Agriculture Reference
In-Depth Information
to its dilating effect on the blood vessels of the sexual organs, thus increasing blood supply, while
it also provides an enhancement of the reflexes involved in the control of ejaculation. 1140 Tests have
shown that treatment with yohimbine indeed results in increased libido and easier ejaculation. The
effects of yohimbine on smooth muscles favor tonus and movement of the intestine. It also acts on
α-2-adrenergenic receptors of adipocytes, resulting in increased lipolysis. However, double-blind
trials on the effectiveness of yohimbine for body weight reduction gave conflicting results, and it is
therefore unclear whether yohimbine is effective in reducing body weight.
In normal volunteers, the sympathetic effect of yohimbine occurred at doses of 45 mg or higher,
between 60 to 90 min after oral administration, lasting on average 4 to 5 h. Similar effects can be
achieved at a very low dose (5.4 mg) in patients with autonomic failure given their denervation
hypersensitivity. 847
Toxicity — The crude yohimbe plant is relatively tolerated at the dosage used in traditional
medicine and the over 50 over-the-counter products that contain bark of Pausinystalia johimbe. The
main active compound, yohimbine, has shown a wide range of adverse effects, including hyperten-
sion, mania, bronchospasm, anxiety, agitation, hallucinations, vertigo, stomach problems, headache,
and weakness. It may also interact with other prescription drugs, including antidepressants, antihy-
pertensives, and cardiac drugs. People with hypertension, prostate problems, or heart diseases are
warned against using yohimbine-based products. Another major compound found in the yohimbe
plant, ajamalicine, also has vasodilating activity. Corynanthine closely resembles yohimbine, but
is more active as a sympatholytic agent and less toxic. 1140 In acute and chronic (long-term) studies,
yohimbine has been found to be relatively free of side effects over the dose range predicted to be
effective in erectile dysfunction. At much higher doses, the most frequently observed effects, con-
sistent with the primary pharmacological action of the drug, are elevation of blood pressure, a slight
anxiogenic action, and increased frequency of urination. These side effects are all easily reversible
on termination of yohimbine therapy. 848,849
Agriculture — The yohimbe tree has not been cultivated to any significant extent in West and
Central Africa. Overharvesting due to increased international demand has put the plant under great
stress. Various experimental cultivations have been undertaken in Nigeria and Cameroon. It has been
shown that P. johimbe is amenable to vegetative propagation through the rooting of leafy stem cuttings
using low-cost technology polythene propagators. 850 Using single-mode leafy cuttings, three experi-
ments were investigated in Cameroon, the first with three propagation media (sawdust, 50:50 mixtures
of sand and sawdust, and sand alone). Initial observation showed that rooting was best in the mixed
medium, but subsequently, cuttings set in the sawdust rooted better than those in sand and the mixture
of sand/sawdust. However, there was no significant ( p > 0:05) treatment effect on rooting percentage
or on the mean number of roots per cutting. Second, three types of auxin at 50 mg per cutting (IAA,
indole-3-acetic acid; IBA, indole-3-butyric acid; and NAA, 1-naphthalene acetic acid) were dissolved
in 10 ml of alcohol. The control treatment received 10 ml of alcohol only. Significant differences
in rooting percentage occurred after 3-4 weeks between the auxin-treated cuttings and the control.
Within the same period, IBA-treated cuttings rooted better than those with NAA and IBA. The third
experiment involved four leaf areas: 0, 50, 100, and 200 cm 2 . Leafy cuttings rooted better than leafless
cuttings after 4-5 weeks, with the 50-cm 2 leaf area the best from week 6. Significantly higher cutting
mortality ( p < 0:05) occurred for leafless cuttings than for leafy cuttings. 850
PHASEOLUS VULGARIS
Botanical Name — Phaseolus vulgaris L.
Synonyms — P. communis Pritzel., P. compessus DC.
Family — Leguminosae
Common Names — Bean, kidney bean, navy bean, French bean, haricot (Fr.)
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