Alkaloids Overview and Functions
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Questions and Answers

Which of the following alkaloids is NOT classified as a tropane alkaloid?

  • Scopolamine
  • Lobeline (correct)
  • Hyoscyamine
  • Atropine

    • Which of these alkaloids is known for its anticholinergic activity?

  • Morphine
  • Caffeine
  • Codeine
  • Atropine (correct)

    • Which alkaloid has a potential use as an expectorant, and is associated with male impotence treatment?

  • Theobromine
  • Pilocarpine
  • Papaverine (correct)
  • Nicotine

    • Which alkaloid is derived from the plant Lobelia inflata and is commonly known as Indian tobacco?

    <p>Lobeline (C)</p> Signup and view all the answers

    Which of these alkaloids is classified as a tetrahydroisoquinoline alkaloid?

    <p>Anhalamine (C)</p> Signup and view all the answers

    Which of the following alkaloids is a potent analgesic and narcotic, commonly used for pain relief but possessing high addictive potential?

    <p>Codeine (B)</p> Signup and view all the answers

    Which of these alkaloids is directly associated with the plant Papaver somniferum commonly known as the opium poppy?

    <p>Codeine (C)</p> Signup and view all the answers

    Which of the following families is typically NOT associated with the presence of alkaloids?

    <p>Rosaceae (B)</p> Signup and view all the answers

    What is the primary reason alkaloids are present in plants?

    <p>As a defense mechanism against herbivores and pathogens (D)</p> Signup and view all the answers

    Which of the following statements is TRUE regarding alkaloids and their structure?

    <p>Alkaloids can contain nitrogen atoms in various oxidation states, such as tertiary, secondary, or quarternary amines. (C)</p> Signup and view all the answers

    Which of the following alkaloid examples can be classified as a CNS stimulant?

    <p>Caffeine (A)</p> Signup and view all the answers

    Based on the text, which of the following aspects provides a foundation for alkaloid classification?

    <p>Their chemical structures based on different organic nitrogen-containing units (D)</p> Signup and view all the answers

    Which classification method for alkaloids is based on the origin of the compound's synthesis within a plant?

    <p>Biogenetic (B)</p> Signup and view all the answers

    Which of the following statements is FALSE regarding the occurrence of Alkaloids?

    <p>Monocots are generally considered to be richer in alkaloids than dicots. (B)</p> Signup and view all the answers

    Which of the following alkaloid examples is classified as a sympathomimetic?

    <p>Ephedrine (D)</p> Signup and view all the answers

    Flashcards

    Alkaloids

    Natural organic nitrogenous bases found mainly in plants, containing nitrogen in a heterocyclic ring.

    Nitrogen presence

    Alkaloids have nitrogen as secondary, tertiary, or quaternary amines, rarely primary.

    Alkaloid classification

    Classified based on nitrogenous structure, e.g., piperidine, quinoline, indole.

    Alkaloid families

    Families rich in alkaloids include Apocynaceae, Rubiaceae, Solanaceae, and Papaveraceae.

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    Defensive mechanism

    Alkaloids serve as a defense mechanism in plants against herbivores.

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    Pharmacological activities

    Most alkaloids have pharmacological effects like CNS depressants or stimulants.

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    Biogenetic classification

    Based on the biogenetic pathway that forms alkaloids, like acetate or shikimate pathway.

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    Types of amines

    Alkaloids can be classified as primary, secondary, or tertiary.

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    Isoquinoline

    A basic alkaloid skeleton involved in various compounds.

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    Tropane Alkaloids

    Alkaloids with anticholinergic activity, used as local anesthetics.

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    Piperidine Alkaloids

    Alkaloids like Lobelin and Piperine, associated with stimulant effects.

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    Quinolizidine Alkaloid

    Includes compounds like Lupinine, which can be toxic.

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    Indole Alkaloids

    Alkaloids with a skeleton that have effects against HIV.

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    Ergot Alkaloids

    Contains compounds derived from the ergot fungus, used for migraine relief.

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    Purine Alkaloids

    Includes caffeine, theobromine, and theophylline, known for CNS stimulation.

