Abstract:
Convolvulus arvensis (Binweed) is a creeping weed widely distributed in the Middle East. During drought animals may be forced to consume the plant. Therefore, this study was carried out to investigate the toxicity of the plant in sheep and rats.
Initially sheep and rats were divided into 3 groups. One group served as controls and fed Rhodes in case of sheep and rat diet in case of rats. The other groups were fed either exclusively on binweed leaves or on 50 % binweed combined with Rhodes or rat diet. Sheep or rats either died or intoxicated by the plant 7 days post dosing with clinical signs included dilated pupil, pale mucous membrane, respiratory distress, ataxia, convulsion and diarrhea. Macroscopic and microscopic lesions included gaseous distended intestine, congestion, oedema and hemorrhage of many organs. Decreased Hb, PCV and RBC count were suggestive of anemia. Elevation of enzymes indicating liver and kidney dysfunction also occurred.
Animals fed 50 % binweed did not develop any signs of toxicity. Oral administration at a dose of 0.5 g rat of binweed for 10 days caused decreased protein in liver homogenate and inhibited the activity of phase-1 drug metabolizing enzymes. Successful extraction of the plant yielded alcoholic and aqueous fractions with LD50 of 160 ± 5 mg / kg and 410 ± 6 mg / kg , respectively, suggesting that the binweed toxicity occurring in sheep and rats may possibly be due to alcoholic fraction. Oral administration of 1/10 LD50 of alcoholic extract blocked diarrhea, enteropooling and intestinal transits induced by castor oil, comparable to that of atropine. Intraperitoneal injection of 1/10 LD50 of aqueous extract to rats significantly increased total leukocytes and percentage lymphocyte, enhanced the phagocytic function of reticular endothelial system and blocked immunosuppressive effect produced by dexamethasone. Furthermore, the aqueous extract significantly increased the concentration of some immunomodulators such as leptin, neopterin, immunoglobulins and lysosmal enzyme activity.
These results show that binweed leaves contain alcoholic soluble atropine-like fraction that was toxic to animals and water soluble fraction that was immunostimulant. The whole plant is toxic to animals, therefore care should be taken that animals are not allowed to eat the plant.
