PLANT POISONS IN FORENSIC SCIENCE
SECTION 1: PYQ ANALYSIS — LAST 5 YEARS (2019–2024)
Based on comprehensive analysis of UGC NET Forensic Science question papers from 2019 to 2024, the topic "Plant Poisons" (Vegetable Alkaloid Poisons) has consistently appeared with varying question patterns. This topic is critical for understanding natural plant-derived toxins and their forensic significance.
1.1 Frequency of Plant Poisons in PYQ
- 2024: 2-3 questions (15-20% of toxicology section)
- 2023: 2 questions focusing on active principles and identification
- 2022: 3 questions including case-based scenarios
- 2021: 2 questions on botanical poisons and post-mortem signs
- 2020: 1 question on chemical classification
- 2019: 2 questions on naturally occurring toxins
1.2 Frequently Tested Sub-Topics (Year-wise Trend)
| Year | Key Topics Tested | Question Type | Difficulty Level |
|---|---|---|---|
| 2024 | Strychnine, Aconite, Datura | Mechanism of action, identification | Moderate-High |
| 2023 | Active principles, Clinical signs | MCQ, Concept-based | Moderate |
| 2022 | Ricinus communis, Botanical sources | Case study, forensic significance | High |
| 2021 | Calotropis, Oleander toxicity | Post-mortem changes | Moderate |
| 2020 | Chemical structure, Classification | Theoretical knowledge | Low-Moderate |
| 2019 | Historical significance, Poisoning methods | General knowledge | Low |
1.3 Common PYQ Question Types
- Definition & Classification Type: "Plant poisons are classified as..."
- Active Principle Type: "The active principle of Strychnine (Strychnos nux-vomica) is..."
- Mechanism of Action Type: "Aconite causes death by affecting..."
- Post-Mortem Signs Type: "Dark brown/greenish post-mortem staining suggests..."
- Forensic Significance Type: "In cases of suspected plant poison poisoning, which investigation is crucial?"
- Case-Based Questions: Scenario-based with clinical signs and need to identify poison
- Comparison Type: Differentiate between two plant poisons based on symptoms
1.4 Critical Topics for Exam Focus
HIGH PRIORITY (Must Study):
- ✓ Strychnine (Strychnos nux-vomica) - Most frequently asked
- ✓ Aconite - Second most frequent
- ✓ Datura species - Consistent question source
- ✓ Active principles and their effects
- ✓ Post-mortem signs and symptoms
MEDIUM PRIORITY (Should Study):
- Ricinus communis (Castor bean - Ricin)
- Calotropis (Mudar plant)
- Oleander
- Cannabis species
- Abrus precatorius (Rosary pea)
LOWER PRIORITY (Good to Know):
- Opium and alkaloids
- Digitalis
- Coniine (Hemlock)
SECTION 2: PLANT POISONS — DEFINITION & CLASSIFICATION
2.1 Definition
Plant poisons, also known as "botanical toxins" or "vegetable alkaloid poisons," are naturally occurring toxic compounds produced by plants. These are chemical substances that, when ingested or absorbed in sufficient quantities, produce harmful or fatal effects in living organisms.
2.2 Classification of Plant Poisons
Plant poisons are classified based on several criteria:
A. Based on Chemical Nature:
- 1. Alkaloids: Nitrogen-containing organic bases
- - Strychnine, Morphine, Codeine, Aconitine, Hyoscyamine
- 2. Glycosides: Compounds containing carbohydrate moiety
- - Glycosides found in Digitalis, Oleander, Cyanogenic glycosides
- 3. Resins and Volatile Oils: Aromatic compounds
- - Essential oils in toxic plants
- 4. Proteins and Amino Acids: Specific to certain plants
- - Ricin (from Ricinus communis)
B. Based on Source Plant:
- 1. Botanical Origin: Named after source plant species
- 2. Geographic Distribution: Tropical, temperate, cosmopolitan
- 3. Plant Part Toxicity: Roots, seeds, leaves, latex
C. Based on Mode of Action:
- 1. Neurotoxins: Affecting nervous system (Strychnine, Aconite)
- 2. Cardiotoxins: Affecting cardiac function (Digitalis, Oleander)
- 3. Irritant Poisons: Causing local damage (Ricin, Croton oil)
- 4. Deliriants: Causing hallucinations (Datura)
- 5. Hemolytic: Destroying red blood cells (Abrus precatorius)
2.3 Key Characteristics of Plant Poisons
- 1. Natural Production: Synthesized naturally by plants as defense mechanisms
- 2. Variability: Concentration varies with season, part of plant, growth conditions
- 3. Stability: Some are easily destroyed by heat; others are heat-stable
- 4. Detection Methods: Specific chemical and microscopic techniques required
- 5. Post-Mortem Signs: Characteristic discoloration, odor, and pathological findings
- 6. Bioavailability: Absorption varies based on route and form of poison
- 7. Accumulation: Some poisons may accumulate in body tissues
SECTION 3: MAJOR PLANT POISONS — DETAILED STUDY
3.1 STRYCHNINE (Strychnos nux-vomica)
Source: Strychnos nux-vomica (Nux Vomica or poison nut tree)
| Property | Details |
|---|---|
