced a significant (p<0.05) decrease in the gastric lacerations induced by both indomethacin and alcohol, similar to that of cimetidine 100 mg kg^-1. The extract in selected dose range of 250-2500 mg kg^-1 were administered intraperitoneally (i.p) to groups of overnight fasted mice (n = 5) an hour before intragastric administration of charcoal meal and the results obtained showed that only high doses of 1250 and 2500 mg kg^-1 produced significant (p<0.05) dose-dependent decrease in intestinal propulsion in rodents. A similar inhibitory effect on the rhythmic contraction of rabbit ileum was obtained in-vitro with concentrations of 28.8-344.0 μg ml^-1 of PLZ. The latter observed effect was similar to that produced by adrenaline (3.9×10^-7 M) and the adrenergic antagonists- prazosin and propranolol used together with the herbal drug, revealed that PLZ effect is partly mediated through the adrenergic mechanism. The effects of atropine and carbachol on PLZ did not show any cholinergic involvement. Phytochemical analysis revealed the presence of alkaloids, tannins, cardiac glycosides, phlobatanins, anthraquinones, reducing sugars, saponins and flavonoids and the i.p route produced an LD₅₀ value of 5296.6 mg kg^-1. The study established the scientific basis for the use of PLZ in the treatment of gastric ulcer and diarrhoea, as well as its possible mechanism of action and relative safety when ingested.

Keywords: Plumbago zeylanica Lead Wort, antiulcer, antidiarrhoeal, gastrointestinal, aqueous extract.