Cerbera odollam

Cerbera odollam
Cerbera odollam, or the "pong-pong" tree
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Gentianales
Family:	Apocynaceae
Genus:	Cerbera
Species:	C. odollam
Binomial name
Cerbera odollam Gaertn.
Synonyms
Cerbera dilatata Markgr.

Cerbera odollam is a tree species in the family Apocynaceae commonly known as the suicide tree or pong-pong. It bears a fruit known as othalanga whose seeds yield a potent poison called cerberin that has been used for trials by ordeal, suicide, and poisonings.

It is native to South and Southeast Asia, Pacific Islands, and Queensland, Australia, growing preferentially along sandy coasts, riverbanks, and by mangrove swamps. It is also grown in tropical areas such as Hawaii as an ornamental.

Description

Diagram of different parts of the Cerbera odollam plant.

Cerbera odollam bears a close resemblance to oleander, another highly toxic plant from the same family. It grows to approximately 10-12 meters in height. Its leaves are glossy and it has white flowers with yellow throats. The plant as a whole yields a milky, white latex.

Its fruit, about 5-10cm in length, starts green and becomes red as it matures. It has a green fibrous shell enclosing an ovoid kernel measuring approximately 2 cm × 1.5 cm and containing two extremely poisonous seeds. On exposure to air, the white kernel turns violet, then dark grey, and ultimately brown, or black.

History

Common names

Cerbera odollam is known by a number of vernacular names, depending on the region. These include othalam (ഒതളം) in the Malayalam language used in Kerala, India; kattu arali (காட்டரளி) in the adjacent state of Tamil Nadu; dabur (ডাবুর) in Bengali; famentana, kisopo, samanta or tangena in Madagascar; and pong-pong, buta-buta, bintaro or nyan in Southeast Asia.

Use in Trials by Ordeal

The poisonous kernel of the Cerbera odollam fruit was used in trials by ordeal like the tangena throughout the regions where it grew. In Madagascar in the 18th and 19th centuries, over 3000 people died per year from consuming Cerbera odollam seeds in a trial by ordeal. These trials were intended to determine whether the subject was guilty of a crime, often witchcraft. In these trials, a dosage of the seed was administered. If the subject lived, they were considered innocent of whatever crime they were accused. If they died, they were considered guilty. These trials relied on the belief that some underlying spirit would distinguish between innocence and guilt.

Trials by ordeal using cerberin were extremely common. In the mid-1800s, leaders attempted to regulate trials by ordeal in Madagascar. For minor crimes, dogs or chickens were used as a substitute for humans. However, it wasn't until the early 1900s that this practice stopped.

Use for Suicide

Cerbera odollam was also frequently used for suicide and continues to be used for this purpose in the modern day. For instance, a 2004 study found that it was responsible for about one suicide death per week between 1989 and 1999 in Kerala, India. To commit suicide, people would remove the kernels from the seed and combine it with jaggery to eat. Death would occur quickly, about 3-6 hours after ingestion.

Toxicity

Cardiac glycosides

Cerberin, the poisonous compound in the kernels of Cerbera odollam, is a species called a cardiac glycoside. Cardiac glycosides are found in many other plants including foxglove and Cerbera manghas as well as some toads. Cardiac glycosides work on the heart and are used in medicine to treat heart failure and arrhythmia, but can easily cause an overdose if used improperly.

All cardiac glycosides are believed to be able to block the heart's sodium and potassium ATPase, however structural differences cause differences in toxicity and symptoms. All cardiac glycosides contain a steroid ring, a lactone ring, and a sugar moiety.

Symptoms

Cerbera odollam

The kernels of C. odollam contain cerberin, a digoxin-type cardiac glycoside toxin that causes disruption of the heart beat, most often fatally. One kernel contains a fatal dose of the toxin. Electrocardiographic abnormalities were noted to be common, the most common being sinus bradycardia. Around half of the patients develop thrombocytopenia. Temporary cardiac pacing has been used in the management, apart from other supportive measures.

Common symptoms of cerberin poisoning include a burning sensation in the mouth, vomiting, retching, nausea, irregular respiration, headache, bradycardia, coma, and death. Some cases are asymptomatic.

Use as a poison

Cerbera odollam was commonly used for poisonings as well as suicide. Its bitter flavor could was easily masked by spicy food, allowing victims to ingest it without noticing. In Kerala, India, C. odollam is responsible for about 50% of plant poisoning cases and 10% of all poisonings.

Only one analytical procedure exists to determine the presence of C. odollam after death, making it hard to detect. This method compares thin layer chromatography of tissues collected in an autopsy suspected to contain C. odollam with chromatograms obtained from the C. odollam kernel. The fatalities from poisonings, particularly from C. odollam, are very underestimated due to the lack of analytical investigation of most deaths. Poisonings outside the tree's natural habitat are considered to be rare but may just be going unnoticed due to a lack of testing.

Modern uses

Flowers of Cerbera odollam

The seeds of C. odollam are used as biopesticides, insect repellants, and rat poisons due to its toxicity to these animals.

Investigations have also been made into the feasibility of using the seeds as a feedstock in the production of biodiesel. Oil can be extracted from the seeds and transesterified into fatty acid methyl esters. This is a good alternative to other plants commonly used for biodiesels because unlike these plants, it grows on typically non-arable land and therefore does not compete with food crops.

See also

• List of poisonous plants