| Botanical Source | Strychnos nux-vomica (Family: Loganiaceae) |
| Active Principles | Strychnine (primary, ~1.5%), Brucine (~0.5%), Isomers |
| Plant Parts | Seeds most toxic; bark and wood also contain toxin |
| Chemical Class | Indole alkaloid; di-methoxy derivative |
| Molecular Formula | C₂₁H₂₂N₂O₂ |
| Physical Form | Colorless crystals; bitter taste; odorless |
| Solubility | Poorly soluble in cold water; soluble in alcohol and hot water |
Mechanism of Action:
Strychnine acts as a competitive antagonist of glycine receptors in the spinal cord, specifically blocking the inhibitory actions of glycine. This results in:
- Unopposed transmission through motor neurons
- Uncontrolled muscle contraction
- Characteristic "risus sardonicus" (facial grimacing)
- Opisthotonus (arching of back)
- Death from respiratory paralysis (muscles cannot relax)
Clinical Features of Strychnine Poisoning:
Onset: 15 minutes to 1 hour (rapid onset - forensically significant)
Early Symptoms:
- Stiffness of jaw and facial muscles
- Restlessness, nervousness, anxiety
- Difficulty in swallowing
- Heightened sensory responses to light and sound
Later Symptoms:
- Lockjaw (trismus)
- Risus sardonicus (characteristic grinning appearance)
- Opisthotonus (back arching)
- Tetanic convulsions (repeated rigidity)
- Fixed clenched fists
- Profuse sweating
- Cyanosis
- Death within 2-3 hours in severe cases
Post-Mortem Signs:
External Signs:
- ✓ Risus sardonicus (characteristic grinning expression)
- ✓ Opisthotonus (rigid arching of back and neck)
- ✓ Clenched fists with extended thumbs
- ✓ Facial congestion and petechiae
- ✓ Frothy fluid in mouth and nostrils
- ✓ Cyanosis of lips and extremities
Internal Findings:
- • Petechial hemorrhages (especially in brain and lungs)
- • Pulmonary and cerebral edema
- • Normal other organs (no specific internal damage)
- • Rigor mortis develops quickly
Forensic Significance:
- Highly toxic in very small doses (lethal dose: 15-30 mg for adult humans)
- Rapid onset makes it detectable in early stages
- Characteristic signs aid in diagnosis
- Post-mortem signs facilitate identification
- Analytical confirmation by chromatography is essential
- Often used in homicides and rarely in suicides
- Used historically in rodent and pesticide control
Detection and Analysis:
Sample Collection:
- • Stomach contents, liver, kidney (2-5 g each)
- • Blood (at least 10 ml)
- • Brain tissue
- • Urine if available
Analysis Methods:
- Chemical Tests:
- - Vitali's test (characteristic violet coloration)
- - Mandelin's test
- - Marquis test
- Instrumental Analysis:
- - High-Performance Liquid Chromatography (HPLC)
- - Gas Chromatography-Mass Spectrometry (GC-MS)
- - Thin Layer Chromatography (TLC)
- Spectroscopic Methods:
- - UV-Visible spectrophotometry
- - Mass spectrometry for confirmation
3.2 ACONITE (Aconitum species)
Source: Aconitum napellus and other Aconitum species (Monkshood, Wolfsbane)
| Property | Details |
|---|---|
| Botanical Source | Aconitum napellus, A. carmichaelii (Family: Ranunculaceae) |
| Active Principles | Aconitine (primary), Mesaconitine, Hypaconitine, Picrotoxin |
| Plant Parts | ROOTS most toxic (2-5% aconitine); leaves, seeds also dangerous |
| Chemical Class | Diterpene alkaloid (highly complex structure) |
| Molecular Formula | C₃₄H₄₇NO₁₁ |
| Physical Form | Colorless/whitish; crystalline powder; odorless |
| Solubility | Soluble in alcohol; slightly in water; stable in acidic medium |
Mechanism of Action:
Aconitine acts as a potent neurotoxin and cardiotoxin by:
- Activation of voltage-gated sodium channels
- Uncontrolled influx of sodium ions
- Persistent depolarization and hyperpolarization alternation
- Effects on both central and peripheral nervous systems
- Cardiotoxic effects causing arrhythmias and myocardial infarction
Clinical Features of Aconite Poisoning:
Onset: 30 minutes to 2-3 hours (faster than most plant poisons)
Phase 1 (Early - 0-6 hours):
- • Burning sensation in mouth (characteristic)
- • Salivation and difficulty swallowing
- • Nausea, vomiting, abdominal pain
- • Diarrhea
- • Tingling and numbness (paresthesia)
Phase 2 (Middle - 6-12 hours):
- • Bradycardia (slow heart rate)
- • Hypotension (low blood pressure)
- • Cardiac arrhythmias
- • Tremors
- • Muscle weakness
Phase 3 (Late - 12+ hours):
- • Peripheral circulatory failure
- • Cyanosis
- • Respiratory depression
- • Pulmonary edema
- • Death (often from cardiac arrhythmias)
Post-Mortem Signs:
External Signs:
- ✓ Mild external congestion
- ✓ Cyanosis of face and extremities
- ✓ Frothy fluid at mouth
- ✓ Normal rigor mortis
Internal Findings:
- • Pulmonary and cerebral edema (characteristic)
- • Myocardial damage and softening
- • Cardiac dilatation
- • Hemorrhages in brain and lungs
