Abrus Precatorius


Abrus precatorius is one of the potential organic Irritant poisons. This plant found in mainly tropical regions. Abrus is green, slender, twining, climbing plant, woody at base.

The plant is found all over India. All parts are poisonous but the seeds are commonly used as poison. The seeds are generally red in colour and black spot at the end. Sometimes, black seeds with a white spot at one end and White seeds with a black spot at one end also encountered. They are tasteless, odourless and egg-shaped. They are about 0.85cm long and 0.65cm broad with an average weight of 120mg. Leaves are alternate, opposite, pinnately feather-like with small oblong leaflets. Leaflets appear in 8 to 15 pairs, and are about ½ inch long. When stems are young, they appear as green but develop grey bark as the plant matures. Flowers are pink, purple, or white and borne in clusters. They appear in the leaf axils along the stems. The distinctive part of the plant is the seed which is oval, 5 mm in diameter, and has an attractive hard glossy outer shell that is usually scarlet red with a black centre. The seeds are present inside fruit pods, each containing 3 to 5 seeds. The pods split open when ripe. The pod is a legume (pea-shaped pod), and is about 3 cm long.

Abrus precatorius have various chemical constituents such as abrasine, abrol, precol and pre-casine from the roots. Seeds are rich in several essential amino acids like alanine, serine, choline, valine, and methyl ester, enzyme, aglucosideabrussic acid, haemagglutinin, albuminous substance named abrin and a quantity of ureas.

Common Name: Jequirity, Indian liquorice, Rosary bead, Crab’s eye, Gunchi or Rati.

Toxic part of Plant:

  • Seed
  • Leave
  • Root

Active Principle

The main active principle is Abrin which is a thermolabile toxalbumin and its action resembles those of viperine snake bite. It is a lectin composed of two polypeptide chains (A and B) connected by a disulfide bridge. This basic structure of two peptide chains linked by a single disulfide chain is similar to that of botulinum toxin, tetanus toxin, cholera toxin, diphtheria toxin, and insulin.

Fatal Dose

The fatal dose is 1-2 seeds by mouth and 90-120mg abrin by injection.

Fatal Period

The fatal period is 3-5 days.


  • The seeds are often used in rosary beads, necklaces, and folk jewellery. Jewellers in India sometimes use the seeds as a weighing measure for gold or precious stones.
  • This is also used for traditional medicine to treat sores, scratches and wound.
  • It is also used with other ingredients to treat leucoderma.
  • The leaves are used in anti-suppurative properties.
  • It is also used to treat tetanus and to prevent rabbies.
  • The seeds are also used to treat diabetes and chronic nephritis.
  • Seeds are also considered to be purgative, emetic, tonic, antiphlogistic, aphrodisiac, antiophthalmic.
  • It is used in veterinary medicine for the treatment of fracture.


  • Extract injected. Placed in the wound.
  • Powder formed into a ‘sui’ and inserted in the body.
  • Powdered seeds are ingested orally also.

Mechanism of Action

Abrin exerts its toxic action by attaching itself to the cell membranes. Abrin’s toxic effect is due to its direct action on the parenchymal cells (e.g., liver and kidney cells) and red blood cells.

Abrin is composed of two polypeptide chains (A and B). These chains are connected by a disulfide bond. Chewing or crushing of seed releases abrin. The “B” polypeptide chain (called as haptomere) binds to the intestinal cell membrane while “A” polypeptide chain (called as effectomer) enters the cytoplasm. A polypeptide chain acts on the 60S ribosomal sub-unit, preventing binding of elongation factor 2, thus inhibiting protein synthesis and leading to cell death.

Absorption by route of exposure- Abrin is very stable in the gastrointestinal tract, from where it is slowly absorbed. It is considerably less toxic after oral administration than after parenteral injection.

Distribution by route of exposure- Abrin is widely distributed in tissues.

Sign and Symptoms

1.If powdered seeds are ingested orally, then they produce symptoms like –

  • Severe irritation of upper Gastrointestinal tract
  • Abdominal pain
  • Nausea
  • Vomiting
  • Bloody Diarrhoea.
  • Weakness
  • Cold perspiration
  • Trembling of the hand
  • Weak pulse
  • Miosis
  • Rectal bleeding
  • Cardiac arrhymias
  • Delayed cytotoxin effects occur in the CNS, liver, kidneys and adrenal glands 2 to 5 days after exposure.

