Dr.Nahla Allagabo
Introduction to Toxic Principles of plants and their
chemistry
 Plants are storehouse of chemicals – diverse biological
activities.
 Harmless and are necessary for the survival of both the
plants and animal kingdoms.
 The simple sugar molecules- glucose- food chain in
nature.
 The protoplasm consists of amino-acid – essential for
sustaining life.
 Plants toxins may be referred to as secondary
plant metabolites which are toxic compounds.
Introduction
 Compounds produced or absorbed by plants could
mediate toxicity in livestock.
 Phytochemical composition is influenced by, among
others:
 Climate
 Season
 Amount of rainfall
 Fertilization
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
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
Introduction….
 Degree of wetness of the ingesta
 Speed of detoxification
 Rate of elimination
 Amount of calcium in the diet….especially with oxalate
poisoning..
Classification on the basis of chemical
constituents:
 Included are:
 Alkaloids
 Polypeptides
 Amines
 Oxalates
 Resins or resinoids
 Phytotoxins (Toxalbumins)
Classification on the basis of chemical
constituents:
 Glycosides (glucosides)
 i).Cyanogenetic (nitrile) glycosides
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ii). Goitrogenic substances
iii). Irritant oils
iv). Coumarin glycosides
v). Steroid and triterpenoid glycosides
vi).Cardiac glycosides
vii). Saponins
Poisonous principles….
 Mineral poisonings… (Copper, lead, cadmium,
fluorine, manganese)
 I. Nitrogen
 i). Nitrites-nitrates
 ii).Nitrosos
 ii).Gaseous oxides of nitrogen
 Selenium
 Molybdenum
Poisonous principles…
 Compounds causing photosensitivity
 i). Primary photosensitization
 ii). Hepatogenic photosensitization
 Fungicidal toxin: Persin
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…
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…………….
Solanine……..
Specific plant poisoning
Alkaloids
 Alkaloids (“alkali-like”) are compounds that contain
nitrogen, usually in a heterocyclic ring, and are generally
basic substances.
 They are usually bitter, and most are toxic.
 They are sub-classified on the basis of the chemical type
of the nitrogen-containing heterocyclic ring.
Specific plant poisoning
Alkaloids
 Alkali like, insoluble in water..
 Distributed in all plant parts
 Detection: chromatography; electrophoresis
Pyrrolizidine Alkaloids
 The nucleus consists of two five-membered rings.
 Pyrrolizidine alkaloids are responsible for the toxicity of
various plant like:
Senecio sp. (tassy ragwort, common groundsel),
Crotalaria sp.,
Heliotropium sp.
 It causes irreversible liver damage.
 Chemical constituents: monocrotaline, heliotrine,
lasiocarpine, and senecionine.
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”.
Piperidine Alkaloids
 The most important piperidine alkaloids in animal
reduction are coniine and related alkaloids found in
Conium maculatum (poison hemlock).
 These alkaloids affect the central nervous system and are
also teratogens.
 Plant ; Conium maculatum (hemlock).
 Chemical constituents: coniine
Pyridine Alkaloids
 Pyridine alkaloids is present in plant Nicotiana sp.
 Example: cultivated and wild tobacco.
 Chemical constituents: nicotine.
Indole Alkaloids
Indole Alkaloids
 Indoles are derivatives of the amino acid tryptophan.
 Examples are the ergot alkaloids.
 The alkaloids such a perloloine present in tall fescue.
 Chemical constituents: 3-methylindole.
 It is an alkaloid implicated in bovine pulmonary
emphysema.
Steroid Alkaloids
Solanum type (e.g., salanidine)
 These are found in green potatoes, tomatoes, and nightshade.
 They are central nervous system poisons and cholinesterase
inhibitors.
 Solanidine in potatoes has human health implications.
Veratrum type (e.g., veratramine)
 False hellebore (Veratrum californicum) contains veratrum
alkaloids that produce teratogenic effects in lambs .
 Death, a source of extensive sheep losses in the American West
in the past, contains alkaloids of this type.
Tropane Alkaloids
 Atropine, found in Datura spp. (Jimson weed), is an
example of a tropane alkaloid.
 It has pronounced effects on the central nervous system.
 Nicotiana (tobacco); Atropa belladona (Deadly night
shade);
 Datura stramonium (Jimson weed); Crotolaria spp.
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, 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
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.
(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)
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…
(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.
(c). Irritant oils
 Contain isothiocyanates…..mainly.. allyl isothiocyanate
and 3-butenyl isothiocyanate; and also
protoanemonine….from ranunculin
 E.g. White mustard….
(d). Coumarin glycosides
 E.g. The sweetclovers (Melitotus alba, and
M.officinalis)……haemorrhagic
 Interfere with clotting by reducing prothrobin
levels…..
(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
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
Compounds causing
photosensitivity
 Primary photosensitization: Hypericum perforatum or
fagopyrin from Fagopyrum esculentum (Buckwheat).
 Secondary photosensitization: Lantana camara
 Role of phylloerythrin
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.
 Detection: diphenylamine test….blue color dev.
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
Oxalates
 Rumex spp.
 Forms of oxalate
 Susceptibility: ruminants vs. nonruminants
 Absorption:
 Deposition in renal tubules…hematuria and renal
failure.
The End