Chemical constituents of poisonous plants

CLASSIFICATION, IDENTIFICATION &

CHEMICAL CONSTITUENTS

OF POISONOUS PLANTS

Dr. Sindhu K

M. V. Sc. Scholar, Dept of VPT,

COVAS, Pookode.

INTRODUCTION TO PLANT TOXICOLOGY

Toxic plant may be defined as “one which detrimentally affects the health of

man or animal when eaten in such amount as would be taken normally or under

special circumstances like restriction of choice of diet or extreme hunger”.

The toxic (active) principles present in the plants = PHYTOTOXINS.

The basic framework of protoplasm = Amino acids (20)

Pathway of metabolism Primary metabolites glucose, AA.

Secondary metabolites alkaloids,

glycosides,

terpenes, resins.

SECONDARY PLANT METABOLITES {SPM}

Plant toxins may be referred as SPM.

SPM defense mechanism / survival adaptations.

Toxic plants are of 2 types

i. Plant containing toxic ingredients & are known to be toxic to animals.

ii. Plants which are normally not toxic to animals but becomes so under

unfavorable conditions.

CLASSIFICATION OF TOXIC PLANTS

I. Alkaloids

II. Terpenes

III.Glycosides

IV. Proteinaceous compounds

V. Organic acids

VI. Resins & Resinoids

ALKALOIDSComplex nitrogen containing

organic compounds having one/more heterocyclic rings.

Alkaline in nature.

Readily soluble in alcohol, but sparingly soluble in water.

Both alkaloids + alkaloid salts precipiated by tannic acid & oxidized by potassium permanganate.

Bitter in taste & often poisonous.

Name ends with suffix –ine.

Eg: atropine, epinephrine, ergotamine, apomorphine.

TROPANE/ATROPINE LIKE ALKALOIDS

Atropine

Datura (jimsonweed)

Erythroxylum (coca tree)

Hyoscyamus (henbane)

Mandragora (mandrake)

PYRROLIZIDINE ALKALOIDS

Retronecine

Senecio (ragwort)

Crotalaria sp.

Heliotropium sp.

Trichodesma sp.

PYRIDINE/PIPERIDINE ALKALOIDS

Conium (Hemlock)

Lobelia (Indian tobacco)

PYRROLIDINE-PYRIDINE ALKALOIDS

Nicotine

Nicotiana sp. (Tobacco)

Equisetum sp. (Horse tail)

PURINE ALKALOIDS

caffeine

Coffea sp. (Coffee)

Theobroma sp. (Cocoa)

Camellia sp. (Tea)

QUINOLINE ALKALOIDS

Quinine

Cinchona sp. (Quinine tree)

Echninops sp. (Globe thistle)

ISOQUINOLINE ALKALOIDS

Morphine

Papaver somniferum

(opium)

Sanguinaria sp.

Dicentra (Blood root)

INDOLE/INDOLIZIDINE ALKALOIDS

Strychnine

Strychnus (strychnine)

Claviceps (Ergot)

Psilocybe (Magic mushroom)

Astragalus sp. (locoweed)

Gelsemium sp.

QUINOLIZIDINE ALKALOIDS

Anagyrine

Laburnum sp. (Golden chain)

Baptisia sp. (False indigo)

Cytisus sp. (Scotch broom)

STEROIDAL GLYCOALKALOIDS

Solanidine

Lycopersicum sp. (Tomato)

Solanum sp. (Nightshades)

STEROIDAL ALKALOIDS

Jervine

Veratrum sp.

Zigadenus sp.

DITERPENOID ALKALOIDS

Aconitine

Delphinium sp. (Larkspur)

Aconitum sp. (Monkshood)

PHENYLAMINE ALKALOIDS

Ephedrine

Lophophora sp. (peyote)

Ephedra sp.

TERPENESBiosynthesized by plants

Contains the branched 5-carbon skeleton of isoprene.

On the basis of number of isoprene units present in the

structure of the molecule, terpenes are categorized as

C-10 compounds monoterpenes

C-15 compounds sesquiterpenes

C-20 compounds diterpenes

C-30 compounds triterpenes

MONOTERPENES• Cantharidine an animal monoterpene

from fly ash.

