Agriculture Reference
In-Depth Information
arranged on the stem; they are roughly heart shaped, pointed at the apex and rounded at the base.
They have toothed margins, with two main veins arising from the midrib. The plant bears fruits
having angular achenes with five narrow and pointed bristles.
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Habitat and Distribution —
It is a deciduous forest plant that occurs in western and eastern
regions of the continent.
Ethnomedicinal Uses —
Ageratum
is used in folk medicine for the treatment of various dis-
eases,
77
especially for the treatment of wounds and burns.
78
It has been dispensed as an emetic, for
treatment of fevers, and externally in lotions for scabies and in eyedrops for inflammations.77
77
For
wound healing, the juice of the bruised leaves is squeezed into the wound and covered by a bruised
but intact leaf.
78
The root decoction or weak infusion of the whole herb is used by the Chagga as a
general remedy for abdominal discomfort and pain. The plant is used in East Africa for the treat-
ment of syphilitic sores; for this purpose, it has been reported that the root is placed in a small
shell, and an adolescent boy, who must be wearing a copper armlet, urinates into it; then, the fluid
is rubbed over a stone, and the slimy mess is applied to the sore with a cock's feather.
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Constituents —
The plant yields essential oil (about 0.16%), of which ageratochromone is the
principal constituent.
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The oil from the leaves also contains 6-dimethoxyagertochromone, phenols,
phenolic esters, coumarin, and traces of eugenol.
80,81
Other constituents of the plant include the
flavonoid conyzorigun, dotriaconthene, 7-methoxy-22-dimethylchromene, and 5,6,7,8,3′,4′5′-hepta-
methoxyflavone.80,82
80,82
An isoflavone glycoside, 5,7,2′,4′-tetrahydroxy-6, 3′-di-(3,3-dimethylallyl)-iso-
flavone 5-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranoside 1, has been isolated from the
stems of
Ageratum conyzoides
.
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Pharmacological Studies —
The plant has broad-spectrum antimicrobial activity.
84
Ageratum
extract has been found effective against
Helicobacter pylori
, a Gram-negative microaerophilic bac-
terium that is a major etiological agent in duodenal, peptic, and gastric ulcers.
85
It has proved useful
in treating wounds, but the activity does not appear to be due to direct antibacterial activity as the
extract has been shown not to be active against microbes isolated from wounds.
86
The incorpora-
tion of
Ageratum
extract in the preparation of traditional West African black soap did not show any
significant effect on the antimicrobial activities exhibited by the various soaps against the bacterial
and fungal organisms tested.
87
The extract also showed
in vitro
anthelmintic activity.
80
The extract
has been evaluated against human lung cancer cell lines (SK-LU 1 and SK-MES1) and the human
skin fibroblast cell line (FS5 cells), with encouraging results.
88
Ageratum
has been used in the management of Alzheimer's disease (AD), a neurodegenerative
disease of the CNS that leads to dementia and behavioral and cognitive impairments. To evalu-
ate the herb as a possible treatment for the preliminary symptoms of AD, the effect of
Ageratum
conyzoides
on learning and memory has been investigated in mice.
Ageratum conyzoides
(250,
500, and 750 mg/kg p.o.) produced a dose-dependent improvement in the memory of young and
aged mice. Furthermore, it also reversed the amnesia induced by scopolamine (0.4 mg/kg i.p.)
and natural aging. It also produced a profound reduction in the whole-brain acetylcholinestrease
act ivit y.
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The dichloromethane extract from the aerial parts of
Ageratum conyzoides
was found to
exhibit broad-spectrum antiprotozoan activity, with pronounced activity (IC
50
= 0.78 µg/mL) against
bloodstream forms of
Trypanosoma brucei
rhodesiense
, the etiologic agent of East African human
trypanosomiasis (East African sleeping sickness). The extract also exhibited noticable activities
against
Leishmania donovani
(kala azar, IC
50
= 3.4 µg/mL) as well as
Plasmodium falciparum
(malaria tropica, IC
50
= 8.0 µg/mL). Five highly methoxylated flavonoids along with the chromene
derivative encecalol methyl ether were isolated. All the isolated compounds did not give the antipro-
tozoan activity found in the dichloromethane extract, which is indicative of the fact that none of the
known isolates from
Ageratum
is responsible for its activity.
90
Of immense therapeutic importance
is the finding that an aqueous extract of
A. conyzoides
has the ability to potentiate the antimalarial
activity of chloroquine and artesunate against induced plasmodiasis in mice.
91
If clinical evalua-
