Belladonna (Atropa belladonna) is a classic source of tropane alkaloids—atropine, hyoscyamine and scopolamine—important for pharmacy students studying medicinal chemistry, pharmacology and toxicology. This concise review focuses on chemistry, biosynthesis, extraction, dose-dependent pharmacodynamics, clinical uses (antimuscarinic therapy, ophthalmology, antispasmodic), adverse effects, poisoning management and analytical assays for quality control. Emphasis is placed on structure–activity relationships, pharmacokinetics, therapeutic monitoring and regulatory aspects of botanical preparations. You will also review muscarinic receptor subtypes, anticholinergic mechanisms, therapeutic index, laboratory identification methods (TLC, HPLC), extraction techniques and antidotal therapy such as physostigmine, and clinical case correlations to enhance exam readiness. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which is the principal tropane alkaloid obtained from Atropa belladonna?
- Atropine
- Caffeine
- Morphine
- Quinine
Correct Answer: Atropine
Q2. Belladonna alkaloids belong to which chemical class?
- Tropane alkaloids
- Indole alkaloids
- Isoquinoline alkaloids
- Steroidal alkaloids
Correct Answer: Tropane alkaloids
Q3. Atropine is best described as which of the following?
- A racemic mixture of hyoscyamine enantiomers
- A pure levo (L) enantiomer of hyoscyamine
- A sulfated glucuronide metabolite of scopolamine
- An esterified derivative of tropic acid only
Correct Answer: A racemic mixture of hyoscyamine enantiomers
Q4. The primary pharmacological action of belladonna alkaloids is:
- Competitive antagonism at muscarinic acetylcholine receptors
- Irreversible inhibition of cholinesterase
- Agonism at nicotinic acetylcholine receptors
- Inhibition of catecholamine reuptake
Correct Answer: Competitive antagonism at muscarinic acetylcholine receptors
Q5. Blockade of which muscarinic receptor subtype by atropine primarily accounts for tachycardia?
- M2
- M1
- M3
- M4
Correct Answer: M2
Q6. A key emergency clinical indication for intravenous atropine is:
- Symptomatic bradycardia
- Acute bacterial meningitis
- Diabetic ketoacidosis
- Severe hypokalemia
Correct Answer: Symptomatic bradycardia
Q7. Which cholinesterase inhibitor is preferred as an antidote for severe central anticholinergic toxicity because it crosses the blood–brain barrier?
- Physostigmine
- Neostigmine
- Edrophonium
- Donepezil
Correct Answer: Physostigmine
Q8. Which classic cluster of signs best describes anticholinergic (belladonna) poisoning?
- Dry as a bone, hot as a hare, blind as a bat, red as a beet, mad as a hatter
- Cold and clammy skin, bradycardia, miosis, hypersalivation
- Diarrhea, vomiting, sweating, pinpoint pupils
- Excessive lacrimation, bronchospasm, hypotension, bradycardia
Correct Answer: Dry as a bone, hot as a hare, blind as a bat, red as a beet, mad as a hatter
Q9. Which antimuscarinic agent is a quaternary ammonium compound and therefore has limited CNS penetration?
- Glycopyrrolate
- Atropine
- Scopolamine
- Hyoscyamine
Correct Answer: Glycopyrrolate
Q10. Which pharmacokinetic property explains why atropine and scopolamine produce central nervous system effects?
- They are tertiary amines and cross the blood–brain barrier
- They are entirely protein-bound and sequestered in bone
- They are substrates for P-glycoprotein and restricted from the CNS
- They are highly ionized at physiological pH and remain peripheral
Correct Answer: They are tertiary amines and cross the blood–brain barrier
Q11. The biosynthesis of tropane alkaloids in plants begins from which amino acid precursor?
- Ornithine
- Tryptophan
- Tyrosine
- Phenylalanine
Correct Answer: Ornithine
Q12. Which enzyme catalyzes the reduction of tropinone to tropine in tropane alkaloid biosynthesis?
- Tropinone reductase
- Monoamine oxidase
- Phenylalanine ammonia-lyase
- Acetyltransferase
Correct Answer: Tropinone reductase
Q13. The standard laboratory technique for isolation of belladonna alkaloids from plant material is:
- Acid–base extraction followed by organic solvent partitioning
- Direct steam distillation of fresh leaves
- Supercritical CO2 extraction without pH adjustment
- Simple aqueous infusion at neutral pH
Correct Answer: Acid–base extraction followed by organic solvent partitioning
Q14. Which analytical technique is commonly used for quantitative assay and quality control of atropine in pharmaceutical preparations?
- High-performance liquid chromatography (HPLC)
- Paper chromatography with iodine detection
- Colorimetric assay with ninhydrin only
- Flame photometry
Correct Answer: High-performance liquid chromatography (HPLC)
Q15. Which belladonna alkaloid is especially associated with central sedation and amnesia due to potency of CNS penetration?
