Adenium obesum

Botanical Name

Adenium obesum (Forssk.) Roem. & Schult. Syst. veg. 4:411 (1819)[1] [2]

Synonyms

Adenium somalense Balf. f. (1888); Adenium socotranum Vierh. (1904); Nerium obesum Forssk., Fl. aegypt. arab. (1775) 205 [2]

Family

Apocynaceae

Vernacular Names

 

Malay Adenium merah
Indonesia Adenium merah
Thailand

Chuan Chom

English

Desert Rose, Impala Lily

French Rose du desert, baob chacal, faux baobab, lis des impalas, pied d’elephant
Portuguese Rosa do deserto, Baoba exotica, djindje pete
Swahili

Mdagu, Mdaguwande, Mwanja [1]

 

Description

Adenium obesum is a succulent shrub or small tree which can reach up to 4–6 m tall sometimes with fleshy tap root. The stem is swollen at the base up to 1–2 m in diameter. The bark is smooth, shiny, green to pale brown with a green slash in colour. The latex is white or translucent.  The stem is smooth, with thickened ends, bearing the scars of fallen leaves, greyish-green in colour. The leaves are alternate, sessile, narrowly obovate, measuring 7-15 cm long and 2-4 cm wide, spirally attached. The blade wider towards the apex, progressively narrowing at the base, with obtuse or mucronate and emarginated apex, glabrous (except for the undersurface of young blades). The nerves are pinnate, hardly prominent, with 6-15 pairs of lateral nerves fusing into a more or less obvious marginal nerve. The inflorescence is a terminal cyme. The flowers are bright pink in colour, with tubular corolla, measuring 5-7 cm long and 4-5 cm in diameter, with 5 curly-edged lobes. The fruit is follicles in clusters of two or three, measuring 15-25 cm long and 1-1.5 cm across, a little divergent, pointing downwards, with elongated acuminate tip, finely pubescent. The seeds are linear, with a pappus at both ends. [1] [4]

Distribution

A. obesum is essentially native of Eastern Africa occurring from Senegal to ethopia and from Somalia to Tanzania. It is also found in Egypt, Saudi Arabia, Oman and Yemen including Socotra. It has naturalised in Sri Lanka and other parts of Southeast Asia especially Thailand. [1]

Plant Use

In Africa the root sap or sometimes the wood or stem latex of A. obesum is used in the preparation of arrow poison. It is a popular poison for hunting large game as it kills quickly and the hunted animal dies within 2 km from the where it was shot. Decoction of the bark and leaves is used as fish poison. In Mauritania and Senegal it is used as ordeal poison and for criminal purposes.[1]

As medicine the decoction of the roots, alone or in combination with other plants is used to treat venereal diseases. The root or bark extract is used as a bath or lotion to treat skin diseases and to kill lice, while the latex is applied to decaying teeth and septic wounds. In Somalia, a root decoction as nose drop is prescribed for rhinitis. In northern Kenya latex is rubbed on the head against head lice and powdered stems are applied to kill skin parasites of camels and cattle. The bark is chewed as an abortifacient. [1]

Toxic Parts

Whole plant including latex and sap [1]

Toxin

In A. obesum the presence of 30 cardiotoxic glycosides have been demonstrated, which act in a similar manner as digitalis. Digitalis acts upon the Na+ K+ - ATPase enzyme that regulates the concentration of Na+ and K+ ions in the body cells and so also modifies the Ca++ concentration. In low doses it is used to treat congestive cardiac failure and heart rhythm problems (atrial arrhythmias) but in high doses it leads to systolic heart failure and death.

Therefore, consuming cardiac glycoside containing plants causes interference with sodium-potassium pump mediated by ATPase, resulting in an increase in intra-cellular sodium and decrease in intracellular potassium. The decrease in intracellular potassium interfere with electrical conduction resulting in progressive electrical changes. The normal resting membrane potential is decreased and eventually a complete loss of normal myocardial electrical function occurs. Hyperkalaemia may be marked with a loss of cardiac excitability and response. [4]

Several of the cardiac glycosides from A. obesum have oleandrigenin as aglycone moiety, e.g. hongheloside A (with D-cymarose), hongheloside C (with D-cymarose and D-Glucose) and 16-acetylstrospeside (with D-digitalose). Other glycosides include: hongeline (composed of digitoxigenin with D-thevetose), somaline (composed of digitoxigenin with D-cymarose) and digitalium verum (composed of gitoxigenin with D-digitalose and D-glucose). The roots and stems contain the same glycosides and in similar amounts. Oleanderigenin and some of the glycosides derived from it have cytotoxic effects and are being studied as potential component anticancer drugs.[1]

