Abrus Precatorius | Plant Poison | Budding Forensic Expert

Forensic Toxicology • Plant Poisons

Abrus Precatorius

Fabaceae ⋅ Rosary Pea ⋅ Jequirity Seed ⋅ Crab’s Eye

Plant Poison Toxalbumin ⚠ Highly Toxic Medicolegal

☰ Contents

1. Taxonomy & Classification
2. Introduction
3. Plant Profile & Active Principle
4. Signs & Symptoms
5. Extraction Methods
6. Detection Tests

01

Taxonomy & Classification

Name	Abrus Precatorius
Kingdom	Plantae
Order	Fabales
Family	Fabaceae
Genus	Abrus
Species	A. Precatorius
Common Names	Gunchi / Rati  •  Crab’s Eye  •  Jequirity Seed  •  Rosary Pea Seed

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02

Introduction

Abrus precatorius is a plant known for its irritant action and toxic properties. It is widely distributed throughout India and other tropical regions of the world. All parts of the plant contain toxins, but the seeds are most commonly used as a poison.

When raw seeds are swallowed whole, they are not poisonous due to their hard coat. However, the extract of these seeds — when injected under the skin as “Sui” (sharp needles) — can cause symptoms similar to a viper bite.

⚠ Toxic Mechanism

The toxic preparation is made by powdering the seeds and mixing them with opium, onion, dhatura, and spirit or water. The Suis are shaped into small sharp needles and hardened by drying in sunlight. Injection causes local swelling (oedema), tissue death (necrosis), bleeding, and agglutination of red blood corpuscles.

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03

Plant Profile & Active Principle

Plant Characteristics	Active Part
Has 10–15 pairs of narrow leaves, small pinkish flowers with seedpods. When ripe, exposes 4–6 seeds. Seeds are bright red with a black spot on one pole, weighing about 105 mg. Historically used by goldsmiths as a weight for gold.	The whole plant is poisonous; however, the seed is most toxic. Seeds are approximately 0.80 cm long and 0.60 cm broad, oval, red in colour, tasteless, odourless, with a black spot on one pole.
Active Principle	Signs and Symptoms
Active principle is Abrin, a toxalbumin (similar in structure to ricin).	Animal becomes apathetic, drowsy, refuses food Unable to move after 3–4 days; drops, becomes comatose Symptoms resemble viper snake bite Human: local painful swelling, ecchymosis, necrosis Vertigo, cardiac arrhythmia, convulsions, death Ingestion: nausea, vomiting, abdominal pain, diarrhoea, collapse
Fatal Dose	Post-mortem Appearances
1–2 seeds orally  |  90–120 mg abrin by injection	Injured site: swollen, inflamed with necrosis Fragments of sui found in the wound Haemorrhagic patches under mucous membrane Internal organs congested with haemorrhages
Fatal Period	Medicolegal Aspects
1–5 days	Suis used to kill cattle Human poisoning by sui held between fingers during a slap Powdered seeds used to produce conjunctivitis (malingering) Also used as an arrow poison

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04

Signs & Symptoms by Route

◆ Topical Contact	◆ Ingestion	◆ Injection
Severe conjunctival inflammation Local painful swelling & ecchymosis Localized necrosis	Immediate Severe irritation Abdominal pain Nausea and vomiting Haemorrhagic gastritis Bloody diarrhoea & rectal bleeding Pupils constricted Pulse: rapid and weak Weakness, cold perspiration, faintness Delayed Cytotoxic effect in CNS, liver, kidney, adrenal gland Convulsions	Local Painful swelling and oedema Ecchymosis Inflammation Necrosis at puncture site General Weakness and faintness Inability to move Drowsiness Coma and death in 3–5 days

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05

Extraction Methods

◆ 1. Ether Extraction

1. Crush the seeds in a mortar until a fine powder is obtained.
2. Add Diethyl Ether to the crushed seeds.
3. Set aside for 20–30 minutes to allow extraction to occur.

◆ 2. Ethanol Extraction

1. Add Ethanol to the crushed seeds.
2. Keep aside for a few minutes to allow extraction.
3. Other organic solvents such as acetic acid, acetone, or methanol may also be used.

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06

Detection Tests

Test 01

Fast Blue B – Potassium Hydroxide Test

To dried residue in a porcelain basin, add a few drops of 5% ethanolic Fast Blue B salt solution, followed by 2 drops of aqueous KOH solution.

◆ Red to Orange colour

Test 02

Marquis Reagent Test

To dried residue of extract, add 2 drops of Marquis Reagent (1 vol. formaldehyde + 9 vol. concentrated H₂SO₄).

◆ Pink colour formed

Test 03

Van Urk Reagent Test

Add one drop of Van Urk Reagent (1 g p-amino benzaldehyde in 100 ml ethanol + 10 ml HCl) to the dried residue of extract.

◆ Green → Blue colour

Test 04

Agglutination Test

Add 2 drops of aqueous extract residue to 2 ml of defibrinated blood (undiluted) in a small test tube.

◆ RBCs agglutinate (sealing-wax mass)