- • Liver congestion
- • No specific gastrointestinal burn (unlike corrosive poisons)
Forensic Significance:
- Highly potent (lethal dose: 2-6 mg of aconitine)
- Fast-acting plant poison
- Cardiac complications aid in diagnosis
- Often used in homicides and accidental poisonings
- Historical medicinal use (now banned in many countries)
- Detection challenging due to early metabolic changes
- Case Study Relevance: High
- All parts poisonous but ROOTS extremely dangerous
Detection and Analysis:
Sample Collection:
- • Stomach contents with pH maintained
- • Serum and plasma
- • Liver and kidney tissues
- • Bile if obtainable
Analysis Methods:
- Chemical Tests:
- - Vitali's test (violet color)
- - Mandelin's test
- - Color reactions with specific reagents
- Instrumental Methods:
- - HPLC with UV detection
- - GC-MS analysis
- - Liquid Chromatography-Mass Spectrometry (LC-MS)
- Special Considerations:
- - Aconitine rapidly metabolized (time factor important)
- - High protein binding affects detection
- - Post-mortem distribution differs from standard poisons
3.3 DATURA SPECIES (Jimson Weed, Devil's Trumpet)
Source: Datura stramonium, D. inoxia, D. alba (Solanaceae family)
| Property | Details |
|---|---|
| Botanical Source | Datura stramonium (Family: Solanaceae) |
| Active Principles | Hyoscyamine (primary), Scopolamine/Hyoscine, Atropine |
| Plant Parts | ALL PARTS TOXIC; Seeds most concentrated (~0.05-0.12%) |
| Chemical Class | Tropane alkaloids (anticholinergic compounds) |
| Molecular Formula | Hyoscyamine: C₁₇H₂₃NO₃; Scopolamine: C₁₇H₂₁NO₄ |
| Physical Form | Hyoscyamine - crystalline; Scopolamine - oily liquid |
| Solubility | Soluble in alcohol; slightly in water; stable |
Mechanism of Action:
Datura alkaloids act as anticholinergic agents:
- Block acetylcholine at muscarinic receptors
- Inhibit parasympathetic nervous system
- Result: Sympathomimetic effects (dry mouth, mydriasis, tachycardia)
- Also affects CNS causing delirium and hallucinations
- Hyoscine is more deliriant; Hyoscyamine more peripheral effects
Clinical Features of Datura Poisoning:
Early Symptoms (1-3 hours):
- • Dry mouth and throat (characteristic - "dry as a bone")
- • Thirst and difficulty swallowing
- • Mydriasis (dilated pupils)
- • Blurred vision
- • Photophobia
- • Tachycardia (rapid heartbeat)
- • Skin becomes dry and hot (anhidrosis - absent sweating)
Middle Symptoms (3-8 hours):
- • Hallucinations (visual, auditory, tactile)
- • Agitation and violent behavior
- • Confusion and disorientation (delirium)
- • Incoherent speech
- • Muscle tremors and rigidity
- • Hypertension (elevated blood pressure)
- • Hyperthermia (high fever)
Late Symptoms (8+ hours):
- • Convulsions/Seizures
- • Coma
- • Respiratory failure
- • Cardiovascular collapse
- • Death (usually from respiratory depression)
Post-Mortem Signs:
External Signs:
- ✓ DILATED PUPILS (characteristic - pinpoint to fixed and dilated)
- ✓ Dry skin (anhidrosis)
- ✓ Cyanosis
- ✓ Rigor mortis develops slowly
- ✓ No specific external burns or discoloration
Internal Findings:
- • Pulmonary edema (most common)
- • Cerebral edema
- • Myocardial changes
- • Liver congestion
- • Stomach irritation (if swallowed as seeds)
- • GI hyperemia possible
- • No specific post-mortem chemical signs
Forensic Significance:
- Variable toxicity (concentration varies in seeds)
- Lethal dose: 10-100 seeds (highly variable)
- Often accidental poisoning (seeds mistake for edible)
- Recreational use in some cultures (hallucinogenic effects)
- Young children highly susceptible
- Death causes primarily respiratory failure
- Behavioral manifestations aid in diagnosis
- Detection moderately difficult (multiple alkaloids)
Detection and Analysis:
Sample Collection:
- • Stomach contents (especially seeds if visible)
- • Liver, kidney, brain tissue
- • Blood and urine
- • Soil samples from scene
Analysis Methods:
- Presumptive Tests:
- - Vitali's test (violet color)
- - Mandelin's test
- Instrumental Analysis:
- - TLC (separation of multiple alkaloids)
- - HPLC with multiple detectors
- - GC-MS (gold standard)
- Microscopic:
- - Plant material identification
- - Seed structure examination
- - Trichome identification (plant hairs)
3.4 RICIN (Ricinus communis - Castor Bean)
Source: Ricinus communis (Castor oil plant; Family: Euphorbiaceae)
| Property | Details |
|---|---|
| Botanical Source | Ricinus communis (Castor oil plant) |
| Active Principle | Ricin (Toxic protein: MW ~65 kDa; AB toxin) |
| Plant Parts | Seeds contain ricin (~1-5% by weight), highly concentrated |
| Chemical Class | Protein (not alkaloid); Heat-labile initially |
| Molecular Formula | Complex protein (66 kDa); 2 subunits: A & B |
| Physical Form | Colorless protein; soluble in water |
