Abrus precatorius, the rosary pea or jequirity bean, is a climbing legume grown across India for its glossy red and black seeds, strung into ornaments, prayer beads and toys. The toxin is abrin, a type 2 ribosome-inactivating glycoprotein related to ricin but several times more potent. The lethal dose by injection is 0.1 to 1 microgram per kilogram, making a single pierced seed potentially lethal if its contents reach the bloodstream.
Three medico-legal patterns recur. First, accidental ingestion by children chewing seeds; the hard coat usually protects the abrin from absorption and intact seeds pass through, but cracked coats are dangerous. Second, occupational injury in jewellery makers who pierce seeds and prick their fingers, producing local necrosis, lymphangitis and systemic shock. Third, the historical "sui" or needle technique, a pellet of seed paste implanted under the skin of cattle (and historically of human victims). The cattle quack tradition in north India has used abrin pellets for livestock insurance fraud since the colonial period; case law from the Allahabad and Patna High Courts goes back to the 1920s.
Oral abrin causes severe gastroenteritis, bloody diarrhoea and delayed multi-organ failure peaking at 48 to 72 hours. Parenteral abrin causes local necrosis and rapid systemic shock. No specific antidote; fluid resuscitation and ICU supportive care are the mainstays.
Cleistanthus collinus, locally Oduvanthalai or "the tree of death", is a small dry-zone tree of the Euphorbiaceae family native to Tamil Nadu, Kerala and Andhra Pradesh. The leaves are boiled in water and the decoction is swallowed; the practice has been a major suicide method in Salem, Erode and Coimbatore since at least the 1960s. The toxins are the cleistanthins, arylnaphthalide lignans that damage the distal renal tubule, producing a type 1 distal renal tubular acidosis with profound hypokalaemia, and inflict diffuse oxidative injury on heart, lung and liver. Mortality between 1970 and 2010, in the peak decades, was reported in JIPMER and CMC Vellore case series at 25 to 50 percent.
The course is stereotyped. Within hours of ingestion the patient develops vomiting, abdominal pain and profound weakness. Serum potassium falls below 2.5 mmol/L. Arterial gas shows a hyperchloraemic non-anion-gap metabolic acidosis. By 24 to 48 hours, hypotension, ARDS and multi-organ failure set in. Death is usually from refractory ventricular arrhythmia secondary to severe hypokalaemia or from respiratory failure.