Effects of Mondia Whytei aqueous root extract on isolated rabbit heart and Jejunum preparations

Abstract

Mondia Whytei is a forest floor plant with aromatic rhizomatous roots. It belongs to the Asclepiadaceae Family. Its roots are rich in bioactive phytochemicals. essential minerals and vitamins. Among the bioactive phytochemicals that have been isolated so far, 2- hydroxy-4-methoxybenzaldehyde is known to be responsible for the taste characteristics of Mondia Whytei root extract. Monilia Whytei roots were harvested. dried and powdered. 100 mg of this powder was extracted with 500 ml water and subsequently freeze-dried. The freeze-dried extract was then reconstituted with physiological salt solutions immediately before carrying out the experiment. Fifteen California white rabbits were sacrificed with the exclusion of the pregnant ones. The objective of the study was to evaluate the overall effects of Mondia Whytei aqueous root extract on the three kind of muscles in vitro namely skeletal, smooth and cardiac muscles. The set-ups involved isolated rabbit heart and jejunum preparations that were mounted in an organ bath. Previous preliminary experiments with phrenic nerve diaphragm had showed that the extract have no effect 01'1 the skeletal muscle neuromuscular junction. On the isolated rabbit heart preparation the size (height) of the twitch represented the heart force whereas the frequency of the twitches represented the heart rate. Mondia Whytei root extract was found to reduce both the heart force and the heart rate. The data obtained was used to plot the graph of: - (i) Percentage drop in the heart force versus concentration of Mondia Whytei. (ii) Percentage drop in the heart rate versus concentration of Mondia Whytei. The 'best line of fir was preferable in data analysis since the data collected fanned a scatter diagram. Above the dose of 4.8 mg Mondia Whytei aqueous root extract caused ceasation of myocardial contractility or the heart but at low doses it exhibited both negative chronotropic and ionotropic effects. Conclusively, the overall effect on both the heart and the jejunum were parasympathomimetic effects The amount of Mondia Whytei that effectively reduced the heart force by half the original force (EDso) was calculated and determined to be 3.6 mg whereas the ED50 for heart rate was calculated to be 5.25 mg of freeze dried Mondia Whytei extract. On isolated rabbit jejunum, Mondia Whytei aqueous root extract caused contraction but the organ recovered its intrinsic activity over a period of ten minutes. It was also observed that the jejunum recovered from the effects (contraction) of Mondia Whytei even without washing it suggesting the probability of having some degrading enzymes that rendered the extract inactive. Further scientific work therefore ought to be done in order to isolate pure compounds and elucidate mechanisms through which Mondia Whytei aqueous root extract mediates the effects presented here and also analyze its toxicological profile.