Introduction and status
Astragalus membranaceus (Fisch) Bge. is a traditional Chinese medicine,
known as "huang-qi" in Chinese or its trade name
"Astragalus" in English. Traditionally it was used to treat fatigue
and strengthen "Qi" or vital energy. In the modern context it has
became an important phytomedicine in China and the subject of a very large
number of published research papers. It has become increasingly important in the
North American market in recent years.
Botany
The genus Astragulus belongs to the legume family (Fabaceae) and is
one of the largest genera of plants with over 1700 species. Astragalus of
commerce is non-toxic and should not be confused with native north American
species such as locoweed, A. mollissimus, which produces a dangerous
neurotoxin affecting cattle. Astragalus grows as a native plant in China from
the far north east province south to Shandong. It prefers successional habitats
and forest margins. It is now generally produced in cultivation for commercial
purposes and dug after one year of growth. The root has been traditionally
harvested in China at 4-5 years.
Uses:
Astragalus is used as an adaptogen, immunostimmulant and tonic. It is indicated
for treatment of infection, immune suppression, ischaemic heart disease and
general disability. It has a long history of use in traditional Chinese medicine
and in both China and Russia as an adaptogen.
Dosage:
Traditionally, the dosage is powdered dried root or decoction in the range of 10-30g/day.
Phytochemistry
Astragalus contains several characteristic triterpenoid saponins known as
Astragalosides which can be used for the identification and standardization of
the plant (Li and Fitzloff, 2001). The principle compound, astragaloside IV is
typically found at 0.15 mg/g. In addition it contains at least 6 isoflavonoids
(total 0.02% w/w) including the estrogenic flavonoid fromononetin. Cell wall
derived polysaccharides have been isolated from A. membranaceus var mongholicus
and designated as astragalans I-III.
Pharmacology and clinical research
Astragalus is an immunostimulant and enhances the activity of NK cells, and
increases phagocytotic activity. Both the polysaccharides and saponins may be
involved in the enhanced immune function. Astragalus treatment restored immune
function in a small study of cancer patients and significantly improved white
blood cell counts in larger trials with patients with leukopoenia. In animal
models, Astragalus decoctions improved learning performance in maze tests and
endurance models. There has been considerable research on the application of
Astragalus in treatment of viral diseases including hepatitis B, parainfluenza
and coxackie B2 virus where Astragalus treatments have had a protective effect
on the host cells. Clinical results in the viral area have had mixed outcomes.
Astragalus provided significant relief from angina compared to controls in a
trial with 92 patients suffering ischaemic heart disease.
Conclusion:
A very promising herb that would benefit from further rigorous examination in N.
America labs and clinics.
References:
- K. Bone and M. Morgan, 1999. Astragalus membranaceus, MediHerb #67, p.1-4
- S. Foster, 1998. Astragalus, a superior herb Herbs for Health Sept/Oct. P.
40-41.
- W. Li and J. Fitzloff, 2001. Determination of astragaloside IV in radix
astragali. J. Chromatogr. Sci. 39:459-62.
© 2002
J. Thor Arnason
U. of Ottawa
for Andy One
KeyHerbs.com
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