Exam aid · Drugs and therapeutics

Drug Sources

Drug → plant → part used → constituent: the pharmacognosy table examiners keep returning to.

Tables to memorise

Cover the right-hand column and test yourself before checking.

Drug	Source (part) → constituent
Opium	Papaver somniferum (unripe capsule latex) → morphine, codeine
Cinchona	Cinchona bark → quinine, quinidine
Belladonna	Atropa belladonna (leaf, root) → hyoscyamine/atropine
Datura	Datura stramonium (leaf, seed) → hyoscine, hyoscyamine
Rauwolfia	Rauwolfia serpentina (root) → reserpine
Vinca	Catharanthus roseus (whole plant) → vincristine, vinblastine
Ergot	Claviceps purpurea (sclerotium on rye) → ergometrine
Nux vomica	Strychnos nux-vomica (seed) → strychnine, brucine
Coca	Erythroxylum coca (leaf) → cocaine
Ephedra	Ephedra species (stem) → ephedrine
Vasaka	Adhatoda vasica (leaf) → vasicine

Drug	Source (part) → constituent
Digitalis	Digitalis purpurea / lanata (leaf) → digitoxin, digoxin
Senna	Cassia angustifolia (leaf, pod) → sennosides
Aloe	Aloe species (leaf juice) → aloin (barbaloin)
Cascara	Rhamnus purshiana (bark) → cascarosides
Rhubarb	Rheum species (rhizome) → anthraquinones
Liquorice	Glycyrrhiza glabra (root) → glycyrrhizin
Squill	Urginea maritima (bulb) → bufadienolides
Bitter almond	Prunus amygdalus (seed) → amygdalin
Gentian	Gentiana lutea (root) → gentiopicroside

Drug	Source → main constituent
Clove	Syzygium aromaticum (flower bud) → eugenol
Peppermint	Mentha piperita (leaf) → menthol
Eucalyptus	Eucalyptus globulus (leaf) → 1,8-cineole
Fennel / anise	Fruit → anethole
Ajwain	Trachyspermum ammi (fruit) → thymol
Lemongrass	Cymbopogon (leaf) → citral
Turmeric	Curcuma longa (rhizome) → curcumin
Ispaghula	Plantago ovata (seed husk) → mucilage
Acacia	Acacia senegal (gum exudate)
Agar	Gelidium (red seaweed)
Alginate	Brown seaweeds

Test	Detects
Dragendorff / Mayer / Wagner / Hager	Alkaloids
Vitali–Morin	Tropane alkaloids
Thalleioquin	Quinine (emerald green)
Murexide	Purines (caffeine)
Keller–Killiani	2-deoxy sugars of cardiac glycosides
Legal / Baljet / Kedde	Cardenolide lactone ring
Borntrager	Anthraquinones
Shinoda	Flavonoids
Froth / haemolysis	Saponins
Ferric chloride / gelatin	Tannins

Digoxin comes from Digitalis lanata; digitoxin mainly from D. purpurea.
Atropine is racemic hyoscyamine formed during extraction.
Charas is cannabis resin; heroin is made from morphine, not directly from opium latex.
Frangula and cascara bark are aged a year to reduce griping anthrones.
Ergometrine is used for postpartum haemorrhage; ergotamine for migraine.

Ka-Le-Ba: Keller, Legal, Baljet: Keller–Killiani finds the deoxy sugar; Legal and Baljet find the lactone ring of cardiac glycosides.

Attempt MCQs on these topics while the sheet is fresh. Anything you get wrong goes to your incorrect list for the next round.