There are numerous
plants on the planet that have a long history of use in traditional
medicine. In fact, there are many societies in the world where
the predominant mode of maintenance of health and well-being
is through the administration of herbs and aliments to cure
disease conditions. There are a number of well-known examples
of drugs in current clinical use that had their beginnings
as natural products isolated from plant or microbial sources.
Examples include the antibiotic penicillin (isolated from
molds of the genus Penicillium), the anticancer drug taxol
(isolated from the Pacific Yew tree), and the analgesic acetyl
salicylic acid (or aspirin), a derivative of salicylic acid
isolated from the willow tree). In principle, there are two
general ways in which plants that may have biological activity
can be chosen for study. Plants can be randomly selected and
subjected to a series of biological assays to determine their
potential biological activity, or they can chosen based upon
a history of use against a particular ailment in a society
or culture. A disadvantage of the first approach is that selected
plants, although demonstrating efficacy in a particular biological
assay, may ultimately be found to be highly toxic. This issue
is, to a certain extent, circumvented in the second approach,
in that the toxicology of the herb is generally know. Put
simply, herbs that kill on ingestion are likely not used in
traditional medicine, and those that have a long and consistent
history of use against a particular ailment have a higher
probability of working (otherwise, there would be no continued
use).
We have launched a program to study natural
products derived from various plants and food crops that have
been used to treat disease in some cultures of the world.
Thus, plants that have a history of use in traditional medicine
are subjected to bioassays to determine the active component,
or combination of active components responsible for the manifested
therapeutic effects. Plants that we are examining in this
way include Croton lechleri which produces a red
sap known as known as ‘dragon’s blood’,
Uncaria tomentosa (also known as cat’s claw),
and beta vulgaris (table beets).
Dragons’ blood is a viscous tree sap
that is used extensively by the indigenous cultures of the
 Amazon
River basin for its remarkable haling properties. When applied
to the skin for abrasions, cuts scratches, blisters, bites
and stings, Dragon’s blood forms a long-standing barrier
possibly due to its ability to coprecipitate with proteins
or other matrix elements. In doing so it is claimed to foster
accelerated wound healing and does so with reduced pain, inflammation
and scarring. We have found in our work that Dragon’s
blood confers benefit by suppressing the activation of sensory
afferent nerve mechanisms, which supports its ethnomedical
use for disorders characterized by neurogenic inflammation.
Cat’s claw is a vine that grows in
the Peruvian Amazon and has been used in traditional medicine
to alleviate inflammation. Ethnomedically, the bark and root
of cat’s claw are the parts of the plant that are most
frequently used, and are prepared as an aqueous  extraction
in hot water. Several groups have reported a wide range of
chemical substituents in cat’s claw, although few studies
have demonstrated that administration of these isolated components
exerts consistent anti-inflammatory effects. Of the compounds
that have been isolated, the most well known are the oxindole
alkaloids. Based on in vitro experiments, it has been indicated
that oxindole alkaloids promote phagocytosis, leading to the
claim that cat’s claw has immunostimulant properties,
and also the ability to induce a lymphocyte-proliferation-regulating
factor in endothelial cells. However, these actions are difficult
to reconcile with the use of cat’s claw to treat chronic
inflammation. Hence, we have continued our efforts to evaluate
alternatives explanations for the mechanisms of action of
cat’s claw. In our own studies, we have found that cat’s
claw exhibits potent antioxidant and anti-inflammatory activity
that is independent of the oxindole content of the plant sample.
There is anecdotal evidence that components
of table beets may have anticancer activity. We have initiated
a bioassay guided fractionation study to determine if there
is scientific support for this.
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