Agriculture Reference
In-Depth Information
sense reticulate venation more prominent below than above. It has solitary inflorescence, with axil-
lary, dichasial, or monochasial cymes, 0.5-2.3 cm long; whitish puberulous; peticels 2-5 mm long,
articulated in the lower half. The flowers are whitish, usually cream colored, 3-25 per cyme, about
2.5 mm in diameter; the petals are oblong, with margins ciliolate to more or less entire. The sepals
are lanceolate to triangular, 0.5-1.25 mm long, apex acute to subacute, margins ciliolate. It produces
long, pale green to reddish fruits enclosing 2-3 shiny red seeds partly embedded in fleshy white or
pale yellow aril.
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Habitat and Distribution —
It is a native to the well-watered savanna regions of the continent.
It is a light-demanding tree of open lowland, riverine forests, and forest margins. It occurs on a
wide range of soils, including sandy, larval, and limestone soils; acid soils are preferred. The plant
is distributed mainly in southeast Africa, including Kenya, Tanzania, Zimbabwe, and Ethiopia. The
species also grows in Nigeria, Ghana, Cameroon, Gabon, Fernando Po, Central African Republic,
Rwanda, Burundi, South Sudan, Uganda, Malawi, Mozambique, and Zambia.
Ethnomedicinal Uses —
The powdered bark is reputed as a Moshi remedy for wounds, ulcers,
and boils. In Togo, a leaf decoction was used for the treatment of mouth infections and wounds
and is still used in folk medicine in West Africa as a mouthwash for mouth ulcers and toothache.
The related species,
M. senegalensis
(Lam.) Excell (the confetti tree), is also used in traditional
medicine; the chipped roots are added to beer and used in Zambia as an aphrodisiac.
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The roots,
which are slightly bitter, are also mildly laxative and are used in various parts of tropical Africa for
gastrointestinal troubles, especially dysentery,
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and a poultice of the green leaves has been used to
dress sores in Tanzania.
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Constituents —
The plant contains the antileukemic ansa macrolides maytansine, originally
isolated from
M. seratta
collected from Ethiopia,
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and maytanbutine.
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The genus also yields
the spermidine alkaloids celacinnine and cellallocinine
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and the nicotinoyl sesquiterpene alka-
loids maytoline and maytolidine, catechin, PACs, and phenoldienone triterpenes.
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Pharmacological Studies —
The main pharmacological activity of this genus is its remarkable
antitumor activity. The compound has been extensively studied as a part of the drug development
program of the Division of Cancer Treatment, National Institutes of Health, Bethesda, Maryland.
The ansa macrolides have shown significant activity against various animal tumors, including B-16
melanoma, lymphatic lymphoma, and carcinosarcoma. Cytotoxic activity appears to be caused
by inhibition of the proper formation of the mitotic spindle and thus cessation of cell division.
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Various side effects were observed in the phase I human studies, including gastrointestinal, hepatic,
and neurological disorders. Adverse reactions such as nausea, vomiting, diarrhea, and lethargy have
been reported as being dose limiting.
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Reviews containing reports of the development of maytan-
sine are available.
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MERREMIA ANGUSTIFOLIA
Botanical Name —
Merremia angustifolia
Hall. f.
Synonyms —
Convolvulus oligodontus
Baker.,
Ipomoea angustifolia
Jacq.,
Xenostegia triden-
tata
(L.) D.F. Austin & Staples
Family —
Convolvulaceae
African Names —
Hausa: yimbururu; Yoruba: atewegbore, abiarunum
Description —
This is a prostrate or climbing herb. It has narrow leaves, alternately arranged
on the stem, about 3 cm long, pointed, almost lanceolate and lobed at the base. The stalks are very
short. The flowers are yellow in color, funnel like, and about 8 mm long, with 5 persistent sepals
and a corolla with 5 lobes. The 5 stamens are attached to the base of the corolla tube. It yields small
rounded fruits.
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