Erun, ordealtree, Sasswood Tree

Erythrophleum suaveolens

Physical Characteristics

Erythrophleum suaveolens is an evergreen Tree growing to 20 m (65ft) by 15 m (49ft) at a slow rate. See above for USDA hardiness. It is hardy to UK zone 10. It can fix Nitrogen. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist soil.

Distribution

Tropical Africa - Sierra Leone to Sudan, south to DR Congo, Zimbabwe and Mozambique.

Habitats

Edible Uses

None known

Medicinal Uses

Anaesthetic Anthelmintic Cardiac Diuretic Emetic Purgative The bark is used as an emetic and purgative[ 299 ]. A diluted decoction of the roots is used as an anthelmintic, especially against tapeworm[ 299 ]. In the Western world, bark extracts were used in the late 19th century to treat heart failure. Side effects and better results with digitoxine ended this practice[ 299 ]. Used externally, the crushed bark is applied to swellings caused by Filaria[ 299 ]. The dried powdered bark is taken as a snuff to cure headache. A decoction of the roots and bark is applied to soothe general body pain[ 299 ]. Research has shown the presence of various medically active substances in the plant, especially alkaloids. The alkaloid content of bark ranges from 0.3% to 1.5%. This varies with the age of the tree: a water extract of the bark contained 0.5% and 0.9% respectively in 60 year- and 150 year-old trees[ 299 ]. The bark extract has excellent local anaesthetic activity on eyes and skin, although its use on the eye was disputed because of its irritant effect on the conjunctiva[ 299 ]. Trials using it as anaesthetic in operations or tooth extractions were less successful, as symptoms of poisoning appeared in higher doses[ 299 ]. The alkaloids have a stimulant effect on the heart similar to that of the cardenolides digitoxine (from Digitalis) and ouabain (from Strophanthus gratus), but the effect is very short-lasting, as the alkaloids are rapidly metabolized in the organism[ 299 ]. Apart from an increase of heart contraction in systole, the alkaloids also demonstrated an increase in diastole[ 299 ]. In addition, cassaine caused a violent state of excitation[ 299 ]. The alkaloids also have strong diuretic effects, and increase contractions of the intestine and uterus[ 299 ]. Norcassamidine has local anaesthetic action, and is a convulsant[ 299 ]. The bark further contains procyanidins (polyphenols) and hence has antioxidant properties[ 299 ]. The relaxant effect of the bark extract of Erythrophleum suaveolens is due to its procyanidins[ 299 ]. The bark also contains the trihydroxystilbene resveratrol. Resveratrol shows antiplatelet aggregation, coronary vasodilator, antileukaemic, antifungal and protein-tyrosine kinase inhibitory activities. Trihydroxystilbenes are thought to protect against atherosclerosis and coronary heart disease[ 299 ]. Resveratrol is, however, only registered as a food supplement, not as a medicine[ 299 ]. The bark contains the flavone luteolin that colours orange after addition of magnesium powder and a few drops of hydrochloric acid. This reaction allows it to be distinguished from the bark of Erythrophleum africanum, which colours violet after treatment because of the presence of 2,3-dihydroxymyricetin[ 299 ]. The main parts of the tree harvested for medicinal purposes are the roots and bark. Traditional herbalists use ad hoc techniques to excavate the roots and debark the stems. Virtually all trees are used, from young to old ones[ 299 ].

Known Hazards

The bark contains a range of alkaloids. In high doses, the bark extract is an extremely strong, rapid-acting cardiac poison, in warm-blooded animals causing shortness of breath, seizures and cardiac arrest in a few minutes[ 299 ]. Although the alkaloid content in the seeds is markedly lower than in the stem bark, the seeds are more toxic. This strong activity is due to a strong haemolytic saponin, which acts in a synergistic way to the alkaloids[ 299 ]. The bark has been used in arrow poisons and as ordeal poison and the bark and leaves as fish poison[ 299 ]. The sawdust may irritate mucous membranes and may cause allergy and asthma of labourers in sawmills[ 299 ].