Pharmacological Studies on three Sudanese Medicinal Plants Possessing Antimicrobial Properties

Abstract

In order to verify or refute the folklorically claimed benefits of some Sudanese plants possessing antimicrobialactivity and to detect any side effects that may be associated with their use, the methanol extract of three plants were studied on selected isolated tissue preparations. The methanol extract of Loranthus acaciae (Zucc.) leaves exhibited a dose dependent non-adrenergic inhibition of the isolated rabbit jejunum preparation, since it was not blocked neither by propranolol (Non selective β–blocker) nor tolazoline (Non-selective αblocker). The extract was devoid of any activity on guinea pig ileum preparation and couldn’t antagonize the Histamine (50ng/ml) induced contraction of the tissue. Prior administration of the extract (2mg/ml) markedly potentiated the Acetylcholine (1µg/ml) contracture on Toadrectus abdominis muscle preparation, while the extract alone was without activity on the preparation . In a dose of 4mg/ml the extract effectively reversed d-tubocurarine (20µg/ml) blockade of Acetylcholine (1µg/ml) contracture on toad rectus abdominis muscle preparation in a manner comparable with that produced by the anticholinestrase Neostigmine (40µg/ml). On both isolated rabbit heart and guinea pig atrium preparations the extract showed a dose dependent inhibition of the force of contraction but without effect on the rate of contraction, its action on the atrium was not affected by prior administration of Atropine sulphate (50µg/ml). Prior administration of the extract (2mg/ml) to the cardiac muscle obviously potentiated acetylcholine (2µg/ml) inhibition of the force of contraction. The methanol extract ofNymphaea lotus (L.) showed a dose dependent (1-4mg/ml) stimulation of the isolated rabbit jejunum preparation, this stimulation was refractory to atropine sulphate (2µg/ml) antagonistic property, but was blocked by Cyproheptadine (40µg/ml) (a non selective 5HT blocker). The extract(2mg/ml) exhibited a contraction of the guinea pig ileum preparation comparable with that of Histamine (10ng/ml) but refractory to the antagonistic action of the antihistamine Chlorpheneramine maleate(40ng/ml),on the other hand the extract(2mg/ml) induced contraction as well as 5Hydroxytreptamine were completely blocked by Cyproheptadine (20ng/ml). On rat fundus strip preparation both xiv 5Hydroxytreptamine (25ng/ml) and Nymphea lotus methanol extract (2mg/ml) showed a prominent contraction that was completely blocked by Cyproheptadine. The extract (2mg/ml)neither blocked nor potentiated the Acetylcholine (1µg/ml) induced contracture of the toad rectus abdominis muscle preparation .the extract per se showed no activity. The methanol extract of Anogeissus leiocarpus (DC.) showed a dose dependent inhibition of the isolatedrabbit jejunum preparation. This relaxant activity was not blocked by Tolazoline (40µg/ml) while propranolol (4µg/ml) completely blocked the inhibition. The extract (2mg/ml) per se was without effecton both isolated guinea pig ileum preparation and isolated toad rectusabdominis muscle preparation. The extract neither antagonized nor potentiated the carbachol (1µg/ml) contraction on the guinea pig ileumpreparation and Acetylcholine (1µg/ml) contracture on toad rectus abdominis muscle preparation. On guinea pig atrium preparation the extract (2mg/ml) decreased markedly the frequency of contraction and was devoid of any activity on the force of contraction. The extract (4mg/ml) neither had any activity on isolated guinea pig tracheal preparation nor affected histamine (400ng/ml) induced contraction of the preparation. On rat uterus preparation the extract (2mg/ml) showed relaxant activity that blocked the Acetylcholine (1µg/ml) contraction of the preparation, prior administration of propranolol (80µg/ml) was without effect.