Akokantera -Acocanthera abyssinica (Hchst.) K. Schum. and other African species of Acocantbera
A. abyssinica is a plant widely distributed in East tropical Africa. The Africans used the bark and wood to produce arrow poison.
Shrub or small tree. The leaves are opposite, thick, leathery, glabrous, shiny, elliptical with a pointed apex, entire, 5-7 cm long, 2-4 cm wide. The flowers are collected in dense whorls (dichasia) in the axils of the leaves. Calyx short, 5-parted, green; corolla white, sometimes pink, tubular, with a wide 5-lobed wheel-shaped limb with 5 small scales in the pharynx; stamens 5; ovary superior, bilocular. The fruit is a dark blue globular berry within 2 cm in diameter, traditionally with one seed (the second nest traditionally does not develop).
It contains ouabain (G-strophantidine) in trunks, branches and roots. Other related species are also rich in this glycoside: Acocanthera coubaio Cath. – ouabayo, tree or large shrub, grows throughout the mountain slopes in East Africa and Somalia, A. schimperi (A. DC.) Schwf. – in East tropical Africa, A. deflersii Schweinf. – in Eritrea in Yemen, A. venenota G. Don. — in South Africa.
In other species, cardiac glycosides of a similar structure were found. For example, Acocanthera longipolia St. – is a shrub, ubiquitous in Tropical Africa, contains a glycoside – acovenoside A and amorphous acolongifloroside K, as well as other little-studied glycosides.
Several poisonous tropical trees and shrubs containing cardiac glycosides belong to the family Arosupaseae, subfamily Plumierioideae, which are studied or studied as promising cardenoylides.
Cerbera odallam Gaerth – odallam. The tree grows along the seashores and is found on about. Madagascar, in India, in the South Asian Islands and in Northwestern Australia. Contains poisonous milky juice, which has a powerful laxative effect. Poisonous and seeds from which the cardiac glycosides cerebrin and odallin are isolated. Cerebrin is located in the seed nucleus, it is cleaved during hydrolysis into the sugar cerebrose and the aglycone cerebrigenin, which is identical to digitoxygenin. Fatty seed oil (up to 40%) has a strong laxative effect.
Tanghinia venenifera Poir. (Cerbera tanghin Hook, f.) – tanginia. A tree that grows only on about. Madagascar. The plant is very poisonous, its leaves and branches contain poisonous green milky juice. Even more poisonous are the seeds from which the glycoside tanginin, which is considered an isomer of cerebrin, has been isolated.
Thevetia neriifolia Juss. – tevetia. It grows wild in the Antilles, cultivated in places in India. The glycoside peruvozide was isolated from the seeds and leaves. Its aglycone cannogenin is associated with α-tevetose. It is similar in structure to adontoxigenin.
A tree growing in northern South America and the Antilles. Contains milky juice, from which the Indians make the poison “vurara”. Glycosides of the cardiac group — urechitin and urechitoxin — have been isolated.
Shrub growing in Upper Senegal (West Africa). The active substance was isolated from the inflorescence in the form of a yellow amorphous powder, and two glycosides were isolated from the stems: gongeloside B and gongeloside C, which have a cardiotonic effect.
The plant contains cardenolides.
PLANTS CONTAINING CARDIAC GLYCOsideS
For centuries, plant products containing cardiac glycosides have remained unchanged. They provide a selective therapeutic effect in heart failure. These plants are known to the peoples of different countries. The ancient Egyptians and Romans used squill as a heart and diuretic. The ancient Greeks used jaundice. Many plants containing cardiac glycosides have been used by the African people since time immemorial to make arrow poison. in Europe since the 18th century. foxglove began to be used.
The therapeutic effect of cardiac glycosides is due mainly to their aglycones (genins). The sugars that make up the glycoside molecule affect the solubility, permeability through cell membranes, the ability to bind to blood and tissue proteins; being inactive, they affect the activity and toxicity of glycoside molecules in general.
Aglycones of cardiac glycosides are derivatives of cyclopentanoperhydrophenanthrene, having at C 17 substitutes: an unsaturated five-membered lactone ring – the cardenolide type or an unsaturated six-membered lactone ring – the bufadienolide type.
The whole variety of aglycones, and hence their properties, is due to the specific features of the substituents. So, for example, a substituent at C 19 can be of different oxidation states – groups CH 3 OCH, CH 2 OH. In addition to a constant hydroxyl at C 3 (here esterification with sugars occurs) and almost constant at C 14 , hydroxyls can be C 5 and C 16 . Even greater differences in the structure are introduced by the number (up to 30) and the diversity of monosaccharides, among which most are specific for cardiac glycosides. According to the number of monosaccharides attached to genin at C 3 , bi-, trio- and tetrazides are distinguished.