Astragalus species

El-Sebakhy, N.A.A. et al., Antimicrobial isoflavans from Astragalus species. Phytochemistry, 36, 1387, 1994. 

Table 2. Astragalus species studied for their cycloartane and oleanane saponins... 

Astragalus genus is one of the richest source of cycloartane saponins. Oleanane type saponins are also found in Astragalus sp., but their occurrence is limited to structures common to Leguminosae. Fig (3) shows the naturally occurring cycloartanes and oleananes which have been isolated from different Astragalus species. 

No rational and corrected review on the so far described Astragalus saponins is presently available. Recently, a paper describing the pharmacological properties of Astragalus species has been published [20]. It reports an overview of the biological properties of the different metabolites present in the genus. 

The medicinal properties of Astragalus species are also described in the Chinese Pharmacopoeia [7], Astragalus species are used in Chinese... 

Table 3. Cycloartane saponins found in Astragalus species... 

Astragalus species are reported to tolerate very high concentrations of V which they utilise in nitrogen fixation (Cannon, 1963). Tolerance of high amounts of V in plants is due to immobilisation of the element as an insoluble product in the root, partial exclusion mechanisms also preventing uptake of the element from enriched soils (Peterson and Girling, 1981). 

Thus, there are two main groups of Astragalus species that are closely related to health the toxic species and the medicinal plants. 

Astragalus plants are cultivated and also selected from wdld stock. Cultivated varieties are mostly selected from A. membranaceus for medical use and cultivated in China, but the limited supply of the important Astragalus species is a nearly insurmoimtable problem connected with production of natural compounds, especially for their clinical evaluation. Development of an alternative production method using cell or tissue cultures might be one solution to overcome this problem and perhaps keep the high quality of the products [131]. 

Coumarins have been isolated and characterized in many Astragalus species the main identified compounds are umbelliferone and scopoletin, as simple coumarins, and skimmin and scopolin, as their glycosides, respectively. Table (7). 

A new HPLC method permitted the separation of 13 triterpene glycosides isolated from different Astragalus species within 40 min. A water/acetonitrile gradient was used as eluent, RP-18 was used as stationary phase, and evaporative light scattering detection was used. The method facilitated differentiation of different Astragalus species. 

Gum tragacanth Astragalus species (Middle East) Thickener stabilizer... 

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