The leaves and stem exude a latex which is used in Adamawa in Northern Nigeria as a fish poison and which was formerly used to poison arrows. In local medicine the latex is appled to chronic wounds and ulcers or to carious teeth. Seven heterodises, honghelosides A – G, were isolated from the stem and roots. Hongheloside B is identical to digitalinum verum from Digitalis purpurea. Hongheloside G is identical with somalin. The plant acts as a cardiac poison in the same way as digitalin, but it also has an effect on the central nervous system, on the nerve mechanism of the heart and even on heart muscle. It does not appear to have been used pharmaceutically.[3]

Latex toxic, can damage the eyes, liable to cause severe diarrhoea. For treatment of wounds and persistent ulcers (psoriasis, against lice), tooth decay. Its latex is reputed to have magic properties (ordeal and exorcism). Roots Venereal disease. Latex – highly poisonous (cardiotoxic). Used especially for fishing or poisoned arrows.[4]

Risk Management

This plant is very popular amongst the Chinese community in Malaysia and those Bonsai enthusiast. There have not been any reported cases of poisoning by this plant so far. However, the attractive colour of the flowers and the configuration of the stem can attract the attention of curious children to the plant. This can pose a danger to toddlers with inquisitive mind who may go to the extent of ingesting the flowers or leaves. It is best not to have such plants when there are toddlers around the house and definitely not a good plant to grow in childcare centres.

Always wash your hands thoroughly if plants injuries have left sap or cell juices on your fingers. Do not rub your eyes while working with this plant.

Clinical Findings

Poisoning causes symptoms and signs similar to digitalis intoxication. There are no adequate documented human poisonings, and clinical descriptions are derived primarily from animal reports. Substantial ingestion may lead to toxicity. Poisoning would be expected to produce clinical findings typical of cardioactive steroids. Toxicity has a variable latent period that depends on the quantity ingested. Dysrrhythmias are usually expressed as sinus bradycardia, premature ventricular contractions, atrio-ventriocular conduction defects, or ventricular tachydysrhytmias. Hyperkalaemia, if present, may be an indicator of toxicity.[5]

Ingestion of plants containing cardioactive steroids may cause abdominal pain and induce vomiting, which serves both as an early sign of toxicity and a mechanism of limiting poisoning. Cardiovascular and electrocardiographic effects include sinus and junctional bradycardia as well as ventricular tachydysrrthmias, including ventricular tachycardia and ventricular fibrillation. Hyperkalaemia may develop and is associated with poor patient outcome. Serum digopxin concentration may be obtained and should not be relied upon to exclude toxicity and other cardioactive steroids will have unpredictable assay cross-reactivity. Consequently, treatment, if clinically indicated, should not await laboratory confirmation.[5]

Management

To conduct gastrointestinal decontamination as appropriate, serial electrocardiograms, and serum potassium determinations should be performed. If serious cardioactive steroid toxicity is considered, digoxin-specific Fab should be administered.[5]

Specific Therapeutics

Most of the available clinical experience with cardioactive steroid poisoning is related to digoxin toxicity. In these patients, standard supportive medical management is often adequate. Therefore, any patient with consequential digoxin poisoning should receive digoxin-specific Fab. This product contains the antigen-binding regions (Fab) of animal derived antidigoxin antibodies. Although specifically designed for the management of digoxin poisoning, digoxin-specific Fab appears to have sufficient cross-recognition of other cardioactive steroids to warrant its administration in other non-digoxin cardioactive steroid poisoning. The empiric dose in 10 vials (400mg) administered intravenously in both adults and children, with additional dosing based on clinical response or additional information. Indications for its use include significant bradycardia, tachydysrhytmias, or hyperkalaemia, with or without an elevated serum digoxin concsntration, in any patient seriously believed to be poisoned by a cardioactive steroid-containing plant.

References

  1. Gaby H. Schmelzer. Plant Resources of Tropical Africa: Medicinal Plants.  PROTA Foundation. Wageningen; 2008. p. 46.
  2. Peter Hanelt. Mansfeld’s Encyclopedia of Agriculture and Horticulture Crops. Springer-Verlag Berlin; 2001. p. 1745.
  3. Bep Oliver-Bever. Medicinal Plants in tropical West Africa. Press Syndicate of the University of Cambridge; 1986. p. 20.
  4. Michel Arbonnier. Trees, Shrubs and Lianas of West Africa Dry Zones. Technical Centre for Agricultural and Rural Cooperation Wageningen; 2002. p. 161.
  5. Lewis N, Richard DS, Michael JB, Kenneth FL. Handbook of Poisonous and Injurious Plants. New York: New York Botanical Garden; 2007. p. 24: 64–65.