Plant Poison: UGC NET Forensic Science Notes

UGC NET Forensic Science Notes: Plant Poisons

Comprehensive notes on plant poisons to ace the NTA-UGC NET Forensic Science exam, covering key toxins, tests, and forensic applications.

1. Introduction to Plant Poisons

Plant poisons are toxic compounds produced by plants as defense mechanisms, causing effects from mild symptoms to death when ingested, inhaled, or absorbed. In forensic science, they are critical for analyzing poisoning cases (accidental, suicidal, or homicidal).

Key Points

• Compounds: Alkaloids, glycosides, terpenoids, phenolics.
• Forensic Role: Identify toxins in viscera, blood, urine, or food for medicolegal cases.
• Exam Focus: Toxin identification, symptoms, extraction, and presumptive tests.

2. Common Plant Poisons

Memorize these high-yield plant-toxin pairs, symptoms, and forensic significance for factual and case-based questions:

Plant	Active Toxin	Symptoms	Forensic Notes
Deadly Nightshade (Atropa belladonna)	Atropine, Scopolamine	Dilated pupils, delirium, tachycardia, dry mouth	Anticholinergic; used in homicides.
Poison Hemlock (Conium maculatum)	Coniine	Muscle paralysis, respiratory failure	Neurotoxic; mimics nerve agent poisoning.
Castor Bean (Ricinus communis)	Ricin, Ricinine	Nausea, organ failure, death	Highly toxic; bioterrorism concern.
Betel Nut (Areca catechu)	Arecoline	Euphoria, tremors, cardiac issues	Cultural use; overdose risk.
Foxglove (Digitalis purpurea)	Digoxin	Cardiac arrhythmias, nausea	Cardiac glycoside; therapeutic misuse.
Yew (Taxus brevifolia)	Taxines	Cardiac arrest, convulsions	Accidental (ornamental plants).
Datura (Datura stramonium)	Scopolamine, Hyoscyamine	Hallucinations, amnesia, coma	Criminal poisoning (e.g., robbery).
Strychnos nux-vomica	Strychnine	Muscle spasms, convulsions	Neurotoxic; used in homicides.

Exam Tip

Focus on atropine, scopolamine, ricin, digoxin, and arecoline for questions like “Which toxin is in castor beans?” or “What causes dilated pupils?”

3. Classification of Plant Poisons

Understand the chemical nature for analytical questions:

Types

• Alkaloids: Nitrogen-containing (e.g., atropine, coniine).
• Glycosides: Sugar-linked (e.g., digoxin).
• Terpenoids: Organic compounds (e.g., taxines).
• Proteins: E.g., ricin.
• Phenolics: Aromatic compounds (e.g., tannins).

Exam Tip

Questions may ask to differentiate alkaloids (e.g., scopolamine) from glycosides (e.g., digoxin).

4. Extraction Methods

Extraction isolates toxins from biological or environmental samples. Key methods include:

Methods

• Stas-Otto: Extracts alkaloids (e.g., atropine) using alcohol and chloroform.
• Solid-Phase Extraction (SPE): Selective isolation for glycosides, alkaloids.
• Liquid-Liquid Extraction (LLE): Separates lipophilic toxins.
• Clean-Up: Removes proteins, lipids via filtration.
• Instrumentation:
  • GC-MS: Volatile alkaloids (e.g., coniine).
  • LC-MS: Non-volatile toxins (e.g., digoxin).
  • UV-Vis: Preliminary screening.

Exam Tip

Memorize Stas-Otto for alkaloids and LC-MS for glycosides. Questions like “How to extract scopolamine?” are common.

5. Presumptive Tests

Initial tests for toxin identification, frequently tested:

Tests

• Marquis: Purple/violet for alkaloids (e.g., atropine).
• Dragendorff’s: Orange precipitate for alkaloids.
• Froehde’s: Green for morphine; other colors for alkaloids.
• Keller-Kiliani: Pink for cardiac glycosides (e.g., digoxin).
• Liebermann’s: Detects phenolics.
• TLC: Separates toxins by Rf values.

Exam Tip

Focus on Marquis, Dragendorff’s, and Keller-Kiliani for questions like “Which test detects digoxin?”

6. Confirmatory Tests

Validate presumptive results for analytical questions:

Tests

• GC-MS: Volatile alkaloids (e.g., atropine).
• LC-MS/MS: Non-volatile toxins (e.g., digoxin, ricin).
• FTIR: Identifies functional groups.
• NMR: Structural analysis (rare).

Exam Tip

Prioritize GC-MS and LC-MS for questions like “Which technique confirms scopolamine?”

7. Forensic Significance

Plant poisons are vital in:

Applications

• Cause of Death: Links symptoms to toxins (e.g., arrhythmias for digoxin).
• Criminal Investigations: Detects intentional poisoning (e.g., Datura, ricin).
• Toxicological Analysis: Quantifies toxins in post-mortem samples.
• Medicolegal Reports: Supports court testimony.
• Chain of Custody: Ensures sample integrity.

Exam Tip

Case-based questions may ask, “Hallucinations indicate which poison?” (Answer: Datura).

8. Sample Collection and Preservation

Procedures

• Samples: Viscera, blood, urine, gastric lavage.
• Preservation: Store at 4°C or freeze at -20°C.
• Packaging: Airtight, tamper-proof containers.
• Forwarding: Send with documentation.

Exam Tip

Know freezing at -20°C for questions like “How to preserve viscera for ricin analysis?”

9. Sample Questions

Question 1: Which alkaloid is found in betel nut?

A) Arecoline

B) Ricinine

C) Coniine

D) Atropine

Answer: A) Arecoline
Explanation: Arecoline is the stimulant alkaloid in betel nut.

Question 2: Which test confirms cardiac glycosides like digoxin?

A) Marquis

B) Keller-Kiliani

C) Dragendorff’s

D) Froehde’s

Answer: B) Keller-Kiliani
Explanation: Keller-Kiliani produces a pink color for cardiac glycosides.

Question 3: A victim shows hallucinations and hot skin. Which poison?

A) Ricin

B) Scopolamine

C) Taxines

D) Coniine

Answer: B) Scopolamine
Explanation: Scopolamine (Datura) causes hallucinations and anticholinergic symptoms.

10. Preparation Tips

Tips to Crack Plant Poison Questions

• Study Time: 3–5 hours for plant poisons within toxicology.
• Memorize: 8–10 plant-toxin pairs and presumptive tests.
• Practice: Solve 20–30 MCQs from 2019–2025 papers.
• Resources: Modi’s Forensic Toxicology, forensicmcq.com, testbook.com.
• Focus: Alkaloids (atropine, scopolamine), glycosides (digoxin), criminal uses (Datura, ricin).