Agriculture Reference
In-Depth Information
Family —
Solanaceae
African Names —
Masai: ol asajet; Nyamwezi: kuvia; Sotho: bofepha, moferangopa, mosala-
marupi; Swati: vinhepi; Xhosa: ubuvuma; Zulu: umuvimba
Description —
It is an erect, much-branched undershrub, growing up to 2 m high with distinc-
tively hairy stems. The leaves are simple, about 10 cm long, elliptic to broadly ovate-lanceolate,
with entire or wavy margins. The flowers are small, about 1 cm long, greenish or yellow, occurring
in short axillary clusters. It produces red globose fruits, about 6 mm in diameter, enclosed in the
inflated and membranous calyx.
Habitat and Distribution —
It grows in the drier tropical regions. It is distributed from Liberia
to Nigeria and in South Africa and the southeastern islands.
Ethnomedicinal Uses —
In West African folk medicine, both roots and leaves are used inter-
nally, and the freshly pounded leaves (also used internally) are used against fever, chills, and rheu-
matism, among several other uses.
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In southern Africa, the Sotho use the plant as an anthelmintic
and as a ritual plant against witchcraft. The Zulu administer an enema of the decorticated root for
the treatment of hyperpyrexia in infants. The Xhosa and the Pedi use the plant to disinfect meat,
particularly if suspected to be infected with anthrax. A decoction of the root and leaf is used by the
Swati for the treatment of eruptive diseases such as smallpox.
79
The plant is reported to be used in
southern Africa in the treatment of asthma and bronchial diseases and syphilis and other venereal
infections, as a remedy for “blach gall-sickness,” and as a general antiseptic for wound dressing.
79
Constituents —
The plant contains alkaloids (e.g., withanine) and a distinctive group of phy-
tosteroids called withanolides. Withaferin A, isolated in 1965 by Lavie et al., is the prototype of this
group of chemotaxonomically important phytosteroids.
1150
Since then, a number of related withanolides
have been isolated, including some naturally occurring chlorinated derivatives.
1151,1152
The glycosylated
derivatives have also been isolated, for example, sitoinoside IX (withaferin A-C27-O
-
β
-
D
-
glucoside)
and sitoinoside X (6′-O
-
palmitoylwithferin-A-C27-O
-
β-D
-
glucoside), which occur in the root of sev-
eral varieties of
W. somnifera
.
1075
The plant also contains volatile oil, tannin, and fatty acids.
Pharmacological Studies —
In India, the plant is well known in folk medicine as a sedative, gen-
eral tonic, and antihypertensive agent.
1076
The withanolides possess different effects on the immune
systems. Withaferin A, for example, produced suppression of adjuvant-induced arthritis in rats and
locally induced graft- (lymphocytes) versus-host reactions in chicks,
1077
as well as depletion of murine
splenic cells
in vitro
in the presence or absence of mitogenic stimulant.
1078
Similar immunostimulant
activities have been reported for other structurally related withanolides.
1079,1080
Aqueous extract of the roots of
W. somnifera
has, however, been reported to have an immuno-
stimulatory effect;
1081
this report appears contradictory to the published immunodepressant effect
cited previously. The likely explanation is that the drug, which is employed as an adaptogenic agent,
possesses components with both stimulatory and depressant action on the immune system. The
aqueous suspension of the root has been shown to abolish the neutropenia induced by a single
dose of cyclophosphamide (200 mg/kg s.c.), and in neutropenic mice infected with
Staphylococcus
aureus,
pretreatment with
W. somnifera
reduced the mortality due to sepsis from 75% in the control
group to 50%. The treated animals developed significant leukocytosis and neutrophilia and dem-
onstrated significant inhibition of leukopenia and neutropenia due to cyclophosphamide-induced
myelosuppression. The extract was found to be effective as an immunostimulant in surgically
induced immunosuppression in mice.
Ghosal et al. reported the isolation of two withanolide glycosides, sitoinosides IX and X, as the
constituents responsible for the immunostimulant activity of the plant.
1081
At a dose of 100-400 µg/
mouse, the two compounds produced statistically significant mobilization and activation of perito-
neal macrophages, phagocytosis, and increased activity of lysosomal enzymes secreted by the acti-
vated macrophages. The two compounds at a dose of 50-200 mg/kg p.o. also produced significant
antistress activity in albino mice and rats and augmented learning acquisition and memory retention
in both young and old rats.
1081