medicinal plants

•  Describe the general chemical features of the major categories of medicinal compounds derived from plants

Glycosides

• Made of two parts:

  • Glycone (sugar) – makes compound inert

  • Aglycone (non-sugar) – becomes biologically active when sugar is removed

• Typically activated after tissue damage or digestion

• Example families: Mustard (glucosinolates), Legumes (coumarin glycosides), and Foxglove (cardiac glycosides)

✅ Alkaloids

• Nitrogen-containing compounds derived from amino acids

• Usually bitter, often neurotoxic

• End in “-ine”: caffeine, morphine, nicotine, quinine, etc.

• Affect the nervous system or muscle control

• Identify the main function of these compounds in plants

They are secondary metabolites, not for basic survival but for:

• Defense: deter herbivores and pathogens

• Communication: attract pollinators or seed dispersers (sometimes via scent)

• Allelopathy: suppress growth of other plants nearby

• Provide examples of species that produce glycosides and alkaloids, and well-known medicines based on these chemicals

Glycosides:

• Foxglove (Digitalis purpurea) – contains digitoxin, a cardiac glycoside (regulates heart function)

• Oleander (Nerium oleander) – contains oleandrin, a toxic cardiac glycoside

• Willow (Salix spp.) – contains salicin, which led to the development of aspirin (acetylsalicylic acid)

• Coumarin glycosides: From beans, used to synthesize Coumadin (blood thinner)

Alkaloids:

• Coca (Erythroxylum coca) – cocaine

• Opium poppy (Papaver somniferum) – morphine, codeine

• Tobacco (Nicotiana) – nicotine

• Belladonna (Atropa belladonna) – atropine, scopolamine

• Ephedra – ephedrine

• Coffee, tea, cacao – caffeine

• Explain how plant-based compounds have a role in the treatment of serious diseases of major importance

  • Cardiovascular disease:

    • Digitoxin from foxglove regulates heart rhythm

  • Pain relief and anesthesia:

    • Morphine from opium poppy used in surgery and chronic pain

  • Infectious disease:

    • Quinine from Cinchona trees treats malaria

    • Artemisinin (from Artemisia annua) is now a leading antimalarial

  • Clotting disorders:

    • Coumadin (from coumarin glycosides) used as a blood thinner

  • Neurological conditions:

    • Scopolamine for motion sickness

    • Atropine for pupil dilation, heart regulation

  • Despite synthetic drug development, ~25% of prescription meds still contain plant compounds, and ~40% contain plant-based synthetic analogs.

• Describe and discuss the history of the US effort to obtain a source of quinine during World War II.

  • Quinine is derived from Cinchona trees, native to the Andes (Peru, Colombia).

  • During WWII, traditional sources in Java and Holland were seized by Axis powers.

  • The U.S. had to urgently seek new sources due to malaria outbreaks among troops.

  • Chemists were unable to fully synthesize quinine until 2001, so efforts focused on:

    • Rediscovering sources in South America

    • Attempting mass cultivation

    • Substitute therapies, like chloroquine and later artemisinin

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