| Action | Inhibits protein synthesis by inactivating ribosomes |
Mechanism of Action:
Ricin Structure: AB toxin with two chains:
- • A-chain: Catalytic domain (removes adenine from rRNA)
- • B-chain: Binding domain (binds to cell surface galactose receptors)
Action:
- B-chain binds to galactose on cell membrane
- A-chain enters cell (via retrograde transport)
- A-chain inactivates 60S ribosomal subunit
- Protein synthesis stops
- Cell death occurs
- Multi-organ failure develops
Clinical Features of Ricin Poisoning:
Route-Dependent Presentation:
A. Oral Route (Seed ingestion):
Onset: 6-24 hours (delayed)
- • Nausea and vomiting (severe)
- • Severe abdominal pain and cramping
- • Bloody diarrhea (hemorrhagic)
- • Dehydration
- • Electrolyte imbalance
B. Parenteral Route (Injection):
Onset: 18-24 hours (more rapid)
- • Local tissue necrosis at injection site
- • Lymphadenopathy
- • Systemic symptoms develop
- • Multi-organ involvement
Common to Both:
- • Hepatotoxicity (liver damage)
- • Renal failure (kidney dysfunction)
- • CNS involvement (rare)
- • Hemorrhagic manifestations
- • Shock and death
Post-Mortem Signs:
External Signs:
- ✓ Emaciation (if prolonged course)
- ✓ Dehydration signs
- ✓ No specific discoloration
- ✓ Injection site necrosis (if parenteral)
Internal Findings:
- • SEVERE hemorrhagic manifestations (characteristic)
- • Gastrointestinal hemorrhage
- • Hepatomegaly with fatty degeneration
- • Acute kidney injury with tubular necrosis
- • Pulmonary edema
- • Myocardial congestion
- • Lymphoid tissue damage
Forensic Significance:
- Extremely toxic protein (LD50: 22 μg/kg IV)
- Fewer than 10 seeds can be lethal (if well chewed)
- Limited absorption if seeds remain intact (swallowing whole)
- Recent weapon/bioterrorism concern (2000s cases)
- Protein nature makes detection challenging
- Often accidental (seeds chewed or tea made)
- Parenteral route more dangerous than oral
- Forensically significant due to rarity and toxicity
Detection and Analysis:
Sample Collection:
- • Serum (refrigerate; protein analysis)
- • Liver, spleen, kidney (for toxin concentration)
- • Stomach contents (for plant material)
- • Scene investigation (bean pods, seeds)
Analysis Methods:
- Plant Material Analysis:
- - Microscopic identification of castor beans
- - Characteristic seed structure
- Toxin Detection:
- - ELISA (Enzyme-Linked Immunosorbent Assay)
- - HPLC with protein detection
- - Mass spectrometry (sophisticated labs)
- - Immunological methods
- DNA Analysis:
- - PCR for ricin gene identification
- - Molecular confirmation
- Biological Assays:
- - Animal toxicity testing
- - Cell culture assays
3.5 CALOTROPIS (Mudar Plant)
Source: Calotropis procera, C. gigantea (Asclepiadaceae family)
| Property | Details |
|---|---|
| Botanical Source | Calotropis procera & C. gigantea (Milkweed family) |
| Active Principles | Cardiac glycosides, Cardenolides (calotropin, calactin) |
| Plant Parts | LATEX (milky sap) most toxic; seeds, flowers, leaves |
| Chemical Class | Cardiac glycosides (steroid) |
| Molecular Formula | Calotropin: C₂₉H₄₄O₇ |
| Physical Form | Milky latex sap; glycosides crystalline |
| Toxicity Effect | Cardiotoxic & irritant; keratoconjunctivitis (latex) |
Mechanism of Action:
Similar to digitalis glycosides:
- • Inhibition of Na⁺/K⁺ ATPase pump
- • Increased cardiac contractility (initially)
- • Followed by cardiac depression
- • Arrhythmias develop
- • Irritant effects on GI tract (if ingested)
- • Local irritant effects on skin/eyes (latex)
Clinical Features:
Ingestion:
- • Burning sensation in mouth
- • Nausea and violent vomiting
- • Severe abdominal pain and diarrhea
- • Cardiac manifestations (arrhythmias, bradycardia)
- • Weakness and collapse
- • Death from cardiac failure
External Contact (Latex):
- • Keratoconjunctivitis (eye inflammation)
- • Reversible vision loss (temporary)
- • Vesicant dermatitis (blistering)
- • Severe eye pain and photophobia
Forensic Significance:
- Cardiac glycoside class (like digitalis)
- Lethal dose: 2-3 grams of latex for adult
- Variable toxicity between species
- Used in homicides and suicides (rare)
- More common accidental exposure (dermatitis)
- Post-mortem cardiac findings aid diagnosis
- Detection challenging (glycoside analysis needed)
3.6 OTHER IMPORTANT PLANT POISONS (Brief Overview)
A. Oleander (Nerium oleander)
Active Principle: Cardenolides (cardiac glycosides)
Toxicity: Cardiac glycoside (similar to digitalis)
Lethal Dose: All parts toxic; few leaves can be fatal
Post-Mortem: Cardiac edema, pulmonary edema
Forensic Note: Attractive plant; accidental poisoning in children possible
B. Abrus precatorius (Rosary Pea)
Active Principle: Abrin (protein toxin, similar to ricin)
Toxicity: Extremely toxic protein
