Synonyms – Kunch, Rati, Precatory bean, Jequirity bean, Crabs eye, Prayer bead, Rosary pea, Lucky bean).
The plant is a slender, woody, climbing plant. The seeds contain the toxic active principle ABRIN which is a TOXALBUMIN. A toxalbumin is a phytotoxin or toxic protein. It is antigenic in character and agglutinates red cells and also causes haemolysis. In these regards, it is similar to bacterial toxins.
Abrus seeds are oval in shape, nearly 8 mm x 6 mm in dimensions, glossy scarlet red in colour over the most surface area with blackish surface at one end. Each mature seed weighs about 105 mg and the weight of the seeds is more or less constant. Abrin is thermolabile and its toxicity is destroyed by boiling the seeds. Hence, though as such deadly poisonous, the seeds are sometimes consumed as food, after boiling. The seeds are also harmless when taken intact, as the seed coat does not allow the toxin to come in contact with the intestinal wall and the seed passes out undigested. Poisoning occurs only when crushed seeds are taken or when the seeds are chewed before swallowing. Abrin is slightly inactivated by the gastric juice. It is most effective when used parenterally. The seeds are tasteless and odourless.
Action – It is a local irritant and C.V.S. depressant. When used parenterally, the toxin causes viper snake bite like action.
Fatal dose –1 to 2 crushed seeds for an average adult.
Fatal period – A few hours to a few days.
Signs and symptoms – When taken orally, there are signs and symptoms of severe gastrointestinal irritation with nausea, vomiting and diarrhoea which often bears evidence of internal haemorrhage. There may be flushing of face, rapid pulse, fall of blood pressure, muscular weakness, dilated pupils, tremor, tetanic spasm, convulsion, coma and death due to circulatory failure. In some cases there may be hallucinations.
When used parenterally in the form of ‘sui’ or spike, there is severe local reaction like viper snake bite. There are oedema, oozing, echhymosis and necrosis of the tissue. Then there are vertigo, general prostration, dyspnoea, fall of blood pressure, weak irregular pulse, circulatory collapse and sometimes convulsion before death.
Treatment – If anti-abrin is available that should be used. However, in any case, treatment is mostly symptomatic. Stomach wash is performed and demulcents are given, if poisoned by mouth. Spikes are taken out from the site of parenteral injection. Calcium gluconate is given to combat tetany. Circulation is maintained and other symptomatic treatment given.
Postmortem appearance – When taken by mouth, there may not be any remarkable external sign. When used in the form of spike then the site of injection will be swollen, inflamed and necrosed with presence of spike in the tissue, at the site of lesion. Internally, when taken by mouth, the G.I. tract is inflamed with evidence of haemorrhagic points. Organs are congested with evidence of haemorrhage in the organs and at the undersurface of visceral covering.
Medicolegal aspects – Most of the poisoning cases are accidental in children who being attracted by the colour may chew the seeds. Homicidal poisoning occurs mostly through parenteral route. For homicidal parenteral use, the seeds are crushed to powder. This alone or mixed with datura and opium is made to paste. Spikes of length of about 1.5 cm, weighing about 100 mg each, commonly known as ‘sui’ or ‘sutari’ are made out of the paste and dried under the sun. These spikes are held in between fingers and the victim is forcefully slapped to insert the spikes in the flesh. The spikes are also used to kill cattles. For this the spikes are fixed on wooden frames and the animal is forcefully hit on the buttock to inject the spikes in its body. Crushed seeds are often taken to commit suicide. Abrus seed pastes are used as arrow poison. This has also been used locally to cause abortion. Seed dust is used by malingerers to produce conjunctivitis. This may cause permanent damage of the eyes.