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    Study Notes

    Alkaloids

    • Derived from Arabic "al kaly" (soda or basic)
    • Natural organic nitrogenous bases, found mainly in plants (also microorganisms and animals)
    • Contain at least one nitrogen atom in a heterocyclic ring and physiologically active.
    • Nitrogen atoms are present as secondary, tertiary, or quaternary amines (rarely primary amines).
    • Classified by the basic nitrogen-containing structures. (e.g., piperidine, quinoline, indole)
    • Dicots are richer in alkaloids than monocots.
    • Families rich in alkaloids include Apocynaceae, Rubiaceae, Solanaceae, and Papaveraceae.
    • Families free from alkaloids include Rosaceae and Labiatae.

    Functions

    • Defense mechanism (nitrogen source or waste)
    • Most have pharmacological activities.
    • CNS: depressant (morphine), stimulant (caffeine)
    • Autonomic NS: sympathomimetic (ephedrine), sympatholytic (yohimbine), parasympathomimetic (pilocarpine), anticholinergic (atropine), ganglioplegic (nicotine)
    • Anaesthesia (cocaine), treat fibrilation (quinidine), antitumor (vinblastine), antimalaria (quinine), antibacteria (berberine), amebicide (emetine)
    • Starting materials for drug synthesis.

    Classification of Alkaloids

    • Biogenetic: Based on the biogenetic pathway, either acetate or shikimate pathway.
    • Botanical Source: Classified according to the plant source.
    • Type of Amines: Primary, secondary, and tertiary alkaloids.

    Basic Alkaloid Skeletons

    • Various chemical structures, including quinoline, quinazoline, isoquinoline, pyrrolidine, pyrrolizidine, purine, indole, imidazole, indolizidine, isoquinoline, tropane, pyridine, piperidine, quinoline, quinoline, and others.

    Tropane Alkaloids

    • Local anaesthetic
    • Primarily used for abuse to create stimulation & euphoria but can lead to dependence and depression.
    • Examples: Cocaine, (S)-(-)-hyoscyamine, (S)-(-)-scopolamine.

    Piperidine Alkaloids

    • Relieve asthma & bronchitis
    • Example: Lobelin

    Pyrrolizidine Alkaloids

    • Inflammatory, rheumatic, and GI disorders
    • Example: Acetyl-lycopsamine

    Quinoline Alkaloids

    • Potentially toxic to humans
    • Examples: Sparteine, Cytisine, Lupinidine

    Indodilizidine Alkaloids

    • Active against AIDS (HIV) virus
    • Examples: Swainsonine, Castanospermine

    Pyridine Alkaloids

    • Respiratory stimulant/depressant
    • Nicotine patch for smoking cessation
    • Example: Nicotine

    Tetrahydroisoquinoline Alkaloids

    • Example: Anhalamine, Lophocerine

    Benzyltetrahydroisoquinoline Alkaloids

    • Used as expectorant and for male impotence
    • Example: Papaverine

    Modified Benzyltetrahydroisoquinoline Alkaloids

    • Powerful analgesic & narcotic
    • Example: Morphine, Codeine, Thebaine or Paramorphine.

    Indole Alkaloids

    • Examples: Vinblastine, Vincristine, Reserpine, Deserpidine, Rescinnamine.

    Ergot Alkaloids

    • Example: Lysergic acid, ergometrine, ergotamine.

    Imidazole Alkaloids

    • Used as miotic eyedrops and glaucoma treatments
    • Example: Pilocarpine

    Purine Alkaloids

    • Caffeine (CNS stimulant & weak diuretic), Theobromine (diuretic & smooth muscle relaxant), Theophylline (smooth muscle relaxant for bronchospasm & diuretic).

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    Alkaloids PDF

    Description

    This quiz explores the fascinating world of alkaloids, which are natural organic nitrogenous bases primarily found in plants. Learn about their classification, physiological activities, and pharmacological functions, including their roles in the central and autonomic nervous systems. Test your knowledge on this vital class of compounds and their significance in nature and medicine.

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