- Scopolamine
- Glycopyrrolate
- Galanthamine
- Pralidoxime
Correct Answer: Scopolamine
Q16. In ophthalmology, belladonna alkaloids are used primarily to produce:
- Mydriasis and cycloplegia
- Increased aqueous outflow in glaucoma
- Lowering of intraocular pressure by cholinergic stimulation
- Topical anesthetic action
Correct Answer: Mydriasis and cycloplegia
Q17. Antimuscarinic drugs such as atropine are contraindicated in which condition?
- Acute narrow-angle glaucoma
- Motion sickness prophylaxis
- Preoperative reduction of secretions
- Symptomatic bradycardia
Correct Answer: Acute narrow-angle glaucoma
Q18. After an oral overdose of belladonna extract presenting early (within 1–2 hours), which decontamination step is commonly recommended?
- Activated charcoal administration
- Gastric lavage without airway protection
- Immediate whole-bowel irrigation for all cases
- Forced diuresis with IV furosemide
Correct Answer: Activated charcoal administration
Q19. Which of the following effects is NOT typically seen in anticholinergic toxicity from belladonna?
- Diarrhea
- Mydriasis
- Urinary retention
- Hyperthermia
Correct Answer: Diarrhea
Q20. The pharmacophore essential for belladonna antimuscarinic activity is:
- The tropane bicyclic nucleus with an ester-linked tropic acid
- A linear aliphatic chain with terminal hydroxyl
- A steroidal ring system with a bridgehead nitrogen
- A flavonoid polyphenolic scaffold
Correct Answer: The tropane bicyclic nucleus with an ester-linked tropic acid
Q21. Which enantiomer of hyoscyamine is primarily responsible for pharmacological activity?
- (–)-Hyoscyamine (levo-hyoscyamine)
- (+)-Hyoscyamine (dextro-hyoscyamine)
- Racemic metahyoscyamine
- Atropine sulfate only
Correct Answer: (–)-Hyoscyamine (levo-hyoscyamine)
Q22. Co-administration of belladonna alkaloids with which drug class increases the risk of severe anticholinergic effects?
- Tricyclic antidepressants (e.g., amitriptyline)
- Beta blockers (e.g., metoprolol)
- Proton pump inhibitors (e.g., omeprazole)
- Thiazide diuretics (e.g., hydrochlorothiazide)
Correct Answer: Tricyclic antidepressants (e.g., amitriptyline)
Q23. For stability and potency retention, belladonna alkaloid-containing formulations should be stored how?
- Protected from light and heat in a cool, dry place
- Open to air at room temperature to prevent moisture accumulation
- Frozen at –20°C to avoid any degradation
- Exposed to direct sunlight for photostability activation
Correct Answer: Protected from light and heat in a cool, dry place
Q24. Which method is most appropriate for confirmatory identification of belladonna alkaloids in a herbal extract?
- Gas chromatography–mass spectrometry (GC–MS)
- Simple color test with ferric chloride
- Polarimetry only
- Flame atomic absorption spectroscopy
Correct Answer: Gas chromatography–mass spectrometry (GC–MS)
Q25. Aside from organophosphate poisoning, a common therapeutic use of belladonna alkaloids is:
- Preanesthetic reduction of secretions
- Long-term treatment of Alzheimer’s disease
- Chronic heart failure management
- Maintenance therapy for asthma
Correct Answer: Preanesthetic reduction of secretions
Q26. The primary route of elimination for atropine and related belladonna alkaloids is:
- Renal excretion of unchanged drug and metabolites
- Exhalation via the lungs as volatile metabolites
- Fecal elimination only without renal clearance
- Complete hepatic biliary excretion without renal involvement
Correct Answer: Renal excretion of unchanged drug and metabolites
Q27. Which of the following plants is another well-known source of tropane alkaloids similar to belladonna?
- Datura stramonium (jimsonweed)
- Digitalis purpurea (foxglove)
- Cinchona officinalis (quinine bark)
- Salvia officinalis (sage)
Correct Answer: Datura stramonium (jimsonweed)
Q28. For forensic confirmation of belladonna alkaloid exposure in a biological sample, the most specific test is:
- GC–MS identification of alkaloid-specific ions
- Urine dipstick for proteins
- Thin-layer chromatography without standards
- Colorimetric pH test
Correct Answer: GC–MS identification of alkaloid-specific ions
Q29. Which manifestation indicates central anticholinergic toxicity rather than a purely peripheral effect?
- Delirium with visual hallucinations
- Dry mouth and decreased sweating
- Tachycardia and flushed skin
- Urinary retention
Correct Answer: Delirium with visual hallucinations
Q30. Regarding regulatory quality control of belladonna-containing preparations, pharmacopeial monographs typically require:
- Specification limits for total tropane alkaloid content and validated assay methods
- No quantification—only botanical identification is required
- Mandatory use of steam distillation for all extracts
- Only organoleptic (taste and smell) evaluation
Correct Answer: Specification limits for total tropane alkaloid content and validated assay methods
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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