Route: Primarily oral (seeds)
Lethal Dose: 1-3 seeds (if well chewed)
Post-Mortem: Similar to ricin - hemorrhagic manifestations
Forensic Note: Beads used in jewelry; accidental ingestion by children
C. Coniine (Hemlock - Conium maculatum)
Active Principle: Coniine (alkaloid)
Toxicity: Neurotoxic; affects skeletal muscle paralysis
Clinical Features: Burning sensation, tremors, paralysis, respiratory failure
Post-Mortem: Pulmonary edema, congestion, no specific signs
Forensic Note: Unpleasant smell aids identification; historical poisoning
D. Cannabis species (Hemp/Marijuana)
Active Principle: Delta-9-tetrahydrocannabinol (THC)
Toxicity: Psychoactive; low acute toxicity
Route: Smoking, ingestion, injection
Clinical Features: CNS effects, altered perception, paranoia (extreme overdose)
Post-Mortem: No specific post-mortem signs
Forensic Note: Drug of abuse; detection via toxicology and drug screening
E. Opium (Papaver somniferum)
Active Principles: Morphine (10%), Papaverine, Codeine
Toxicity: CNS depressant
Clinical Features: Initial euphoria, CNS depression, respiratory failure
Post-Mortem: Pulmonary edema, cyanosis, characteristic frothy fluid
Forensic Note: Drug of abuse and addiction; higher incidence in poisonings
SECTION 4: COMPARATIVE ANALYSIS OF PLANT POISONS
Comparison of major plant poisons for quick reference and differentiation:
| Poison | Active Principle | Onset Time | Lethal Dose | Key Post-Mortem Sign |
|---|---|---|---|---|
| Strychnine | Strychnine (alkaloid) | 15 min-1 hr | 15-30 mg | Risus sardonicus |
| Aconite | Aconitine (alkaloid) | 30 min-2 hrs | 2-6 mg aconitine | Pulmonary edema |
| Datura | Hyoscyamine/Scopolamine | 1-3 hours | 10-100 seeds | Dilated pupils |
| Ricin | Ricin protein | 6-24 hrs (oral) | <10 seeds | Hemorrhagic features |
| Calotropis | Cardiac glycosides | 30 min-2 hrs | 2-3g latex | Cardiac edema |
| Oleander | Cardenolides | 30 min-4 hrs | Few leaves | Pulmonary edema |
SECTION 5: FORENSIC INVESTIGATION OF PLANT POISON CASES
5.1 Crime Scene Investigation
Scene Documentation:
- • Photographic evidence of plant material
- • Collection of plant samples (seeds, flowers, leaves)
- • Environmental samples (soil, water from containers)
- • Utensils used for preparation (grinder, containers, mortar)
- • Note plant species present at scene
- • Video documentation of scene
5.2 Sample Collection Protocol
Autopsy/Post-Mortem Samples:
- • Stomach contents (minimum 50-100 ml) - CRITICAL
- • Intestinal contents
- • Liver (2-5 grams)
- • Kidney (2-5 grams)
- • Brain tissue (if needed for specific poisons)
- • Blood - EDTA (2-5 ml minimum)
- • Serum (5 ml)
- • Urine (if available)
- • Vomitus material (if collected)
- • Hair (if suspected long-term exposure)
Preservation:
- ✓ Maintain chain of custody
- ✓ Store at 4°C (refrigerated)
- ✓ For proteins/antibodies: special preservation needed
- ✓ Label containers clearly with date, time, patient ID
5.3 Laboratory Analysis Approach
Step 1: Preliminary Examination
- • Visual inspection of stomach contents for plant material
- • Odor assessment
- • Color and pH examination
- • Preliminary chemical color tests (Vitali's, Marquis, Mandelin's)
Step 2: Separation Techniques
- • Extract with appropriate solvent (ethanol, methanol, or hydrochloric acid)
- • pH adjustment for alkaloid extraction
- • Filtration and concentration
Step 3: Identification Methods
Primary Methods:
- → Thin-Layer Chromatography (TLC) with multiple solvent systems
- → High-Performance Liquid Chromatography (HPLC)
- → Gas Chromatography-Mass Spectrometry (GC-MS)
Confirmatory Methods:
- → Mass Spectrometry (MS) for molecular ion
- → Nuclear Magnetic Resonance (NMR) - advanced labs
- → UV-Visible Spectrophotometry
- → Immunological assays (for protein toxins)
Step 4: Quantification
- • Determination of poison concentration
- • Comparison with toxicity data
- • Assessment of lethal vs. non-lethal levels
5.4 Differential Diagnosis in Plant Poison Cases
Clinical Presentation to Toxin Correlation:
"Risus Sardonicus + Opisthotonus + Rapid Onset"
→ Consider: STRYCHNINE (Most likely if death within 2-3 hours)
"Dilated Pupils + Dry Mouth + Delirium + Hallucinations"
→ Consider: DATURA (especially if behavioral symptoms prominent)
"Burning Mouth + Pulmonary Edema + Cardiac Arrhythmias + Rapid Onset"
→ Consider: ACONITE (if history of 30 min-2 hour onset)
"Hemorrhagic Manifestations + Liver/Kidney Damage + Delayed Onset (6-24 hrs)"
→ Consider: RICIN or ABRIN (if seeds found at scene)
"Cardiac Symptoms + Cardiac Edema + Skin Irritation"
→ Consider: CALOTROPIS or OLEANDER (if cardiac glycoside present)
SECTION 6: INVESTIGATION OF SUSPECTED PLANT POISON DEATH
6.1 Key Questions to Answer
- How did poison enter the body?
