Lecture 15: Medicinal Alkaloids (Except MIAs)

What are alkaloids?

Secondary metabolites containing nitrogen, mainly from plants or fungi, with biological activity.

What is the primary structural feature of alkaloids?

A basic nitrogen atom, often within a heterocyclic ring.

Name three sources of alkaloids.

Plants, fungi, and some animals.

Which plant families are major producers of alkaloids?

Solanaceae, Fabaceae, Rubiaceae, Papaveraceae, Apocynaceae.

What are two main functions of alkaloids in plants?

Defense against herbivores and attraction of pollinators.

Which alkaloid was involved in Socrates’ execution?

Coniine (from hemlock).

What alkaloid did Cleopatra allegedly use to dilate her pupils?

Atropine (from henbane).

What was quinine historically used for?

Treating malaria.

Who was the first to isolate an alkaloid, and which one was it?

Sertürner, Morphine (1806).

What was the significance of the discovery of quinine?

It enabled European exploration of tropical regions by preventing malaria.

Name two alkaloids used as pain relievers.

Morphine, Codeine.

Which alkaloid acts as a stimulant and is found in coffee?

Caffeine.

Name an alkaloid used in chemotherapy.

Colchicine.

Which alkaloid is used in treating glaucoma?

Pilocarpine.

Which alkaloid is known for its role in neurodegeneration treatment?

Galanthamine.

What is the primary precursor for morphine biosynthesis?

Tyrosine.

Name a key intermediate in morphine biosynthesis.

(S)-Norcoclaurine.

What type of enzyme is involved in the oxidation steps of morphine biosynthesis?

Phenol oxidase.

What is the biosynthetic precursor of tropane alkaloids?

Putrescine (from Arg or Glu).

Which enzyme is crucial in the early steps of benzylisoquinoline alkaloid biosynthesis?

Norcoclaurine synthase.

How does morphine exert its effects?

Binds to the μ-opioid receptor (μOR), inhibiting pain signals.

What are endogenous ligands for the μ-opioid receptor?

Enkephalins, endorphins, dynorphins.

What is a major side effect of morphine?

Respiratory depression.

How does cocaine work at the synaptic level?

Blocks the reuptake of dopamine, norepinephrine, and serotonin.

How does pilocarpine affect the eye?

Once pronated, it resembles the structure of ACh. It acts as an agonist at the mAChR, binding to the mAChR M3 in the iris. This binding constricts the pupils and induces sweating and salivation.

Which alkaloid is derived from Erythroxylum coca?

Cocaine.

Which alkaloid is used to induce vomiting and is found in ipecac?

Emetine.

Which alkaloid is found in tobacco?

Nicotine.

Which alkaloid is used in motion sickness treatment?

Scopolamine (Hyoscine).

What alkaloid is extracted from Rauwolfia serpentina and used to treat hypertension?

Reserpine.

What is the primary danger of atropine overdose?

Hallucinations, rapid heart rate, and dry mouth.

Why is nicotine highly addictive?

It stimulates dopamine release in the brain.

What is a major side effect of opioid use?

Constipation.

What is a dangerous effect of cocaine abuse?

Heart complications.

What is a possible effect of scopolamine in high doses?

Amnesia and disorientation.

What alkaloid is the main component of opium?

Morphine.

What class of alkaloids does morphine belong to?

Benzylisoquinolines.

Which alkaloids are found in Atropa belladonna?

Hyoscyamine, Scopolamine.

What alkaloid is derived from Colchicum autumnale?

Colchicine.

Which alkaloid is a cholinesterase inhibitor and used in Alzheimer’s treatment?

Galanthamine.

What is the main medical use of morphine?

Pain relief (analgesic).

What is the main use of quinine?

Treatment of malaria.

What is atropine used for in emergency medicine?

Treating nerve gas poisoning.

Which alkaloid is a local anesthetic?

Cocaine.

What alkaloid is used as a pupil dilator in eye exams?

Atropine.

In which plant structure does morphine biosynthesis occur?

Laticifers.

What type of cells produce morphine biosynthetic enzymes?

Companion cells.

What is the role of sieve elements in alkaloid biosynthesis?

They host key steps of morphine synthesis.

What is the key intermediate in cocaine biosynthesis?

Tropinone.

What amino acid serves as a precursor for indole alkaloids?

Tryptophan.

Which alkaloid is an antagonist of muscarinic receptors?

Atropine.

How does hyoscyamine affect heart rate?

Increases heart rate (tachycardia).

Which alkaloid is used as a “truth serum”?

Scopolamine.

Which alkaloid is responsible for “zombification” effects?

Scopolamine.

What alkaloid is used to treat irritable bowel syndrome?

Hyoscyamine.

What is heroin derived from?

Morphine.

What is naloxone used for?

Reversing opioid overdose.

What opioid is mainly used in palliative care?

Morphine.

Which opioid is commonly used in cough syrups?

Codeine.

What is the function of thebaine in opioid production?

It serves as a precursor for semi-synthetic opioids.

What plant is the main source of opium?

Papaver somniferum.

What alkaloid is found in Datura stramonium?

Hyoscine.

Which alkaloid inhibits tubulin polymerization?

Colchicine.

What is a key difference between atropine and pilocarpine?

Atropine dilates pupils, while pilocarpine constricts them.

What is a major stimulant alkaloid found in tea?

Caffeine.

What neurotransmitter does nicotine primarily affect?

Acetylcholine.

What alkaloid inhibits DNA topoisomerase and is used in cancer treatment?

Ellipticine.

What is a major symptom of opioid withdrawal?

Intense pain and nausea.

What is the mechanism of action of SNDRI drugs like cocaine?

Blocks serotonin, norepinephrine, and dopamine reuptake.

What is the primary pharmacological action of pilocarpine?

Muscarinic receptor agonist (stimulates acetylcholine receptors).