Agriculture Reference
In-Depth Information
medicinal extract. In summary, scientific studies revealed that
H. procumbens
exhibits analgesic,
antioxidant, antidiabetic, antiepileptic, antimicrobial, and antimalarial activities.
636
Iridoid glyco-
sides and phenylpropanoid glycosides have been the focus of phytochemical investigations as the
biological activity has been ascribed to the iridoid glycosides (such as harpagoside and harpagide),
which are common in nature and are known to possess anti-inflammatory activity. It has been
shown, however, that the hydrolyzed products of harpagoside and harpagide have more pronounced
anti-inflammatory activity when compared to the unhydrolyzed compounds.
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Clinical Applications —
Harpagophytum
extracts have been used by Africans for a long time
in the treatment of rheumatic diseases and gastrointestinal disorders. It was introduced into Europe
as an herbal tea for the same purpose by a German farmer, G. H. Mehnert. Grapple plant tea is indi-
cated in the treatment rheumatic diseases, especially arthritis and low back pain due to spondylosis.
Good results have been reported in the use of the drug for the treatment of rheumatoid arthritis,
neuralgia, and headaches. The drug has also been found effective in the treatment of diseases of the
upper duodenum with pancreatic involvement, as well as for improvement of enterohepatic circula-
tion and bile acid activation.
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Clinical evaluation of patients with hypercholesterolemia indicated
a marked reduction in blood cholesterol and neutral fatty levels. The drug was therefore found to
be beneficial for the treatment of elderly patients with rheumatic complaints, obesity, and hyperlip-
idemia. The plant is available in Europe as medicinal teas for oral administration, in ampoules for
parenteral medication, and as an ointment for external use.
The effects of the crude methanol extract, harpagoside, and harpogide on some smooth muscles
in vitro
have been studied by Occhiuta et al.
637
It was suggested that harpagoside and other constitu-
ents interfere with the mechanism that regulates the influx of calcium in the cells. In Langendorff
preparations of rat heart, hyperkinetic ventricular arrhythmias (HVAs) induced by an ischemic per-
fusion were prevented by extract of
H. procumbens
and harpagoside in a dose-dependent manner.
638
The major problem with the use of
Harpagophytum
is that of availability, and many of the
products currently marketed in Europe are derived from
Scrophularia nodose
and
Verbascum thap-
siforme,
which are said to contain the iridoids harpagoside and harpagide. It should be noted that
the activity of the grapple plant has not been specifically linked to any of its constituents. The use of
the so-called active constituents must be considered with caution. It has been reported that when the
constituents deemed to be the biologically active compounds were isolated, the efficacy was lower
than that of the whole extract. This means that it is likely that the whole plant is necessary, and all
the constituents may be working in synergy to exert the observed pharmacological effects.
Toxicity and Contraindication —
Harpagophytum
is reported to have some oxytocic proper-
ties and should not be taken during pregnancy.
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HELIOTROPIUM INDICUM
Botanical Name —
Heliotropium indicum
L.
Synonyms —
Eliopia riparia
Raf.,
Tiaridium indicum
(L.) Lehm.
Common Names —
Indian heliotrope, turnsole, Cock's comb
Family —
Boraginaceae
African Names —
Hausa: kalkaashin korama; Yoruba: agogo-igun
Description —
It has a characteristic long terminal, brush-like inflorescence of stalkless, whit-
ish flowers. It is a small herb, about 1 m long. The leaves are oval in shape, about 10 cm long and
7 cm wide, shortly pointed at the apex and rounded or very slightly wedge shaped at the base. The
leaf surface is raised between the veins, with saw-edged margins. The fruits consists of two cells,
about 8 mm in diameter.
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Ethnomedicinal Uses —
The plant is a major ingredient for the preparation of
agbo
, a Yoruba
traditional remedy. It is employed as an alcoholic extract for the treatment of venereal diseases. In