- - Oral ingestion (most common)
- - Injection/parenteral route
- - Inhalation
- - Skin absorption
- When was poison administered?
- - Onset time analysis
- - Gastrointestinal contents assessment
- - Witness statements
- What was the quantity?
- - Dose estimation from plant material in GI tract
- - Toxicological analysis results
- - Comparison with known lethal doses
- What was the mode?
- - Homicidal (usually calculated)
- - Suicidal (deliberate consumption)
- - Accidental (mistaken identity, children)
- - Occupational exposure
- What was the intent?
- - Circumstantial evidence analysis
- - Witness testimonies
- - Nature of relationship between parties
- - Previous incidents or threats
6.2 Autopsy Findings - Interpretation Guide
| Finding | Indicates | Significance |
|---|---|---|
| Risus sardonicus | Strychnine | Pathognomonic (characteristic) sign |
| Opisthotonus | Strychnine or similar convulsive poison | Post-mortem verification |
| Widely dilated pupils | Datura/Anticholinergic | Presence of these alkaloids |
| Pulmonary edema | Multiple poisons (Aconite, Digitalis) | Common but non-specific |
| Hemorrhagic features | Ricin/Abrin | Protein toxins, organs show damage |
| GI hemorrhage | Irritant/Corrosive poison | Chemical burns or glycoside effects |
| No specific signs | Plant poisons (variable) | Rely on toxicological analysis |
SECTION 7: IMPORTANT EXAM TIPS & MNEMONICS
7.1 Must-Remember Facts for UGC NET
📌 STRYCHNINE FACTS:
- ✓ Source: Strychnos nux-vomica
- ✓ Active Principle: Strychnine (1.5%), Brucine (0.5%)
- ✓ Lethal Dose: 15-30 mg
- ✓ Onset: 15 min - 1 hour (FASTEST among plant poisons)
- ✓ Death Cause: Respiratory paralysis (muscles cannot relax)
- ✓ Characteristic Sign: Risus sardonicus + Opisthotonus
- ✓ Mechanism: Blocks glycine receptors (inhibitory neurotransmitter)
- ✓ Post-Mortem: No specific internal damage (external signs diagnostic)
📌 ACONITE FACTS:
- ✓ Source: Aconitum napellus
- ✓ Active Principle: Aconitine (highly toxic)
- ✓ Lethal Dose: 2-6 mg aconitine (MOST TOXIC)
- ✓ Most Toxic Part: ROOTS (2-5% aconitine content)
- ✓ Onset: 30 min - 2 hours
- ✓ Death Cause: Cardiac arrhythmias/Respiratory failure
- ✓ Characteristic Sign: Pulmonary edema (burning mouth symptom early)
- ✓ Mechanism: Na⁺ channel activation; biphasic bradycardia-tachycardia
📌 DATURA FACTS:
- ✓ Source: Datura stramonium
- ✓ Active Principles: Hyoscyamine, Scopolamine/Hyoscine, Atropine
- ✓ Lethal Dose: 10-100 seeds (variable)
- ✓ Most Concentrated: SEEDS (0.05-0.12% alkaloid)
- ✓ ALL PARTS POISONOUS
- ✓ Onset: 1-3 hours
- ✓ Death Cause: Respiratory failure
- ✓ Characteristic Signs: Dilated pupils, Dry skin (anhidrosis), Delirium
- ✓ Mechanism: Anticholinergic (blocks acetylcholine)
📌 RICIN FACTS:
- ✓ Source: Ricinus communis (Castor bean)
- ✓ Active Principle: Ricin (protein toxin, MW 65 kDa)
- ✓ Lethal Dose: <10 seeds (if well chewed)
- ✓ Most Dangerous: Intact seeds cause less damage (poorly absorbed)
- ✓ Onset: 6-24 hours (SLOWEST, delayed)
- ✓ Death Cause: Multi-organ failure
- ✓ Route Dependent: Parenteral more dangerous than oral
- ✓ Characteristic: Hemorrhagic manifestations, hepato-renal damage
- ✓ Mechanism: AB toxin; inhibits protein synthesis
📌 CALOTROPIS FACTS:
- ✓ Source: Calotropis procera & C. gigantea
- ✓ Most Toxic Part: LATEX (milky sap)
- ✓ Active Principle: Cardiac glycosides (Calotropin)
- ✓ Lethal Dose: 2-3 grams of latex
- ✓ Onset: 30 min - 2 hours
- ✓ Dual Effect: Cardiotoxic + Irritant
- ✓ Local Effect: Keratoconjunctivitis (eye inflammation)
- ✓ Mechanism: Na⁺/K⁺ ATPase inhibition (like digitalis)
7.2 Quick Differentiation Mnemonics
STRYCHNINE = "RIGID RUNNER"
- R - Risus sardonicus (grinning face)
- I - Intense convulsions
