THE TOXIC EFFECT OF SIX COMMONLY OCCURRING PLANTS IN NIGERIAN PASTURES

Abstract

The toxicology of six suspected poisonous plants Leucaena leucocephala Benth, Tribulus terrestris Linn Eugenia uniflora Linn, Dichapetalum madagascasience Poir, Lantana camara Linn, and Solanum torvum Benth); were evaluated in Sprague Dawley rats weighing between 200-300 grams. Two of these plants, Lantana camara and D. madagascasience were re-evaluated in West African dwarf goats. Spectrophotometric and titrimetric methods were also used to determine some inorganic and metallic contents of the plant. The extracts of all the poisonous plants except S. torvum and D. madagascasiense produced dose dependent effects on rat serum proteins. The extracts of these plants which produced statistically significant changes (P< 0.05) in serum proteins of the rat include the 400 and 600mg/kg doses of the extrct of 1.. leucocephala; 400 mg/kg dose level for extract of T. terrestris; 200 mg/kg dose level for the extract of E. uniflora; , 400 and 600 mg/kg dose levels extract of L. camara. The globulin fraction did not show any significant changes in all the rats treated with the poisonous plants. No changes were also observed in the serum dectrolytes analYsed. T.terrestris, L. Camara and E. uniflora produced dose related increases in activities of serum enzymes, alanine aminotransferase ALT (EC 2:6.1.2), aspartate aminotransferase (AST) (EC.2.6.1.1.), and alkaline phosphatase (ALP) (EC.3.1.3.1.) . All the plants produced significant increases in ALT except L. Leucocepha!a and torvum whereas E. uniflora, L. camara, and D. madagascasie use produced significant changes in AST (P<.0.05). An evaluation of the haematological parameters of the treated rats, revealed that only extracts of T. terrestris, and L. Camara produced dose dependent decreases in the total red cell blood count. These decreases were significant for, all the doses of the extracts of T. terrestris; the 400 and 600 mg/kg dose levels of L. camara (P < 0.05). The decreases in erythrocyte counts were associated with decreases in haemoglobin concentration. The piosonous plants did not cause changes in the blood coagulation time. Only the extract of T. terrestris produced decreases in total leucocyte count. Similarly, only the extract of T. terrestris caused clinical symptoms in the rats which included depression and inappetence. However, all the plant extracts except that of S. torvum produced gross pathologic lesions in the liver including pin point or ecchymotic hemorrhages. Histopathologic lesions include necrotic lesions of the hepatic tissues and vacuolation of some hepatic lobules. T. terrestris, L.camara, E. uniflora and L. Leucocephala produced gross lesions of the renal tissue. Histologically the affected renal parenchyma was hyperemic and the tubular epithelium showed degeneration. The extracts of D.madag-gascasience and L.-camara produced gastrointestinal lesions including superficial necrosis of intestinal epithelial lining and desquamation of patches of the gastric and ileal mucosa. In the West African Dwarf goats, L. camara and D. madagascasience produced increases in the serum activities of ALT, AST and ALP. Furthermore, these plants also produced increased total blood protein level and blood urea nitrogen. Lantana toxicity in the goats also produced decreased total RBC counts, decreases hematocrit and increased haemoglobin concentration. Animals with Lantana toxicity also showed anorexia and were emaciated. Q. madagascasience did not produce changes in haematological parameters. Phytochemical analysis showed different levels of cyanide, (CN-), nitrate (N03-) nitrite (N02-), oxalate and elements such as lead )Pb+), zinc+), iron (Fe++), manganese (Mn+), and copper (Cu++) in all the plants These studies therefore shows that T. terrestris E. unifora, L. leucocephala, L. camara but particularly L. camara and T. terrestris are hepatotoxic, produce renal lesions and also affect hemopoiesis. Thus these plants are toxic to livestock and their growth among normal pasture could post potential risk to livestock production in Nigeria.