Isoquinoline Alkaloids & Opium-Derived Compounds

28 vocabulary flashcards covering isoquinoline alkaloids, opium constituents, related pharmacology, and representative plant‐derived and synthetic compounds.

Isoquinoline Alkaloids

Alkaloids possessing the isoquinoline ring; found in diverse plant families, including Papaveraceae and Rubiaceae.

Phenanthrene Alkaloids

Opium alkaloids (e.g., morphine, codeine, thebaine) whose skeleton contains a fused phenanthrene nucleus, biosynthesized from benzylisoquinoline precursors.

Benzylisoquinoline Intermediate

Biosynthetic precursor that undergoes coupling/oxidation to form the phenanthrene nucleus of major opium alkaloids.

Opium (Gum Opium)

Air-dried milky exudate from unripe capsules of Papaver somniferum; contains >30 alkaloids including morphine (4–21%).

Morphine

Principal opium alkaloid; phenanthrene derivative with both phenolic & alcoholic OH groups; potent narcotic analgesic and hypnotic (usual parenteral dose 10 mg).

Codeine

3-O-methylmorphine; widely used narcotic analgesic & antitussive; less potent & less habit-forming than morphine (analgesic dose 15–60 mg).

Heroin (Diacetylmorphine)

Acetylated morphine (both OH groups acetylated); action more potent than morphine; manufacture & medical use banned due to high addiction risk.

Papaverine

Isoquinoline alkaloid (~1 % in opium); used as smooth-muscle relaxant (oral dose 150 mg; IM 30 mg).

Thebaine

Minor opium alkaloid; not used therapeutically but serves as precursor for semi-synthetic opioids.

Noscapine (Narcotine)

Non-narcotic opium alkaloid (1.3–10 %); used as antitussive (15 mg up to 4×/day).

Meconic Acid

Organic acid (3–5 % of opium) giving red color with FeCl₃; specific test for detecting opium.

Opiates

Naturally occurring or directly refined compounds from poppy latex (e.g., opium, morphine, codeine).

Opioids

Synthetic or semi-synthetic compounds that act on opioid receptors (e.g., oxycodone, fentanyl, methadone).

Quaternary Central Carbon (Analgesic Pharmacophore)

Structural feature common to centrally acting analgesics: tetrasubstituted carbon bearing a phenyl ring and linked to a tertiary nitrogen by a 2-carbon bridge.

Poppy Seed (Maw Seed)

Dried seed of Papaver somniferum var. nigrum; contains ~50 % fixed oil, no significant alkaloids; used in baking and oil production.

Ipecacuanha

Dried roots/rhizomes of Cephalis ipecacuanha or C. acuminata; source of emetine, cephaline, psychotrine.

Emetine

Major ipecac alkaloid; levorotatory, non-phenolic; anti-amoebic but highly toxic; used chiefly as emetic.

Cephaline

Phenolic ipecac alkaloid that yields emetine on methylation; shares emetic properties.

Psychotrine

Phenolic yellow-prism ipecac alkaloid; converts to cephaline on reduction and to emetine after reduction+methylation.

Curare

Dried extract (arrow poison) from Chondrodendron tomentosum or Strychnos spp.; contains neuromuscular blocker d-tubocurarine.

d-Tubocurarine

Water-soluble, phenolic, dextrorotatory isoquinoline alkaloid; competitive nicotinic receptor antagonist used as skeletal muscle relaxant.

Competitive Neuromuscular Blocker

Agent (e.g., tubocurarine) that binds nicotinic receptors without activating them, preventing acetylcholine-induced depolarization and muscle contraction.

Myasthenia Gravis Diagnostic Aid

Clinical use of tubocurarine to assess neuromuscular weakness by transiently worsening symptoms at low doses.

Skeletal Muscle Relaxant

Drug class exemplified by tubocurarine; facilitates surgery or controls convulsions by blocking neuromuscular transmission.

Antitussive

Medication that suppresses cough reflex; examples include codeine and noscapine.

Narcotic Analgesic

Drug that relieves severe pain and induces sleep; high abuse potential (e.g., morphine, codeine).

Smooth-Muscle Relaxant

Agent that reduces tone of visceral smooth muscles; papaverine is a classic example.

Dover’s Powder

Historical mixture of ipecac alkaloids and opium used as diaphoretic; obsolete in modern therapy.