Cycloartane from Astragalus

Fig. (3). Tetranor-cycloartane and oleanane triterpenoids isolated from Astragalus sp.

Astragaloside II, a cycloartane triterpene oligoglycoside from Astragalus spinosus afforded close to 100% protection of T lymphocytes in vitro against cytopathic effects of HIV infection. The EC50of c.a. 2.5. 10 5 molar was difficult to achieve in vivo [148]. 

Among cycloartane glycosides from Astragalus Turkish species, only astragaloside I (88) was able to stimulate NF-kB expression in macrophages. This implies that they are critical structural features responsible for macrophage activation by saponins [71]. 

Gan LX, Han XB, Chen YQ (1986a) Astrasieversianins IX, XI and XV, cycloartane derived saponins from Astragalus sieversianus. Phytochemistiy 25(6) 1437-1441... 

Taxonomy Cycloartane Triterpenoids Astragalus orbiculatus Ledeb. (Leguminosae) [1-3]. Mp 256-258°C (from MeOH). 

Taxonomy Cycloartane Glycosides Astragalus alopecurus Pall. (Leguminosae) [1]. Astragalus ephemerotorum Gontsch. Leguminosae) [2]. Mp 253-254°C (from MeOH), [a]o -26.3° (c 0.53, MeOH). 

Taxonomy Cycloartane Glycosides Astragalus unifoliolatus Bunge Leguminosae) [1]. Mp 192-195°C (from MeOH). 

Taxonomy Cycloartane Glycosides Astragalus tragacantha Habl. (Leguminosae) [1]. Mp 240-242°C (from CHCla-MeOH, 1 1), [aJo 30.6° (c 1.11, MeOH). 

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. 

Astragaloside II, a cycloartane triterpene glycoside isolated from the Egyptian Astragalus spinosus, was tested at minimum of five concentrations 10-fold dilution against a total of 60 human tumor cell lines derived from seven cancer types (lung, colon, melanoma, renal, ovarian, brain and leukemia). The results indicated that the colon cancer (SW-620) and the leukemias (CCRF-CEM, HL-60) were the most sensitive cell lines [98]... 

Cycloartane saponins seemingly contribute to the immunomodulatory properties of Astragalus, in fact, curculigosaponin G from Curculigo orchioides was reported to significantly promote the proliferation of spleen lymphocytes in mice compared to controls, without a marked influence on antibody formation [167]. 

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