POISONOUS PLANTS Lecture notes available at: ; .

1. POISONOUS PLANTS Lecture notes available at: ; . bvm20103@gmail.com By Dr. Joseph M Nguta, PhD, (Pharmacol &Toxicol)

2. Introduction • Compounds produced or absorbed by plants could mediate toxicity in livestock. • Phytochemical composition in influenced by, among others: • Climate • Season • Amount of rainfall • Fertilization

3. Introduction……. • Stage of growth • Ecological zone • Availability of water • Part of the plant in question • Factors influencing occurrence of poisoning in livestock include: • Potential of the given plant/part to contain poisonous principles

4. Introduction… • Amount of free toxic principle in the plant before ingestion • Size and kind of livestock species involved • Speed of ingestion • Speed of release of the toxic principle during ingestion • Ingesta present in the digestive tract

5. Introduction…. • Degree of wetness of the ingesta • Speed of detoxification • Rate of elimination • Amount of calcium in the diet….especially with oxalate poisoning..

6. (A). Poisonous principles • Included are: • Alkaloids • Polypeptides • Amines • Oxalates • Resins or resinoids • Phytotoxins (Toxalbumins)

7. Poisonous principles… • Glycosides (glucosides) • i).Cyanogenetic (nitrile) glycosides • ii). Goitrogenic substances • iii). Irritant oils • iv). Coumarin glycosides • v). Steroid and triterpenoid glycosides • vi).Cardiac glycosides • vii). Saponins

8. Poisonous principles…. • Mineral poisonings… (Copper, lead, cadmium, fluorine, manganese) • I. Nitrogen • i). Nitrites-nitrates • ii).Nitrosos • ii).Gaseous oxides of nitrogen • Selenium • Molybdenum

9. Poisonous principles… • Compounds causing photosensitivity • i). Primary photosensitization • ii). Hepatogenic photosensitization • Fungicidal toxin: Persin

10. Poisonous principles… • A number of species of plants contain a toxic substance unique to each e.g. hydroquinone in xanthium species. • Other poisonings are due to anti-factors e.g Thiaminase in Pteridium aquilinum (Brackern fern). • Some spp. Contain two or more toxic principles….in different classes…

11. Poisonous principles… • e.g. a liver toxin and potentially toxic nitrate levels in Tribulus terrestris • Some toxic principles share concurrent membership in many classes e.g. solanine found in species of Solanum (nightshades, etc.)……a glycoside; an alkaloid; steroid glycoside; saponin……due to its physical characteristics…………….

12. Solanine……..

13. Specific plant poisoning • Alkaloids (Nicotiana (tobacco); Atropa belladona (Deadly night shade); Datura stramonium (Jimson weed); Crotolaria spp. (Rattlebox); Senecio spp. (Senecio); Solanum type….tomatoes; potato; nightshades.. • Alkali like, insoluble in water, bitter in taste.. • Distributed in all plant parts • Detection: chromatography; electrophoresis

14. Alkaloids…. • Mainly produce CNS signs…. • Some types of alkaloids, however, produce completely different syndromes e.g. Pyrrolizidine alkaloids cause severe liver damage. • Git related signs with some nightshades • The poisonous principle of Astragulus has been stated to be of alkaloidal nature. Some members of this genus are selenium accumulators. Others are responsible for the nervous disease of horses, sheep and cattle called, “loco”.

15. Polypeptides and amines • Certain algae e.g. Microcystis, a blue green algae, fungi e.g. Amanita, a mushroom, and higher plants e.g. Blighia sapida, akee, contain toxic peptides. • Phoradendron flavescens contain amines (Phenylethylamine, tyramine) which are credited with toxic action. • Ergot (Claviceps) alkaloids are accompanied with amines which may be partially responsible for the toxicity

16. Glycosides • Toxic glycosides include: cyanogenetic (nitrile) glycosides, goitrogenic substances, irritant oils, coumarin glycosides and steroid (cardiac and saponic) glycosides • The amount of a particular glycoside elaborated in a plant depends not only on intrinsic factors such as genetics, part of plant, age of plant, and sometimes even sex of plant, but also to a large degree on extrinsic factors such as climate, moisture supply and soil fertility.

