Alkaloids Classification Quiz

Alkaloids

• Scopolamine is a datura alkaloid, used to treat travel sickness and causes pupil dilation.
• Coca alkaloids are found in Erythroxylum coca, and cocaine is a local anesthetic.

Xanthine Alkaloids

• Found in beverages, such as:
  • Caffeine in coffee (Coffea sp.)
  • Theophylline in tea (Camellia sinensis)
  • Theobromine in cocoa (Theobroma cacao)
• They are CNS stimulants and diuretics, used to treat fatigue and drowsiness.

Pyrrolidizine Alkaloids

• These alkaloids are toxic, genotoxic, and cytotoxic, and pose a health risk to humans.
• They can contaminate food, including grain, milk, honey, and eggs, as well as plant-derived pharmaceuticals and supplements.
• Examples include those found in Comfrey (Symphytum officinale) and some Chinese medicinal herbs.

Phenylalkylamine Alkaloids

• Ephedrine is a CNS stimulant, and pseudoephedrine is a bronchodilator, found in Ephedra sinica (herbal ephedra).
• Mescaline is a psychedelic found in Lophophora sp., used in tribal religious ceremonies.

Piperidine Alkaloids

• Derived mostly from the amino acid lysine.
• Very toxic to adult livestock, can cause congenital defects in embryonic livestock, and can lead to cardiorespiratory failure in humans.
• Examples include:
  • Piperine in black pepper
  • Nicotine in Nicotiana tabacum
  • Lobeline in Indian tobacco
  • Selenopsin in fire ant venom
  • Coniine in poison hemlock (Conium maculatum)
  • Phencyclidine, a socially abused drug

Glycosides

• Molecules containing a glycone (carbohydrate residue) and a aglycone (non-carbohydrate) residue.
• Classification:
  • By glycone: glucoside, fructoside, glucuronide, etc.
  • By type of glycosidic bond: α-glycosides or β-glycosides
  • By aglycone: depending on the chemical nature of the aglycone (R-group)
  • Examples include:
    • Salicin, found in the genus Salix, converted into salicylic acid in the body.

Quinoline Alkaloids

• Found in Peruvian Jesuit bark.
• Quinine: an antimalarial that binds to haem, forming a toxic conjugate to Plasmodium parasite.
• Quinidine: used to treat cardiac arrhythmias.

Isoquinoline Alkaloids

• Second most abundant and diverse of the alkaloids.
• Structural isomers of quinoline alkaloids.
• Many are medically important, including:
  • Muscle relaxants/anaesthetics: curare, morphine, codeine, papaverine
  • Antispasmodic: papaverine
  • Poison: tubocurarine
  • Emetic: Ipecac (Caephaelis sp.), induces vomiting in cases of drug overdose or poisoning
  • Antimicrobial/antifungal: sanguinarine

Tropane Alkaloids

• Derived from the amino acid tyrosine.
• Possess the tropane nucleus, with a methylated nitrogen and an ester formed with an aromatic acid.
• 2 main types:
  • Solanaceous alkaloids (tomato and potato).
  • Atropine (hyoscyamine & hyoscine) found in Atropa sp.