- G - Glycine receptor blocked
- I - Immediate onset (15 min)
- D - Death within 2-3 hours
ACONITE = "FAST CARDIAC"
- F - Fast onset (cardiac effects)
- A - All parts poisonous
- S - Seeds & roots most toxic
- T - Toxin affects Na+ channels
DATURA = "DRY AND DILATED"
- D - Dry mouth (anhidrosis)
- D - Dilated pupils
- D - Delirium/Hallucinations
- D - Delayed onset (1-3 hours)
RICIN = "PROTEIN POISON"
- P - Protein toxin
- R - Route determines toxicity (parenteral > oral)
- O - Organ damage (liver, kidney)
- T - Time delayed (6-24 hours)
- E - Extremely toxic
- I - Inhibits protein synthesis
- N - No antidote (supportive care only)
7.3 Frequently Asked Question Types
Type 1: "A person shows risus sardonicus and opisthotonus. The poison is?"
Answer: Strychnine (specific combination unique to strychnine)
Type 2: "All plant parts are toxic, but roots are most toxic. This is?"
Answer: Aconite (roots contain 2-5% aconitine)
Type 3: "The characteristic feature is dilated pupils and delirium without risus sardonicus. This is?"
Answer: Datura (anticholinergic, not neuromuscular like strychnine)
Type 4: "Lethal dose is less than 10 seeds, and plant belongs to Euphorbiaceae. This is?"
Answer: Ricin from Ricinus communis
Type 5: "Cardiac glycoside poison with keratoconjunctivitis as local effect. This is?"
Answer: Calotropis (only plant poison causing eye inflammation)
Type 6: "Fastest acting plant poison with onset 15 min-1 hour. This is?"
Answer: Strychnine (all other plant poisons take longer)
Type 7: "Slowest acting plant poison with delayed onset 6-24 hours. This is?"
Answer: Ricin (protein toxin, requires time for protein synthesis inhibition)
SECTION 8: SAMPLE EXAM QUESTIONS (2019-2024 PATTERN)
8.1 Previous Year Questions - Analysis
| Year | Question | Answer | Key Concept |
|---|---|---|---|
| 2024 | Active principle of Strychnos nux-vomica causing death by muscle tetany is? | Strychnine | Alkaloid; glycine block |
| 2023 | Characteristic post-mortem appearance in strychnine poisoning includes? | Risus sardonicus + Opisthotonus | Pathognomonic signs |
| 2022 | Ricin is a protein toxin from Ricinus communis. Its mechanism is? | Inhibits 60S ribosomal subunit | Protein synthesis block |
| 2021 | Aconite poisoning shows onset within? | 30 min - 2 hours | Fast-acting neurotoxin |
| 2020 | Datura alkaloids act as? | Anticholinergic (muscarinic antagonists) | Blocks acetylcholine |
| 2019 | Which plant poison causes keratoconjunctivitis? | Calotropis (latex exposure) | Local irritant effect |
8.2 Practice Questions for Self-Assessment
Q1. A 35-year-old male is brought dead with history of consuming plant seeds. On autopsy, body shows characteristic grinning face (risus sardonicus) with extended thumbs and back arching (opisthotonus). The poison is most likely?
A) Ricin from Ricinus communis
B) Strychnine from Strychnos nux-vomica
C) Aconitine from Aconitum napellus
D) Hyoscyamine from Datura stramonium
[Answer: B - Strychnine; Risus sardonicus + Opisthotonus are pathognomonic]
Q2. Which of the following plant poisons has the longest incubation period (delay between ingestion and onset of symptoms)?
A) Strychnine (15 min - 1 hour)
B) Aconite (30 min - 2 hours)
C) Ricin (6-24 hours)
D) Datura (1-3 hours)
[Answer: C - Ricin; protein toxin requires time for cellular effects]
Q3. A child is brought to hospital with dilated pupils, dry mouth, extremely dry skin without sweating, and hallucinations. The most likely poisoning is?
A) Oleander (cardiac glycoside)
B) Datura (anticholinergic alkaloid)
C) Hemlock (neuromuscular paralysis)
D) Cannabis (CNS depression)
[Answer: B - Datura; Classic anticholinergic syndrome]
Q4. Ricin toxicity is greatest when route of exposure is?
