PCOG

• The term "alkaloid" (alkali-like) is commonly used to designate basic heterocyclic nitrogenous compounds of plant origin that are physiologically active
• Alkaloids


  • Rare in lower plants
  • Dicots are more rich in alkaloids than Monocots
• Families rich in alkaloids

  • Apocynaceae (Dogbane Family)
  • Rubiaceae (Coffee family, Bedstraw family)
  • Solanaceae (Nightshade Family)
  • Papaveraceae (Poppy family)
• Families free in alkaloids

  • Labiatae (Mint Family)
• Primary amines


  1. NH2 e.g., Norephedrine
• Secondary amines


  R2-NH e.g., Ephedrine
• Tertiary amines

  R3-N e.g., Atropine
• Quaternary ammonium salts

  R4-N e.g., d-Tubocurarine
• Basicity

  • R2-NH > R-NH2 > R3 -N
  • Saturated hexacyclic amines is more basic than aromatic amines

  
• Nomenclature

  • The genus of the plant: Atropine (Atropa belladona)
  • The plant species: Cocaine (Erythroxylon coca)
  • The common name: Ergotamine (ergot)
  • The name of the discoverer: Pelletierine (Pelletier)
  • The physiological action: Emetine (emetic)
  • A prominent physical character: Hygrine that is hygroscopic
• Solubility

  • Alkaloidal bases and their salts are soluble in alcohol
  • Bases are soluble in organic solvents and insoluble in water
  • Salts are usually soluble in water and, insoluble or sparingly soluble in organic solvents
  • Exceptions: quinine monosulphate is insoluble in water, lobeline and apoatropine hydrochlorides are soluble in chloroform
• Alkaloids

  • Most are crystalline solids, although a few are amorphous
  • Coniine, nicotine, and sparteine, which lack oxygen in their molecules, are liquids
  • Alkaloidal salts are crystalline- useful means in microscopic identification

  
• Classification based on the ring structure or nucleus of the chief alkaloid group in the plant drug

  • Pyridine and Piperidine e.g., Lobeline, Nicotine
  • Tropane e.g., Atropine
  • Quinoline e.g., Quinine and Quinidine
  • Isoquinoline e.g., Papaverine
  • Indole e.g., Ergometrine
  • Imidazole e.g., Pilocarpine
  • Purine e.g., Caffeine
  • Steroidal e.g., Solanum, Veratrum Alkaloids
  • Alkaloidal Amines

  
• Amino acids that most often serve as alkaloidal precursors

  • Phenylalanine
  • Tyrosine
  • Tryptophan
  • Histidine
  • Anthranilic Acid
  • Lysine
  • Ornithine
• Pyridine

  A tertiary base

  
• Piperidine

  Formed by reduction of Pyridine, a secondary base

  
• Pyridine and Piperidine subgroups

  • Derivatives of piperidine, including lobeline from lobelia
  • Derivatives of nicotinic acid, including from areca
  • Derivatives of both pyridine and pyrrolidine, including nicotine from tobacco

  
• Nicotine


  • Biosynthesized from nicotinic acid and proline
  • Primarily a product of root metabolism, but small amounts and subsequent reactions can occur in the leaves
• Nicotine use


  Bound to an ion exchange resin in a chewing gum base as a temporary aid to the cigarette smoker seeking to give up smoking. Brand: Nicorette
• Areca


  • The dried, ripe seed of Areca catechu Linne (Fam. Palmae)
  • India is a major producer but mostly consumed domestically
• Areca alkaloids

  • ARECOLINE (arecaidine methyl ester)
  • Arecaidine (N-methyl guvacine)
  • Guvacine (tetrahydronicotinic acid)
  • Guvacoline (guvacine methyl ester)
• Areca use and dose

  • Classified as an anthelmintic in veterinary practice and employed as a vermicide and taenifuge
  • Usual dose in dogs is 2 to 4 g; in sheep, 4 to 8 g, based on the weight of the animal
  • Mixed with lime and Piper betle leaves, used as a stimulant masticatory in India and the East Indies
• Nganga is consumed as a stimulant masticatory
• Lobelia

  • Consists of the dried leaves and tops of Lobelia inflata Linne' (Fam. Lobeliaceae)
  • Its emetic properties were first observed in 1785, and the drug was introduced into medicine in 1807
  • Contains 14 alkaloids, of which LOBELINE is the major and most important
• Lobeline use and dose


  A 2.0-mg dose of lobeline sulfate is incorporated in tablets or lozenges that are intended to aid in breaking the tobacco habit (smoking deterrents)
• Tropane

  A dicyclic compound formed by the condensation of a pyrrolidine precursor (ornithine) with 3 acetate-derived carbon atoms. Both pyrrolidine and piperidine ring systems can be discerned in the molecule

  
• Tropane alkaloids


  • Atropine
  • Scopolamine
  • Hyoscyamus
  • Stramonium
  • Hyoscyamine

  
• Hyoscyamine


  The tropine ester of (-) tropic acid and is asymmetric and accounts for the natural occurrence of the optical isomer

  
• Hyoscyamine sulfate


  The sulfate of the alkaloid obtained from species of Hyoscyamus Linne or other genera of Solanaceae. It is extremely poisonous
• Hyoscyamine uses in the GIT

  Control of gastric secretion, visceral spasm, hypermotility in spastic colitis, pylorospasm and cramps
• Hyoscyamine uses for Parkinsonism


  Tremors, rigidity, Sialorrhea and associated hyperhidrosis
• Atropine

  Optically inactive but usually contains some levorotatory hyoscyamine, the limit of which produces an angular rotation not to exceed - 0.70°
• Atropine sulfate


  Occurs as colorless crystals or as a white, crystalline powder. It is extremely poisonous, effloresces in dry air, is slowly affected by light, and is an ANTICHOLINERGIC
• Belladonna

  • Consists of the dried leaf and flowering or fruiting top of Atropa belladonna Linne' or of its variety acuminata Royle ex Lindley (Fam. Solanaceae)
  • The leaf yields alkaloids in concentrations ranging up to more than 1%. About three fourths of the isolated alkaloid mixture is (-)-hyoscyamine; the remainder is atropine
• Belladonna uses


  Used as a Parasympathetic Depressant, as Spasmolytic Agent, for digestive disorders, ulcerative colitis, diarrhea, diverticulitis, pancreatitis
• Parasympathetic Depressant (Anticholinergic Effect)

  Has Drying effect on mucus secretion. Used to control spasm of the Urinary Tract and motor effect at GIT. Antidiarrheal
• Belladonna leaf is commonly administered
• Datura acuminata


  Royle ex Lindley (Fam. Solanaceae)
• Leaf of Datura acuminata


  • Yields alkaloids in concentrations ranging up to more than 1%
  • About three fourths of the isolated alkaloid mixture is (-)-hyoscyamine
  • The remainder is atropine
• Atropine


  Formed by racemization during the extraction process