2. When the seeds are swallowed raw or after after cooking, they are not poisonous but when abrin is injected in skin (Dermal manifestations), then it produce inflammation, swelling, odema, ecchymoses and leading to necrosis at the site of injection. Similarly there will be faintness, peripheral vascular collapse, vertigo, vomiting, dyspnoea and Convulsions may precede death from cardiac failure. The symptoms resemble those of viper snakebite.

3. Ocular exposure: Causes redness, chemosis, swelling and conjunctivitis.

4. The seeds may be crushed and mixed with dhatura, opium and onion to form a paste, which is then made in the form of needles which are then hardened in the sun. These needles are then placed in a wooden handle. The needle is 15 mg long and weighs about 90-120 mg. These are inserted into the animals, especially around genitalia, anus or vagina. In a few hours, inflammation and oedema appear on the site. Later necrosis may occur. An animal dies within 3–4 days due to peripheral shock.

Test for Detection

Test for Seed Powder

Tests of Alkaloids: 10 grams of the seed powder was extracted with 50 ml of dilute HCl. Then the extract was filtered and mixed with dilute NH4OH after that then extracted with CHCl3 followed by redissolved in 1 ml of dilute HCl. If the color of the solute change into white turbidity with Mayer’s reagent (Potassium Mercuric Iodide), brown precipitate with Wagner’s reagent (iodine potassium iodide solution) or orange color with Dragendorffs reagent (potassium bismuth iodide), this indicates the presence of alkaloids.

Test for Flavonoids:

a. Alkaline Reagent Test: Dried seed powder (5 g) were macerated overnight in 150 ml of cold 1% HCl and filtered. Ten milliliters of the filtrate were alkalinized with NaOH. The formation of a yellow color indicates the presence of flavonoid compounds.

b. Lead acetate Test: The Extract was treated with few drops of lead acetate solution. Formation of yellow colour precipitate indicates the presence of flavonoids.

Tests of Glycosides:

a. Keller Killiani Test: Test solution was treated with few drops of glacial acetic acid and Ferric chloride solution and mixed. Concentrated sulphuric acid was added, and observed for the formation of two layers. Lower reddish brown layer and upper acetic acid layer which turns bluish green would indicate a positive test for glycosides.

b. Borntrager’s Test: To the 3ml of aqueous extract, dil. H2SO4 was added. The solution was then boiled and filtered. The filtrate was cooled and equal volume of benzene was added to it. The solution was shaken well and the organic layer was separated. Equal volume of dilute ammonia solution was added to the organic layer. The ammonia layer turned pink indicating the presence of glycosides.

For Leaves

  • Scanning electron microscope (SEM) analysis
  • EDAX measurements

Other Tests:

  • Thin Liquid Chromatography
  • Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)
  • Uv and IR Spectrophometry
  • Nuclear Magnetic Resonance
  • High Performance Liquid Chromatography


  • Gastric decontamination (lavage).
  • Injection of anti-abrin.
  • The needle should be dissected out.
  • Activated charcoal.
  • Whole bowel irrigation is said to be helpful, but some investigators dispute this.
  • Supportive measures, with special emphasis on rehydration. Close attention should be given to hematological parameter.
  • Alkalinisation of the urine probably has a role in preventing crystallisation of haemoglobin, and should be considered in severe poisonings.
  • Renal failure can be managed by haemodialysis.
  • Ocular exposure necessitates copious irrigation with running water for at least 15 minutes.
  • Convulsions can be controlled by diazepam/lorazepam.

Postmortem Appearances

  • The injured site is swollen, inflamed and necrosed.
  • Local-fragments of the sui or needle are usually found in the wound and skin.
  • Haemorrhagic patches are seen under mucuous membranes.
  • Internal organs are congested and haemorrhagic.
  • Cerebral edema.

Evidentiary Clues

  • Residue of powdered seeds etc in the wound.
  • Cloths of the victims.
  • Body site Attacked.
  • Paraphernalia used.

Medicolegal Aspects

● Accidental poisoning may occur in children while exploring the seeds.

● Homicide by sui prepared with abrin (sui is needle or spike made with crushed seed alone or mixed with onion paste. Then the needle is dried under sun. The sui is kept between two fingers and is pushed into skin of other person).

●Sui are also used to kill cattle either to produce cheap hides or for revenge.

● Malingerers use powder of abrus seed to produce conjunctivitis.

● When intact seeds are swallowed or when seeds are boiled or cooked, they are not poisonous.

●When taken internally they disturb the uterine function and prevent conception.

● The seeds are used as an abortifacient and as arrow poison.


  1. Dr. K.S. Narayan Reddy. The essential of forensic medicine and toxicology.34th edition.
  2. VV Pillay.Modern medical toxicology.4th edition.
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