Agriculture Reference
In-Depth Information
was excreted as the unchanged drug and the remaining as various metabolites. The elimination of
the drug administered orally followed different patterns. Only 11% of the given dose was excreted
with a half-life of elimination of 22 h. Eighty percent of the quantity consisted mainly of conjugated
K-strophanthoside and other metabolites; only 6% was excreted as the unchanged drug.
1003
Toxicity —
The strophanthins, including ouabain, are very potent drugs and therefore can
be extremely dangerous. Deaths due to strophanthin intoxication are uncommon.
511
Such deaths
are mainly due to overdosage or acute
Strophanthus
intolerance. In diabetic patients, it was found
that tolbutamide and carbutamide enhanced the toxicity of strophanthin and digitalis glycosides.
Glibenclamide, on the other hand, decreased the toxicity due to strophanthin in a dose-dependent
manner.
1004
It is therefore advisable to treat diabetics requiring cardiac glycoside therapy with gil-
benclamide instead of the other antidiabetic agents to avoid the enhancement of multifocal ectopic
beats or coupling due to premature ectopic ventricular beats during strophanthin therapy.
STRYCHNOS ICAJA
Botanical Name —
Strychnos icaja
Baill.
Synonyms —
Strychnos kipapa
Gilg.,
Strychnos dewevrei
Gilg.,
Strychnos pusilliflora
S. Moor.,
Strychnos mildbraedii
Gilg.,
Strychnos dundunsanensis
De Wild.,
Strychnos venulosa
Hutch.
Family —
Loganiaceae
African Names —
Hausa: k'ok'ihmo (
S. tricalysiods?
); Twi: pepere; Cameroon: mbondo, kpo,
mempandi, kpombondo; Zandi: mbenge; Ndebele: umhlati; Kiswahili: mwavi; Kitembo: kinyakabi
turumbu; Tschiluba: kampopi; Babua: benge; Kitalinga: bwende; Shona: matamba; Swati: umk-
wakwa; Ugwalla: dama, ghasambe, sambedale; Zulu: umkuhlu
Description —
Strychnos icaja
is a
medium-size liane, 20-100 m long, 4-15 cm in width,
with pale gray to dark brown bark, and often umbellately branched. The leaves are long, glabrous,
opposite, and petiolate; the petiole is 4-12 mm long, with the size of the leaves varying according
to access to light. The flowers are hermaphrodite, 4-merous, with pale green sepals, broadly ovate
to suborbicular, 0.4-1 mm wide; the corolla is greenish yellow-white. The fruits are basset, indehis-
cent, dark yellow, and globose.
1005
Habitat and Distribution —
The species is found in various vegetation zones of the continent,
including rain forest, secondary forest, swamp, and gallery forests. The plants have been reported in
an FAO monograph
33
as occurring in Sierra Leone, Liberia, Ivory Coast, Ghana, Nigeria, Cameroon,
Central African Republic, Rio Muni, Gabon, Congo, Zaire, and Angola.
Ethnomedicinal Uses —
The species is considered toxic and does not find wide applications as a
folk remedy but is usually administered under the supervision of a traditional medicine man. The main
use of the plant is in the treatment of skin diseases and chronic and persistent malaria. A cold infu-
sion of palm wine has been reported for treating painful gastrointestinal conditions and hernia.
1006,1007
Constituents —
It produces a mixture of closely related tertiary indole alkaloids based on the strych-
nine moiety. Strychnine itself and 12-hydroxystrychnine have been isolated from the leaves, stems, and
roots.
1003,1008
Dimeric tertiary alkaloids exemplified by bisnorhydrotoxiferine and sungucine have been
shown to occur in the roots.
1009
Also found in the roots are quaternary alkaloids such as
N-
strychninium.
1010
Pharmacological Studies —
Two distinct pharmacological activities have been associated with
alkaloids of
S. icaja.
The strychnine-type compounds exert convulsant action, whereas the bisindoles
have muscle relaxant properties. The activity of the extracts is therefore dependent on the method and
solvent of extraction. Kambu et al. have shown that it may be possible to prepare alkaloid extracts that
have either predominantly convulsant (strychnine-like) or muscle-relaxant properties.
1011
The authors
have shown that the quaternary alkaloidal fraction, which is more water soluble than the tertiary
alkaloidal fraction, has a pronounced muscle relaxant activity and strong cardiotonic action, with
negative chronotropic and inotropic effects ending in irreversible cardiac arrest.