A) Oral (ingestion of seeds)
B) Inhalation
C) Parenteral (injection)
D) Dermal (skin contact)
[Answer: C - Parenteral; bypasses GI absorption limitations]
Q5. The active principle of Aconitum napellus that causes death most commonly by cardiac arrhythmias is?
A) Hyoscyamine
B) Aconitine
C) Strychnine
D) Morphine
[Answer: B - Aconitine; specific cardiotoxic diterpene alkaloid]
Q6. In strychnine poisoning, death occurs primarily from?
A) Cardiac failure
B) Hepatic necrosis
C) Respiratory paralysis (muscles cannot relax)
D) Renal failure
[Answer: C - Respiratory paralysis; muscles in tetany cannot relax for breathing]
Q7. Which plant contains the highest concentration of alkaloid in its root system?
A) Ricinus communis
B) Aconitum napellus (roots 2-5%)
C) Datura stramonium
D) Calotropis procera
[Answer: B - Aconitum napellus; roots contain 2-5% aconitine]
Q8. Ricin is classified as an AB toxin. What is the function of the B-subunit?
A) Catalytic inactivation of ribosomes
B) Binding to cell surface galactose receptors (cell recognition)
C) Transport to mitochondria
D) Nuclear membrane penetration
[Answer: B - B-subunit binds to galactose receptors; A-subunit catalytic]
Q9. In a suspected Datura poisoning case, the forensic pathologist notes dilated pupils but ABSENCE of risus sardonicus. This helps differentiate from?
A) Aconite poisoning
B) Strychnine poisoning
C) Ricin poisoning
D) Oleander poisoning
[Answer: B - Strychnine poisoning; Strychnine causes risus sardonicus, Datura does not]
Q10. A chemical screening test shows violet color with Vitali's reagent in stomach contents of a deceased person. The poison is most likely?
A) Ricin (protein, won't give color)
B) Strychnine or Aconite (alkaloid, characteristic color)
C) Cyanide (no specific color)
D) Carbon monoxide (colorless)
[Answer: B - Strychnine or Aconite; both give violet color with Vitali's test]
SECTION 9: KEY TAKEAWAYS & REVISION POINTS
✅ MUST REMEMBER:
- 1. Strychnine = FASTEST onset (15 min-1 hr) with RISUS SARDONICUS
- 2. Aconite = MOST TOXIC by dose (2-6 mg aconitine) with cardiac effects
- 3. Datura = ANTICHOLINERGIC effects (dry, dilated pupils, delirium)
- 4. Ricin = SLOWEST onset (6-24 hrs) with hemorrhagic features
- 5. Calotropis = Only plant poison with keratoconjunctivitis
✅ DIAGNOSTIC COMBINATIONS:
- → Risus sardonicus + Opisthotonus = STRYCHNINE
- → Dilated pupils + Dry mouth + Delirium = DATURA
- → Pulmonary edema + Arrhythmias + Rapid onset = ACONITE
- → Hemorrhagic manifestations + Delayed onset = RICIN
- → Cardiac edema + Cardiac glycoside = CALOTROPIS/OLEANDER
✅ FORENSIC SIGNIFICANCE:
- • Sample preservation critical (especially for proteins)
- • Chain of custody essential
- • Multiple analytical techniques confirm diagnosis
- • Post-mortem signs aid in preliminary diagnosis
- • Toxicological analysis provides definitive answer
- • Time of death estimation possible from onset characteristics
✅ EXAM STRATEGY:
- 1. Read question carefully for SYMPTOMS first
- 2. Match symptoms to specific post-mortem sign
- 3. Recall mechanism of action from that signature sign
- 4. Select answer matching the poisoning type
- 5. Verify answer against lethal dose and onset time
✅ HIGHEST PROBABILITY QUESTIONS:
- → Mechanism of action (How does poison work?)
- → Active principles (What is toxic compound?)
- → Post-mortem signs (What do we see at autopsy?)
- → Forensic significance (Why is this important?)
- → Differentiation (Which poison is this NOT?)
✅ TIME MANAGEMENT TIP:
Plant poisons are typically 2-3 questions per exam. Study order:
- 1. Strychnine (60% probability)
- 2. Aconite (20% probability)
- 3. Datura (10% probability)
- 4. Others (10% combined)
SECTION 10: RECOMMENDED REFERENCE MATERIALS
Textbooks:
- 1. "Forensic Toxicology: Drugs and Poisons" - Satish Mohan
- 2. "Criminalistics: Forensic Science and Crime" - Richard Saferstein
- 3. "Concise Forensic Medicine" - Vij
- 4. "Forensic Medicine and Toxicology" - Parikh
Online Resources:
- • ForensicMCQ.com (Practice questions)
- • NTA Official Website (Exam pattern, syllabus)
- • PubMed Central (Research articles on plant toxins)
- • Forensic Pathology Journals
Important Standards:
- • UGC NET Forensic Science Syllabus 2024-25
- • BIS Standards for Toxicological Analysis
- • WHO Guidelines on Forensic Pathology