• Picrotoxin from Anamirta cocculus

(Fish berries).

SESQUITERPENES• Coramyrtin from Coriaria myrtifolia

• Geigerin from Geigeria

• Helenalin from Helenium microcephalum

DITERPENES• Andromedotoxin

• Mezerein

• Aconitine from Aconitum sp.

TRITERPENES• Cicurbitacins (toxic principles of bittergourd)

• Lantadenes from Lantana sp.

GLYCOSIDES

Complex organic compounds having glycone attached to

aglycone/genin moiety by ether linkage

Neutral in reaction

Soluble in alcohol, less soluble in water & insoluble in ether

They don’t combine with acids to form salts

Names ends with suffix –in.

Eg: digitoxin, ouabin, scillarin, glycyrrhizin, senegin.

CYANOGENIC GLYCOSIDES

Amygdalin

Amygdalin (Almond seed)

HCN in Hydrangea, Linum

(Linseed)

Prunus (Wild cherry)

Sorghum vulgare (Jowar)

Sorghum sudanese (Sudan grass)

Gossypol (cotton seed)

STEROIDAL (CARDIONILIDES/CARDIAC

GLYCOSIDES)

Digitoxin

Digoxin from Digitalis sp.

Oubain from Strophanthus

Convallarin from Convallaria

Ascleipas (Milk weed)

Nerium oleander

STEROIDAL (SAPONIGENICGLYCOSIDES)

Argostemme (Corn cockle)

Phytolacca (Poke weed)

Hedera (English ivy)

COUMARIN GLYCOSIDES

Esculin

Ausculus glabra

Moldy Meliolotus sp. (White sweet clover)

Ipomoea sp. (Sweet potato)

ANTHRAQUINONEGLYCOSIDES

Cassia fistula (Senna)

Aloe sp.

MUSTARD GLYCOSIDES

Sinigrin

Thiocyanates/isothiocyanates

of mustard oil.

(Brasssica nigra)

PROTEINACEOUS COMPOUNDS

Plant proteins = harmless + beneficial agents.

Plant protein + seed reserve proteins important source of food.

Ingestion protein hydrolysis enzymatic reactions in GIT

absorption of amino acids protein biosynthesis in the body.

However; there are no. of proteins, peptides/amines which are of

toxicological importance.

Eg: toxalbumins, polypeptides, amines.

TOXALBUMINS(PROTEINS)

• Abrin from Abrus precatorius

• Ricin from Ricinus communis

POLYPEPTIDES • Amatoxins, phallotoxins &

phalloidin from Amanita sp.

AMINES• Aminotryptaline from seeds of Sativus odoratus

• Phoradendron sp. (Berries of mistle toe)

• Mimosine from Mimosa pudica

• Canavanine from Canavalia ensiformis (Jack beans)

• Leucaena leucocephala (Subabul)

ORGANIC ACIDS

Acids accumulated in plants, particularly in their fruits but are non-toxic.

1. Malic acid

2. Tartaric acid

3. Citric acid

4. Ascorbic acid

But other plant acids possess significant toxic property solely due to their acidity

Eg: plant oxalic acid & its soluble Na, K or NH4 salts.

OXALIC ACID & SOLUBLE SALTS• Oxalic acid

• Potassium oxalate

• Sodium oxalate

RESINS & RESINOIDSToxic plant resins = phenolic compounds

Important naturally occurring phenolic resin in plants

Exists as amorphous & brittle solids

Insoluble in water, soluble in organic solvents (alcohol, chloroform

& ether)

I. Tetrahydrocannabinol

II. Hypericin

III. Urushiol

TETRAHYDROCANNABINOL

• Cannabis sativa

(marijuana or hemp)

HYPERICIN • Hypericum perforatum

URUSHIOL• Poison ivy

• Poison oak

• Rhus sp.

DISCUSSION

REFERENCES

Textbook of veterinary toxicology by Harpal singh Sandhu &

Rajinder Singh Brar.

Veterinary toxicology by Satish K. Garg.

Indian medicinal plants (I-IV volumes) by Arya Vaidya Sala.

Google images.