Agriculture Reference
In-Depth Information
porcine coronary artery rings. The vasorelaxant activity was dependent on their phenolic content
and appears to involve mainly PACs. This finding provides a probable mechanism for the antihyper-
tensive activity of
P. biglobosa
leaves.
846
Commerce —
The fermented seeds of African locust bean, known as
soumbala
,
dawa dawa
,
netetu
,
ogiri
,
iru
,
afitin,
, and
nététou
, serve primarily as a condiment for seasoning sauces and soups.
Roasted seeds are used as a coffee substitute known as “Sudan coffee” or “café nègre.” The extract
of the stem bark is used in the preparation of a preventive medicine for cattle known as “cure salee.”
The African locust bean is therefore highly valued in Africa, and it is an article of trade in many
parts of the continent.
PAUSINYSTALIA YOHIMBA
Botanical Name —
Pausinystalia johimba
(K.Schum.) Pierre ex Beille
Synonyms —
Corynanthe yohimba
K.Schum.,
Pausinystalia trillesii
Beille,
Pausinystalia
zenkeri
W. B r a n d t
Family —
Rubiaceae
Common Names —
Johimbe, yohimba
African Names —
Yoruba (Nigeria): idagbon; Duala (Cameroon): djombe-wa
Description —
Yohimba is an evergreen, medium-size tree and grows up to 30(-35) m tall; the
bole is straight, up to 50(-60) cm in diameter, without buttresses but grooved at the base; the bark is
easy to peel off and bitter tasting; the bark surface is longitudinally fissured, with transverse cracks,
gray to reddish brown; inner bark is fibrous, pinkish and turns reddish brown on exposure; the crown
is compact, with branches in whorls. Leaves appear in whorls of 3 and are simple; stipules are 1.5-2
cm long, glabrous, and caducous; the petiole is up to 5(-8) mm long; the blade is obovate or oblan-
ceolate, (11-)13-47 × 5-17.5(-19) cm; the base is cordate, cuneate, or rounded; the apex is short-
acuminate; and the margin is often wavy, glabrous, pinnately veined with (8-)10-20 pairs of lateral
veins. Inflorescence is a terminal or axillary panicle 5-21(-30) × 9-15 cm, branched in whorls of 3,
with flowers in clusters at the ends of branches; the main axes are glabrous; the peduncle is 0.5-5
cm long with 3 ridges. Flowers are bisexual, regular, and fragrant; the calyx consists of a short tube
and triangular or rounded lobes.
Pausinystalia johimbe
can be distinguished from
Pausinystalia
macroceras
by its larger leaves with shorter or no petioles. In addition, the bark of
Pausinystalia
johimbe
is extremely bitter tasting and is easy to peel off, whereas that of
Pausinystalia macroceras
is less bitter and difficult to peel off.
1140
Habitat and Distribution —
Pausinystalia
comprises 5 species and occurs in West and Central
Africa.
P. johimbe
occurs in evergreen lowland forest, in primary as well as secondary forest, and
at relatively low densities. It is common in southern Nigeria, Cameroon, Gabon, and Central Africa
Republic.
Ethnomedicinal Uses —
Yohimbe tree has a reputation as a potent aphrodisiac and for the
treatment of male erectile dysfunction. The bark is sold in markets throughout West and Central
Africa for the preparation of a general tonic. It has also been used as a local anesthetic, as a hal-
lucinogen, for the treatment of angina, against constipation and intestinal worms, as a performance
enhancer for athletes, and to increase the clarity of singers' voices. In Congo, a bark decoction is
drunk for the treatment of pelvic pain and for body pain.
Pharmacological Studies —
More than 40 alkaloids have been isolated from
Pausinystalia
johimbe,
including the indole alkaloids yohimbine (10-15%), mesoyohimbine, yohimbinine,
corynanthine, alloyohimbine, and ajamalicine. Yohimbine (also known as aphrodine, quebrachine,
or corynine) is a selective inhibitor of α-2-adrenergenic receptors. It has hypertensive activity at
low doses but is hypotensive at high doses, through vasodilation of peripheral vessels. Yohimbine
raises the heart rate and norepinephrine levels. The use of yohimbine as an aphrodisiac is attributed