17. (a).Cyanogenetic (nitrile) glycosides • E.g. Cassava; common bean; sorghum; maize; • Yield HCH on hydrolysis • Effect of wilting on HCH release • Ruminant animals…highly susceptible (role of ruminal microflora and pH) • MoA • Mgt strategies..role of sodium nitrite and sodium thiosulfate…..

18. HCN….. • Detoxicfication • In gross aspect, symptoms of cyanide poisoning consist primarily of: early stimulation of respiration; rapidly changing to dyspnea; excitement; gasping; staggering; paralysis; prostration; convulsions; coma and death. • The mucous membranes of mouth and eye may present evidence of congestion • Detection: Picrate test for cyanide…color change from yellow to red…

19. (b). Goitrogenic substances • E.g. Brassica family…cabbages, kale, soybean, rape seed; • Contain thiocyanates & thiooxazolidone…goitrogenic • In the case of poultry, a residual goitrogenic effect may be utilized constructively to produce slightly heavier birds on less feed.

20. (c). Irritant oils • Contain isothiocyanates…..mainly.. allyl isothiocyanate and 3-butenyl isothiocyanate; and also protoanemonine….from ranunculin • E.g. horseradish; White mustard….

21. (d). Coumarin glycosides • E.g. The sweetclovers (Melitotus alba, and M.officinalis)……haemorrhagic • Interfere with clotting by reducing prothrobin levels…..

22. (e). Steroid glycosides and triterpenoid glycosides • Consists of cardioactive glycosides (N.oleander & Thevetia peruviana; Digitallis spp.) and noncardioactive (sapogenic glycosides)….alfafa, rattle box… • MoA: Saponins • Absorption

23. Phytotoxins • E.g. Ricin from castor bean;…cytotoxic..are proteolytic: poisoning is associated with breakdown critical natural proteins and accumulation of ammonia • Ricinus communis agglutinin….aggglutination of rbcs • Poisoning is due to ricin, since RCA cannot penetrate the intestinal wall… • Detected by precipitin reactions with sera containing known antibodies

24. Compounds causing photosensitivity • Primary photosensitization: Hypericum perforatum (St. Johns Wort) or fagopyrin from Fagopyrum esculentum (Buckwheat). • Secondary photosensitization: Lantana camara • Role of phylloerythrin

25. Nitrates-Nitrites • Many crop plants (especially oat hay, corn and sorghum), vegetables and weeds (especially of the amaranth (Amaranthaceae), goosefoot (Chenopodiaceae), mustard (Cruciferae) composite (Compositae) and nightshade (Solanaceae) families contain nitrates at a potentially toxic level. • Role of 2,4-D • Detection: diphenylamine test….blue color dev.

26. Poisonous plants containing fluoroacetate • Some plants are known to concentrate sodium fluoroacetate, one of the most poisonous substances known. • In Kenya, Dichapetalum cymosum is found in the coastal region, where it is known as “ludi” locally. A few leaves are capable of killing a big bull

27. Oxalates • Rumex spp. • Forms of oxalate • Susceptibility: ruminants vs. nonruminants • Absorption: • Deposition in renal tubules…hematuria and renal failure.

28. Fungicidal toxin: Persin • From ovacado.. fruit, leaves, stems, and seeds • Associated with myocardial necrosis in mammals and birds and with mastitis in lactating mammals • Avocado causes necrosis and hemorrhage of mammary gland epithelium of lactating mammals and myocardial necrosis in birds and mammals. Persin isolated from avocado leaves has caused lesions similar to those reported in natural cases.

29. Treatment • NSAID and analgesics may benefit animals with mastitis. Treatment for congestive heart failure (eg, diuretics, antiarrhythmic drugs) may be of benefit, but may not be economically feasible in livestock

30. Brainy quote……….. • Nothing in the world can take the place of Persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan 'Press On' has solved and always will solve the problems of the human race. • Calvin Coolidge 30th president of US (1872 - 1933)